Debt instrument, periodic principal payments, percentage of aggregate outstanding amount.

No definition available.

Name:	svmk_DebtInstrumentPeriodicPrincipalPaymentsPercentageOfAggregateOutstandingAmount
Namespace Prefix:	svmk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=114001942&loc=d3e12355-112629

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114001942&loc=d3e12317-112629

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_DomesticLineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=svmk_TwoThousandThirteenCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=svmk_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=svmk_TwoThousandSeventeenRefinancingFacilityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
Debt - Additional Information (Details) - USD ($)	Apr. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Feb. 28, 2013
Debt Instrument [Line Items]
Loss on debt extinguishment		$ 0	$ 0	$ 0	$ 194,000
Revolving Credit Facility \| Domestic Line of Credit
Debt Instrument [Line Items]
Debt instrument, due date				Apr. 30, 2022
2013 Credit Facility \| Term Loan
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity						$ 315,000,000
Loss on debt extinguishment			$ 200,000		$ 200,000
2013 Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity						$ 75,000,000
Debt instrument, due date	Apr. 13, 2022
2017 Refinancing Facility Agreement
Debt Instrument [Line Items]
Debt instrument, due date				Apr. 30, 2024
Line of credit facility, remaining borrowing capacity		$ 42,200,000		$ 42,200,000
2017 Refinancing Facility Agreement \| Term Loan
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 300,000,000
Debt instrument, periodic principal payments, percentage of aggregate outstanding amount	0.25%
Debt instrument, due date	Apr. 13, 2024
2017 Refinancing Facility Agreement \| Term Loan \| Base Rate
Debt Instrument [Line Items]
Applicable margin	3.50%
2017 Refinancing Facility Agreement \| Term Loan \| LIBOR
Debt Instrument [Line Items]
Applicable margin	4.50%
2017 Refinancing Facility Agreement \| Revolving Credit Facility \| Domestic Line of Credit
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 75,000,000
2017 Refinancing Facility Agreement \| Revolving Credit Facility \| Base Rate \| Domestic Line of Credit
Debt Instrument [Line Items]
Applicable margin	3.00%
2017 Refinancing Facility Agreement \| Revolving Credit Facility \| LIBOR \| Domestic Line of Credit
Debt Instrument [Line Items]
Applicable margin	4.00%