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Stock-Based Compensation - Liability-Classified Awards Narrative (Details)
$ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
Dec. 31, 2019
award
shares
Dec. 31, 2018
award
Liability-classified awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Targeted number of units outstanding (in shares) | shares   87,645  
Estimate of future expense for all types of RSUs outstanding $ 2.5    
Unrecognized compensation cost, period for recognition (in years) 1 year 4 months 24 days    
Total cash paid for vesting and dividend payments $ 9.9    
Liability-classified awards | Key Employee      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of award types | award   3 3
Market based RSUs      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period (in years)   3 years 3 years
Performance based RSUs      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period (in years)   3 years 3 years
Time vested RSUs      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period (in years)   3 years 3 years