Related Party Transactions (Narratives) (Details) - USD ($) $ in Millions	9 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Sac Holdings [Member]
Related party notes receivable:
Interest paid (received) in cash on derivative contracts	$ 22.6	$ 22.7
Related party costs and expenses:
Cash flow, related party	20.9	1.8
Revenue generated by the dealer agreement from related parties		21.0
Commission expenses, generated from dealer agreement with related parties	1.8
Private Mini [Member]
Related party costs and expenses:
Commission expenses, generated from dealer agreement with related parties	65.7	71.3
Sac Holdings, Mercury, Four Sac, Five Sac, Galaxy and Private Mini [Member]
Property Management Fee [Abstract]
Property Management Fee Revenue	$ 25.0	24.9
Sac Holdings, Mercury, Four Sac, Five Sac, Galaxy and Private Mini [Member] | Minimum [Member]
Property Management Fee [Abstract]
Management fee rate	4.00%
Sac Holdings, Mercury, Four Sac, Five Sac, Galaxy and Private Mini [Member] | Maximum [Member]
Property Management Fee [Abstract]
Management fee rate	10.00%
Sac Holdings, Four Sac, Five Sac, Galaxy, and Private Mini [Member]
Related party costs and expenses:
Payments For Purchase Of Other Assets 1	$ 305.2	$ 339.5