Income Taxes - Components of Income Tax Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Current income tax provision (benefit):
Federal		$ (145)	$ 10
State	$ 473	(186)	56
Foreign	11,150	5,868	5,537
Total current income tax provision	11,623	5,537	5,603
Deferred income tax provision (benefit):
Federal	538	68,300	(1,773)
State	31	4,000	(104)
Foreign	(52)	(2,027)	(296)
Total deferred income tax provision (benefit)	517	70,273	(2,173)
Income tax provision	$ 12,140	$ 75,810	$ 3,430