Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jan. 30, 2009
Class of Stock [Line Items]
Preferred Stock, Shares Sold	266,657	266,657
Exercise price of warrants (in usd per share)	$ 10.00
Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Sold	266,657
Preferred stock, total exercise price of warrant	$ 267
U.S. Treasury | Common Stock
Class of Stock [Line Items]
Preferred Stock, Shares Sold			266,657
Number of shares auctioned by warrants			1,000,000
Exercise price of warrants (in usd per share)			$ 62.00
Preferred stock, total exercise price of warrant			$ 267
U.S. Treasury | Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, dividend rate per annum (as a percent)	9.00%