CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid in Capital	Accumulated Loss	Accumulated Loss Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock	Accumulated Other Comprehensive Loss	Noncontrolling Interest
Beginning balance at Dec. 31, 2017	$ (2,027)	$ (11)	$ 1	$ 808	$ (2,461)	$ (11)	$ (175)	$ (200)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net redemption of common stock in connection with stock options and RSUs	(16)			16
Stock-based compensation	43			43
Net loss	(352)				(352)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(352)
Other Comprehensive Income (Loss), Net of Tax	(100)							(100)
Ending balance at Dec. 31, 2018	$ (2,463)		1	835	(2,824)		(175)	(300)	0
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201905Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net redemption of common stock in connection with stock options and RSUs	$ 12			12
Gain (Loss) on Disposition of Stock in Subsidiary	419
Proceeds from Issuance Initial Public Offering				328					91
Stock-based compensation	34			33
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	1
Net loss	(130)				(130)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	12
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(118)
Other Comprehensive Income (Loss), Net of Tax	8							8
Ending balance at Dec. 31, 2019	(2,108)	$ (6)	1	1,208	(2,954)	$ (6)	(175)	(292)	104
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net redemption of common stock in connection with stock options and RSUs	4			4
Stock-based compensation	60			56					4
Net loss	(569)				(569)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	21
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(548)
Other Comprehensive Income (Loss), Net of Tax	74							74
Ending balance at Dec. 31, 2020	$ (2,524)		$ 1	$ 1,268	$ (3,529)		$ (175)	$ (218)	$ 129