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Debt and Financing Arrangements - Additional Information (Details) - USD ($)
Sep. 30, 2021
Dec. 31, 2020
Debt Instrument [Line Items]    
Outstanding balance under applicable credit facility $ 190,200,000 $ 108,000,000
Outstanding letters of credit 3,400,000 1,700,000
Other line of credit    
Debt Instrument [Line Items]    
Revolving loan commitment 20,000,000  
Outstanding line of credit 0  
2018 Credit Facility    
Debt Instrument [Line Items]    
Unsecured credit facility 400,000,000  
Outstanding balance under applicable credit facility 190,200,000 $ 108,000,000
Available funds under credit facility 201,600,000  
Outstanding letters of credit $ 3,400,000