Stock-Based Compensation - Narrative (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 2,700,000 $ 3,000,000  
Accrued employee compensation and benefits 10,913,000   25,722,000
Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total compensation cost not yet recognized 5,700,000    
Total compensation cost not yet recognized, period for recognition (in years) 1 year 9 months 17 days    
Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total compensation cost not yet recognized 15,000,000    
Total compensation cost not yet recognized, period for recognition (in years) 1 year 9 months 24 days    
LTIP      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 3 years    
Share-based compensation expense 300,000 (200,000)  
Accrued employee compensation and benefits $ 2,300,000   $ 4,000,000
LTIP | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Multiplier for target award based on total shareholder return on common stock (percent) 0.00%    
LTIP | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Multiplier for target award based on total shareholder return on common stock (percent) 200.00%