Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Retained Earnings (Deficit) [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2017	$ 1,185			$ 2,019	$ (730)		$ (105)
Beginning balance, shares at Dec. 31, 2017			108
Beginning balance, Common stock value at Dec. 31, 2017			$ 1
Net income (loss)	52				52
Stock-based compensation	16			16
Exercise of stock options	1			1
Shares withheld for taxes	(2)			(2)
Other comprehensive income (loss)	(38)						(38)
Ending balance at Dec. 31, 2018	1,214			2,034	(678)		(143)
Ending balance, shares at Dec. 31, 2018			108
Ending balance, Common stock value at Dec. 31, 2018			$ 1
Net income (loss)	(97)				(97)
Stock-based compensation	13			13
Exercise of stock options	2			2
Vesting of restricted stock, shares			1
Shares withheld for taxes	(3)			(3)
Other comprehensive income (loss)	15						15
Ending balance at Dec. 31, 2019	1,144	$ (6)		2,046	(775)	$ (6)	(128)
Ending balance, shares at Dec. 31, 2019			109
Ending balance, Common stock value at Dec. 31, 2019	1		$ 1
Net income (loss)	(427)				(427)
Stock-based compensation	6			6
Vesting of restricted stock, shares			1
Shares withheld for taxes	(1)			(1)
Other comprehensive income (loss)	(17)						(17)
Ending balance at Dec. 31, 2020	699			$ 2,051	$ (1,208)		$ (145)
Ending balance, shares at Dec. 31, 2020			110
Ending balance, Common stock value at Dec. 31, 2020	$ 1		$ 1