Life Insurance Liabilities (Sensitive Life Insurance Type Products) (Details) - USD ($)	3 Months Ended	6 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Interest expense	$ 90,305,000	$ 71,498,000	$ 172,635,000	$ 138,716,000
Life Insurance Segment [Member] \| Oxford
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Gross premiums	$ 23,444,000	$ 25,043,000	23,444,000	25,043,000
Interest expense			$ 7,394,000	$ 7,589,000
Expected future lifetime (persistency) of policies in force (years)	6 years 8 months 12 days	6 years 9 months 18 days	6 years 8 months 12 days	6 years 9 months 18 days
Weighted average original interest rate of the liability for future policy benefits	4.91%	4.97%	4.91%	4.97%
Weighted average current interest rate of the liability for future policy benefits	4.37%	5.13%	4.37%	5.13%
Life Insurance Segment [Member] \| Oxford \| Expected gross premiums:
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Undiscounted balance	$ 675,928,000	$ 723,862,000	$ 675,928,000	$ 723,862,000
Discounted balance at original discount rate	247,543,000	272,992,000	247,543,000	272,992,000
Discounted balance at current discount rate	248,018,000	266,964,000	248,018,000	266,964,000
Life Insurance Segment [Member] \| Oxford \| Expected policy benefits:
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Undiscounted balance	319,669,000	350,890,000	319,669,000	350,890,000
Discounted balance at original discount rate	470,113,000	503,526,000	470,113,000	503,526,000
Discounted balance at current discount rate	$ 471,382,000	$ 493,213,000	$ 471,382,000	$ 493,213,000
Life Insurance Segment [Member] \| Oxford \| Lapses actual experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0715	0.0506	0.0715	0.0506
Life Insurance Segment [Member] \| Oxford \| Mortality expected experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0667	0.0544	0.0667	0.0544
Life Insurance Segment [Member] \| Oxford \| Lapses actual experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0231	0.019	0.0231	0.019
Life Insurance Segment [Member] \| Oxford \| Lapses expected experience
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Market Risk Benefit Measurement Input	0.0312	0.0273	0.0312	0.0273

Discounted balance at original discount rate, subsidiary.

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Amount of interest expense classified as operating and nonoperating. Includes, but is not limited to, cost of borrowing accounted for as interest expense.

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Current weighted-average discount rate used to measure liability for future policy benefit.

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Amount, before effect of reinsurance, of discounted balance for expected future gross premium component of liability for future policy benefit.

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Amount, before effect of reinsurance, of undiscounted balance for expected future policy benefit and expense component of liability for future policy benefit.

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Weighted-average duration of liability for future policy benefit, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Original weighted-average discount rate at contract issue date used to measure liability for future policy benefit.

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- Definition

Value of measurement input used to measure contract or contract feature in long-duration contract issued by insurance entity that both protects contract holder from other-than-nominal capital market risk and exposes insurance entity to other-than-nominal capital market risk.

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Amount before valuation allowance of reinsurance recoverables on paid losses.

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