Warrants (Details) - USD ($)
$ / shares in Units, $ in Millions
9 Months Ended
Sep. 30, 2016
Dec. 31, 2015
Jan. 30, 2009
Class of Warrant or Right [Line Items]      
Preferred Stock, Shares Sold (in shares) 0 266,657  
Series C Preferred Stock      
Class of Warrant or Right [Line Items]      
Preferred Stock, Shares Sold (in shares)     266,657
Preferred stock, total exercise price of warrant     $ 267
May Investors      
Class of Warrant or Right [Line Items]      
Warrants exercised (in shares) 32,721    
Warrants outstanding (in shares) 583,240    
Exercise price of warrants (in usd per share) $ 10    
Liability from warrants $ 10 $ 8  
May Investors | Common Stock      
Class of Warrant or Right [Line Items]      
Shares, Issued 21,068    
Troubled Asset Relief Program      
Class of Warrant or Right [Line Items]      
Exercise price of warrants (in usd per share)     $ 62.00
Number of shares auctioned by warrants     645,138