Policy Benefits And Losses Claims And Loss Expenses Payable (Present Value Expected Future Policy Benefits) (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Liability For Future Policy Benefit Expected Future Policy Benefit [Roll Forward]
Payout annuities and market risk benefits	$ 2,393,590		$ 2,398,884
Life and annuity ICOS and IBNR / Reinsurance losses payable					$ 41,438
Policy benefit and losses, claims and loss expense balance, end of period	865,397		880,202
Oxford
Liability For Future Policy Benefit Expected Future Policy Benefit [Roll Forward]
Balance, beginning of year	720,581	$ 830,363	740,992	$ 971,882
Beginning balance at original discount rate	734,392	812,235	760,198	821,286
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			(4,780)	2,744
Adjusted beginning of year balance			755,418	824,030
Issuances	5,288	16,536
Interest accrual	17,568	19,105
Net premium collected	(43,882)	(47,436)
Other	0	0
Ending balance at original discount rate	734,392	812,235
Effect of changes in discount rate assumptions (AOCI)	(13,811)	18,128
Balance, end of the year	720,581	830,363
End of period, LFPB, net	323,265	342,038
Payout annuities and market risk benefits	30,685	33,157
Life and annuity ICOS and IBNR / Reinsurance losses payable	10,101	11,226
Life DPL/Other life and health	26,556	37,130
End of period balance, Oxford	390,607	423,551
Balance, Moving and Storage	324,642	348,854
Balance, Property and Casualty	150,148	156,998
Policy benefit and losses, claims and loss expense balance, end of period	865,397	929,403
Life Insurance Segment [Member] | Oxford
Liability For Future Policy Benefit Expected Future Policy Benefit [Roll Forward]
Balance, beginning of year	524,729	577,061	530,938	672,254
Beginning balance at original discount rate	523,780	551,154	533,688	552,109
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			(565)	1,031
Adjusted beginning of year balance			533,123	553,140
Issuances	5,211	14,083
Interest accrual	13,166	13,714
Net premium collected	(27,720)	(29,783)
Other	0	0
Ending balance at original discount rate	523,780	551,154
Effect of changes in discount rate assumptions (AOCI)	949	25,907
Balance, end of the year	524,729	577,061
Health Insurance Product Line [Member]
Liability For Future Policy Benefit Expected Future Policy Benefit [Roll Forward]
Life and annuity ICOS and IBNR / Reinsurance losses payable					$ 0
Health Insurance Product Line [Member] | Oxford
Liability For Future Policy Benefit Expected Future Policy Benefit [Roll Forward]
Balance, beginning of year	195,852	253,302	210,054	299,628
Beginning balance at original discount rate	210,612	261,081	226,510	269,177
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			(4,215)	1,713
Adjusted beginning of year balance			$ 222,295	$ 270,890
Issuances	77	2,453
Interest accrual	4,402	5,391
Net premium collected	(16,162)	(17,653)
Other	0	0
Ending balance at original discount rate	210,612	261,081
Effect of changes in discount rate assumptions (AOCI)	(14,760)	(7,779)
Balance, end of the year	$ 195,852	$ 253,302