Fair Value Measurements (Table Text Block)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Financial Instruments, Carrying and Estimated fair values	Fair Value Hierarchy Year Ended 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/capital leases payable $ 4,651,068 $ – $ 4,651,068 $ – $ 4,342,308 Total $ 4,651,068 $ – $ 4,651,068 $ – $ 4,342,308	Fair Value Hierarchy Year Ended March 31, 2019   Carrying Value   Level 1   Level 2   Level 3   Total Estimated Fair Value     (In thousands) Assets                     Reinsurance recoverables and trade receivables, net $ 224,785 $ – $ – $ 224,785 $ 224,785 Mortgage loans, net   225,829   –   –   225,829   225,829 Other investments   74,907   –   –   74,907   74,907 Total $ 525,521 $ – $ – $ 525,521 $ 525,521                                             Liabilities                     Notes, loans and finance/capital leases payable $ 4,192,243   – $ 4,192,243 $ – $ 4,192,243 Total $ 4,192,243 $ – $ 4,192,243 $ – $ 4,192,243
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	Year Ended 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 $ –	Year Ended March 31, 2019   Total   Level 1   Level 2   Level 3     (In thousands) Assets                 Short-term investments $ 463,847 $ 463,599 $ 248 $ – Fixed maturities - available for sale   2,209,761   7,327   2,202,213   221 Preferred stock   8,257   8,257   –   – Common stock   17,379   17,379   –   – Derivatives   1,607   1,468   139   – Total $ 2,700,851 $ 498,030 $ 2,202,600 $ 221                                     Liabilities                 Derivatives $ – $ – $ – $ – Total $ – $ – $ – $ –