XML 135 R103.htm IDEA: XBRL DOCUMENT v3.3.1.900
Equity - Preferred Stock Terms (Details) - $ / shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
8.5% Convertible perpetual preferred stock      
Class of Stock [Line Items]      
Preferred stock, dividend rate, percentage 8.50% 8.50% 8.50%
Liquidation preference per share (usd per share) $ 100.00    
Annual dividend per share (usd per share) $ 8.50    
Conversion rate per share to common stock (shares) 12.4805    
7.0% Convertible perpetual preferred stock      
Class of Stock [Line Items]      
Preferred stock, dividend rate, percentage 7.00% 7.00% 7.00%
Liquidation preference per share (usd per share) $ 100.00    
Annual dividend per share (usd per share) $ 7.00    
Conversion rate per share to common stock (shares) 12.8791