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Tax on deferred undistributed foreign earnings not provided.

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Undistributed foreign earnings.

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Unrecognized deferred tax assets.

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The amount of the additional liability or refund received or expected based on a final settlement with a taxing authority.

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The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations.

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The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations.

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The increase (decrease) during the reporting period in the account that represents the temporary difference that results from Income or Loss that is recognized for accounting purposes but not for tax purposes and vice versa.

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The estimated lower bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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The estimated upper bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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Income Taxes - Taxes - Additional Information (Detail) (USD $)	12 Months Ended			3 Months Ended		6 Months Ended	3 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Jan. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Apr. 30, 2014	Apr. 30, 2012	Mar. 05, 2012
Taxes [Line Items]
Increase in valuation allowance	$ 2,600,000
Unrecognized deferred tax assets	70,700,000snps_UnrecognizedDeferredTaxAssets						70,700,000snps_UnrecognizedDeferredTaxAssets
Undistributed foreign earnings	948,000,000snps_UndistributedForeignEarnings						948,000,000snps_UndistributedForeignEarnings
Tax on deferred undistributed foreign earnings	206,000,000
Increase in gross unrecognized tax benefits	6,300,000
Gross unrecognized tax benefits	124,102,000us-gaap_UnrecognizedTaxBenefits	117,760,000us-gaap_UnrecognizedTaxBenefits	109,680,000us-gaap_UnrecognizedTaxBenefits			117,760,000us-gaap_UnrecognizedTaxBenefits	124,102,000us-gaap_UnrecognizedTaxBenefits
Unrecognized tax benefits affecting effective tax rate	120,500,000	117,800,000				117,800,000	120,500,000
The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations	500,000	200,000	(5,800,000)
The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations	1,300,000	800,000				800,000	1,300,000
Estimated potential decrease in underlying unrecognized tax benefits, minimum	0						0
Estimated potential decrease in underlying unrecognized tax benefits, maximum	25,000,000						25,000,000
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities	1,858,000	4,967,000
Internal Revenue Service (IRS) \| Fiscal Years 2010 and 2011
Taxes [Line Items]
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities				24,700,000
Tax impact from tax settlements				15,900,000
Internal Revenue Service (IRS) \| Fiscal Year 2012
Taxes [Line Items]
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities					10,000,000	6,000,000
Decrease in deferred tax assets						4,900,000
Tax impact from tax settlements						1,100,000
Internal Revenue Service (IRS) \| Fiscal Year 2013
Taxes [Line Items]
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities							5,500,000
Taiwan \| Fiscal Year 2008
Taxes [Line Items]
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities			16,500,000
Tax impact from tax settlements			14,700,000
Taiwan \| Fiscal Years 2009 and 2010
Taxes [Line Items]
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities								5,100,000
Tax impact from tax settlements								3,900,000
Hungary \| Fiscal Year 2006 Through 2008
Taxes [Line Items]
Cash payments as a result of settlement										5,100,000
Hungary \| Fiscal Year 2006 Through 2010
Taxes [Line Items]
Decrease in unrecognized tax benefits resulting from settlement with taxing authorities				24,200,000					27,000,000
Hungary \| Fiscal Years 2009 and 2010
Taxes [Line Items]
Tax impact from tax settlements			6,300,000
Hungary \| Fiscal Years 2009 and 2010 \| Cash Payment Obligations
Taxes [Line Items]
Cash payments as a result of settlement			3,200,000
Hungary \| Fiscal Years 2009 and 2010 \| Cash payment
Taxes [Line Items]
Cash payments as a result of settlement			$ 10,900,000