CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016
Cash Generated From Operations
Net income		$ 193	[1]	$ 198	[2]
Depreciation		73		71	[2]
Amortization of debt issue costs reported as interest expense		1		1	[2]
Amortization of realized loss on derivative instrument		1		1	[2]
Equity earnings from equity investments (Note 3 and 4)		(87)		(75)	[2]
Distributions received from operating activities of equity investments (Note 3)		106		125	[2]
Change in operating working capital (Note 10)		24		11	[2]
Net Cash Provided by (Used in) Operating Activities		311		332	[2]
Investing Activities
Distribution received from Iroquois as return of investment (Note 4)		3
Capital expenditures		(26)		(21)	[2]
Other	[2]			3
Net Cash Provided by (Used in) Investing Activities		(756)		(215)	[2]
Financing Activities
Distributions paid to non-controlling interests		(5)		(12)	[2]
Common unit issuance, net (Note 7)		126		35	[2]
Common unit issuance subject to rescission, net (Note 7)	[2]			83
Long-term debt issued, net of discount (Note 5)		732		200	[2]
Long-term debt repaid (Note 5)		(164)		(196)	[2]
Debt issuance costs		(2)
Total financing activities		454		(95)	[2]
Decrease in cash and cash equivalents		9		22	[2]
Cash and cash equivalents, beginning of period	[2]	64		55
Cash and cash equivalents, end of period		73		77	[2]
Class B Units
Financing Activities
Distributions paid (Note 7)		(22)		(12)	[2]
Common units and General Partner interest combined
Financing Activities
Distributions paid (Note 9)		(210)		(184)	[2]
Northern Border
Cash Generated From Operations
Equity earnings from equity investments (Note 3 and 4)		(50)		(52)
Investing Activities
Investment/Acquisition of interests		(83)
Great Lakes
Cash Generated From Operations
Equity earnings from equity investments (Note 3 and 4)		(24)		(23)
Investing Activities
Investment/Acquisition of interests		(4)		(4)	[2]
Portland Natural Gas Transmission System
Investing Activities
Investment/Acquisition of interests	[2]			(193)
Financing Activities
Distributions paid to former parent of PNGTS		(1)		$ (9)	[2]
Portland Natural Gas Transmission System And Iroquois Acquisition
Investing Activities
Investment/Acquisition of interests		$ (646)

[1] Recast to consolidate PNGTS for all periods presented (Refer to Notes 2 and 6).

[2] Recast to consolidate PNGTS for all periods presented (Refer to Notes 2 and 6).