Reconciliation Between the U.S. Federal Statutory Income Tax Rate and Effective Tax Rate (Detail) (USD $) In Thousands	12 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Income Taxes [Line Items]
Income tax provision at U.S. federal statutory rate	$ 34,117	$ 32,306	$ 34,150
State income taxes, net of U.S. federal benefit	2,770	2,452	1,383
Foreign taxes	(6,045)	(4,721)	(3,469)
Research credits	(2,559)	(353)	(1,950)
Domestic production deduction	(2,494)	(1,204)	(1,421)
Reduction in valuation allowance			(148)
Other	104	(633)	3,560
Recorded income tax provision	$ 25,893	$ 27,847	$ 32,105

Income Taxes [Line Items]

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The sum of other amounts reflected in the reconciliation of the statutory tax provision (benefit) to the actual tax provision (benefit).

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to foreign tax credits generated or utilized under enacted tax laws during the period.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to research tax credits generated or utilized under enacted tax laws during the period.

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