CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 23,748	$ 9,127	$ 49,776	$ 22,184
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(12,547)	(5,852)	717	3,793
Unrealized gains (losses) on marketable securities, net of tax effects of $0 during each of the three and six months ended March 31, 2021, and $0 during each of the three and six months ended March 31, 2020		(3)		7
Actuarial gains (losses), net of tax effects of ($4 )and $1 during the three and six months ended March 31, 2021, $1 and $2 during the three and six months ended March 31, 2020	39		1	(12)
Total other comprehensive income, net of tax	(12,508)	(5,855)	718	3,788
Comprehensive income	$ 11,240	$ 3,272	$ 50,494	$ 25,972