Fair Value Measurements (Table Text Block)	6 Months Ended
	Sep. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Financial Instruments, Carrying and Estimated fair values	Fair Value Hierarchy     Carrying               Total Estimated As of September 30, 2020   Value   Level 1   Level 2   Level 3   Fair Value     (Unaudited) Assets   (In thousands) Reinsurance recoverables and trade receivables, net $ 213,397 $ - $ - $ 213,397 $ 213,397 Mortgage loans, net   331,772   -   -   331,772   331,772 Other investments   93,755   -   -   93,755   93,755 Total $ 638,924 $ - $ - $ 638,924 $ 638,924                                             Liabilities                     Notes, loans and finance/capital leases payable   4,731,768   -   4,731,768   -   4,462,111 Total $ 4,731,768 $ - $ 4,731,768 $ - $ 4,462,111       Fair Value Hierarchy     Carrying               Total Estimated As of March 31, 2020   Value   Level 1   Level 2   Level 3   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/capital 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 September 30, 2020   Total   Level 1   Level 2   Level 3     (Unaudited) Assets   (In thousands) Short-term investments $ 1,003,057 $ 1,002,755 $ 302 $ - Fixed maturities - available for sale   2,457,629   7,651   2,449,818   160 Preferred stock   19,786   19,786   -   - Common stock   17,927   17,927   -   - Derivatives   5,666   5,666   -   - Total $ 3,504,065 $ 1,053,785 $ 2,450,120 $ 160                                     Liabilities                 Derivatives   7,165   -   7,165   - Total $ 7,165 $ - $ 7,165 $ -   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 $ -