Fair Value Measurements (Table Text Block)	12 Months Ended
	Mar. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Financial Instruments, Carrying and Estimated fair values	Fair Value Hierarchy As of March 31, 2021   Carrying Value   Level 1   Level 2   Level 3   Total Estimated Fair Value     (In thousands) Assets                     Reinsurance recoverables and trade receivables, net $ 224,426 $ - $ - $ 224,426 $ 224,426 Mortgage loans, net   391,230   -   -   391,230   391,230 Other investments   98,529   -   -   98,529   98,529 Total $ 714,185 $ - $ - $ 714,185 $ 714,185                                             Liabilities                     Notes, loans and finance leases payable $ 4,698,615 $ - $ 4,698,615 $ - $ 4,449,691 Total $ 4,698,615 $ - $ 4,698,615 $ - $ 4,449,691         Fair Value Hierarchy As of March 31, 2020   Carrying Value   Level 1   Level 2   Level 3   Total Estimated Fair Value     (In thousands) Assets                     Reinsurance recoverables and trade receivables, net $ 186,672 $ - $ - $ 186,672 $ 186,672 Mortgage loans, net   262,688   -   -   262,688   262,688 Other investments   97,685   -   -   97,685   97,685 Total $ 547,045 $ - $ - $ 547,045 $ 547,045                                             Liabilities                     Notes, loans and finance leases payable $ 4,651,068   - $ 4,651,068 $ - $ 4,342,308 Total $ 4,651,068 $ - $ 4,651,068 $ - $ 4,342,308
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	As of March 31, 2021   Total   Level 1   Level 2   Level 3     (In thousands) Assets                 Short-term investments $ 839,250 $ 839,250 $ - $ - Fixed maturities - available for sale   2,653,539   6,967   2,646,415   157 Preferred stock   21,677   21,677   -   - Common stock   20,440   20,440   -   - Derivatives   6,601   6,601   -   - Total $ 3,541,507 $ 894,935 $ 2,646,415 $ 157                                     Liabilities                 Derivatives $ 5,141 $ - $ 5,141 $ - Total $ 5,141 $ - $ 5,141 $ -   As of March 31, 2020   Total   Level 1   Level 2   Level 3     (In thousands) Assets                 Short-term investments $ 369,279 $ 368,968 $ 311 $ - Fixed maturities - available for sale   2,466,048   7,156   2,458,731   161 Preferred stock   6,675   6,675   -   - Common stock   20,015   20,015   -   - Derivatives   5,944   5,944   -   - Total $ 2,867,961 $ 408,758 $ 2,459,042 $ 161                                     Liabilities                 Derivatives $ 8,214 $ - $ 8,214 $ - Total $ 8,214 $ - $ 8,214 $ -