Acquisitions - GIROXX (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Goodwill		$ 58.1	$ 54.7
Acquired finite-lived intangible asset, weighted average useful life		1 year
GIROXX
Business Acquisition [Line Items]
Percentage of stock purchased	100.00%
Purchase price	$ 4.4
Cash and cash equivalents	6.5
Property and equipment, net	0.1
Accounts payable and other accrued liabilities	0.6
Payable to clients	5.8
Goodwill	2.3
Operating revenues post-acquisition results of the acquired business			0.5
Net income (loss) post-acquisition results of the acquired business			$ (0.6)
GIROXX | Licensing Agreements
Business Acquisition [Line Items]
Purchase price allocated to client base intangible assets acquired	0.4
GIROXX | Capitalized software development
Business Acquisition [Line Items]
Purchase price allocated to client base intangible assets acquired	$ 1.5
Acquired finite-lived intangible asset, weighted average useful life	3 years