Segment Information - Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Total adjusted EBITDA	$ 2,089	$ 2,085	$ 4,246	$ 4,294
Depreciation and amortization	(1,041)	(1,162)	(2,191)	(2,322)
OPERATING INCOME	1,006	903	1,993	1,883
Total other expense, net	(332)	(390)	(687)	(937)
INCOME BEFORE INCOME TAXES	674	513	1,306	946
Income tax expense	168	136	325	255
NET INCOME	506	377	981	691
Operating Segments
Segment Reporting Information [Line Items]
Total adjusted EBITDA	3,575	3,747	7,241	7,537
Operations and Other
Segment Reporting Information [Line Items]
Total adjusted EBITDA	(1,486)	(1,662)	(2,995)	(3,243)
Depreciation and amortization	(1,041)	(1,162)	(2,191)	(2,322)
Other operating expenses	(1,486)	(1,662)	(2,995)	(3,243)
Stock-based compensation	(42)	(20)	(62)	(89)
OPERATING INCOME	1,006	903	1,993	1,883
Total other expense, net	$ (332)	$ (390)	$ (687)	$ (937)