CONSOLIDATED STATEMENT OF PARTNERS' CAPITAL - USD ($) $ in Millions	Total	Accumulated Other Comprehensive Income (Loss)	Limited Partner [Member]
Balance at Dec. 31, 2017	$ 1,345	$ (3)	$ 1,348
Other comprehensive income, net of tax	(42)	(42)	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax	(42)
Non-Cash Equity Contribution	31	0	31
Net income (loss)	108	0	108
Distribution to partners	(95)	0	(95)
Panhandle Merger	(15)	2	(17)
Balance at Dec. 31, 2018	1,362	(47)	1,409
Other comprehensive income, net of tax	23		0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax	23
Net income (loss)	589	0	589
Distribution to partners	(375)	0	(375)
Panhandle Merger	(3)	0	(3)
Balance at Dec. 31, 2019	1,602	(24)	1,626
Other comprehensive income, net of tax	21		0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax	21
Non-Cash Equity Contribution	4	0	4
Net income (loss)	171	0	171
Panhandle Merger	4	6	(2)
Balance at Dec. 31, 2020	$ 1,794	$ (9)	$ 1,803