CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 13,696	$ 7,254	$ 35,880	$ 25,090
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	3,690	2,724	7,484	888
Unrealized gains on marketable securities, net of tax effects of $0 during each of the three and nine months ended June 30, 2020, and $0 during each of the three and nine months ended June 30, 2019			7	111
Actuarial (losses) gains, net of tax effects of $2 and $4 during the three and nine months ended June 30, 2020, ($3) and $0 during the three and nine months ended June 30, 2019	(13)	9	(25)
Total other comprehensive income, net of tax	3,677	2,733	7,466	999
Comprehensive income	$ 17,373	$ 9,987	$ 43,346	$ 26,089