Variable Interest Entities Special Purpose Entities, including Variable Interest Entities - Summary of Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Debt Securities, Available-for-sale, Amortized Cost	$ 289,712	$ 266,292
Fixed maturity securities, at fair value		263,179
Restricted Cash		17,596	$ 17,669	$ 10,937
Derivative assets		210	0
Other assets		107,829	92,317
Total assets		8,253,282	8,058,378	$ 8,428,615
Interest Payable		2,695	2,560
Derivative Liability		0	317
Other Liabilities		91,429	89,036
Liabilities		7,041,817	6,862,857
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	260	881
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 5,351	$ 3,994	$ 5,351