Accounting Policies (Narratives) (Details) - USD ($)	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021	Jan. 01, 2021
Cash, Insured and Uninsured [Abstract]
Cash, FDIC Insured Amount	$ 250,000
Cash, CDIC insured amount	$ 100,000
LIFO Method Related Items [Abstract]
Percentage of LIFO inventory	94.00%	93.00%
Inventory, LIFO reserve	$ 47,065,000	$ 37,400,000
Effect of LIFO inventory liquidation on income	1,600,000	100,000	$ 400,000
Disposition of Property, Plant and Equipment
Net amount of (gains) losses netted against depreciation expense	$ 247,100,000	214,200,000	54,100,000
Schedule of rental trucks depreciation:
Percentage reduction for year one, depreciation	16.00%
Percentage reduction for year two, depreciation	13.00%
Percentage reduction for year three, depreciation	11.00%
Percentage reduction for year four, depreciation	9.00%
Percentage reduction for year five, depreciation	8.00%
Percentage reduction for year six, depreciation	7.00%
Percentage reduction for year seven, depreciation	6.00%
Salvage value percentage under the old declining balance method	15.00%
Salvage value percentage	5.70%
Real Estate Companies Disclosures [Abstract]
Carrying value of surplus real estate	$ 72,200,000	67,800,000
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Accrued insurance, noncurrent	21,600,000	19,700,000
Marketing and Advertising Expense [Abstract]
Advertising expense	11,100,000	13,700,000	18,000,000.0
Policyholder Benefits and Claims Incurred [Abstract]
Deferred sales inducements, net	16,600,000	15,700,000
Deferred sales inducements, amortization expense	3,700,000	4,700,000	4,300,000
Adoption of New Accounting Pronounements
Other components of net periodic benefit cost	1,216,000	1,120,000	$ 987,000
Operating lease commitment, asset	474,765,000	620,824,000
Operating lease commitment, liability	58,373,000
Prior Period Adjustment [Abstract]
Equity impact, net	6,528,335,000	5,952,492,000
All Nonrental Equipment [Member]
LIFO Method Related Items [Abstract]
Inventory, LIFO reserve	$ 47,100,000	$ 37,400,000
Accumulated Other Comprehensive Income (Loss) [Member] | Minimum [Member] | Revision Of Prior Period Accounting Standards Update Adjustment [Member]
Prior Period Adjustment [Abstract]
Equity impact, net				$ 110,000,000.0
Accumulated Other Comprehensive Income (Loss) [Member] | Maximum [Member] | Revision Of Prior Period Accounting Standards Update Adjustment [Member]
Prior Period Adjustment [Abstract]
Equity impact, net				$ 130,000,000.0