Goodwill and Intangible Assets - Amortization Expense Associated with Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 1,796	$ 1,502
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	575	494
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	1,140	1,008
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	37	0
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 44	$ 0