Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Equity Incentive Plans Narrative (Details)

v3.24.0.1
Stockholders' Equity - Equity Incentive Plans Narrative (Details) - USD ($)
shares in Thousands, $ in Millions
12 Months Ended
Jan. 01, 2022
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Oct. 06, 2021
Common Stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Issuance of common stock in connection with the employee stock purchase plan (in shares)   272      
ESPP shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares reserved for issuance (in shares)   2,900      
Annual increase in shares authorized, percent   1.00%      
Maximum shares available for issuance (in shares)   29,000      
Share-based compensation arrangement by share-based payment award, maximum employee subscription rate   15.00%      
Offering period   6 months      
Purchase price of commons stock, percent   90.00%      
Share-based compensation expense   $ 1.2 $ 0.1    
Unrecognized share-based compensation expense   $ 0.8      
Unrecognized share-based compensation expense, period of recognition   4 months 24 days      
Stock options          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   $ 11.8 19.8 $ 320.5  
Unrecognized share-based compensation expense, period of recognition   2 years 7 months 6 days      
Stock options | Center operations          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   $ 0.5 1.4 12.7  
Stock options | General, administrative and marketing          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   11.0 17.8 303.3  
Stock options | Other operating          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   0.3 0.5 4.5  
Restricted stock units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   $ 18.1 12.4 6.6  
Unrecognized share-based compensation expense, period of recognition   2 years      
Restricted stock units | Center operations          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   $ 2.1 1.4 0.2  
Restricted stock units | General, administrative and marketing          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   15.5 10.6 6.3  
Restricted stock units | Other operating          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   $ 0.5 $ 0.4 $ 0.1  
2015 Equity Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares reserved for issuance (in shares)       30,600  
Shares available for issuance (in shares)   1,000      
2021 Equity Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares reserved for issuance (in shares)         14,500
Annual increase in shares authorized, percent   4.00%      
Stock available for issuance, additional, (in shares) 7,700        
Term of plan   10 years      
Shares available for future grants (in shares)   17,600      
Share-based compensation expense   $ 19.0      
2021 Equity Plan | General, administrative and marketing          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   17.1      
2021 Equity Plan | Other operating          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense   $ 1.9