Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Current:
Federal	$ 50,631	$ 23,646	$ 42,570
State	2,900	(5,381)	4,221
Foreign	7,597	10,405	7,487
Current income tax	61,128	28,670	54,278
Deferred:
Federal	(23,592)	(5,004)	(15,401)
State	(225)	1,422	(1,093)
Foreign	(2,190)	(2,352)	468
Deferred income taxes	(26,007)	(5,934)	(16,026)
Total provision	$ 35,121	$ 22,736	$ 38,252