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Stock-Based Compensation - Stock-Based Compensation Narrative (Details)
$ in Millions
12 Months Ended
Dec. 31, 2019
USD ($)
shares
Dec. 31, 2018
USD ($)
Share-based Payment Arrangement, Option [Member]    
[Line Items]    
Compensation cost not yet recognized | $ $ 2.5  
Unrecognized compensation expense, expected weighted average period for recognition 2 years 3 months 18 days  
Restricted Stock Units (RSUs) [Member]    
[Line Items]    
Compensation cost not yet recognized | $ $ 32.1  
Unrecognized compensation expense, expected weighted average period for recognition 1 year 10 months 24 days  
Phantom Share Units (PSUs) [Member]    
[Line Items]    
Compensation cost not yet recognized | $ $ 5.3  
Unrecognized compensation expense, expected weighted average period for recognition 2 years 1 month 6 days  
Deferred compensation share-based arrangements, liability, current | $ $ 2.3 $ 1.5
Employee Stock [Member]    
[Line Items]    
Number of shares available for future grant under the Stock Incentive Plan (in shares) | shares 232,563  
SSNI Plan [Member]    
[Line Items]    
Number of shares authorized for issuance under the Stock Incentive Plan (in shares) | shares 2,299,591  
Stock Incentive Plan [Member]    
[Line Items]    
Number of shares authorized for issuance under the Stock Incentive Plan (in shares) | shares 12,623,538  
Number of shares available for future grant under the Stock Incentive Plan (in shares) | shares 5,977,990  
Reduction in stock options available for issue (in shares) 1  
Authorized share reserve reduction in awards other than stock options or share appreciation rights available for issue, conversion ratio 1.7