Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)
Beginning balance at Dec. 31, 2015	$ 1,529	$ 267	$ 1	$ 1,486	$ 2	$ (227)
Beginning balance, shares at Dec. 31, 2015		266,657	56,483,258
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	86					86
Total other comprehensive income (loss)	(21)				(21)
Stock-based compensation, value	5			5
Stock-based compensation, shares			92,521
Ending balance at Jun. 30, 2016	1,599	$ 267	$ 1	1,491	(19)	(141)
Ending balance, shares at Jun. 30, 2016		266,657	56,575,779
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	47
Total other comprehensive income (loss)	(8)
Ending balance at Jun. 30, 2016	1,599	$ 267	$ 1	1,491	(19)	(141)
Ending balance, shares at Jun. 30, 2016		266,657	56,575,779
Beginning balance at Dec. 31, 2016	1,336	$ 0	$ 1	1,503	(7)	(161)
Beginning balance, shares at Dec. 31, 2016		0	56,824,802
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	68					68
Total other comprehensive income (loss)	(2)				(2)
Stock-based compensation, value	2			2
Stock-based compensation, shares			182,316
Warrant exercise	4			4
Warrant exercise, shares			154,313
Ending balance at Jun. 30, 2017	1,408	$ 0	$ 1	1,509	(9)	(93)
Ending balance, shares at Jun. 30, 2017		0	57,161,431
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	41
Total other comprehensive income (loss)	(3)
Ending balance at Jun. 30, 2017	$ 1,408	$ 0	$ 1	$ 1,509	$ (9)	$ (93)
Ending balance, shares at Jun. 30, 2017		0	57,161,431