Allowance for Credit Losses (Reserve Allowance Various Credit Loss) (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2020 USD ($)
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	$ 3,684
Transition adjustment expected credit loss current	2,017
Write-offs against allowance	0
Recoveries	0
December 31, 2020	5,701
Trade Receivables
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	2,680
Transition adjustment expected credit loss current	196
Write-offs against allowance	0
Recoveries	0
December 31, 2020	2,876
Investments, Fixed Maturities
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	503
Transition adjustment expected credit loss current	1,811
Write-offs against allowance	0
Recoveries	0
December 31, 2020	2,314
Investments, Other
Valuation And Qualifying Accounts [Abstract]
March 31, 2020	501
Transition adjustment expected credit loss current	10
Write-offs against allowance	0
Recoveries	0
December 31, 2020	$ 511