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, 2014	$ 1,373	$ 267	$ 1	$ 1,482	$ 8	$ (385)
Beginning balance, shares at Dec. 31, 2014		266,657	56,332,307
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	125					125
Total other comprehensive loss	4				4
Stock-based compensation, value	2			2
Stock-based compensation, shares			103,719
Ending balance at Sep. 30, 2015	1,504	$ 267	$ 1	1,484	12	(260)
Ending balance, shares at Sep. 30, 2015		266,657	56,436,026
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	143					143
Total other comprehensive loss	(22)				(22)
Stock-based compensation, value	8			8
Stock-based compensation, shares			114,013
Preferred stock redemption	(267)	$ (267)				0
Preferred stock redemption (shares)		(266,657)
Dividends on preferred stock	(105)					(105)
Ending balance at Sep. 30, 2016	$ 1,286	$ 0	$ 1	$ 1,494	$ (20)	$ (189)
Ending balance, shares at Sep. 30, 2016		0	56,597,271