Income Taxes - Income Tax Benefit (Provision) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Domestic													$ 10,966	$ 11,071	$ 8,992
Foreign													(2,164)	(1,662)	(12,980)
Income (loss) before income taxes													8,802	9,409	(3,988)
Federal—current													0	0	(117)
Federal—deferred													(1,387)	(2,182)	639
State—current													(78)	(46)	(438)
State—deferred													457	67	515
Foreign—current													(1,119)	(436)	594
Foreign—deferred													1,303	1,002	2,071
Income tax benefit (provision)	$ (637)	$ (304)	$ (417)	$ 534	$ (1,135)	$ (231)	$ (188)	$ (41)	$ (1,597)	$ 2,712	$ 794	$ 1,355	$ (824)	$ (1,595)	$ 3,264