BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Transaction related costs
Expenses, related to the Offerings and the Incremental Term Loan	$ 0	$ 0.9	$ 0	$ 1.6

Represents information pertaining to transaction related costs related to the IPO, the Secondary Offering, and other strategic alternative costs.

No definition available.

Name:	gnc_IPOSecondaryOfferingsAndOtherStrategicAlternativeCosts
Namespace Prefix:	gnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration