View Filing Data

Print Document View Excel Document

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2017	May 02, 2017
Document and Entity Information
Entity Registrant Name	TC PIPELINES LP
Entity Central Index Key	0001075607
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		68,938,577
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Transmission revenues	$ 89	$ 86
Equity earnings (Note 4)	43	42
Operation and maintenance expenses	(12)	(10)
Property taxes	(5)	(5)
General and administrative	(2)	(2)
Depreciation	(22)	(21)
Financial charges and other (Note 13)	(16)	(17)
Net income	75	73
Net income (loss) attributable to controlling interest allocation
General Partner	3	2
Net income	75	73
Common units
Net income (loss) attributable to controlling interest allocation
Limited partners	$ 72	$ 71
Net income (loss) per common unit (Note 7) - basic (in dollars per unit)	$ 1.05	$ 1.10
Net income (loss) per common unit (Note 7) - diluted (in dollars per unit)	$ 1.05	$ 1.10
Weighted average common units outstanding - basic (in units)	68.3	64.4
Weighted average common units outstanding - diluted (in units)	68.3	64.4
Common units outstanding, end of year (in units)	68.6	64.7

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 75	$ 73
Other comprehensive income
Change in fair value of cash flow hedges (Note 11)	1	(2)
Comprehensive income	$ 76	$ 71

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 60	$ 50
Accounts receivable and other (Note 12)	34	37
Distribution receivable from affiliate (Note 10)	2	3
Inventories	7	7
Other	4	5
Total current assets	107	102
Equity investments (Note 4)	1,062	1,044
Plant, property and equipment (Net of $914 accumulated depreciation; 2016- $892)	1,866	1,881
Goodwill	130	130
Other assets	1	1
Total assets	3,166	3,158
Current Liabilities
Accounts payable and accrued liabilities	24	27
Accounts payable to affiliates (Note 10)	6	7
Accrued interest	13	9
Current portion of long-term debt (Note 5)	23	23
Total current liabilities	66	66
Long-term debt, net (Note 5)	1,786	1,835
Other liabilities	28	28
Total liabilities	1,880	1,929
Common units subject to rescission (Note 6)	64	83
Partners' Equity
General partner	28	27
Accumulated other comprehensive loss	1
Controlling interests	1,222	1,146
Total liabilities and partners' equity	3,166	3,158
Common units
Partners' Equity
Limited partner	1,098	1,002
Class B units
Partners' Equity
Limited partner	$ 95	$ 117

CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
CONSOLIDATED BALANCE SHEETS
Accumulated depreciation	$ 914	$ 892

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash Generated From Operations
Net income	$ 75	$ 73
Depreciation	22	21
Amortization of debt issue costs reported as interest expense		1
Equity earnings from equity investments (Note 3 and 4)	(43)	(42)
Distributions received from operating activities of equity investments (Note 3)	31	41
Change in operating working capital (Note 9)	5	6
Total cash generated from operations	90	100
Investing Activities
Capital expenditures	(7)	(11)
Total investing activities	(11)	(208)
Financing Activities
Common unit issuance, net (Note 6)	71
Common unit issuance subject to rescission, net (Note 6)		19
Long-term debt issued, net of discount (Note 5)		195
Long-term debt repaid (Note 5)	(50)	(25)
Total financing activities	(69)	117
Increase/(decrease) in cash and cash equivalents	10	9
Cash and cash equivalents, beginning of year	50	39
Cash and cash equivalents, end of year	60	48
Class B units
Financing Activities
Distributions paid (Note 6)	(22)	(12)
Common units and General Partner interest combined
Financing Activities
Distributions paid (Note 8)	(68)	(60)
Great Lakes
Cash Generated From Operations
Equity earnings from equity investments (Note 3 and 4)	(17)	(15)
Investing Activities
Investment/Acquisition of interests	(4)	(4)
Portland Natural Gas Transmission System
Cash Generated From Operations
Equity earnings from equity investments (Note 3 and 4)	$ (7)	(9)
Investing Activities
Investment/Acquisition of interests		$ (193)

CONSOLIDATED STATEMENT OF CHANGES IN PARTNERS' EQUITY - 3 months ended Mar. 31, 2017 - USD ($)
shares in Millions, $ in Millions

Limited Partners

Common units

Limited Partners

Class B units

General Partner

Accumulated Other Comprehensive Income

^[1]

Common units

ATM Equity Issuance Program

Total

Partners' Equity at beginning of year at Dec. 31, 2016

$ 1,002

$ 117

$ 27

$ 1,146

Partners' Equity at beginning of year (in units) at Dec. 31, 2016

67.4

1.9

Increase (Decrease) in Partners' Equity

Net income

$ 72

Other Comprehensive Loss

$ 1

ATM Equity Issuance, net (Note 6)

$ 69

ATM Equity Issuance, net (Note 6) (in units)

1.2

Reclassification of common units no longer subject to rescission (Note 6 )

$ 19

Distributions

(64)

$ (22)

(4)

(90)

Partners' Equity at end of year at Mar. 31, 2017

$ 1,098

$ 95

$ 28

$ 1

$ 1,222

Partners' Equity at end of year (in units) at Mar. 31, 2017

68.6

1.9

[1]

Income related to cash flow hedges reported in Accumulated Other Comprehensive Income and expected to be reclassified to Net Income in the next 12 months is estimated to be $1 million. These estimates assume constant interest rates over time; however, the amounts reclassified will vary based on actual value of interest rates at the date of settlement.

CONSOLIDATED STATEMENT OF CHANGES IN PARTNERS' EQUITY (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
CONSOLIDATED STATEMENT OF CHANGES IN PARTNERS' EQUITY
Income expected to be reclassified to Net Income in the next 12 months	$ 1

ORGANIZATION	3 Months Ended
ORGANIZATION	Mar. 31, 2017
ORGANIZATION
ORGANIZATION	NOTE 1 ORGANIZATION TC PipeLines, LP and its subsidiaries are collectively referred to herein as the Partnership. The Partnership was formed by TransCanada PipeLines Limited, a wholly-owned subsidiary of TransCanada Corporation (TransCanada Corporation together with its subsidiaries collectively referred to herein as TransCanada), to acquire, own and participate in the management of energy infrastructure assets in North America. The Partnership owns its pipeline assets through three intermediate limited partnerships (ILPs), TC GL Intermediate Limited Partnership, TC PipeLines Intermediate Limited Partnership and TC Tuscarora Intermediate Limited Partnership.

SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
SIGNIFICANT ACCOUNTING POLICIES	Mar. 31, 2017
SIGNIFICANT ACCOUNTING POLICIES
SIGNIFICANT ACCOUNTING POLICIES	NOTE 2 SIGNIFICANT ACCOUNTING POLICIES The accompanying financial statements and related notes have been prepared in accordance with United States generally accepted accounting principles (GAAP) and amounts are stated in U.S. dollars. The results of operations for the three months ended March 31, 2017 and 2016 are not necessarily indicative of the results that may be expected for the full fiscal year. The accompanying financial statements should be read in conjunction with the financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2016. That report contains a more comprehensive summary of the Partnership’s significant accounting policies. In the opinion of management, the accompanying financial statements contain all of the appropriate adjustments, all of which are normally recurring adjustments unless otherwise noted, and considered necessary to present fairly the financial position of the Partnership, the results of operations and cash flows for the respective periods. Our significant accounting policies are consistent with those disclosed in our Annual Report on Form 10-K for the year ended December 31, 2016, except as described in Note 3, Accounting Pronouncements. Use of Estimates The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Although management believes these estimates are reasonable, actual results could differ from these estimates.

ACCOUNTING PRONOUNCEMENTS	3 Months Ended
ACCOUNTING PRONOUNCEMENTS	Mar. 31, 2017
ACCOUNTING PRONOUNCEMENTS
ACCOUNTING PRONOUNCEMENTS	NOTE 3 ACCOUNTING PRONOUNCEMENTS Retrospective application of ASU No 2016-15 “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments” In August 2016, the FASB issued an amendment of previously issued guidance, which intends to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The new guidance is effective January 1, 2018, however as early adoption is permitted, the Partnership elected to retrospectively apply this guidance effective December 31, 2016. The Partnership has elected to classify distributions received from equity method investees using the nature of distributions approach as it is more representative of the nature of the underlying activities of the investees that generated the distributions. As a result, certain comparative period distributions received from equity method investees, amounting to $8 million for the three months ended March 31, 2016, have been reclassified from investing activities to cash generated from operations in the consolidated statement of cash flows. Effective January 1, 2017 Inventory In July 2015, the FASB issued new guidance on simplifying the measurement of inventory. The new guidance specifies that an entity should measure inventory within the scope of this update at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. This new guidance was effective January 1, 2017, and was applied prospectively and did not have a material impact on the Partnership’s consolidated balance sheet. Equity method and joint ventures In March 2016, the FASB issued new guidance that simplifies the transition to equity method accounting. The new guidance eliminates the requirement to retroactively apply the equity method of accounting when an increase in ownership interest in an investment qualifies for equity method accounting. The new guidance is effective January 1, 2017 and was applied prospectively. The application of this guidance did not have a material impact on the Partnership’s consolidated financial statements. Consolidation In October 2016, the FASB issued new guidance on consolidation relating to interests held through related parties that are under common control. The new guidance amends the consolidation requirements such that if a decision maker is required to evaluate whether it is the primary beneficiary of a variable interest entry (VIE), it will need to consider only its proportionate indirect interest in the VIE held through common control party. The guidance was effective January 1, 2017, was applied retrospectively and did not result in any change to our consolidation conclusions. Future accounting changes Revenue from contracts with customers In 2014, the FASB issued new guidance on revenue from contracts with customers. The new guidance requires that an entity recognize revenue in accordance with a five-step model. This model is used to depict the transfer of promised goods or services to customers in an amount that reflects the total consideration to which it expects to be entitled during the term of the contract in exchange for those goods or services. The new guidance also requires additional disclosures about the nature, amount, timing and uncertainty of revenue and the related cash flows. The Partnership will adopt the new standard on the effective date of January 1, 2018. There are two methods in which the new standard can be adopted: (1) a full retrospective approach with restatement of all prior periods presented, or (2) a modified retrospective approach with a cumulative-effect adjustment as of the date of adoption. The Partnership is evaluating both methods of adoption as it works through its analysis. The Partnership has identified all existing customer contracts that are within the scope of the new guidance and is in the process of analyzing individual contracts or groups of contracts on a segmented basis to identify any significant changes in how revenues are recognized as a result of implementing the new standard. As the Partnership continues its contract analysis, it will also quantify the impact, if any, on prior period revenues. The Partnership will address any system and process changes necessary to compile the information to meet the recognition and disclosure requirements of the new standard. As the Partnership is currently evaluating the impact of this standard, it has not yet determined the effect on its consolidated financial statements. Leases In February 2016, the FASB issued new guidance on the accounting for leases. The new guidance amends the definition of a lease requiring the customer to have both (1) the right to obtain substantially all of the economic benefits from the use of the asset and (2) the right to direct the use of the asset in order for the arrangement to qualify as a lease. The new guidance requires lessees to recognize most leases, including operating leases, on the balance sheet as lease assets and lease liabilities. The new standard does not make extensive changes to lessor accounting. Lessees may also be required to reassess assumptions associated with existing leases as well as to provide expanded qualitative and quantitative disclosures. The new guidance is effective January 1, 2019. The Partnership is currently identifying existing lease agreements that may have an impact on the Company’s consolidated financial statements as a result of adopting this new guidance. Goodwill Impairment In January 2017, the FASB issued new guidance on simplifying the test for goodwill impairment by eliminating the requirement to calculate the implied fair value of goodwill to measure the impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. This new guidance is effective January 1, 2020 and will be applied prospectively. Early adoption is permitted. The Partnership is currently evaluating the impact of the adoption of this guidance and has not yet determined the effect on its consolidated financial statements.

EQUITY INVESTMENTS

3 Months Ended

Mar. 31, 2017

EQUITY INVESTMENTS

EQUITY INVESTMENTS

NOTE 4 EQUITY INVESTMENTS

Northern Border, Great Lakes and PNGTS are regulated by FERC and are operated by TransCanada. The Partnership uses the equity method of accounting for its interests in its equity investees. The Partnership’s equity investments are held through our ILPs that are considered to be variable interest entities (VIEs) (refer to Note 16).

	Ownership		Equity Earnings		Equity Investments
	Interest at		Three months
(unaudited)	March 31,		ended March 31,		March 31,	December 31,
(millions of dollars)	2017		2017	2016	2017	2016

Northern Border(a)	50	%	19	18	441	444
Great Lakes	46.45	%	17	15	489	474
PNGTS (b)	49.9	%	7	9	132	126

			43	42	1,062	1,044

(a)

Equity earnings from Northern Border is net of the 12-year amortization of a $10 million transaction fee paid to the operator of Northern Border at the time of the Partnership’s additional 20 percent interest acquisition in April 2006.

(b)

For the three months ending March 31, 2017 and 2016, the Partnership recorded no undistributed earnings from PNGTS.

Northern Border

The Partnership did not have undistributed earnings from Northern Border for the three months ended March 31, 2017 and 2016.

The summarized financial information for Northern Border is as follows:

(unaudited)
(millions of dollars)	March 31, 2017		December 31, 2016

ASSETS
Cash and cash equivalents	18		14
Other current assets	36		36
Plant, property and equipment, net	1,085		1,089
Other assets	15		14

	1,154		1,153


LIABILITIES AND PARTNERS’ EQUITY
Current liabilities	44		38
Deferred credits and other	29		28
Long-term debt, including current maturities, net	430		430
Partners’ equity
Partners’ capital	653		659
Accumulated other comprehensive loss	(2	)	(2	)

	1,154		1,153

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017		2016

Transmission revenues	74		74
Operating expenses	(17	)	(16	)
Depreciation	(15	)	(15	)
Financial charges and other	(4	)	(6	)

Net income	38		37

Great Lakes

The Partnership made an equity contribution to Great Lakes of $4 million in the first quarter of 2017. This amount represents the Partnership’s 46.45 percent share of a $9 million cash call from Great Lakes to make a scheduled debt repayment.

The Partnership did not have undistributed earnings from Great Lakes for the three months ended March 31, 2017 and 2016.

The summarized financial information for Great Lakes is as follows:

(unaudited)
(millions of dollars)	March 31, 2017	December 31, 2016

ASSETS
Current assets	86	66
Plant, property and equipment, net	708	714

	794	780


LIABILITIES AND PARTNERS’ EQUITY
Current liabilities	31	40
Long-term debt, including current maturities, net	269	278
Partners’ equity	494	462

	794	780

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017		2016

Transmission revenues	63		61
Operating expenses	(14	)	(15	)
Depreciation	(7	)	(7	)
Financial charges and other	(5	)	(6	)

Net income	37		33

DEBT AND CREDIT FACILITIES

3 Months Ended

Mar. 31, 2017

DEBT AND CREDIT FACILITIES

DEBT AND CREDIT FACILITIES

NOTE 5 DEBT AND CREDIT FACILITIES

(unaudited) (millions of dollars)	March 31, 2017	Weighted Average Interest Rate for the Quarter Ended March 31, 2017		December 31, 2016	Weighted Average Interest Rate for the Year Ended December 31, 2016

TC PipeLines, LP
Senior Credit Facility due 2021	110	2.03	%	160	1.72	%
2013 Term Loan Facility due July 2018	500	2.03	%	500	1.73	%
2015 Term Loan Facility due September 2018	170	1.93	%	170	1.63	%
4.65% Unsecured Senior Notes due 2021	350	4.65	%(a)	350	4.65	%(a)
4.375% Unsecured Senior Notes due 2025	350	4.375	%(a)	350	4.375	%(a)
GTN
5.29% Unsecured Senior Notes due 2020	100	5.29	%(a)	100	5.29	%(a)
5.69% Unsecured Senior Notes due 2035	150	5.69	%(a)	150	5.69	%(a)
Unsecured Term Loan Facility due 2019	65	1.73	%	65	1.43	%
Tuscarora
Unsecured Term Loan due 2019	10	1.91	%	10	1.64	%
3.82% Series D Senior Notes due 2017	12	3.82	%(a)	12	3.82	%(a)

	1,817			1,867
Less: unamortized debt issuance costs and debt discount	8			9
Less: current portion	23			23

	1,786			1,835

(a)

Fixed interest rate

The Partnership’s Senior Credit Facility consists of a $500 million senior revolving credit facility with a banking syndicate, maturing November 10, 2021, under which $110 million was outstanding at March 31, 2017 (December 31, 2016 - $160 million), leaving $390 million available for future borrowing. The LIBOR-based interest rate on the Senior Credit Facility was 2.04 percent at March 31, 2017 (December 31, 2016 — 1.92 percent).

As of March 31, 2017, the variable interest rate exposure related to 2013 Term Loan Facility was hedged by fixed interest rate swap arrangements and our effective interest rate was 2.31 percent (December 31, 2016 — 2.31 percent). Prior to hedging activities, the LIBOR-based interest rate on 2013 Term Loan Facility was 2.04 percent at March 31, 2017 (December 31, 2016 — 1.87 percent).

The LIBOR-based interest rate on the 2015 Term Loan Facility was 1.93 percent at March 31, 2017 (December 31, 2016 — 1.77 percent).

The 2013 Term Loan Facility and the 2015 Term Loan Facility (Term Loan Facilities) and the Senior Credit Facility require the Partnership to maintain a certain leverage ratio (debt to adjusted cash flow [net income plus cash distributions received, extraordinary losses, interest expense, expense for taxes paid or accrued, and depreciation and amortization expense less equity earnings and extraordinary gains]) no greater than 5.00 to 1.00 for each fiscal quarter, except for the fiscal quarter and the two following fiscal quarters in which one or more acquisitions has been executed, in which case the leverage ratio is to be no greater than 5.50 to 1.00. The leverage ratio was 4.04 to 1.00 as of March 31, 2017.

GTN’s Unsecured Senior Notes, along with GTN’s Unsecured Term Loan Facility contain a covenant that limits total debt to no greater than 70 percent of GTN’s total capitalization. GTN’s total debt to total capitalization ratio at March 31, 2017 was 44.7 percent. The LIBOR-based interest rate on the GTN’s Unsecured Term Loan Facility was 1.73 percent at March 31, 2017 (December 31, 2016 — 1.57 percent).

Tuscarora’s Series D Senior Notes, which require yearly principal payments until maturity, are secured by Tuscarora’s transportation contracts, supporting agreements and substantially all of Tuscarora’s property. The note purchase agreements contain certain provisions that include, among other items, limitations on additional indebtedness and distributions to partners. The Series D Senior Notes contain a covenant that limits total debt to no greater than 45 percent of Tuscarora’s total capitalization. Tuscarora’s total debt to total capitalization ratio at March 31, 2017 was 21.05 percent. Additionally, the Series D Senior Notes require Tuscarora to maintain a Debt Service Coverage Ratio (cash available from operations divided by a sum of interest expense and principal payments) of greater than 3.00 to 1.00. The ratio was 3.92 to 1.00 as of March 31, 2017.

The LIBOR-based interest rate on the Tuscarora’s Unsecured Term Loan Facility was 2.12 percent at March 31, 2017 (December 31, 2016 —1.90 percent).

At March 31, 2017, the Partnership was in compliance with its financial covenants, in addition to the other covenants which include restrictions on entering into mergers, consolidations and sales of assets, granting liens, material amendments to the Third Amended and Restated Agreement of Limited Partnership (Partnership Agreement), incurring additional debt and distributions to unitholders.

