General form of registration statement for all companies including face-amount certificate companies

Long-term Debt (Details)

v3.21.2
Long-term Debt (Details)
$ in Millions
Oct. 01, 2020
USD ($)
Sep. 30, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Jul. 31, 2018
USD ($)
Sep. 20, 2017
USD ($)
Debt Instrument [Line Items]            
Unamortized debt issuance cost     $ 1.4 $ 0.9    
Maximum total net leverage ratio   3.5 3.5      
Minimum fixed charge coverage ratio   1.25 1.25      
Minimum            
Debt Instrument [Line Items]            
Percentage of commitment fee payable periodically 0.25%          
Maximum            
Debt Instrument [Line Items]            
Percentage of commitment fee payable periodically 0.40%          
New Revolving Credit Facility            
Debt Instrument [Line Items]            
Aggregate principal amount $ 150.0          
Outstanding amount   $ 0.0 $ 22.0      
New Revolving Credit Facility | LIBOR            
Debt Instrument [Line Items]            
Line of credit facility bears interest (as a percent) 2.25%          
Letter of Credit            
Debt Instrument [Line Items]            
Maximum borrowing capacity $ 15.0       $ 5.0 $ 3.0