Nature of Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Other investments	$ 1,060,000	$ 1,643,000
Depreciation and amortization, property and equipment	23,500,000	24,200,000	$ 22,600,000
Foreign exchange gains (losses)	1,000,000.0	0.0	400,000
Advertising and promotion costs	8,700,000	3,600,000	4,100,000
Capitalized Contract Cost, Impairment Loss	$ 0	$ 0	$ 0
Minimum
Property, Plant and Equipment [Line Items]
Stock option awards vesting period	3 years
Maximum
Property, Plant and Equipment [Line Items]
Stock option awards vesting period	4 years
Software Development \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	2 years
Software Development \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	3 years

Amount of impairment loss for asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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The total expense recognized in the period for promotion, public relations, and brand or product advertising.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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