CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
OPERATING REVENUES:
Total operating revenues	$ 113		$ 132	$ 439	$ 402
OPERATING EXPENSES:
Operating and maintenance	54		40	141	129
General and administrative	8		10	26	29
Depreciation and amortization	26		27	78	79
Total operating expenses	88		77	245	237
OPERATING INCOME	25		55	194	165
OTHER INCOME (EXPENSE):
Interest expense, net	(4)		(3)	(11)	(10)
Interest expense — related company	(4)		(8)	(14)	(25)
Other, net	(1)		(1)	(1)	(5)
INCOME BEFORE INCOME TAX BENEFIT	16		43	168	125
Income tax expense	0		(1)	0	(2)
NET INCOME	16	$ 126	44	168	127
OTHER COMPREHENSIVE INCOME, NET OF TAX
Actuarial gain relating to postretirement benefit plans	0	$ 6	4	6	13
COMPREHENSIVE INCOME	16		48	174	140
Natural Gas, US Regulated [Member]
OPERATING REVENUES:
Transportation and storage of natural gas	108		127	425	388
Product and Service, Other [Member]
OPERATING REVENUES:
Transportation and storage of natural gas	$ 5		$ 5	$ 14	$ 14