The principal repayments required of the Partnership on its debt are as follows:

(unaudited)
(millions of dollars)

2017		23
2018		691
2019		43
2020		100
2021		460
Thereafter		500

		1,817

PARTNERS' EQUITY	3 Months Ended
PARTNERS' EQUITY	Mar. 31, 2017
PARTNERS' EQUITY
PARTNERS' EQUITY	NOTE 6 PARTNERS’ EQUITY ATM equity issuance program (ATM program) During the three months ended March 31, 2017, we issued 1,197,749 common units under our ATM program generating net proceeds of approximately $69 million, plus $2 million from the General Partner to maintain its effective two percent general partner interest. The commissions to our sales agents in the three months ended March 31, 2017 were approximately $704,000. The net proceeds were used for general partnership purposes. Class B units issued to TransCanada The Class B Units we issued on April 1, 2015 to finance a portion of the 2015 GTN Acquisition represent a limited partner interest in us and entitle TransCanada to an annual distribution based on 30 percent of GTN’s annual distributions as follows: (i) 100 percent of distributions above $20 million through March 31, 2020; and (ii) 25 percent of distributions above $20 million thereafter. For the year ending December 31, 2017, the Class B units’ equity account will be increased by the excess of 30 percent of GTN’s distributions over the annual threshold of $20 million until such amount is declared for distribution and paid in the first quarter of 2018. During the three months ended March 31, 2017, the threshold has not been exceeded. For the year ended December 31, 2016, the Class B distribution was $22 million and was declared and paid in the first quarter of 2017. Common unit issuance subject to rescission In connection with a late filing of an employee-related Form 8-K with the SEC in March 2016, the Partnership became ineligible to use the then effective shelf registration statement upon filing of its 2015 Annual Report. As a result, it was determined that the purchasers of the 1.6 million common units that were issued from March 8, 2016 to May 19, 2016 under the Partnership’s ATM program may have a rescission right for an amount equal to the purchase price paid for the units, plus statutory interest and less any distributions paid, upon the return of such units to the Partnership. No unitholder has claimed or attempted to exercise any rescission rights to date and these rights expire one year from the date of purchase of the unit. At December 31, 2016, $83 million was recorded as Common units subject to rescission on the consolidated balance sheet. The Partnership classified all the 1.6 million common units sold under its ATM program from March 8, 2016 up to and including May 19, 2016, which may be subject to rescission rights, outside of equity given the potential redemption feature which is not within the control of the Partnership. These units are treated as outstanding for financial reporting purposes. At March 31, 2017, $19 million of the Common units subject to rescission on the consolidated balance sheet were reclassified back to equity. The amount reclassified represents the net proceeds received from the 0.4 million units sold from March 8, 2016 up to and including March 31, 2016 as the rescission rights attached to these units expired.

NET INCOME PER COMMON UNIT

3 Months Ended

Mar. 31, 2017

NET INCOME PER COMMON UNIT

NET INCOME PER COMMON UNIT

NOTE 7 NET INCOME PER COMMON UNIT

Net income per common unit is computed by dividing net income attributable to controlling interests, after deduction of amounts attributable to the General Partner and Class B units by the weighted average number of common units outstanding.

The amounts allocable to the General Partner equals an amount based upon the General Partner’s effective two percent general partner interest, plus an amount equal to incentive distributions. Incentive distributions are paid to the General Partner if quarterly cash distributions on the common units exceed levels specified in the Partnership Agreement.

The amount allocable to the Class B units in 2017 equals 30 percent of GTN’s distributable cash flow during the year ended December 31, 2017 less $20 million (December 31, 2016 —$20 million). During the three months ended March 31, 2017 and 2016, no amounts were allocated to the Class B units as the annual threshold of $20 million has not been exceeded.

Net income per common unit was determined as follows:

(unaudited)	Three months ended March 31,
(millions of dollars, except per common unit amounts)	2017			2016

Net income attributable to controlling interests	75			73
Net income attributable to the General Partner	(1		)	(1		)
Incentive distributions attributable to the General Partner (a)	(2		)	(1		)

Net income attributable to common units	72			71

Weighted average common units outstanding (millions) — basic and diluted (b)	68.3			64.4
Net income per common unit — basic and diluted	$	1.05		$	1.10

(a)

Under the terms of the Partnership Agreement, for any quarterly period, the participation of the incentive distribution rights (IDRs) is limited to the available cash distributions declared. Accordingly, incentive distributions allocated to the General Partner are based on the Partnership’s available cash during the current reporting period, but declared and paid in the subsequent reporting period.

(b)

Includes the common units subject to rescission. These units are treated as outstanding for financial reporting purposes. Refer to Note 6.

CASH DISTRIBUTIONS TO COMMON UNITS	3 Months Ended
CASH DISTRIBUTIONS TO COMMON UNITS	Mar. 31, 2017
CASH DISTRIBUTIONS TO COMMON UNITS
CASH DISTRIBUTIONS TO COMMON UNITS	NOTE 8 CASH DISTRIBUTIONS TO COMMON UNITS During the three months ended March 31, 2017, the Partnership distributed $0.94 per common unit (March 31, 2016 — $0.89 per common unit) for a total of $68 million (March 31, 2016 - $60 million). The distribution paid to our General Partner during the three months ended March 31, 2017 for its effective two percent general partner interest was $2 million along with an IDR payment of $2 million for a total distribution of $4 million (March 31, 2016 - $1 million for the effective two percent interest and a $1 million IDR payment).

CHANGE IN OPERATING WORKING CAPITAL

3 Months Ended

Mar. 31, 2017

CHANGE IN OPERATING WORKING CAPITAL

CHANGE IN OPERATING WORKING CAPITAL

NOTE 9 CHANGE IN OPERATING WORKING CAPITAL

(unaudited)	Three months ended March 31,
(millions of dollars)	2017		2016

Change in accounts receivable and other	3		(1	)
Change in other current assets	2		—
Change in accounts payable and accrued liabilities	(3	)	3	(a)
Change in accounts payable to affiliates	(1	)	(1	)
Change in accrued interest	4		5

Change in operating working capital	5		6

(a)

The accrual of $10 million for the construction of GTN’s Carty Lateral in December 31, 2015 was paid during the first quarter of 2016. Accordingly, the payment was reported as capital expenditures in our cash flow statement during the first quarter of 2016.

RELATED PARTY TRANSACTIONS

3 Months Ended

Mar. 31, 2017

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS

NOTE 10 RELATED PARTY TRANSACTIONS

The Partnership does not have any employees. The management and operating functions are provided by the General Partner. The General Partner does not receive a management fee in connection with its management of the Partnership. The Partnership reimburses the General Partner for all costs of services provided, including the costs of employee, officer and director compensation and benefits, and all other expenses necessary or appropriate to the conduct of the business of, and allocable to, the Partnership. Such costs include (i) overhead costs (such as office space and equipment) and (ii) out-of-pocket expenses related to the provision of such services. The Partnership Agreement provides that the General Partner will determine the costs that are allocable to the Partnership in any reasonable manner determined by the General Partner in its sole discretion. Total costs charged to the Partnership by the General Partner were $1 million for each of the three months ended March 31, 2017 and 2016.

As operator, TransCanada’s subsidiaries provide capital and operating services to our pipeline systems. TransCanada’s subsidiaries incur costs on behalf of our pipeline systems, including, but not limited to, employee salary and benefit costs, and property and liability insurance costs.

Capital and operating costs charged to our pipeline systems for the three months ended March 31, 2017 and 2016 by TransCanada’s subsidiaries and amounts payable to TransCanada’s subsidiaries at March 31, 2017 and December 31, 2016 are summarized in the following tables:

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017	2016

Capital and operating costs charged by TransCanada’s subsidiaries to:
Great Lakes (a)	8	7
Northern Border (a)	10	6
PNGTS (a)	2	2
GTN (a)	7	6
Bison (b)	1	(1	)
North Baja	1	1
Tuscarora	1	1
Impact on the Partnership’s net income:
Great Lakes	3	3
Northern Border	3	3
PNGTS	1	1
GTN	7	5
Bison	1	1
North Baja	1	1
Tuscarora	1	1

(unaudited)
(millions of dollars)	March 31, 2017	December 31, 2016

Net amounts payable to TransCanada’s subsidiaries is as follows:
Great Lakes (a)	3	4
Northern Border (a)	3	4
PNGTS (a)	1	1
GTN	3	3
Bison	—	1
North Baja	—	1
Tuscarora	1	1

(a)

Represents 100 percent of the costs.

(b)

In March 2016, Bison sold excess pipe (at cost) to an affiliate.

Great Lakes earns significant transportation revenues from TransCanada and its affiliates, some of which are provided at discounted rates and some at maximum recourse rates. For the three months ended March 31, 2017, Great Lakes earned 67 percent of transportation revenues from TransCanada and its affiliates (March 31, 2016 — 76 percent).

At March 31, 2017, $16 million was included in Great Lakes’ receivables in regards to the transportation contracts with TransCanada and its affiliates (December 31, 2016 — $19 million).

Great Lakes operates under a FERC approved 2013 rate settlement that includes a revenue sharing mechanism that requires Great Lakes to share with its shippers certain percentages of any qualifying revenues earned above a certain return on equity threshold. For the year ended December 31, 2016, Great Lakes recorded an estimated 2016 revenue sharing provision of $7.2 million. For the three months ended March 31, 2017, Great Lakes recorded an estimated 2017 revenue sharing provision of $3.4 million. Great Lakes expects that a significant percentage of this refund will be paid to its affiliates.

On March 31, 2017, PNGTS declared its first quarter 2017 distribution of $5 million, of which the Partnership received its 49.9 percent share or $2 million on April 18, 2017.

FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2017

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS

NOTE 11 FAIR VALUE MEASUREMENTS

(a) Fair Value Hierarchy

Under ASC 820, Fair Value Measurements and Disclosures, fair value measurements are characterized in one of three levels based upon the inputs used to arrive at the measurement. The three levels of the fair value hierarchy are as follows:

Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access at the measurement date.

Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

Level 3 inputs are unobservable inputs for the asset or liability.

When appropriate, valuations are adjusted for various factors including credit considerations. Such adjustments are generally based on available market evidence. In the absence of such evidence, management’s best estimate is used.

(b) Fair Value of Financial Instruments

The carrying value of cash and cash equivalents, accounts receivable and other, accounts payable and accrued liabilities, accounts payable to affiliates and accrued interest approximate their fair values because of the short maturity or duration of these instruments, or because the instruments bear a variable rate of interest or a rate that approximates current rates. The fair value of the Partnership’s debt is estimated by discounting the future cash flows of each instrument at estimated current borrowing rates. The fair value of interest rate derivatives is calculated using the income approach, which uses period-end market rates and applies a discounted cash flow valuation model.

Long-term debt is recorded at amortized cost and classified in Level 2 of the fair value hierarchy for fair value disclosure purposes. Interest rate derivative assets and liabilities are classified in Level 2 for all periods presented where the fair value is determined by using valuation techniques that refer to observable market data or estimated market prices. The estimated fair value of the Partnership’s debt at March 31, 2017 and December 31, 2016 was $1,863 million and $1,908 million, respectively.

Market risk is the risk that changes in market interest rates may result in fluctuations in the fair values or cash flows of financial instruments. The Partnership’s floating rate debt is subject to LIBOR benchmark interest rate risk. The Partnership uses interest rate derivatives to manage its exposure to interest rate risk. We regularly assess the impact of interest rate fluctuations on future cash flows and evaluate hedging opportunities to mitigate our interest rate risk.

The interest rate swaps are structured such that the cash flows of the derivative instruments match those of the variable rate of interest on the 2013 Term Loan Facility. The Partnership hedged interest payments on the variable-rate 2013 Term Loan Facility with interest rate swaps maturing July 1, 2018, at a weighted average fixed interest rate of 2.31 percent. At March 31, 2017, the fair value of the interest rate swaps accounted for as cash flow hedges was an asset of $2 million (both on a gross and net basis). At December 31, 2016, the fair value of the interest rate swaps accounted for as cash flow hedges was an asset of $1 million and a liability of $1 million (on a gross basis) and an asset of nil million (on a net basis). The Partnership did not record any amounts in net income related to ineffectiveness for interest rate hedges for the three months ended March 31, 2017 and 2016. The change in fair value of interest rate derivative instruments recognized in other comprehensive income was a gain of $1 million for the three months ended March 31, 2017 (March 31, 2016 — loss of $2 million). For the three months ended March 31, 2017, the net realized loss related to the interest rate swaps was nil million and was included in financial charges and other (March 31, 2016 — nil million) (refer to Note 13).

The Partnership has no master netting agreements; however, it has derivative contracts containing provisions with rights of offset. The Partnership has elected to present the fair value of derivative instruments with the right to offset on a gross basis in the balance sheet. Had the Partnership elected to present these instruments on a net basis, there would be no effect on the consolidated balance sheet as of March 31, 2017 (net asset of nil million as of December 31, 2016).

ACCOUNTS RECEIVABLE AND OTHER

3 Months Ended

Mar. 31, 2017

ACCOUNTS RECEIVABLE AND OTHER

ACCOUNTS RECEIVABLE AND OTHER

NOTE 12 ACCOUNTS RECEIVABLE AND OTHER

(unaudited)
(millions of dollars)	March 31, 2017	December 31, 2016

Trade accounts receivable, net of allowance of nil	31	34
Imbalance receivable from affiliates	1	2
Other	2	1

	34	37

FINANCIAL CHARGES AND OTHER

3 Months Ended

Mar. 31, 2017

FINANCIAL CHARGES AND OTHER

FINANCIAL CHARGES AND OTHER

NOTE 13 FINANCIAL CHARGES AND OTHER

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017	2016

Interest Expense (a)	16	17
Net realized loss related to the interest rate swaps (b)	—	—
Other Income (b)	—	—

	16	17

(a)

Includes debt issuance costs and amortization of discount costs.

(b)

Nil million for both periods.

CONTINGENCIES	3 Months Ended
CONTINGENCIES	Mar. 31, 2017
CONTINGENCIES
CONTINGENCIES	NOTE 14 CONTINGENCIES Great Lakes v. Essar Steel Minnesota LLC, et al. — On October 29, 2009, Great Lakes filed suit in the U.S. District Court, District of Minnesota, against Essar Minnesota LLC (Essar Minnesota) and certain Foreign Essar Affiliates (collectively, Essar) for breach of its monthly payment obligation under its transportation services agreement with Great Lakes. Great Lakes sought to recover approximately $33 million for past and future payments due under the agreement. On September 16, 2015, following a jury trial, the federal district court judge entered a judgment in the amount of $32.9 million in favor of Great Lakes. On September 20, 2015, Essar appealed the decision to the United States Court of Appeals for the Eighth Circuit (Eighth Circuit) based on an allegation of improper jurisdiction and a number of other rulings by the federal district judge. Essar was required to post a performance bond for the full value of the judgment pending appeal. In July 2016, Essar Minnesota filed for Bankruptcy. The performance bond was released into the bankruptcy court proceedings.The Foreign Essar Affiliates have not filed for bankruptcy. The Eighth Circuit heard the appeal on October 20, 2016. A decision on the appeal was received in December 2016 and the Eighth Circuit vacated Great Lakes’ judgment against Essar finding that there was no federal jurisdiction. Great Lakes filed a Request for Rehearing with the Eighth Circuit and it was denied in January 2017. Great Lakes currently is proceeding against Essar Minnesota in the bankruptcy court and its case against the Foreign Essar Affiliates in Minnesota state court remains pending. In April, after reaching agreement with creditors on an allowed claim, the Bankruptcy court approved Great Lakes’ claim in the amount of $31.5 million.

- Definition

The entire disclosure for loss and gain contingencies. Describes any existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible loss incurred by an entity that will ultimately be resolved when one or more future events occur or fail to occur, and typically discloses the amount of loss recorded or a range of possible loss, or an assertion that no reasonable estimate can be made.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14472-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12021-110248

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14394-108349

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12053-110248

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14453-108349

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14615-108349

+ Details

REGULATORY	3 Months Ended
REGULATORY	Mar. 31, 2017
REGULATORY
REGULATORY	NOTE 15 REGULATORY North Baja —On January 6, 2017, North Baja notified FERC that current market conditions do not support the replacement of the compression that was temporarily abandoned in 2013 and requested authorization to permanently abandon two compressor units and a nominal volume of unsubscribed firm capacity. FERC approved the permanent abandonment request on February 16, 2017. The abandonments will not have any impact on existing firm transportation service. Great Lakes- Great Lakes is required to file a new section 4 rate case with rates effective no later than January 1, 2018 as part of the settlement agreement with customers approved in November 2013. On March 31, 2017, Great Lakes submitted a General Section 4 Rate Filing and Tariff Changes with FERC. The rates proposed in the filing will become effective on October 1, 2017, subject to refund, if alternate resolution to the proceeding is not reached prior to that date. Great Lakes has initiated customer discussions regarding the details of the filing and will seek to achieve a mutually beneficial resolution through settlement with its customers.

VARIABLE INTEREST ENTITIES

3 Months Ended

Mar. 31, 2017

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES

NOTE 16 VARIABLE INTEREST ENTITIES

In the normal course of business, the Partnership must re-evaluate its legal entities under the newly effective consolidation guidance to determine if those that are considered to be VIEs are appropriately consolidated or if they should be accounted for under other US GAAP. A variable interest entity (VIE) is a legal entity that does not have sufficient equity at risk to finance its activities without additional subordinated financial support or is structured such that equity investors lack the ability to make significant decisions relating to the entity’s operations through voting rights or do not substantively participate in the gains or losses of the entity. A VIE is appropriately consolidated if the Partnership is considered to be the primary beneficiary. The VIE’s primary beneficiary is the entity that has both (1) the power to direct the activities of the VIE that most significantly impact the VIEs economic performance and (2) the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE.

As a result of its analysis, the Partnership continues to consolidate all legal entities in which it has a variable interest and for which it is considered to be the primary beneficiary. VIEs where the Partnership is not the primary beneficiary, but has a variable interest in the entity, are accounted for as equity investments.

Consolidated VIEs

The Partnership’s consolidated VIEs consist of the Partnership’s ILPs that hold interests in the Partnership’s pipeline systems. After considering the purpose and design of the ILPs and the risks that they were designed to create and pass through to the Partnership, the Partnership has concluded that it is the primary beneficiary of these ILPs because of the significant amount of variability that it absorbs from the ILPs’ economic performance.

The assets and liabilities held through these VIEs that are not available to creditors of the Partnership and whose investors have no recourse to the credit of the Partnership are held through GTN, Tuscarora, Northern Border, Great Lakes and PNGTS due to their third party debt. The following table presents the total assets and liabilities of these entities that are included in the Partnership’s Consolidated Balance Sheet:

(unaudited)
(millions of dollars)	March 31, 2017		December 31, 2016

ASSETS (LIABILITIES) *
Accounts receivable and other	21		24
Inventories	6		6
Other current assets	3		4
Equity investments	1,062		1,044
Plant, property and equipment	844		847
Other assets	2		2
Accounts payable and accrued liabilities	(18	)	(20	)
Accounts payable to affiliates, net	(21	)	(28	)
Accrued interest	(5	)	(1	)
Current portion of long-term debt	(23	)	(23	)
Long-term debt	(313	)	(313	)
Other liabilities	(26	)	(25	)

*North Baja and Bison, which are also assets held through our consolidated VIEs, were excluded as the assets of these entities can be used for purposes other than the settlement of the VIE’s obligations.

