Fair Value Measurements (Table Text Block)	3 Months Ended	12 Months Ended
	Jun. 30, 2021	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     Carrying               Total Estimated As of June 30, 2021   Value   Level 1   Level 2   Level 3   Fair Value     (Unaudited) Assets   (In thousands) Reinsurance recoverables and trade receivables, net $ 233,056 $ – $ – $ 233,056 $ 233,056 Mortgage loans, net   428,140   –   –   428,140   428,140 Other investments   97,753   –   –   97,753   97,753 Total $ 758,949 $ – $ – $ 758,949 $ 758,949                                             Liabilities                     Notes, loans and finance leases payable   4,702,127   –   4,702,127   –   4,497,078 Total $ 4,702,127 $ – $ 4,702,127 $ – $ 4,497,078       Fair Value Hierarchy     Carrying               Total Estimated As of March 31, 2021   Value   Level 1   Level 2   Level 3   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 June 30, 2021   Total   Level 1   Level 2   Level 3     (Unaudited) Assets   (In thousands) Short-term investments $ 1,311,376 $ 1,311,376 $ – $ – Fixed maturities - available for sale   2,703,053   7,185   2,695,712   156 Preferred stock   29,408   29,408   –   – Common stock   22,672   22,672   –   – Derivatives   6,789   6,789   –   – Total $ 4,073,298 $ 1,377,430 $ 2,695,712 $ 156                                     Liabilities                 Derivatives   4,222   –   4,222   – Total$ 4,222 $ – $ 4,222 $ –	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 $ –