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Summary of Significant Accounting Policies - Narrative (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2021
Mar. 31, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]            
Projected benefit obligation       $ (6,000)    
Gain on curtailment of pension obligation $ 0   $ 0 2,032 $ 0  
Other post-retirement benefits income (loss), net of tax $ 0   $ 0 $ 3,996 $ 0  
Change in discount rate   23.00%        
Rate of compensation increase (in percent)   3.00%        
Weighted Average            
Defined Benefit Plan Disclosure [Line Items]            
Weighted average discount rate (in percent)   3.25%       2.65%