Aggregate Stock Options Granted Under Director Plan

No definition available.

Name:	snps_AggregateStockOptionsGrantedUnderDirectorPlan
Namespace Prefix:	snps_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Of Option Shares Granted

+ References

No definition available.

+ Details

Name:	snps_FairValueOfOptionSharesGranted
Namespace Prefix:	snps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Share based compensation arrangement assumed stock plans remaining outstanding shares.

+ References

No definition available.

+ Details

Name:	snps_ShareBasedCompensationArrangementAssumedStockPlansRemainingOutstandingShares
Namespace Prefix:	snps_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share based compensation arrangement for options contractual term.

+ References

No definition available.

+ Details

Name:	snps_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsContractualTermOne
Namespace Prefix:	snps_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The addition or reduction in the number of reserved shares that could potentially be issued under the option plan attributable to reasons other than grants, exercises, forfeitures, and expirations during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOtherIncreasesDecreasesInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate value of stock related to Restricted Stock Awards issued during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

+ Details

Name:	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=snps_TwoThousandAndSixEmployeeEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=snps_TwoThousandAndFiveNonEmployeeDirectorsEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=snps_TwoThousandSeventeenNonEmployeeDirectorsEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=snps_OtherAssumedStockPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Employee Benefit Plans (Equity Compensation Plans) - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
	Apr. 05, 2018	Oct. 31, 2018	Oct. 31, 2017	Apr. 06, 2017	Oct. 31, 2016	Oct. 31, 2015
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate restricted stock units outstanding (in shares)		3,769,000	3,843,000		4,035,000	3,928,000
Restricted Stock Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, (in years)		3 years
Restricted Stock Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, (in years)		4 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate restricted stock units outstanding (in shares)		20,000	38,000
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)		12,439,000	12,583,000		11,244,000	11,883,000
2006 Employee Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement for options contractual term (in years)		7 years
Vesting period, (in years)		4 years
Additional reserved for future issuance under the 2006 Employee Plan (in shares)	3,000,000
Shares available for future grant (in shares)		12,400,000
2006 Employee Equity Incentive Plan \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate restricted stock units outstanding (in shares)		3,600,000
2006 Employee Equity Incentive Plan \| Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate stock options outstanding (in shares)		5,900,000
2005 Non Employee Directors Plan \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate restricted stock units outstanding (in shares)		5,178
2005 Non Employee Directors Plan \| Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate stock options outstanding (in shares)		65,060
Aggregate stock options granted under 2005 director plan (in shares)			188,709
Fair value of option shares granted			$ 6.7
2005 Non Employee Directors Plan \| Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, (in years)			3 years
2005 Non Employee Directors Plan \| Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, (in years)			4 years
2017 Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for future issuance (in shares)		415,613		450,000
Restricted stock awards issued (in shares)		14,763
Aggregate grant date fair value of restricted stock awards		$ 1.2
2017 Directors Plan \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate restricted stock units outstanding (in shares)		14,763
2017 Directors Plan \| Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate stock options outstanding (in shares)		0
Other Assumed Stock Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assumed shares remaining outstanding (in shares)		500,000