Fair Value Measurements (Financial instruments level within the fair value hierarchy) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Mar. 31, 2023
Assets:
Fixed maturities - available for sale	$ 2,474,624	$ 2,709,037
Preferred stock	20,141	21,982
Common stock	39,534	39,375
Derivatives	13,881	9,606
Total	2,548,180	2,780,000
Liabilities:
Guaranteed residual values of TRAC leases	9,645
Total	9,645
Level 1 [Member]
Assets:
Fixed maturities - available for sale	217,917	251,832
Preferred stock	20,141	21,982
Common stock	39,534	39,375
Derivatives	8,795	4,295
Total	286,387	317,484
Liabilities:
Guaranteed residual values of TRAC leases	0
Total	0
Level 2 [Member]
Assets:
Fixed maturities - available for sale	2,256,648	2,457,146
Preferred stock	0	0
Common stock	0	0
Derivatives	5,086	5,311
Total	2,261,734	2,462,457
Liabilities:
Guaranteed residual values of TRAC leases	0
Total	0
Level 3 [Member]
Assets:
Fixed maturities - available for sale	59	59
Preferred stock	0	0
Common stock	0	0
Derivatives	0	0
Total	59	$ 59
Liabilities:
Guaranteed residual values of TRAC leases	9,645
Total	$ 9,645