CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Cash Generated From Operations
Net income		$ 138	$ 138	[1]
Depreciation		49	48	[1]
Amortization of debt issue costs reported as interest expense		1	1	[1]
Amortization of realized loss on derivative instrument		(1)	(1)	[1]
Accrual for costs related to the 2017 Acquisition		1
Deferred state income tax recovery (Note 18)	[1]		(7)
Equity earnings from equity investments (Note 3 and 4)		(60)	(53)	[1]
Distributions received from operating activities of equity investments (Note 3)		68	95	[1]
Change in operating working capital (Note 10)		7	12	[1]
Net Cash Provided by (Used in) Operating Activities		205	235	[1]
Investing Activities
Capital expenditures		(16)	(18)	[1]
Other	[1]		2
Net Cash Provided by (Used in) Investing Activities		(625)	(213)	[1]
Financing Activities
Distributions paid to non-controlling interests		(5)	(9)	[1]
Common unit issuance, net (Note 7)		92
Common unit issuance subject to rescission, net (Note 7)	[1]		83
Long-term debt issued, net of discount (Note 5)		607	205	[1]
Long-term debt repaid (Note 5)		(128)	(165)	[1]
Debt issuance costs		(1)
Total financing activities		407	(25)	[1]
Decrease in cash and cash equivalents		(13)	(3)	[1]
Cash and cash equivalents, beginning of period	[1]	64	55
Cash and cash equivalents, end of period		51	52	[1]
Class B Units
Financing Activities
Distributions paid (Note 7)		(22)	(12)	[1]
Common units and General Partner interest combined
Financing Activities
Distributions paid (Note 9)		(135)	(119)	[1]
Great Lakes
Cash Generated From Operations
Equity earnings from equity investments (Note 3 and 4)		(23)	(19)
Investing Activities
Investment/Acquisition of interests		(4)	(4)	[1]
Portland Natural Gas Transmission System
Investing Activities
Investment/Acquisition of interests	[1]		(193)
Financing Activities
Distributions paid to former parent of PNGTS		(1)	$ (8)	[1]
Portland Natural Gas Transmission System And Iroquois Acquisition
Investing Activities
Investment/Acquisition of interests		$ (605)

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