Reconciliation Between Federal Statutory Income Tax Rate and Effective Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Income tax provision at U.S. federal statutory rate	$ 46,595	$ 46,194	$ 47,685
State income taxes, net of U.S. federal benefit	2,832	2,689	3,663
Foreign Tax Rate Differential	(4,592)	(2,855)	(3,616)
Intercompany Interest	(1,246)	0	0
Research credits	(302)	(2,412)	(375)
Domestic production deduction	(3,141)	(2,168)	(3,054)
Federal and State Audit Settlements	(5,886)	0	(1,203)
Foreign	(1,654)	0	0
Valuation Allowance	3,888	2,310	0
Intercompany dividend	150	(32)	2,692
Effective Income Tax Rate Reconciliation, Deduction, Other, Amount	1,608	(1,837)	(1,553)
Total provision	$ 38,252	$ 41,889	$ 44,239