Asset Backed Securities - Summary of Net Carrying Amount of Assets Transferred and Related Debt (Details) - USD ($) $ in Millions	Feb. 28, 2022	Aug. 31, 2021	Feb. 28, 2021
Assets [Abstract]
Restricted cash	$ 15.7	$ 24.6	$ 8.6
Accounts receivable, net	399.0	306.4
Equipment on operating leases, net	650.4	609.8
Liabilities [Abstract]
Notes payable, net	1,209.2	$ 826.5
GBX Leasing
Assets [Abstract]
Restricted cash	7.0
Equipment on operating leases, net	408.7
Liabilities [Abstract]
Notes payable, net	$ 318.3

Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant