Income Taxes - Components of Income Tax (Provision) Benefit (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income (Loss) before taxes by component
Domestic													$ 8,992	$ (1,584)	$ 4,057
Foreign													(12,980)	(7,157)	(886)
Income (loss) before income taxes													(3,988)	(8,741)	3,171
Federal—current													(117)	(87)	(127)
Federal—deferred													639	(4,537)	8,291
State—current													(438)	(26)	(20)
State—deferred													515	773	2,748
Foreign—current													594	(270)	29
Foreign—deferred													2,071	1,081	0
Income tax benefit (provision)	$ (1,597)	$ 2,712	$ 794	$ 1,355	$ (783)	$ 1,430	$ (99)	$ (3,614)	$ 11,012	$ (17)	$ (74)	$ 0	$ 3,264	$ (3,066)	$ 10,921