SUBSEQUENT EVENTS	3 Months Ended
SUBSEQUENT EVENTS	Mar. 31, 2017
SUBSEQUENT EVENTS.
SUBSEQUENT EVENTS	NOTE 17 SUBSEQUENT EVENTS Management of the Partnership has reviewed subsequent events through May 4, 2017, the date the financial statements were issued, and concluded there were no events or transactions during this period that would require recognition or disclosure in the consolidated financial statements other than what is disclosed here and/or those already disclosed in the preceding notes. On April 25, 2017, the board of directors of our General Partner declared the Partnership’s first quarter 2017 cash distribution in the amount of $0.94 per common unit and payable on May 15, 2017 to unitholders of record as of May 5, 2017. The declared distribution totaled $68 million and payable in the following manner: $65 million to common unitholders (including $5 million to the General Partner as a holder of 5,797,106 common units and $11 million to another subsidiary of TransCanada as holder of 11,287,725 common units) and $3 million to our General Partner, which included $1 million for its effective two percent general partner interest and $2 million of IDRs. Northern Border declared its March 2017 distribution of $13 million on April 7, 2017, of which the Partnership received its 50 percent share or $7 million on April 28, 2017. Great Lakes declared its first quarter 2017 distribution of $43 million on April 19, 2017, of which the Partnership received its 46.45 percent share or $20 million. The distribution was paid on May 1, 2017. On April 24, 2017, Great Lakes reached an agreement on the terms of a potential new long-term transportation capacity contract with its affiliate, TransCanada. The contract is for a term of 10 years with a total contract value of up to $758 million. The contract may commence as soon as November 1, 2017 and contains termination options beginning in year three. The contract is subject to the satisfaction of certain conditions, including but not limited to approval by the Canadian National Energy Board of an associated contract between TransCanada and third party customers. Great Lakes current rate structure includes a revenue sharing mechanism that requires Great Lakes to share with its customers certain percentages of any qualifying revenues earned above a calculated return on equity threshold. Additionally, Great Lakes is currently pursuing resolution of its March 31, 2017 General Section 4 Rate Filing (refer to Note 15). We cannot predict the cumulative impact of these circumstances to the Partnership’s earnings at this time. On May 3, 2017, the Partnership entered into agreements to purchase from subsidiaries of TransCanada a 49.34 percent interest in Iroquois Gas Transmission System, L.P. (Iroquois), including a future option to acquire a further 0.66 percent in Iroquois, together with an additional 11.81 percent interest in PNGTS resulting in the Partnership owning a 61.71 percent in PNGTS (2017 Acquisition). The total purchase price of the 2017 Acquisition is $765 million comprised of $597 million in cash and the assumption of a total $168 million of proportional Iroquois and PNGTS debt. The Partnership expects to fund the cash portion of the transaction through a combination of debt and equity issuances including proceeds from our ATM Program and borrowing under our Senior Credit Facility. The transaction is expected to close mid-2017. The Iroquois pipeline transports natural gas under long-term contracts and extends from the TransCanada Mainline system at the U.S. border near Waddington, New York to markets in the U.S. northeast, including New York City, Long Island and Connecticut. Iroquois is currently jointly owned by affiliates of TransCanada Corporation and Dominion Resources, Inc. via a joint venture. The transaction was approved by the Board of Directors of the General Partner based on approval and recommendation from the Board’s Conflicts Committee, which is comprised entirely of independent directors. In connection with the transaction, Evercore served as independent financial advisor to the Conflicts Committee. Latham & Watkins served as legal counsel to the Conflicts Committee and Vinson & Elkins served as legal counsel to the Partnership. Wood Mackenzie served as commercial and market advisor to the Conflicts Committee.

SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2017
SIGNIFICANT ACCOUNTING POLICIES
Use of Estimates	Use of Estimates The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Although management believes these estimates are reasonable, actual results could differ from these estimates.

EQUITY INVESTMENTS (Tables)

3 Months Ended

Mar. 31, 2017

EQUITY INVESTMENTS

Schedule of equity investments and summarized financial information for equity investees

	Ownership		Equity Earnings		Equity Investments
	Interest at		Three months
(unaudited)	March 31,		ended March 31,		March 31,	December 31,
(millions of dollars)	2017		2017	2016	2017	2016

Northern Border(a)	50	%	19	18	441	444
Great Lakes	46.45	%	17	15	489	474
PNGTS (b)	49.9	%	7	9	132	126

			43	42	1,062	1,044

(a)

(b)

For the three months ending March 31, 2017 and 2016, the Partnership recorded no undistributed earnings from PNGTS.

Northern Border

EQUITY INVESTMENTS

Schedule of equity investments and summarized financial information for equity investees

(unaudited)
(millions of dollars)	March 31, 2017		December 31, 2016

ASSETS
Cash and cash equivalents	18		14
Other current assets	36		36
Plant, property and equipment, net	1,085		1,089
Other assets	15		14

	1,154		1,153


LIABILITIES AND PARTNERS’ EQUITY
Current liabilities	44		38
Deferred credits and other	29		28
Long-term debt, including current maturities, net	430		430
Partners’ equity
Partners’ capital	653		659
Accumulated other comprehensive loss	(2	)	(2	)

	1,154		1,153

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017		2016

Transmission revenues	74		74
Operating expenses	(17	)	(16	)
Depreciation	(15	)	(15	)
Financial charges and other	(4	)	(6	)

Net income	38		37

Great Lakes

EQUITY INVESTMENTS

Schedule of equity investments and summarized financial information for equity investees

(unaudited)
(millions of dollars)	March 31, 2017	December 31, 2016

ASSETS
Current assets	86	66
Plant, property and equipment, net	708	714

	794	780


LIABILITIES AND PARTNERS’ EQUITY
Current liabilities	31	40
Long-term debt, including current maturities, net	269	278
Partners’ equity	494	462

	794	780

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017		2016

Transmission revenues	63		61
Operating expenses	(14	)	(15	)
Depreciation	(7	)	(7	)
Financial charges and other	(5	)	(6	)

Net income	37		33

DEBT AND CREDIT FACILITIES (Tables)

3 Months Ended

Mar. 31, 2017

DEBT AND CREDIT FACILITIES

Schedule of debt and credit facilities

(unaudited) (millions of dollars)	March 31, 2017	Weighted Average Interest Rate for the Quarter Ended March 31, 2017		December 31, 2016	Weighted Average Interest Rate for the Year Ended December 31, 2016

TC PipeLines, LP
Senior Credit Facility due 2021	110	2.03	%	160	1.72	%
2013 Term Loan Facility due July 2018	500	2.03	%	500	1.73	%
2015 Term Loan Facility due September 2018	170	1.93	%	170	1.63	%
4.65% Unsecured Senior Notes due 2021	350	4.65	%(a)	350	4.65	%(a)
4.375% Unsecured Senior Notes due 2025	350	4.375	%(a)	350	4.375	%(a)
GTN
5.29% Unsecured Senior Notes due 2020	100	5.29	%(a)	100	5.29	%(a)
5.69% Unsecured Senior Notes due 2035	150	5.69	%(a)	150	5.69	%(a)
Unsecured Term Loan Facility due 2019	65	1.73	%	65	1.43	%
Tuscarora
Unsecured Term Loan due 2019	10	1.91	%	10	1.64	%
3.82% Series D Senior Notes due 2017	12	3.82	%(a)	12	3.82	%(a)

	1,817			1,867
Less: unamortized debt issuance costs and debt discount	8			9
Less: current portion	23			23

	1,786			1,835

(a)

Fixed interest rate

Schedule of principal repayments required on debt

(unaudited)
(millions of dollars)

2017		23
2018		691
2019		43
2020		100
2021		460
Thereafter		500

		1,817

NET INCOME PER COMMON UNIT (Tables)

3 Months Ended

Mar. 31, 2017

NET INCOME PER COMMON UNIT

Schedule of net income per common unit

(unaudited)	Three months ended March 31,
(millions of dollars, except per common unit amounts)	2017			2016

Net income attributable to controlling interests	75			73
Net income attributable to the General Partner	(1		)	(1		)
Incentive distributions attributable to the General Partner (a)	(2		)	(1		)

Net income attributable to common units	72			71

Weighted average common units outstanding (millions) — basic and diluted (b)	68.3			64.4
Net income per common unit — basic and diluted	$	1.05		$	1.10

(a)

(b)

Includes the common units subject to rescission. These units are treated as outstanding for financial reporting purposes. Refer to Note 6.

CHANGE IN OPERATING WORKING CAPITAL (Tables)

3 Months Ended

Mar. 31, 2017

CHANGE IN OPERATING WORKING CAPITAL

Schedule of change in operating working capital

(unaudited)	Three months ended March 31,
(millions of dollars)	2017		2016

Change in accounts receivable and other	3		(1	)
Change in other current assets	2		—
Change in accounts payable and accrued liabilities	(3	)	3	(a)
Change in accounts payable to affiliates	(1	)	(1	)
Change in accrued interest	4		5

Change in operating working capital	5		6

(a)

RELATED PARTY TRANSACTIONS (Tables)

3 Months Ended

Mar. 31, 2017

RELATED PARTY TRANSACTIONS

Summary of capital and operating costs charged to pipeline systems by related party

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017	2016

Capital and operating costs charged by TransCanada’s subsidiaries to:
Great Lakes (a)	8	7
Northern Border (a)	10	6
PNGTS (a)	2	2
GTN (a)	7	6
Bison (b)	1	(1	)
North Baja	1	1
Tuscarora	1	1
Impact on the Partnership’s net income:
Great Lakes	3	3
Northern Border	3	3
PNGTS	1	1
GTN	7	5
Bison	1	1
North Baja	1	1
Tuscarora	1	1

(a)

Represents 100 percent of the costs.

(b)

In March 2016, Bison sold excess pipe (at cost) to an affiliate.

Summary of amount payable to related party for costs charged

(unaudited)
(millions of dollars)	March 31, 2017	December 31, 2016

Net amounts payable to TransCanada’s subsidiaries is as follows:
Great Lakes (a)	3	4
Northern Border (a)	3	4
PNGTS (a)	1	1
GTN	3	3
Bison	—	1
North Baja	—	1
Tuscarora	1	1

(a)

Represents 100 percent of the costs.

