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Summary of Significant Accounting Policies - Share-based Compensation (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2018
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation cost recognition period 3 years    
Performance shares      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award requisite service period 3 years 1 year  
Shares awarded as a percentage of granted 100.00%   200.00%
Performance Share Units with Total Shareholder Return Conditions      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Performance Restricted Share Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award requisite service period 3 years    
Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Expiration period 10 years    
Minimum | Performance shares      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award requisite service period 1 year    
Shares awarded as a percentage of granted 0.00%    
Target award shares percent 50.00%    
Minimum | Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Maximum | Performance shares      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award requisite service period 3 years    
Shares awarded as a percentage of granted 200.00%    
Target award shares percent 80.00%    
Maximum | Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 5 years