Borrowings (Long-term Debt Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Mar. 31, 2021
Debt instrument, maturities:
Debt Instrument Carrying Amount	$ 5,127,100	$ 5,127,100	$ 4,449,691
Notes, loans and finance/capital leases payable	5,364,279	5,364,279	4,698,615
Less: Debt issuance costs	(29,001)	(29,001)	(29,708)
Total notes, loans and finance/capital leases payable, net	$ 5,335,278	5,335,278	4,668,907
Real estate loan (amortizing term) [Member]
Debt instrument, maturities:
Debt instrument, maturity year	2023
Debt Instrument Carrying Amount	$ 53,591	$ 53,591	82,913
Real estate loan (amortizing term) [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.58%	1.58%
Senior Mortgages [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2022
Debt instrument, maturity year range, end	2038
Debt Instrument Carrying Amount	$ 2,186,376	$ 2,186,376	2,125,324
Senior Mortgages [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.76%	2.76%
Senior Mortgages [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	5.50%	5.50%
Real estate loans (revolving credit) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2023
Debt instrument, maturity year range, end	2025
Debt Instrument Carrying Amount	$ 535,000	$ 535,000	535,000
Real estate loans (revolving credit) [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.33%	1.33%
Real estate loans (revolving credit) [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	3.14%	3.14%
Fleet loans (amortizing term) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2022
Debt instrument, maturity year range, end	2028
Debt Instrument Carrying Amount	$ 149,931	$ 149,931	176,295
Fleet loans (amortizing term) [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.61%	1.61%
Fleet loans (amortizing term) [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.66%	4.66%
Fleet loans (revolving credit) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2024
Debt instrument, maturity year range, end	2026
Debt Instrument Carrying Amount	$ 548,000	$ 548,000	535,000
Fleet loans (revolving credit) [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.24%	1.24%
Fleet loans (revolving credit) [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.33%	1.33%
Capital Leases (rental equipment) [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2021
Debt instrument, maturity year range, end	2026
Debt Instrument Carrying Amount	$ 426,155	$ 426,155	513,623
Capital Leases (rental equipment) [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.92%	1.92%
Capital Leases (rental equipment) [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	5.04%	5.04%
Finance capital lease [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start		2024
Debt instrument, maturity year range, end	2029
Debt Instrument Carrying Amount	$ 778,146	$ 778,146	644,375
Finance capital lease [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.60%	1.60%
Finance capital lease [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	4.22%	4.22%
Private Placement
Debt instrument, maturities:
Debt instrument, maturity year range, start	2029
Debt instrument, maturity year range, end	2033
Debt Instrument Carrying Amount	$ 600,000	$ 600,000	0
Private Placement | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.43%	2.43%
Private Placement | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	2.78%	2.78%
Other Obligations [Member]
Debt instrument, maturities:
Debt instrument, maturity year range, start	2021
Debt instrument, maturity year range, end	2049
Debt Instrument Carrying Amount	$ 87,080	$ 87,080	$ 86,085
Other Obligations [Member] | Minimum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	1.75%	1.75%
Other Obligations [Member] | Maximum [Member]
Debt instruments, interest rate, stated percentage:
Debt instrument, interest rate, stated percentage	8.00%	8.00%