Summary of Significant Accounting Policies and Select Balance Sheet Information - Impact of Adoption of ASC Topic 606 on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
Assets
Contract assets — royalties and license fees	$ 6,108	$ 8,210
Deferred income taxes	7,315	6,176		$ 6,304
Income tax receivable	2,391	558		1,152
Liabilities and Stockholders' Equity
Deferred revenue, current portion				9,646
Deferred revenue, less current portion				11,247
Retained earnings	$ 111,828	$ 110,705		$ 97,615
Adoption of ASC Topic 606 [Member]
Assets
Contract assets — royalties and license fees			$ 6,904
Deferred income taxes			5,089
Income tax receivable			762
Liabilities and Stockholders' Equity
Deferred revenue, current portion			9,628
Deferred revenue, less current portion			11,066
Retained earnings			103,113
Adjustments | Adoption of ASC Topic 606 [Member]
Assets
Contract assets — royalties and license fees			6,904
Deferred income taxes			(1,215)
Income tax receivable			(390)
Liabilities and Stockholders' Equity
Deferred revenue, current portion			(18)
Deferred revenue, less current portion			(181)
Retained earnings			$ 5,498