Fair Value Measurements (Table Text Block)	12 Months Ended
	Mar. 31, 2022	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, 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   –   –   423,163   450,347 Other investments   120,592   –   –   120,592   120,592 Total $ 773,098 $ – $ – $ 773,098 $ 800,282                                             Liabilities                     Notes, loans and finance leases payable $ 6,059,713 $ – $ 6,059,713 $ – $ 5,875,781 Total$ 6,059,713 $ – $ 6,059,713 $ – $ 5,875,781	.   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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	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 $ –	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 $ –