Goodwill and Intangible Assets - Amortization Expense Associated with Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 1,048	$ 1,448	$ 4,046	$ 4,453
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	406	452	1,444	1,440
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	561	996	2,359	3,013
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	37	0	112	0
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 44	$ 0	$ 131	$ 0