National Advertising Fund - Additional Information (Detail) - Planet Fitness NAF, LLC [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Percentage of franchise membership billing revenue	2.00%
Percentage of monthly membership billing contribution	2.00%
Initial administrative fees charged	$ 1,700	$ 1,340	$ 1,010

Amount of revenue from providing administrative services, including, but not limited to, accounting, tax, legal, regulatory filing, and share registration activities of managed funds and investment accounts of independent third parties and related and affiliated entities.

No definition available.

Name:	us-gaap_AdministrativeServicesRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration