Fair Value Measurements (Table Text Block)	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
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, 2023   Carrying Value   Level 1   Level 2   Level 3   Total Estimated Fair Value     (In thousands) Assets                     Reinsurance recoverables and trade receivables, net $ 189,498 $ – $ – $ 189,498 $ 189,498 Mortgage loans, net   466,531   –   –   444,957   444,957 Other investments   109,009   –   –   109,009   109,009 Total $ 765,038 $ – $ – $ 743,464 $ 743,464                                             Liabilities                     Notes, loans and finance leases payable $ 6,143,350 $ – $ 5,710,735 $ – $ 5,710,735 Total$ 6,143,350 $ – $ 5,710,735 $ – $ 5,710,735	.   Fair Value Hierarchy As of March 31, 2022   Carrying Value   Level 1   Level 2   Level 3   Total Estimated Fair Value     (In thousands) Assets                     Reinsurance recoverables and trade receivables, net $ 229,343 $ – $ – $ 229,343 $ 229,343 Mortgage loans, net   423,163   –   –   450,347   450,347 Other investments   120,592   –   –   120,592   120,592 Total $ 773,098 $ – $ – $ 800,282 $ 800,282                                             Liabilities                     Notes, loans and finance leases payable $ 5,875,781   – $ 5,875,781 $ – $ 5,875,781 Total$ 5,875,781 $ – $ 5,875,781 $ – $ 5,875,781
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	As of March 31, 2023   Total   Level 1   Level 2   Level 3     (In thousands) Assets                 Short-term investments $ 1,809,441 $ 1,808,797 $ 644 $ – Fixed maturities - available for sale   2,709,037   251,832   2,457,146   59 Preferred stock   21,982   21,982   –   – Common stock   39,375   39,375   –   – Derivatives   9,606   4,295   5,311   – Total $ 4,589,441 $ 2,126,281 $ 2,463,101 $ 59                                     Liabilities                 Derivatives $ – $ – $ – $ – Total$ – $ – $ – $ –	As of March 31, 2022   Total   Level 1   Level 2   Level 3     (In thousands) Assets                 Short-term investments $ 2,482,154 $ 2,482,154 $ – $ – Fixed maturities - available for sale   2,821,092   26,914   2,794,086   92 Preferred stock   26,095   26,095   –   – Common stock   46,212   46,212   –   – Derivatives   7,474   7,474   –   – Total $ 5,383,027 $ 2,588,849 $ 2,794,086 $ 92                                     Liabilities                 Derivatives $ 587 $ – $ 587 $ – Total$ 587 $ – $ 587 $ –