(b)

In March 2016, Bison sold excess pipe (at cost) to an affiliate.

ACCOUNTS RECEIVABLE AND OTHER (Tables)

3 Months Ended

Mar. 31, 2017

ACCOUNTS RECEIVABLE AND OTHER

Schedule of accounts receivable and other

(unaudited)
(millions of dollars)	March 31, 2017	December 31, 2016

Trade accounts receivable, net of allowance of nil	31	34
Imbalance receivable from affiliates	1	2
Other	2	1

	34	37

FINANCIAL CHARGES AND OTHER (Tables)

3 Months Ended

Mar. 31, 2017

FINANCIAL CHARGES AND OTHER

Schedule of components of financial charges and other

	Three months ended
(unaudited)	March 31,
(millions of dollars)	2017	2016

Interest Expense (a)	16	17
Net realized loss related to the interest rate swaps (b)	—	—
Other Income (b)	—	—

	16	17

(a)

Includes debt issuance costs and amortization of discount costs.

(b)

Nil million for both periods.

VARIABLE INTEREST ENTITIES (Tables)

3 Months Ended

Mar. 31, 2017

VARIABLE INTEREST ENTITIES

Schedule of assets and liabilities held through VIEs whose assets cannot be used for purposes other settlement of their obligations

(unaudited)
(millions of dollars)	March 31, 2017		December 31, 2016

ASSETS (LIABILITIES) *
Accounts receivable and other	21		24
Inventories	6		6
Other current assets	3		4
Equity investments	1,062		1,044
Plant, property and equipment	844		847
Other assets	2		2
Accounts payable and accrued liabilities	(18	)	(20	)
Accounts payable to affiliates, net	(21	)	(28	)
Accrued interest	(5	)	(1	)
Current portion of long-term debt	(23	)	(23	)
Long-term debt	(313	)	(313	)
Other liabilities	(26	)	(25	)

- Definition

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

+ References + Details

ORGANIZATION - Ownership Interests in Natural Gas Pipeline Systems (Details)	3 Months Ended
	Mar. 31, 2017 LimitedPartnership
ORGANIZATION
Number of intermediate limited partnerships through which pipeline assets are owned	3

ACCOUNTING PRONOUNCEMENTS - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
ACCOUNTING PRONOUNCEMENTS
Distributions received from operating activities of equity investments (Note 3)	$ 31	$ 41
Adjustment \| ASU 2016-15, Statement of Cash Flows
ACCOUNTING PRONOUNCEMENTS
Cumulative distributions in excess of equity earnings		(8)
Distributions received from operating activities of equity investments (Note 3)		$ 8

EQUITY INVESTMENTS (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
EQUITY INVESTMENTS (Details) - USD ($) $ in Millions	Apr. 30, 2006	Mar. 31, 2017	Mar. 31, 2016	May 01, 2017	Apr. 28, 2017	Apr. 18, 2017	Dec. 31, 2016
EQUITY INVESTMENTS
Equity Earnings		$ 43	$ 42
Equity Investments		1,062					$ 1,044
LIABILITIES AND PARTNERS' EQUITY
Current portion of long-term debt		23					23
Amount borrowed			195
Great Lakes
EQUITY INVESTMENTS
Total cash call issued to fund debt repayment		$ 9
Northern Border
EQUITY INVESTMENTS
Ownership interest (as a percent)		50.00%			50.00%
Equity Earnings		$ 19	18
Equity Investments		441					444
Amortization period of transaction fee	12 years
Transaction fee	$ 10
Additional ownership interest acquired (as a percent)	20.00%
Assets
Cash and cash equivalents		18					14
Other current assets		36					36
Plant, property and equipment, net		1,085					1,089
Other assets		15					14
Assets, total		1,154					1,153
LIABILITIES AND PARTNERS' EQUITY
Current liabilities		44					38
Deferred credits and other		29					28
Long-term debt, including current maturities, net		430					430
Partners' equity
Partners' equity		653					659
Accumulated other comprehensive loss		(2)					(2)
Liabilities and Partners' Equity, total		1,154					1,153
Revenues (expenses)
Transmission revenues		74	74
Operating expenses		(17)	(16)
Depreciation		(15)	(15)
Financial charges and other		(4)	(6)
Net income		$ 38	37
Great Lakes
EQUITY INVESTMENTS
Ownership interest (as a percent)		46.45%		46.45%
Equity Earnings		$ 17	15
Equity Investments		489					474
Equity contribution		4	4
Assets
Current assets		86					66
Plant, property and equipment, net		708					714
Assets, total		794					780
LIABILITIES AND PARTNERS' EQUITY
Current liabilities		31					40
Long-term debt, including current maturities, net		269					278
Partners' equity
Partners' equity		494					462
Liabilities and Partners' Equity, total		794					780
Revenues (expenses)
Transmission revenues		63	61
Operating expenses		(14)	(15)
Depreciation		(7)	(7)
Financial charges and other		(5)	(6)
Net income		$ 37	33
Portland Natural Gas Transmission System
EQUITY INVESTMENTS
Ownership interest (as a percent)		49.90%				49.90%
Equity Earnings		$ 7	9
Equity Investments		132					$ 126
Undistributed earnings		$ 0
Equity contribution			$ 193

DEBT AND CREDIT FACILITIES - Amounts Outstanding and Description of Terms (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) entity	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Credit facilities, short-term loan facility and long-term debt
Long-term debt	$ 1,817,000,000
Debt and credit facilities	1,817,000,000		$ 1,867,000,000
Less: unamortized debt issuance costs and debt discount	8,000,000		9,000,000
Less: current portion	23,000,000		23,000,000
Long-term debt	$ 1,786,000,000		1,835,000,000
Amount borrowed		$ 195,000,000
Senior Credit Facility and the Term Loan Facilities due in 2018
Credit facilities, short-term loan facility and long-term debt
Leverage ratio, actual (as a percent)	4.04%
Senior Credit Facility and the Term Loan Facilities due in 2018 \| Debt agreement covenants, initial period after occurrence of acquisition
Credit facilities, short-term loan facility and long-term debt
Additional period immediately following the fiscal quarter in which a specified material acquisition occurs	6 months
Senior Credit Facility and the Term Loan Facilities due in 2018 \| Debt agreement covenants, initial period after occurrence of acquisition \| Minimum
Credit facilities, short-term loan facility and long-term debt
Number of acquisitions \| entity	1
Senior Credit Facility and the Term Loan Facilities due in 2018 \| Debt agreement covenants, initial period after occurrence of acquisition \| Maximum
Credit facilities, short-term loan facility and long-term debt
Leverage ratio, covenant (as a percent)	550.00%
Senior Credit Facility and the Term Loan Facilities due in 2018 \| Debt agreement covenants, periods subsequent to initial period after occurrence of acquisition \| Maximum
Credit facilities, short-term loan facility and long-term debt
Leverage ratio, covenant (as a percent)	500.00%
Revolving credit facility \| TC Pipelines, LP Senior Credit Facility due 2021
Credit facilities, short-term loan facility and long-term debt
Debt and credit facilities	$ 110,000,000		$ 160,000,000
Weighted Average Interest Rate (as a percent)	2.03%		1.72%
Maximum borrowing capacity	$ 500,000,000
Amount outstanding under credit facility	110,000,000		$ 160,000,000
Remaining borrowing capacity	$ 390,000,000
Revolving credit facility \| TC Pipelines, LP Senior Credit Facility due 2021 \| LIBOR
Credit facilities, short-term loan facility and long-term debt
Debt interest rate, at period end (as a percent)	2.04%		1.92%
Term loan \| TC PipeLines, LP 2013 Term Loan Facility due July 2018
Credit facilities, short-term loan facility and long-term debt
Debt and credit facilities	$ 500,000,000		$ 500,000,000
Weighted Average Interest Rate (as a percent)	2.03%		1.73%
Term loan \| TC PipeLines, LP 2013 Term Loan Facility due July 2018 \| LIBOR borrowings \| LIBOR
Credit facilities, short-term loan facility and long-term debt
Debt interest rate, at period end (as a percent)	2.04%		1.87%
Term loan \| TC PipeLines, LP 2013 Term Loan Facility due July 2018 \| LIBOR borrowings \| LIBOR \| Hedges of cash flows \| Interest rate swaps
Credit facilities, short-term loan facility and long-term debt
Weighted Average Interest Rate (as a percent)	2.31%		2.31%
Term loan \| TC PipeLines, LP 2015 Term Loan Facility due September 2018
Credit facilities, short-term loan facility and long-term debt
Debt and credit facilities	$ 170,000,000		$ 170,000,000
Weighted Average Interest Rate (as a percent)	1.93%		1.63%
Term loan \| TC PipeLines, LP 2015 Term Loan Facility due September 2018 \| LIBOR
Credit facilities, short-term loan facility and long-term debt
Debt interest rate, at period end (as a percent)	1.93%		1.77%
Unsecured debt \| TC PipeLines, LP 4.65% Senior Notes due 2021
Credit facilities, short-term loan facility and long-term debt
Stated interest rate (as a percent)	4.65%		4.65%
Debt and credit facilities	$ 350,000,000		$ 350,000,000
Weighted Average Interest Rate (as a percent)	4.65%		4.65%
Unsecured debt \| TC PipeLines, LP 4.375% Senior Notes due 2025
Credit facilities, short-term loan facility and long-term debt
Stated interest rate (as a percent)	4.375%		4.375%
Debt and credit facilities	$ 350,000,000		$ 350,000,000
Weighted Average Interest Rate (as a percent)	4.375%		4.375%
Unsecured debt \| GTN 5.29% Senior Notes due 2020
Credit facilities, short-term loan facility and long-term debt
Stated interest rate (as a percent)	5.29%		5.29%
Debt and credit facilities	$ 100,000,000		$ 100,000,000
Weighted Average Interest Rate (as a percent)	5.29%		5.29%
Unsecured debt \| GTN 5.69% Senior Notes due 2035
Credit facilities, short-term loan facility and long-term debt
Stated interest rate (as a percent)	5.69%		5.69%
Debt and credit facilities	$ 150,000,000		$ 150,000,000
Weighted Average Interest Rate (as a percent)	5.69%		5.69%
Unsecured debt \| GTN Term Loan Facility due 2019
Credit facilities, short-term loan facility and long-term debt
Debt and credit facilities	$ 65,000,000		$ 65,000,000
Weighted Average Interest Rate (as a percent)	1.73%		1.43%
Unsecured debt \| Tuscarora Term Loan due 2019
Credit facilities, short-term loan facility and long-term debt
Debt and credit facilities	$ 10,000,000		$ 10,000,000
Weighted Average Interest Rate (as a percent)	1.91%		1.64%
Secured debt \| Tuscarora 3.82% Series D Senior Notes due 2017
Credit facilities, short-term loan facility and long-term debt
Stated interest rate (as a percent)	3.82%		3.82%
Debt and credit facilities	$ 12,000,000		$ 12,000,000
Weighted Average Interest Rate (as a percent)	3.82%		3.82%
GTN \| Unsecured debt \| Senior Notes and Term Loan Facility due 2019
Credit facilities, short-term loan facility and long-term debt
Debt interest rate, at period end (as a percent)	1.73%		1.57%
Percentage of debt to total capitalization, actual	44.70%
GTN \| Unsecured debt \| Senior Notes and Term Loan Facility due 2019 \| Maximum
Credit facilities, short-term loan facility and long-term debt
Percentage of debt to total capitalization, covenant	70.00%
Tuscarora Gas Transmission Company \| Unsecured debt \| Tuscarora Term Loan due 2019 \| LIBOR
Credit facilities, short-term loan facility and long-term debt
Debt interest rate, at period end (as a percent)	2.12%		1.90%
Tuscarora Gas Transmission Company \| Unsecured debt \| Tuscarora 3.82% Series D Senior Notes due 2017
Credit facilities, short-term loan facility and long-term debt
Percentage of debt to total capitalization, actual	21.05%
Debt Service Coverage, Actual (as a percent)	3.92%
Tuscarora Gas Transmission Company \| Unsecured debt \| Tuscarora 3.82% Series D Senior Notes due 2017 \| Minimum
Credit facilities, short-term loan facility and long-term debt
Debt Service Coverage, covenant (as a percent)	300.00%
Tuscarora Gas Transmission Company \| Unsecured debt \| Tuscarora 3.82% Series D Senior Notes due 2017 \| Maximum
Credit facilities, short-term loan facility and long-term debt
Percentage of debt to total capitalization, covenant	45.00%

