CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Total operating revenue	$ 7,313	$ 8,052	$ 8,395
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)	1,995	2,333	2,669
Selling, general and administrative	564	659	799
Operating expenses - affiliates	728	812	831
Depreciation and amortization	1,315	1,364	1,436
Total operating expenses	4,602	5,168	5,735
OPERATING INCOME	2,711	2,884	2,660
OTHER (EXPENSE) INCOME
Interest expense	(279)	(380)	(448)
Interest expense - affiliates, net	(74)	(62)	(57)
Other (expense) income, net	(56)	26	4
Total other expense, net	(409)	(416)	(501)
INCOME BEFORE INCOME TAXES	2,302	2,468	2,159
Income tax expense	595	641	494
NET INCOME	1,707	1,827	1,665
Non-Affiliate Services
Revenue from Contract with Customer [Abstract]
Total operating revenue	4,826	5,179	5,460
Affiliate services
Revenue from Contract with Customer [Abstract]
Total operating revenue	$ 2,487	$ 2,873	$ 2,935