Investments	9 Months Ended
	Dec. 31, 2021
Investments Debt Equity Securities [Abstract]
3. Investments	3. Investments Expected maturities may differ from contractual maturities as borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. We deposit bonds with insurance regulatory authorities to meet statutory requirements. The adjusted cost of bonds on deposit with insurance regulatory authorities was $ 26.6 million and $ 27.7 million as of December 31, 2021 and March 31, 2021, respectively. Available-for-Sale Investments Available-for-sale investments as of December 31, 2021 were as follows:     Cost Amortized   Unrealized Gains Gross   Unrealized Losses More than 12 Months Gross   Unrealized Losses Less than 12 Months Gross   Allowance for Expected Credit Losses   Market Value Estimated     (Unaudited)     (In thousands) U.S. treasury securities and government obligations $ 118,140 $   9,039 $   – $   (678) $   – $   126,501 U.S. government agency mortgage-backed securities   57,083   370   –   (2,439)   –   55,014 Obligations of states and political subdivisions   191,141   16,734   (80)   (474)   –   207,321 Corporate securities   2,029,477   157,250   (26)   (5,818)   –   2,180,883 Mortgage-backed securities   163,430   10,003   (1)   –   –   173,432   $ 2,559,271 $   193,396 $   ( 107 ) $   ( 9,409 ) $   – $   2,743,151   Available-for-sale investments as of March 31, 2021 were as follows:     Cost Amortized   Unrealized Gains Gross   Unrealized Losses More than 12 Months Gross   Unrealized Losses Less than 12 Months Gross   Allowance for Expected Credit Losses   Market Value Estimated           (In thousands) U.S. treasury securities and government obligations $ 92,429 $   12,941 $   – $   – $   – $   105,370 U.S. government agency mortgage-backed securities   61,427   911   (1)   (132)   –   62,205 Obligations of states and political subdivisions   230,521   25,249   (59)   (3)   –   255,708 Corporate securities   1,846,507   199,447   (163)   (641)   (1,319)   2,043,831 Mortgage-backed securities   174,728   11,706   (1)   (8)   –   186,425   $ 2,405,612 $   250,254 $   ( 224 ) $   ( 784 ) $   ( 1,319 ) $   2,653,539   We sold available-for-sale securities with a fair value of $278.8 million during the first nine months of fiscal 2022. The gross realized gains on these sales totaled $4.7 million. The gross realized losses on these sales totaled $3.0 million. For available-for-sale debt securities in an unrealized loss position, we first assess whether the security is below investment grade. For securities that are below investment grade, we evaluate whether the decline in fair value has resulted from credit losses or other factors such as the interest rate environment. Declines in value due to credit are recognized as an allowance. In making this assessment, management considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse market conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, cumulative default rates based on ratings are used to determine the potential cost of default, by year. The present value of these potential costs is then compared to the amortized cost of the security to determine the credit loss, limited by the amount that the fair value is less than the amortized cost basis. Declines in fair value that have not been recorded through an allowance for credit losses, such as declines due to changes in market interest rates, are recorded through accumulated other comprehensive income, net of applicable taxes. If we intend to sell a security, or it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis, the security is written down to its fair value and the write down is charged against the allowance for credit losses, with any incremental impairment reported in earnings. Reversals of the allowance for credit losses are permitted and should not exceed the allowance amount initially recognized. Changes in the allowance for credit losses are recorded as provision for (or reversal of) credit loss expense. There were no incremental impairment charges recorded during the first nine months as of December 31, 2021. The adjusted cost and estimated market value of available-for-sale investments by contractual maturity were as follows:     December 31, 2021   March 31, 2021     Cost Amortized   Market Value Estimated   Cost Amortized   Market Value Estimated     (Unaudited)         (In thousands) Due in one year or less $ 69,891 $ 71,172 $ 90,142 $ 91,190 Due after one year through five years   572,812   609,255   562,442   601,818 Due after five years through ten years   677,891   745,523   672,733   754,536 Due after ten years   1,075,247   1,143,769   905,567   1,019,570     2,395,841   2,569,719   2,230,884   2,467,114                   Mortgage-backed securities   163,430   173,432   174,728   186,425   $ 2,559,271 $ 2,743,151 $ 2,405,612 $ 2,653,539 As of December 31, 2021 and March 31, 2021, our common stock and non-redeemable preferred stock that are included in Investments, fixed maturities and marketable equities on our balance sheet are stated in the table below. The changes in the fair value of these equity investments are recognized through Net investment and interest income. Equity investments of common stock and non-redeemable preferred stock were as follows:     December 31, 2021   March 31, 2021     Amortized   Estimated   Amortized   Estimated     (Unaudited)             (In thousands)                   Common stocks $ 9,775 $ 24,179 $ 9,775 $ 20,440 Non-redeemable preferred stocks   26,054   28,112   20,034   21,677   $ 35,829 $ 52,291 $ 29,809 $ 42,117