Business Organization - Additional Information (Detail) $ / shares in Units, $ in Thousands, Member in Millions						1 Months Ended			12 Months Ended
	Nov. 22, 2016 $ / shares shares	Sep. 28, 2016 $ / shares shares	Jun. 28, 2016 $ / shares shares	Aug. 11, 2015 USD ($) $ / shares shares	Aug. 05, 2015 shares	Nov. 30, 2016 $ / shares shares	Sep. 30, 2016 $ / shares shares	Jun. 30, 2016 $ / shares shares	Dec. 31, 2016 Member Store State shares	Dec. 31, 2015 USD ($) Store shares	Nov. 27, 2016	Sep. 27, 2016	Jun. 27, 2016	Dec. 31, 2014 Store	Dec. 31, 2013 Store
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of members | Member									8.9
Number of owned and franchised locations | Store									1,313	1,124				918	749
Number of states in which entity operates | State									48
Date of formation									Mar. 16, 2015
Proceeds from issuance of Class A common stock sold in initial public offering, net of underwriting discounts and commissions | $										$ 156,946
Continuing LLC Owners [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Percentage of economic interest	38.20%						49.40%	54.90%	37.70%		48.50%	54.90%	62.90%
Stock issued during period, shares, conversion of units									1,271,146
Class A Common Stock [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period	15,000,000	8,000,000	11,500,000			15,000,000	8,000,000	11,500,000	1,271,146	10,491,000
Share price | $ / shares	$ 23.22	$ 19.62	$ 16.50			$ 23.22	$ 19.62	$ 16.50
Stock issued during period, shares, conversion of units									24,705,000
Class A Common Stock [Member] | Continuing LLC Owners [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period	10,136,285	5,406,019	7,891,160			10,136,285	5,406,019	7,891,160	1,271,146
Number of shares exchanged									24,704,610	10,491,055
Class A Common Stock [Member] | Direct TSG Investors [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period	4,863,715	2,593,981	3,608,840	5,033,945		4,863,715	2,593,981	3,608,840
Class B Common Stock [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period										(10,491,000)
Number of shares exchanged									1,271,146
Stock issued during period, shares, conversion of units									(24,705,000)
Class B Common Stock [Member] | Continuing LLC Owners [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period					72,602,810
Number of shares exchanged	10,136,285	5,406,019	7,891,160			10,136,285	5,406,019	7,891,160	1,271,146
Pla-Fit Holdings, LLC [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Percentage of ownership	100.00%				100.00%		100.00%	100.00%	100.00%		100.00%	100.00%	100.00%
Number of units held by owners	10,136,285	5,406,019	7,891,160			10,136,285	5,406,019	7,891,160	1,271,146
Percentage of economic interest	61.80%						50.60%	45.10%	62.30%		51.50%	45.10%	37.10%
Pla-Fit Holdings, LLC [Member] | Class A Common Stock [Member] | IPO [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period				15,525,000
Share price | $ / shares				$ 16.00
Pla-Fit Holdings, LLC [Member] | Class A Common Stock [Member] | IPO [Member] | Continuing LLC Owners [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period				10,491,055
Proceeds from issuance of Class A common stock sold in initial public offering, net of underwriting discounts and commissions | $				$ 156,946
Pla-Fit Holdings, LLC [Member] | Class B Common Stock [Member] | Continuing LLC Owners [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of stock issued during period					72,602,810
Planet Intermediate, LLC [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Percentage of ownership					100.00%
Planet Fitness Holdings, LLC [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Percentage of ownership					100.00%