Allowance for Credit Losses (Reserve Allowance Various Credit Loss) (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2021 USD ($)
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	$ 3,684
Transition adjustment expected credit loss current	972
Write-offs against allowance	0
Recoveries	0
March 31, 2021	4,656
Trade Receivables
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	2,680
Transition adjustment expected credit loss current	155
Write-offs against allowance	0
Recoveries	0
March 31, 2021	2,835
Investments, Fixed Maturities
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	503
Transition adjustment expected credit loss current	817
Write-offs against allowance	0
Recoveries	0
March 31, 2021	1,320
Investments, Other
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	501
Transition adjustment expected credit loss current	0
Write-offs against allowance	0
Recoveries	0
March 31, 2021	$ 501