CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Cash Generated from Operations
Net income	$ 68	$ 59	$ 223	$ 216
Depreciation and amortization	29	19	68	58
Amortization of debt issue costs reported as interest expense			1	1
Equity earnings from equity investments (Note 5)	(39)	(31)	(123)	(115)
Distributions received from operating activities of equity investments (Note 5)			161	168
Equity allowance for funds used during construction (AFUDC Equity)			(6)	(1)
Change in operating working capital (Note 11)			17	16
Other			(2)	1
Cash Generated from Operations			339	344
Investing Activities
Proceeds from return of investment			29	58
Capital expenditures			(159)	(48)
Customer advances for construction			(1)	0
Investing Activities			(136)	1
Financing Activities
Distributions paid to common units, including the General Partner (Note 10)			(142)	(142)
Distributions paid to Class B units (Note 8)			(8)	(13)
Distributions paid to non-controlling interests			(18)	(18)
Long-term debt issued, net of discount (Note 7)			235	21
Long-term debt repaid (Note 7)			(100)	(136)
Financing Activities			(33)	(288)
Increase in cash and cash equivalents			170	57
Cash and cash equivalents, beginning of period			83	33	$ 33
Cash and cash equivalents, end of period	253	90	253	90	$ 83
Great Lakes
Cash Generated from Operations
Equity earnings from equity investments (Note 5)	(10)	(8)	(39)	(37)
Distributions received from operating activities of equity investments (Note 5)	11	9	48	48
Investing Activities
Investment in Great Lakes (Note 5)			(5)	(5)
Iroquois
Cash Generated from Operations
Equity earnings from equity investments (Note 5)	(7)	(8)	(27)	(28)
Investing Activities
Investment in Great Lakes (Note 5)			0	(4)
Proceeds from return of investment			29	8
Northern Border
Cash Generated from Operations
Equity earnings from equity investments (Note 5)	(22)	(15)	(57)	(50)
Distributions received from operating activities of equity investments (Note 5)	$ 22	$ 21	68	121
Investing Activities
Proceeds from return of investment			$ 0	$ 50