Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Current:
Federal	$ 23,646	$ 42,570	$ 31,469
State	(5,381)	4,221	2,755
Foreign	10,405	7,487	3,994
Current income tax	28,670	54,278	38,218
Deferred:
Federal	(5,004)	(15,401)	(468)
State	1,422	(1,093)	2,069
Foreign	(2,352)	468	2,070
Deferred income taxes	(5,934)	(16,026)	3,671
Total provision	$ 22,736	$ 38,252	$ 41,889