Stockholders' Equity (Preferred Stock Issued and Outstanding) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Dec. 31, 2015	Aug. 03, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Shares Issued and Outstanding	1,485		885
Liquidation Preference	$ 1,485		$ 885
Carrying Value	$ 1,459		$ 872
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Shares Issued and Outstanding	400		400
Preferred stock liquidation preference (per share)	$ 1,000		$ 1,000
Liquidation Preference	$ 400		$ 400
Carrying Value	$ 396		$ 395
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Shares Issued and Outstanding	485		485
Preferred stock liquidation preference (per share)	$ 1,000		$ 1,000
Liquidation Preference	$ 485		$ 485
Carrying Value	$ 480		$ 477
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Shares Issued and Outstanding	600
Preferred stock liquidation preference (per share)	$ 1,000	$ 1,000
Liquidation Preference	$ 600
Carrying Value	$ 583