Income Taxes - Significant Components of Net Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Accruals and reserves not currently deductible	$ 12,456	$ 11,050
Federal, state and foreign tax credits	20,434	20,084
Other assets	3,523	1,859
Net operating loss carryforwards	67,380	101,717
Inventory reserves and valuation	9,956	9,052
Deferred tax assets	113,749	143,762
Depreciation and intangible amortization	12,198	12,208
Deferred tax liabilities	12,198	12,208
Valuation allowance	(18,354)	(16,509)
Net deferred tax asset (liability)	$ 83,197	$ 115,045