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Stock Incentive Plans - Narrative (Details)
3 Months Ended 12 Months Ended
Dec. 31, 2016
USD ($)
shares
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
Mar. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Sep. 30, 2015
USD ($)
Jun. 30, 2015
USD ($)
Mar. 31, 2015
USD ($)
Dec. 31, 2016
USD ($)
Participant
shares
Dec. 31, 2015
USD ($)
shares
Dec. 31, 2014
USD ($)
shares
May 20, 2014
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Award vesting period                 3 years      
Total intrinsic value of stock options exercised in period                 $ 1,300,000 $ 1,800,000 $ 5,200,000  
Total aggregate fair value of options vested in period                 $ 0 $ 0 $ 300,000  
Stock options granted (in shares) | shares                 0 0 0  
Stock-based compensation cost $ 600,000 $ 1,900,000 $ 1,700,000 $ 1,900,000 $ 2,000,000 $ 2,700,000 $ 2,100,000 $ 1,900,000 $ 6,100,000 $ 8,700,000 $ 6,100,000  
Stock-based compensation expense                 $ 6,100,000 8,700,000 6,100,000  
Forfeiture rate since inception of plans                 4.00%      
Number of plan participants since inception of plans | Participant                 94      
Total unrecognized compensation cost related to non-vested share-based compensation arrangements $ 3,700,000               $ 3,700,000      
Expected period to recognize total unrecognized compensation cost related to non-vested share-based compensation arrangements                 1 year 2 months 2 days      
Options                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Award expiration period                 7 years      
Restricted stock units (RSUs)                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Total intrinsic value of equity instruments other than options exercised in period                 $ 9,300,000 5,800,000 5,300,000  
Total aggregate fair value of equity instruments other than options vested in period                 9,300,000 5,800,000 5,400,000  
Performance shares                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Total intrinsic value of equity instruments other than options exercised in period                 5,100,000 2,700,000 1,100,000  
Total aggregate fair value of equity instruments other than options vested in period                 $ 5,100,000 $ 2,700,000 $ 1,100,000  
2004 LTIP                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Shares cliff vest percentage                 33.30%      
2005 LTIP                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Shares cliff vest percentage                 33.30%      
2007 LTIP                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Shares cliff vest percentage                 33.30%      
Remaining period following first vesting commencement date                 2 years      
2007 LTIP | Options                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Stock options granted (in shares) | shares                 0      
2010 LTIP                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Number of shares authorized (in shares) | shares                       1,800,000
Shares available for issuance (in shares) | shares 2,684,821               2,684,821      
Annual award limits to any one participant (in shares) | shares                 200,000      
2010 LTIP | Options                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Stock options granted (in shares) | shares                 0      
2010 LTIP | Restricted Stock Units and Performance Shares [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Award vesting period                 3 years