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

Nature of Business and Summary of Significant Accounting Policies - Summary of Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail)

v3.21.2
Nature of Business and Summary of Significant Accounting Policies - Summary of Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) - Fair Value, Recurring [Member] - USD ($)
$ in Millions
Jun. 30, 2021
Jun. 30, 2020
Cash, cash equivalents, and restricted cash [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, Fair Value Disclosure [Abstract]    
Assets, Fair Value Disclosure $ 102.4 $ 120.0
Cash, cash equivalents, and restricted cash [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, Fair Value Disclosure [Abstract]    
Assets, Fair Value Disclosure 0.0 0.0
Cash, cash equivalents, and restricted cash [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, Fair Value Disclosure [Abstract]    
Assets, Fair Value Disclosure 0.0 0.0
Discretionary retirement plan [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, Fair Value Disclosure [Abstract]    
Assets, Fair Value Disclosure 3.4 2.4
Liabilities, Fair Value Disclosure [Abstract]    
Financial and Nonfinancial Liabilities, Fair Value Disclosure 3.4 2.4
Discretionary retirement plan [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, Fair Value Disclosure [Abstract]    
Assets, Fair Value Disclosure 0.8 1.1
Liabilities, Fair Value Disclosure [Abstract]    
Financial and Nonfinancial Liabilities, Fair Value Disclosure 0.8 1.1
Discretionary retirement plan [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, Fair Value Disclosure [Abstract]    
Assets, Fair Value Disclosure 0.0 0.0
Liabilities, Fair Value Disclosure [Abstract]    
Financial and Nonfinancial Liabilities, Fair Value Disclosure $ 0.0 $ 0.0