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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards classified as noncurrent.

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- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
Taxes - Additional Information (Detail) - USD ($)	Jan. 31, 2019	Jan. 31, 2018	Oct. 31, 2018
Taxes [Line Items]
Statutory federal income tax rate	21.00%
Deferred income taxes	$ 337,824,000		$ 404,166,000
Provision (benefit) for income taxes	(6,459,000)	$ 123,794,000
Minimum
Taxes [Line Items]
Estimated potential decrease in underlying unrecognized tax benefits	0
Maximum
Taxes [Line Items]
Estimated potential decrease in underlying unrecognized tax benefits	21,000,000
Retained Earnings \| Accounting Standards Update 2016-16 [Member] [Member]
Taxes [Line Items]
Cumulative effect adjustment	130,500,000
Foreign Tax Authority \| Hungarian Tax Authority
Taxes [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	22,800,000
Synopsys Hungary \| Foreign Tax Authority \| Tax Year 2011 - Tax Year 2013 \| Hungarian Tax Authority
Taxes [Line Items]
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority		25,000,000
Estimate of additional penalties and interest		$ 11,000,000
snps_FiscalYear2017 [Member] \| TAIWAN, PROVINCE OF CHINA
Taxes [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 5,500,000