Equity (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Feb. 15, 2012
Dec. 31, 2013
Automatic Conversion of Shares [Member]
Dec. 31, 2013
Common Stock [Member]
Conversion of Stock          
Number of common stock shares issued upon conversion of one convertible preferred stock         1.5
Percentage of outstanding shares of preferred stockholders required for conversion       66.00%  
Minimum post-offering valuation on a fully diluted basis required       $ 150  
Minimum proceeds required       $ 25  
Common stock, shares authorized 100,000,000 100,000,000 100,000,000    
Common stock, par value $ 0.01 $ 0.01 $ 0.01    
Preferred stock, shares authorized 10,000,000 10,000,000 10,000,000    
Preferred stock, par value $ 0.01 $ 0.01 $ 0.01