Allowance for Credit Losses (Reserve Allowance for Various Credit Loss) (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Valuation And Qualifying Accounts [Abstract]
March 31, 2022	$ 9,210	$ 6,242
Transition adjustment current expected credit losses	(3,554)	2,968
Write-offs against allowance	0	0
Recoveries	0	0
September 30, 2022	5,656
Trade Receivables
Valuation And Qualifying Accounts [Abstract]
March 31, 2022	8,649	4,421
Transition adjustment current expected credit losses	(5,506)	4,228
Write-offs against allowance	0	0
Recoveries	0	0
September 30, 2022	3,143
Investments, Fixed Maturities
Valuation And Qualifying Accounts [Abstract]
March 31, 2022	60	1,320
Transition adjustment current expected credit losses	1,948	(1,260)
Write-offs against allowance	0	0
Recoveries	0	0
September 30, 2022	2,008
Investments, Other
Valuation And Qualifying Accounts [Abstract]
March 31, 2022	501	501
Transition adjustment current expected credit losses	4	0
Write-offs against allowance	0	0
Recoveries	0	$ 0
September 30, 2022	$ 505