Accounting Policies (Narratives) (Details)	12 Months Ended
	Mar. 31, 2024 USD ($) Segment	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Cash, Insured and Uninsured [Abstract]
Cash, FDIC Insured Amount	$ 250,000
Cash, CDIC insured amount	100,000
Reinsurance Disclosures [Abstract]
Available for sale securities, accrued interest receivable	$ 29,300,000	$ 29,600,000
LIFO Method Related Items [Abstract]
Percentage of LIFO inventory	94.00%	94.00%
Inventory, LIFO reserve	$ 46,331,000	$ 47,065,000
Effect of LIFO inventory liquidation on income		1,600,000	$ 100,000
Disposition of Property, Plant and Equipment
Net amount of (gains) losses netted against depreciation expense	$ 154,000,000	$ 247,100,000	214,200,000
Allowance For Credit Loss [Abstract]
Trade receivable components | Segment	2
Average Historical Chargeback Term	For credit card receivables, the Company uses a trailing 13 months average historical chargeback percentage of total credit card receivables. The Company rents equipment to corporate customers in which payment terms are 30 days.
Percentage of estimated gain loss	5.00%	4.00%
Allowance for expected credit losses	$ 2,300,000	$ 3,800,000
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Policy benefits and losses, claims and loss expenses payable	849,113,000	880,202,000		$ 909,701,000	$ 1,040,951,000
Guaranteed Interest Contracts	2,411,400,000	2,398,900,000
Self insurance reserve	318,900,000	335,200,000
Accrued insurance, noncurrent	396,900,000
Retained earnings	$ 7,600,090,000	7,003,148,000		$ 5,025,568,000	$ 5,017,451,000
Leases [Abstract]
Finance lease term	7 years
Marketing and Advertising Expense [Abstract]
Advertising expense	$ 13,800,000	11,100,000	13,700,000
Policyholder Benefits and Claims Incurred [Abstract]
Deferred sales inducements, net	14,900,000	16,600,000
Deferred sales inducements, amortization expense	2,900,000	3,700,000	$ 4,700,000
All Nonrental Equipment [Member]
LIFO Method Related Items [Abstract]
Inventory, LIFO reserve	$ 46,300,000	47,100,000
Revision Of Prior Period Accounting Standards Update Adjustment [Member]
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Policy benefits and losses, claims and loss expenses payable		5,168,000
Retained earnings		5,567,000
Minimum [Member] | Rental Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful lives	2 years
Minimum [Member] | Buildings and Non-rental Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful lives	3 years
Maximum [Member]
Leases [Abstract]
Operating lease term	88 years
Maximum [Member] | Rental Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful lives	20 years
Maximum [Member] | Buildings and Non-rental Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful lives	10 years
Life Insurance Segment [Member]
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Policy benefits and losses, claims and loss expenses payable	$ 20,400,000	$ 21,600,000