DEBT AND CREDIT FACILITIES - Principal Payments Required (Details) $ in Millions	Mar. 31, 2017 USD ($)
Principal repayments required on debt
2017	$ 23
2018	691
2019	43
2020	100
2021	460
Thereafter	500
Total debt	$ 1,817

PARTNERS' EQUITY - ATM Equity Issuance Program (Details) - USD ($)	1 Months Ended	2 Months Ended	3 Months Ended	4 Months Ended	9 Months Ended
	Mar. 31, 2016	May 09, 2016	Mar. 31, 2017	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2016
Partners' Equity
Net proceeds from issuance of common units			$ 71,000,000
Common units subject to rescission			64,000,000				$ 83,000,000
General Partner
Partners' Equity
Net proceeds from issuance of common units			$ 2,000,000
TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Ownership interest in the Partnership (as a percent)			2.00%		2.00%	2.00%
ATM Equity Issuance Program \| Common units
Partners' Equity
Units sold			1,197,749
Net proceeds from issuance of common units			$ 69,000,000
Sales agent commissions			704,000
Period of time for Section 5 Securities violations to be filed within				1 year
Reclassification of common unit issuance subject to rescission, net (in units)	400,000	1,600,000
Common units subject to rescission							$ 83,000,000
ATM Equity Issuance Program \| TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Equity contribution			$ 2,000,000

PARTNERS' EQUITY - Class B Units (Details) - USD ($)	3 Months Ended
PARTNERS' EQUITY - Class B Units (Details) - USD ($)	Mar. 31, 2017	Mar. 31, 2016
Class B units
Partners' Equity
Limited Partners, Distributions paid	$ 22,000,000	$ 12,000,000
Common units
Partners' Equity
Net income attributable to limited partners	$ 72,000,000	71,000,000
GTN \| TransCanada \| Distributions \| Class B units
Partners' Equity
Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)	30.00%
Percentage applied to 30 percent of GTN's distributions above threshold through March 31, 2020	100.00%
Threshold of GTN's total distributable cash flows for payment to Class B units	$ 20,000,000
Percentage applied to GTN's distributions above threshold after March 31, 2020	25.00%
Percentage applied to GTN's distributable cash flow for the twelve month period ending December 31, 2017	30.00%
Net income attributable to limited partners	$ 0	$ 0

PARTNERS' EQUITY - Reclassification of units (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2016
Partners' Equity
Common units issuance subject to rescission net			$ 19
Net proceeds from issuance of common units		$ 71
Reclassification of common units no longer subject to rescission (Note 6 )		$ 19
Common units
Partners' Equity
Reclassification of common units no longer subject to rescission (Note 6 )	$ 19

NET INCOME PER COMMON UNIT - General Partner Effective Interest and Allocated Incentive Distributions (Details)	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2015
TC PipeLines GP, Inc. \| General Partner
Partners' Equity
General partner interest (as a percent)	2.00%	2.00%	2.00%

NET INCOME PER COMMON UNIT - Terms of Class B Unit Distributions and Determination of Net Income (Loss) per Common Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Net income (loss) per common unit
Net income attributable to controlling interests	$ 75	$ 73
Net income attributable to General Partner	(1)	(1)
Incentive distributions attributable to the General Partner	(2)	(1)
Common units
Net income (loss) per common unit
Net income attributable to limited partners	$ 72	$ 71
Weighted average common units outstanding - basic (in units)	68.3	64.4
Weighted average common units outstanding - diluted (in units)	68.3	64.4
Net income per common unit - basic (in dollars per unit)	$ 1.05	$ 1.10
Net income per common unit - diluted (in dollars per unit)	$ 1.05	$ 1.10
GTN \| Class B units \| TransCanada \| Distributions
Net income (loss) per common unit
Net income attributable to limited partners	$ 0	$ 0
Distributions
Percentage applied to GTN's distributable cash flow for the twelve month period ending December 31, 2017	30.00%
Threshold of GTN's distributions for payment to Class B units	$ 20		$ 20
Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)	30.00%

CASH DISTRIBUTIONS TO COMMON UNITS - Distributions Paid (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Common units
Distributions
Per Unit Distribution, paid (in dollars per unit)	$ 0.94	$ 0.89
Total cash distribution	$ 68	$ 60
Common units and General Partner interest combined
Distributions
Total distribution of general partner interest and IDR payment	4
TC PipeLines GP, Inc. \| General Partner
Distributions
Total distribution for General Partner interest	$ 2	1
General partner interest (as a percent)	2.00%		2.00%	2.00%
TC PipeLines GP, Inc. \| Common units and General Partner interest combined
Distributions
Incentive distribution paid to the General Partner	$ 2	$ 1

CHANGE IN OPERATING WORKING CAPITAL - Components (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CHANGE IN OPERATING WORKING CAPITAL
Change in accounts receivable and other	$ 3	$ (1)
Change in other current assets	2
Change in accounts payable and accrued liabilities	(3)	3
Change in accounts payable to affiliates	(1)	(1)
Change in accrued interest	4	5
Change in operating working capital	$ 5	$ 6

CHANGE IN OPERATING WORKING CAPITAL - GTN's Carty Lateral Construction Accrual (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2015
Non-cash items
Capital expenditures	$ 7	$ 11
GTN
Non-cash items
Accruals for capital expenditures			$ 10
Capital expenditures		$ 10

