v3.26.1
Stockholders' equity (Details) - USD ($)
 3 Months Ended 6 Months Ended
Jan. 12, 2026
Dec. 16, 2025
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Dec. 31, 2025
Dec. 15, 2025
Dec. 12, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 13, 2024
Class of Stock [Line Items]                          
Repurchase and retirement of common stock     $ 202,061,000 $ 2,029,000 $ 253,413,000 $ 52,483,000              
Preferred stock authorized (in shares)     50,000,000   50,000,000     50,000,000          
Preferred stock issued (in shares)     0   0     0          
Preferred stock outstanding (in shares)     0   0     0          
2024 Share Repurchase Program                          
Class of Stock [Line Items]                          
Authorized stock repurchase program amount                         $ 500,000,000.0
Share repurchase excise tax           $ 400,000              
2025 Accelerated Share Repurchase Agreement                          
Class of Stock [Line Items]                          
Authorized stock repurchase program amount                   $ 350,000,000.0      
Accelerated cash paid   $ 350,000,000.0                      
2025 Share Repurchase Program                          
Class of Stock [Line Items]                          
Authorized stock repurchase program amount                 $ 500,000,000.0        
Share repurchase excise tax         $ 3,200,000                
Remaining authorized amount     $ 250,000,000.0   $ 250,000,000.0                
Investor | Pla-Fit Holdings, LLC | Secondary Offering and Exchange                          
Class of Stock [Line Items]                          
Percentage of economic interest(in percentage)         99.60%                
Continuing LLC Owners | Secondary Offering and Exchange                          
Class of Stock [Line Items]                          
Number of units held by owners (in shares)     316,128   316,128                
Continuing LLC Owners | Pla-Fit Holdings, LLC | Secondary Offering and Exchange                          
Class of Stock [Line Items]                          
Percentage of economic interest(in percentage)         0.40%                
Class B common stock                          
Class of Stock [Line Items]                          
Shares exchanged for Class A common stock (in shares)         1                
Common stock, shares outstanding (in shares)     316,000   316,000     316,000          
Class B common stock | Common stock                          
Class of Stock [Line Items]                          
Common stock, shares outstanding (in shares)     316,000 316,000 316,000 316,000 316,000 316,000     342,000 342,000  
Class B common stock | Continuing LLC Owners | Secondary Offering and Exchange                          
Class of Stock [Line Items]                          
Number of units held by owners (in shares)     316,128   316,128                
Class B common stock | Continuing LLC Owners | Continuing LLC Owners | Pla-Fit Holdings, LLC | Secondary Offering and Exchange                          
Class of Stock [Line Items]                          
Economic interest(in percentage)     0.40%   0.40%                
Holdings units                          
Class of Stock [Line Items]                          
Shares exchanged for Class A common stock (in shares)         1                
Class A common stock                          
Class of Stock [Line Items]                          
Common stock, shares outstanding (in shares)     75,197,000   75,197,000     80,446,000          
Class A common stock | 2024 Share Repurchase Program                          
Class of Stock [Line Items]                          
Repurchase and retirement of common stock (in shares)       21,519   565,745              
Repurchase and retirement of common stock       $ 2,100,000   $ 52,100,000              
Class A common stock | 2025 Accelerated Share Repurchase Agreement                          
Class of Stock [Line Items]                          
Repurchase and retirement of common stock (in shares) 754,644 2,548,234                      
Repurchase and retirement of common stock   $ 280,000,000.0                      
Percent of total ASR agreement value   80.00%                      
Weighted average cost per share (in usd per share) $ 108.76                        
Increase to accumulated deficit   $ 70,000,000.0                      
Class A common stock | 2025 Share Repurchase Program                          
Class of Stock [Line Items]                          
Repurchase and retirement of common stock (in shares)     3,965,298   4,579,023                
Repurchase and retirement of common stock     $ 200,000,000.0   $ 250,000,000.0                
Class A common stock | Common stock                          
Class of Stock [Line Items]                          
Common stock, shares outstanding (in shares)     75,197,000 83,907,000 75,197,000 83,907,000 79,124,000 80,446,000     83,836,000 84,323,000  
Repurchase and retirement of common stock (in shares)     3,966,000 22,000 5,334,000 566,000              
Class A common stock | Common Stockholders | Investor | Common stock                          
Class of Stock [Line Items]                          
Common stock, shares outstanding (in shares)     75,197,081   75,197,081                
Class A common stock | Common Stockholders | Investor | Common stock | Planet Fitness, Inc.                          
Class of Stock [Line Items]                          
Economic interest(in percentage)     99.60%   99.60%                
Class A common stock | Continuing LLC Owners | Investor                          
Class of Stock [Line Items]                          
Common stock, shares outstanding (in shares)     75,197,081   75,197,081