Fair Value Measurements (Carrying and Estimated Fair Values within Fair Value Hierarchy) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Mar. 31, 2020
Assets
Reinsurance recoverables and trade receivables, net	$ 213,397	$ 186,672
Mortgage loans, net	331,772	262,688
Other investments	93,755	97,685
Total	638,924	547,045
Liabilities
Notes, loans and leases payable, gross	4,462,111	4,342,308
Total	4,462,111	4,342,308
Level 1 [Member]
Assets
Reinsurance recoverables and trade receivables, net	0	0
Mortgage loans, net	0	0
Other investments	0	0
Total	0	0
Liabilities
Notes, loans and leases payable, gross	0	0
Total	0	0
Level 2 [Member]
Assets
Reinsurance recoverables and trade receivables, net	0	0
Mortgage loans, net	0	0
Other investments	0	0
Total	0	0
Liabilities
Notes, loans and leases payable, gross	4,731,768	4,651,068
Total	4,731,768	4,651,068
Level 3 [Member]
Assets
Reinsurance recoverables and trade receivables, net	213,397	186,672
Mortgage loans, net	331,772	262,688
Other investments	93,755	97,685
Total	638,924	547,045
Liabilities
Notes, loans and leases payable, gross	0	0
Total	0	0
Carrying Value [Member]
Assets
Reinsurance recoverables and trade receivables, net	213,397	186,672
Mortgage loans, net	331,772	262,688
Other investments	93,755	97,685
Total	638,924	547,045
Liabilities
Notes, loans and leases payable, gross	4,731,768	4,651,068
Total	$ 4,731,768	$ 4,651,068