Fair Value Measurements (Carrying and Estimated Fair Values within Fair Value Hierarchy) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Mar. 31, 2021
Assets
Reinsurance recoverables and trade receivables, net	$ 227,935	$ 224,426
Mortgage loans, net	471,566	391,230
Other investments	100,376	98,529
Total	799,877	714,185
Liabilities
Notes, loans and leases payable, gross	5,127,100	4,449,691
Total	5,127,100	4,449,691
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	5,364,279	4,698,615
Total	5,364,279	4,698,615
Level 3 [Member]
Assets
Reinsurance recoverables and trade receivables, net	227,935	224,426
Mortgage loans, net	471,566	391,230
Other investments	100,376	98,529
Total	799,877	714,185
Liabilities
Notes, loans and leases payable, gross	0	0
Total	0	0
Carrying Value [Member]
Assets
Reinsurance recoverables and trade receivables, net	227,935	224,426
Mortgage loans, net	471,566	391,230
Other investments	100,376	98,529
Total	799,877	714,185
Liabilities
Notes, loans and leases payable, gross	5,364,279	4,698,615
Total	$ 5,364,279	$ 4,698,615