Leases (Components of our right-of-use assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021
Finance Lease [Abstract]
Buildings and Improvements	$ 135,174	$ 132,901
Furniture and equipment	22,176	22,316
Rental trailers and other rental equipment	197,981	203,594
Rental trucks	1,395,144	1,494,098
Right-of-use assets, gross	1,750,475	1,852,909
Less: Accumulated depreciation	(846,231)	(883,366)
Right of use assets, net	904,244	969,543
Finance Lease [Member]
Finance Lease [Abstract]
Buildings and Improvements	0	0
Furniture and equipment	22,176	22,316
Rental trailers and other rental equipment	197,981	203,594
Rental trucks	1,395,144	1,494,098
Right-of-use assets, gross	1,615,301	1,720,008
Less: Accumulated depreciation	(800,426)	(842,970)
Right of use assets, net	814,875	877,038
Operating Lease [Member]
Finance Lease [Abstract]
Buildings and Improvements	135,174	132,901
Furniture and equipment	0	0
Rental trailers and other rental equipment	0	0
Rental trucks	0	0
Right-of-use assets, gross	135,174	132,901
Less: Accumulated depreciation	(45,805)	(40,396)
Right of use assets, net	$ 89,369	$ 92,505