CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 39,166	$ 13,696	$ 88,942	$ 35,880
Other comprehensive income, net of tax:
Foreign currency translation adjustments	4,003	3,691	4,721	7,484
Unrealized gains (losses) on marketable securities, net of tax effects of $0 during each of the three and nine months ended June 30, 2021, and $0 during each of the three and nine months ended June 30, 2020				7
Actuarial losses, net of tax effects of $3 and $4 during the three and nine months ended June 30, 2021, respectively, $2 and $4 during the three and nine months ended June 30, 2020 respectively	(21)	(13)	(20)	(25)
Total other comprehensive income, net of tax	3,982	3,678	4,701	7,466
Comprehensive income	$ 43,148	$ 17,374	$ 93,643	$ 43,346