Debt Instrument, Original Issuance Discount

No definition available.

Name:	gnc_DebtInstrumentOriginalIssuanceDiscount
Namespace Prefix:	gnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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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

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
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Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=gnc_AmendedTermLoanFacilityDueMarchTwoThousandTwentyOneMember
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Data Type:	na
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_AssetBackedSecuritiesMember
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Data Type:	na
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- Details

Name:	us-gaap_CreditFacilityAxis=gnc_TermLoanMember
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Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=gnc_FILOAssetbasedTermLoanFacilityMember
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
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- Details

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- Details

Name:	gnc_DebtRestructuringTrancheAxis=gnc_TrancheOneMember
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- Details

Name:	gnc_DebtRestructuringTrancheAxis=gnc_TrancheTwoMember
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LONG-TERM DEBT / INTEREST EXPENSE - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Feb. 28, 2018	Feb. 27, 2018	Dec. 31, 2017	Jun. 30, 2017
Debt Instrument
Net carrying amount	$ 1,251,686			$ 1,297,023
Unpaid original issuance discount	13,231			0	$ 0
Debt issuance costs	(976)			(1,285)
Less: current debt	(205,617)			0
Long-term debt	1,046,069			1,297,023
Term Loan Facility Due March 2019
Debt Instrument
Net carrying amount			$ 1,131,200
Term Loan Facility \| Amended Term Loan Facility Due March 2021
Debt Instrument
Net carrying amount		$ 704,300
Asset-backed Securities \| Term Loan \| FILO Asset-based Term Loan Facility
Debt Instrument
Net carrying amount	262,721			0
Convertible Senior Notes \| 1.5% Convertible Senior Notes, Due 2020
Debt Instrument
Net carrying amount	171,701			167,988
Tranche B-1 \| Term Loan Facility \| Term Loan Facility Due March 2019
Debt Instrument
Net carrying amount	149,516	$ 151,900		1,130,320
Tranche B-2 \| FILO Asset-based Term Loan Facility
Debt Instrument
Unpaid original issuance discount	13,200
Tranche B-2 \| Term Loan Facility \| Amended Term Loan Facility Due March 2021
Debt Instrument
Net carrying amount	$ 655,493			$ 0