CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Millions	Total	Common Stock and Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2018	$ 375	$ 641	$ (266)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercise of stock options		1
Stock-based compensation expense		9
Net income	63		63
Repurchase of common stock			(38)
Awards effectively repurchased for required employee withholding taxes			(4)
Other comprehensive income				0
Balance at Mar. 31, 2019	406	651	(245)	0
Balance at Dec. 31, 2019	475	694	(219)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercise of stock options		0
Stock-based compensation expense		9
Net income	91		91
Repurchase of common stock	(40)		(40)
Awards effectively repurchased for required employee withholding taxes			(4)
Other comprehensive income				2
Balance at Mar. 31, 2020	$ 533	$ 703	$ (172)	$ 2