CONSOLIDATED CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Cumulative effect of accounting change	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Cumulative effect of accounting change	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance at Dec. 31, 2019	$ 656	$ (1)	$ 1	$ 6,741	$ (785)	$ (1)	$ (157)	$ (5,144)
Beginning Balance (in shares) at Dec. 31, 2019			137.1					(63.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(158)				(158)
Net current-period other comprehensive income (loss)	(99)						(99)
Total comprehensive loss	(257)
Net activity related to restricted stock units (in shares)								0.3
Net activity related to restricted stock units	$ (8)			(79)				$ 71
Issuance of common stock (in shares)	0.4
Issuance of common stock	$ 15			15
Repurchases of common stock (in shares)								(5.0)
Repurchases of common stock	(113)							$ (113)
Ending Balance at Mar. 31, 2020	292		$ 1	6,677	(944)		(256)	$ (5,186)
Ending Balance (in shares) at Mar. 31, 2020			137.1					(67.5)
Beginning Balance at Dec. 31, 2020	(155)		$ 1	6,668	(1,470)		(187)	$ (5,167)
Beginning Balance (in shares) at Dec. 31, 2020			137.1					(67.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(170)				(170)
Net current-period other comprehensive income (loss)	24						24
Total comprehensive loss	$ (146)
Net activity related to restricted stock units (in shares)	0.1							0.2
Net activity related to restricted stock units	$ (5)			(26)				$ 21
Repurchases of common stock (in shares)								(0.1)
Repurchases of common stock	(10)							$ (10)
Ending Balance at Mar. 31, 2021	$ (316)		$ 1	$ 6,642	$ (1,640)		$ (163)	$ (5,156)
Ending Balance (in shares) at Mar. 31, 2021			137.1					(67.2)