BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012
Transaction related costs
Expenses, related to the Offering	$ 0	$ 0.7

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