Provision for Taxes	12 Months Ended
	Mar. 31, 2023
Disclosure Text Block [Abstract]
Provision for Taxes	Note 14.   Provision for Taxes Earnings before taxes and the provision for taxes consisted of the following:     Years Ended March 31,     2023   2022   2021     (In thousands) Pretax earnings:             U.S. $ 1,178,264 $ 1,431,155 $ 773,030 Non-U.S.   39,659   44,342   23,628 Total pretax earnings $ 1,217,923 $ 1,475,497 $ 796,658               Current provision             Federal $ 115,171 $ 189,488 $ 100,521 State   42,121   55,518   16,572 Non-U.S.   5,150   6,893   3,404     162,442   251,899   120,497 Deferred provision             Federal   114,355   90,852   53,957 State   14,077   6,355   9,795 Non-U.S.   4,051   3,105   1,553     132,483   100,312   65,305               Provision for income tax expense $ 294,925 $ 352,211 $ 185,802               Income taxes paid (received) $ 145,680 $ ( 4,548 ) $ 29,044   The difference between the tax provision at the statutory federal income tax rate and the tax provision attributable to income before taxes was as follows:     Years Ended March 31,       2023   2022   2021       (In percentages)   Statutory federal income tax rate   21.00 % 21.00 % 21.00 % Increase (reduction) in rate resulting from:               State taxes, net of federal benefit   3.56 % 3.24 % 2.53 % Foreign rate differential   0.08 % 0.05 % – % Federal tax credits   (0.48) % (0.19) % (0.99) % Tax-exempt income   (0.08) % (0.03) % (0.08) % Dividend received deduction   (0.01) % – % (0.01) % Other   0.15 % (0.20) % 0.87 % Actual tax expense of operations   24.22 % 23.87 % 23.32 % Significant components of our deferred tax assets and liabilities were as follows:     March 31,     2023   2022 Deferred tax assets:   (In thousands) Net operating loss and credit carry forwards $ 33,778 $ 36,394 Accrued expenses   112,971   103,723 Policy benefit and losses, claims and loss expenses payable, net   31,436   30,572 Unrealized losses on investments   48,179   – Operating leases   12,058   15,540 Total deferred tax assets $ 238,422 $ 186,229           Deferred tax liabilities:         Property, plant and equipment $ 1,545,628 $ 1,405,604 Operating leases   12,175   15,540 Deferred policy acquisition costs   12,038   12,962 Unrealized gains on investments   –   36,299 Other   3,008   1,973 Total deferred tax liabilities   1,572,849   1,472,378 Net deferred tax liability $ 1,334,427 $ 1,286,149 On March 27, 2020, former President Trump signed into U.S. federal law the Coronavirus Aid, Relief and Economic Security Act (the “CARES Act”), which was aimed at providing emergency assistance and health care for individuals, families, and businesses affected by COVID-19 global pandemic and generally supporting the U.S. economy.   The CARES Act, among other things, includes provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations, increased limitations on qualified charitable contributions, and technical corrections to tax depreciation methods for qualified improvement property. In particular, the CARES Act allows for net operating losses (“NOL“) generated in 2018, 2019, or 2020 to be carried back 5 years.    As a result, we filed applicable forms with the IRS to carryback NOLs. The statutory tax rate for the carryback years was 35% as compared to 21% at present.   Consequently, we recognized a benefit amount of $ 146 million for fiscal year 2020. These refund claims total approximately $ 366 million, of which we have received approximately $ 243 million in fiscal 2022 and are reflected in prepaid expense. As refunds are received, they will reduce this amount. We have estimated and recorded the overall effects of the CARES Act and do not anticipate a material change. As a result, the NOL and credit carry-forwards in the above table are primarily attributable to state NOLs. As of March 31, 2023 and 2022, we had state NOLs of $ 480.0 million and $ 458.5 million, respectively, that will begin to expire March 31, 2024, if not utilized. On March 3, 2021, the IRS notifiied us that our federal inome tax returns for the tax years March 31, 2014, 2015, 2016, 2018 and 2019 were selected for examination. The IRS agent in charged confirmed that this is a limited scope examination arising out of NOL carryback claims and is a standard procedure for the IRS to process the refund. As such, the scope of the exam is expected to be limited to the items reported on Forms 1139 and related schedules only. As of now, we are still working with the IRS agent and there is no audit adjustment for any of the above tax periods. No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to transition tax, or any additional outside basis difference inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations. Determining the amount of unrecognized deferred tax liability related to any remaining undistributed foreign earnings not subject to the transition tax and additional outside basis difference in these entities (i.e., basis difference in excess of that subject to the one-time transition tax) is not practicable. We account for uncertainty in income taxes by recognizing the tax benefit or expense from an uncertain tax position only if it is more likely than not that the tax position will be sustained upon examination by the taxing authorities, based on the technical merits of the position. The Company measures the tax benefits and expenses recognized in the consolidated financial statements from such a position based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution. A reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of the period are as follows:     Unrecognized Tax Benefits     March 31,     2023   2022     (In thousands)           Unrecognized tax benefits beginning balance $ 48,851 $ 31,069 Additions based on tax positions related to the current year   7,226   8,257 Reductions for tax positions of prior years   (443)   – Additions for tax provisions of prior years   2,473   9,525 Unrecognized tax benefits ending balance $ 58,107 $ 48,851 We recognize interest related to unrecognized tax benefits as interest expense, and penalties as income tax expenses. As of March 31, 2023 and 2022, the amount of interest accrued on unrecognized tax benefits was $ 17.7 million and $ 15.7 million, respectively, net of tax. During the current year, we recorded expense from interest in the amount of $ 2.0 million, net of tax. We file income tax returns in the U.S. federal jurisdiction, and various states and Canadian jurisdictions. While the Company has ongoing audits in Canada and various state jurisdictions, there have been no proposed or anticipated adjustments that would materially impact the financial statements. With some exceptions, we are no longer subject to audit for years prior to the fiscal year ended March 31, 2020.