SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF GNC HOLDINGS, INC. - Statements of Operations and Comprehensive (Loss) Income (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements
Operating income (loss)	$ 13,889	$ 26,654	$ 48,718	$ 35,482	$ (2,881)	$ 19,961	$ 48,884	$ 46,389	$ 124,743	$ 112,353	$ (256,816)
Interest expense, net									106,709	127,080	64,221
Gains on convertible notes transactions									(3,214)	0	(10,996)
Loss (gain) on forward contracts for the issuance of convertible preferred stock				$ 16,800	$ (88,900)				16,787	(88,942)	0
Income (loss) before income taxes and income from equity method investments									4,461	57,475	(310,041)
Income tax expense (benefit)									44,869	(12,305)	(159,779)
Net (loss) income before income from equity method investments									(40,408)	69,780	(150,262)
Other comprehensive (loss) income:
Net change in unrecognized loss on interest rate swaps, net of tax									(2,574)	(2,214)
Net change in unrecognized loss on interest rate swaps, net of tax											0
Foreign currency translation gain (loss)									403	(2,510)	2,866
Other comprehensive (loss) income									(2,171)	(4,724)	2,866
Comprehensive (loss) income									$ (37,283)	$ 65,056	$ (147,396)
(Loss) earnings per share:
Basic (in USD per share)	$ (0.46)	$ (0.09)	$ 0.13	$ (0.23)	$ 0.69	$ (0.10)	$ 0.16	$ 0.07	$ (0.64)	$ 0.83	$ (2.18)
Diluted (in USD per share)	$ (0.46)	$ (0.09)	$ 0.11	$ (0.23)	$ 0.62	$ (0.10)	$ 0.16	$ 0.07	$ (0.64)	$ 0.81	$ (2.18)
Weighted average common shares outstanding:
Basic (in shares)	83,878	83,823	83,663	83,510	83,476	83,412	83,332	83,232	83,720	83,364	68,789
Diluted (in shares)	83,878	83,823	140,942	83,510	94,388	83,412	83,409	83,368	83,720	86,171	68,789
GNC Holdings
Condensed Financial Statements
Selling, general and administrative									$ 1,489	$ 1,490	$ 1,238
Subsidiary loss									13,668	14,647	162,874
Operating income (loss)									(15,157)	(16,137)	(164,112)
Interest expense, net									4,751	5,040	10,399
Gains on convertible notes transactions									(3,214)	0	(15,041)
Loss (gain) on forward contracts for the issuance of convertible preferred stock									16,787	(88,942)	0
Income (loss) before income taxes and income from equity method investments									(33,481)	67,765	(159,470)
Income tax expense (benefit)									1,631	(2,015)	(9,208)
Net (loss) income before income from equity method investments									(35,112)	69,780	(150,262)
Other comprehensive (loss) income:
Net change in unrecognized loss on interest rate swaps, net of tax									(2,574)	(2,214)
Net change in unrecognized loss on interest rate swaps, net of tax											0
Foreign currency translation gain (loss)									403	(2,510)	2,866
Other comprehensive (loss) income									(2,171)	(4,724)	2,866
Comprehensive (loss) income									$ (37,283)	$ 65,056	$ (147,396)
(Loss) earnings per share:
Basic (in USD per share)									$ (0.64)
Diluted (in USD per share)									$ (0.64)
Weighted average common shares outstanding:
Basic (in shares)									83,720
Diluted (in shares)									83,720