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Stock Based Compensation - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Oct. 08, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock based compensation expense $ 2.9 $ 2.8 $ 8.9 $ 8.4  
RSUs          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Unrecognized compensation expense 10.5   $ 10.5    
Weighted average period over which unrecognized compensation expense is expected to be recognized     1 year 8 months 12 days    
RSUs | Employees          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     3 years    
RSUs | Directors          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     1 year    
PSUs          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     3 years    
Unrecognized compensation expense $ 5.1   $ 5.1    
Weighted average period over which unrecognized compensation expense is expected to be recognized     1 year 7 months 6 days    
Settlement date, period following performance period     60 days    
Grant date fair value     $ 2.5 $ 3.7  
Class A Common Stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares authorized for issuance (in shares)         11,800,000
Class A Common Stock | PSUs          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Contingent right to receive common stock, number of shares receivable for each PSU (in shares) 1   1    
Class A Common Stock | PSUs | Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting percentage     0.00%    
Class A Common Stock | PSUs | Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting percentage     150.00%