Summary of Significant Accounting Policies - Additional Information (Details)	6 Months Ended
Jun. 30, 2020
Planet Fitness NAF, LLC
Significant Accounting Policies [Line Items]
Percentage of franchise membership billing revenue	2.00%

The percentage of gross monthly membership billing collected from franchises on behalf of the related party for marketing, advertising and related programs.

No definition available.

Name:	plnt_PercentageOfMembershipBillingsCollectedOnBehalfOfRelatedParty
Namespace Prefix:	plnt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration