Acquisitions - GIROXX (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Remaining excess allocated to goodwill		$ 54.7	$ 51.2
Acquired finite-lived intangible asset, weighted average useful life		1 year
GIROXX [Member]
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
Remaining excess allocated to 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 [Member] | Licensing Agreements [Member]
Business Acquisition [Line Items]
Purchase price allocated to client base intangible assets acquired		0.4
GIROXX [Member] | Software Development [Member]
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