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Benefit Plans - Additional Information (Details)
12 Months Ended
Dec. 31, 2020
USD ($)
Plan
shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Compensation And Retirement Disclosure [Abstract]      
Employer discretionary contribution amount $ 8,300,000 $ 5,300,000 $ 5,900,000
Number of non-contributory defined benefit pension plans | Plan 2    
Period of average compensation for pension benefit computation 5 years    
Deferred compensation arrangement with Individual, recorded liability $ 8,900,000    
Deferred compensation arrangement with individual, value of shares issued $ 8,925,065    
Deferred compensation arrangement with individual, shares issued | shares 553,665    
Long-term portion of the pension liability $ 33,200,000 37,200,000  
AOCI net prior service cost 10,900,000    
Future amortization of prior service cost $ 800,000    
Retirement age 65 years    
Rabbi trust balance $ 35,700,000    
Expense related to contributions 100,000 100,000 $ 100,000
Total deferred compensation liability 36,900,000 29,500,000  
Deferred compensation liability, current $ 2,000,000.0 $ 1,500,000