Revenue Recognition - Additional Information (Details) - USD ($)	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue recognized included in contract liability balance at the beginning of the period	$ 5,600,000	$ 4,200,000
Impairment losses recognized on contract costs	0	0
Selling and marketing
Disaggregation of Revenue [Line Items]
Contract costs included in selling and marketing expenses	600,000	$ 400,000
Other Current and Non-current Assets
Disaggregation of Revenue [Line Items]
Contract costs	$ 1,500,000		$ 1,500,000