Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions		Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)
Balance (in shares) at Dec. 31, 2016			56,824,802
Balance at Dec. 31, 2016		$ 1,336	$ 1	$ 1,503	$ (7)	$ (161)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		63				63
Total other comprehensive income (loss)		(9)			(9)
Shares issued for Employee Stock Purchase Plan (in shares)			48,032
Warrant exercise (in shares)			154,313
Warrant exercise		4		4
Stock-based compensation (in shares)			294,081
Stock-based compensation		5		5
Balance (in shares) at Dec. 31, 2017			57,321,228
Balance at Dec. 31, 2017		1,399	$ 1	1,512	(16)	(98)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		187				187
Total other comprehensive income (loss)		(26)			(26)
Shares issued for Employee Stock Purchase Plan (in shares)			114,385
Shares issued for Employee Stock Purchase Plan		10		10
Stock-based compensation (in shares)			318,560
Stock-based compensation		0		0
Reclassification of certain income tax effects	[1]				(5)	5
Repurchase of shares included in treasury stock (in shares)			(4,709)
Balance (in shares) at Dec. 31, 2018			57,749,464
Balance at Dec. 31, 2018		1,570	$ 1	1,522	(47)	94
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		218				218
Total other comprehensive income (loss)		48			48
Shares issued for Employee Stock Purchase Plan (in shares)			106,881
Shares issued for Employee Stock Purchase Plan		0		0
Dividends declared and paid (in shares)			376
Dividends declared and paid		(9)				(9)
Stock-based compensation (in shares)			292,220
Stock-based compensation		11		11
Repurchase of shares included in treasury stock (in shares)			(1,517,705)
Repurchase of common shares		(50)		(50)
Balance (in shares) at Dec. 31, 2019			56,631,236
Balance at Dec. 31, 2019		$ 1,788	$ 1	$ 1,483	$ 1	$ 303

[1] Income tax effects of the Tax Cuts and Jobs Act are reclassified from AOCI to retained earnings due to the adoption of ASU 2018-02.