Provision for Taxes (Significant components of deferred tax assets and liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2021
Deferred tax assets:
Net operating loss and credit carry forwards	$ 36,367	$ 30,432
Accrued expenses	114,152	109,740
Policy benefits and losses, claims and loss expenses payable, net	30,572	26,799
Operating leases, assets	15,540	19,370
Total deferred tax assets	196,631	186,341
Deferred tax liabilities:
Property, plant and equipment	1,395,216	1,280,703
Operating leases, liabilities	15,540	19,370
Deferred policy acquisition costs	12,962	13,696
Unrealized gains	36,299	48,667
Other	1,972	2,394
Total deferred tax liabilities	1,461,989	1,364,830
Net deferred tax liability	$ 1,265,358	$ 1,178,489