Segment Information - Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total segment adjusted EBITDA	$ 2,209	$ 2,228
Depreciation and amortization	(1,160)	(1,188)
Impairment of goodwill	0	(6,506)
Stock-based compensation	(69)	(33)
Total other expense, net	(547)	(528)
INCOME (LOSS) BEFORE INCOME TAXES	433	(6,027)
Income tax expense	(119)	(138)
NET INCOME (LOSS)	314	(6,165)
Operating segments
Segment Reporting Information [Line Items]
Total segment adjusted EBITDA	3,828	3,974
Operations and Other
Segment Reporting Information [Line Items]
Total segment adjusted EBITDA	(1,619)	(1,746)
Depreciation and amortization	(1,160)	(1,188)
Impairment of goodwill	0	(6,506)
Other operating expenses	(1,619)	(1,746)
Operating income (loss)	980	(5,499)
Total other expense, net	$ (547)	$ (528)