Income Taxes - Components of Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Current income tax provision (benefit):
Federal	$ (145)	$ 10	$ 15
State	(186)	56	177
Foreign	5,868	5,537	1,417
Total current income tax provision	5,537	5,603	1,609
Deferred income tax (benefit):
Federal	68,300	(1,773)	(2,276)
State	4,000	(104)	(35)
Foreign	(2,027)	(296)	(1,278)
Total deferred income tax (benefit)	70,273	(2,173)	(3,589)
Income tax provision (benefit)	$ 75,810	$ 3,430	$ (1,980)