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Millions			3 Months Ended		12 Months Ended
	Apr. 18, 2017	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	May 01, 2017	Apr. 28, 2017
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable		$ 6.0	$ 6.0		$ 7.0
Amount included in receivables from related party		$ 1.0	1.0		2.0
Partnership distribution			90.0
Partnership's share of distributions			$ 31.0	$ 41.0
Great Lakes
Capital and operating costs charged to the pipeline systems and amount payable
Interest acquired (as a percent)		46.45%	46.45%			46.45%
Great Lakes \| FERC
Capital and operating costs charged to the pipeline systems and amount payable
Estimated revenue sharing provision			$ 3.4		7.2
Northern Border
Capital and operating costs charged to the pipeline systems and amount payable
Interest acquired (as a percent)		50.00%	50.00%				50.00%
Portland Natural Gas Transmission System
Capital and operating costs charged to the pipeline systems and amount payable
Interest acquired (as a percent)	49.90%	49.90%	49.90%
Portland Natural Gas Transmission System \| Distribution declared
Capital and operating costs charged to the pipeline systems and amount payable
Partnership distribution		$ 5.0
Portland Natural Gas Transmission System \| Cash Distribution Paid
Capital and operating costs charged to the pipeline systems and amount payable
Partnership's share of distributions	$ 2.0
General Partner \| Reimbursement of costs of services provided
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 1.0	1.0
TransCanada's subsidiaries \| GTN
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable		3.0	3.0		3.0
TransCanada's subsidiaries \| GTN \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			7.0	6.0
Impact on the Partnership's net income attributable to controlling interests			$ 7.0	$ 5.0
Percentage of capital and operating costs charged			100.00%	100.00%
TransCanada's subsidiaries \| Northern Border
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable		3.0	$ 3.0		4.0
Percentage of capital and operating costs charged			100.00%	100.00%
TransCanada's subsidiaries \| Northern Border \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 10.0	$ 6.0
Percentage of capital and operating costs charged			100.00%	100.00%
TransCanada's subsidiaries \| Portland Natural Gas Transmission System
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable		1.0	$ 1.0		1.0
Percentage of capital and operating costs charged			100.00%	100.00%
TransCanada's subsidiaries \| Portland Natural Gas Transmission System \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 2.0	$ 2.0
Percentage of capital and operating costs charged			100.00%	100.00%
TransCanada's subsidiaries \| Bison
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable					1.0
TransCanada's subsidiaries \| Bison \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 1.0
Revenue, net of costs charged				$ (1.0)
Impact on the Partnership's net income attributable to controlling interests			1.0	$ 1.0
TransCanada's subsidiaries \| Great Lakes
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable		3.0	$ 3.0		4.0
Percentage of capital and operating costs charged			100.00%	100.00%
Amount included in receivables from related party		16.0	$ 16.0		19.0
TransCanada's subsidiaries \| Great Lakes \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 8.0	$ 7.0
Percentage of capital and operating costs charged			100.00%	100.00%
TransCanada's subsidiaries \| North Baja Pipeline, LLC
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable					1.0
TransCanada's subsidiaries \| North Baja Pipeline, LLC \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			$ 1.0	$ 1.0
Impact on the Partnership's net income attributable to controlling interests			1.0	1.0
TransCanada's subsidiaries \| Tuscarora Gas Transmission Company
Capital and operating costs charged to the pipeline systems and amount payable
Net amounts payable		$ 1.0	1.0		$ 1.0
TransCanada's subsidiaries \| Tuscarora Gas Transmission Company \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged			1.0	1.0
Impact on the Partnership's net income attributable to controlling interests			1.0	1.0
TransCanada's subsidiaries \| Great Lakes \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Impact on the Partnership's net income attributable to controlling interests			$ 3.0	$ 3.0
TransCanada's subsidiaries \| Great Lakes \| Transportation contracts \| Total net revenues \| Customer concentration risk
Capital and operating costs charged to the pipeline systems and amount payable
Percent of total revenues			67.00%	76.00%
TransCanada's subsidiaries \| Northern Border \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Impact on the Partnership's net income attributable to controlling interests			$ 3.0	$ 3.0
TransCanada's subsidiaries \| Portland Natural Gas Transmission System \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Impact on the Partnership's net income attributable to controlling interests			$ 1.0	$ 1.0

FAIR VALUE MEASUREMENTS - Estimated Fair Value of Debt (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value \| Level 2
Financial Instruments
Fair value of debt	$ 1,863	$ 1,908

FAIR VALUE MEASUREMENTS - Interest Rate Swaps (Details) - Interest rate swaps - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Term loan \| TC PipeLines, LP 2013 Term Loan Facility due July 2018
Interest rate derivatives
Weighted average fixed interest rate (as a percent)	2.31%
Hedges of cash flows
Interest rate derivatives
Change in fair value of interest rate derivative instruments recognized in other comprehensive income (loss)	$ 1	$ (2)
Hedges of cash flows \| Financial charges and other.
Interest rate derivatives
Net realized loss related to the interest rate swaps	0	$ 0
Hedges of cash flows \| Recurring fair value measurement \| Level 2
Interest rate derivatives
Fair value of derivatives, net	2
Designated as hedge \| Recurring fair value measurement \| Level 2
Interest rate derivatives
Fair value of derivative asset, gross	$ 2
Fair value of derivative liability, gross			$ 0
Designated as hedge \| Hedges of cash flows \| Level 2
Interest rate derivatives
Fair value of derivative asset, gross			1
Fair value of derivative liability, gross			$ 1

ACCOUNTS RECEIVABLE AND OTHER (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
ACCOUNTS RECEIVABLE AND OTHER
Trade accounts receivable, net of allowance of nil	$ 31	$ 34
Imbalance receivable from affiliates	1	2
Other	2	1
Accounts receivable and other	34	37
Trade accounts receivable, allowance	$ 0	$ 0

FINANCIAL CHARGES AND OTHER (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
FINANCIAL CHARGES AND OTHER
Interest Expense	$ 16	$ 17
Financial charges and other	$ 16	$ 17

CONTINGENCIES (Details) - Great Lakes v. Essar Steel Minnesota LLC, et al. - Great Lakes - USD ($) $ in Millions			1 Months Ended
	Sep. 16, 2015	Oct. 29, 2009	Apr. 30, 2017
Contingencies
Judgement awarded			$ 31.5
Essar
Contingencies
Recovery sought		$ 33.0
Judgement awarded	$ 32.9

REGULATORY (Details)	Jan. 06, 2017 item
North Baja Pipeline, LLC \| FERC
Goodwill and Regulatory Matters
Number of compression units	2

VARIABLE INTEREST ENTITIES - Consolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
ASSETS (LIABILITIES)
Accounts receivable and other	$ 34	$ 37
Inventories	7	7
Other current assets	4	5
Equity investments	1,062	1,044
Plant, property and equipment	1,866	1,881
Other assets	1	1
Accounts payable and accrued liabilities	(24)	(27)
Accounts payable to affiliates	(6)	(7)
Accrued interest	(13)	(9)
Current portion of long-term debt	(23)	(23)
Long-term debt	(1,786)	(1,835)
Other liabilities	(28)	(28)
Consolidated VIEs \| Restricted VIEs
ASSETS (LIABILITIES)
Accounts receivable and other	21	24
Inventories	6	6
Other current assets	3	4
Equity investments	1,062	1,044
Plant, property and equipment	844	847
Other assets	2	2
Accounts payable and accrued liabilities	(18)	(20)
Accounts payable to affiliates	(21)	(28)
Accrued interest	(5)	(1)
Current portion of long-term debt	(23)	(23)
Long-term debt	(313)	(313)
Other liabilities	$ (26)	$ (25)

SUBSEQUENT EVENTS - Distributions (Details) - USD ($) $ / shares in Units, $ in Millions											3 Months Ended		9 Months Ended
	May 15, 2017	May 03, 2017	May 01, 2017	Apr. 28, 2017	Apr. 25, 2017	Apr. 24, 2017	Apr. 19, 2017	Apr. 18, 2017	Apr. 07, 2017	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Distributions
Partnership distribution											$ 90.0
Partnership's share of distributions											$ 31.0	$ 41.0
Northern Border
Distributions
Ownership interest (as a percent)				50.00%						50.00%	50.00%
Great Lakes
Distributions
Ownership interest (as a percent)			46.45%							46.45%	46.45%
Portland Natural Gas Transmission System
Distributions
Ownership interest (as a percent)								49.90%		49.90%	49.90%
Distribution declared \| Portland Natural Gas Transmission System
Distributions
Partnership distribution										$ 5.0
Cash Distribution Paid \| Portland Natural Gas Transmission System
Distributions
Partnership's share of distributions								$ 2.0
Subsequent Events
Distributions
Total cash distribution	$ 68.0
Subsequent Events \| Distribution declared \| Northern Border
Distributions
Partnership distribution									$ 13.0
Subsequent Events \| Distribution declared \| Great Lakes
Distributions
Partnership distribution							$ 43.0
Subsequent Events \| Cash Distribution Paid \| Northern Border
Distributions
Partnership's share of distributions				$ 7.0
Subsequent Events \| Cash Distribution Paid \| Great Lakes
Distributions
Partnership's share of distributions			$ 20.0
Common units and General Partner interest combined
Distributions
Total distribution of general partner interest and IDR payment											$ 4.0
General Partner
Distributions
Partnership distribution											4.0
TC PipeLines GP, Inc. \| Subsequent Events
Distributions
General partner cash distributions					$ 3.0
Ownership interest (as a percent)					2.00%
Total Distribution For General Partner Interest					$ 1.0
TC PipeLines GP, Inc. \| Common units and General Partner interest combined
Distributions
General Partner IDRs paid											$ 2.0	1.0
TC PipeLines GP, Inc. \| General Partner
Distributions
Ownership interest in the Partnership (as a percent)											2.00%		2.00%	2.00%
Total Distribution For General Partner Interest											$ 2.0	1.0
TC PipeLines GP, Inc. \| General Partner \| Subsequent Events \| Distribution declared
Distributions
Distribution declared for IDRs					$ 2.0
TransCanada \| Subsequent Events \| Great Lakes
Distributions
Contract term						10 years
Total contract value						$ 758.0
Forecast \| Subsequent Events \| Iroquois
Distributions
Ownership interest (as a percent)		49.34%
Future option to acquire (as a percent)		0.66%
Forecast \| Subsequent Events \| Portland Natural Gas Transmission System
Distributions
Interest acquired by Partnership (as a percent)		11.81%
Forecast \| Subsequent Events \| Portland Natural Gas Transmission System
Distributions
Ownership interest, including acquired interest (as a percent)		61.71%
Forecast \| Subsequent Events \| Portland Natural Gas Transmission System \| Portland Natural Gas Transmission System And Iroquois Acquisition
Distributions
Purchase price		$ 765.0
Cash consideration		597.0
Assumption of proportional debt		$ 168.0
Common units
Distributions
Total cash distribution											$ 68.0	$ 60.0
Number of units										68,600,000	68,600,000	64,700,000
Common units \| Subsequent Events
Distributions
Per Unit Distribution, declared (in dollars per unit)					$ 0.94
Distribution declared					$ 65.0
Common units \| Limited Partners
Distributions
Partnership distribution											$ 64.0
Common units \| TC PipeLines GP, Inc. \| Subsequent Events
Distributions
Limited Partners, Distributions paid	5.0
Common units \| TC PipeLines GP, Inc. \| Limited Partners
Distributions
Number of units					5,797,106
Common units \| TransCanada \| Subsequent Events
Distributions
Limited Partners, Distributions paid	$ 11.0
Common units \| TransCanada \| TC PipeLines GP, Inc.
Distributions
Number of units					11,287,725
Class B units
Distributions
Distribution declared											22.0
Limited Partners, Distributions paid											22.0	$ 12.0
Class B units \| Limited Partners
Distributions
Partnership distribution											$ 22.0