Annual report pursuant to Section 13 and 15(d)

Nature of Operations and Summary of Significant Accounting Policies - Clinics in Operation Under Franchise Agreements or Company-Owned or Managed (Details)

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Nature of Operations and Summary of Significant Accounting Policies - Clinics in Operation Under Franchise Agreements or Company-Owned or Managed (Details) - clinic
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Product Information, Franchised Clinics, Company-Owned Or Managed Clinics, Activity [Roll Forward]    
Clinics open at beginning of period 579  
Clinics in operation at the end of the period 706 579
Clinic licenses sold but not yet developed 245 212
Executed letters of intent for future clinic licenses 38 41
Franchised Units    
Product Information, Franchised Clinics, Company-Owned Or Managed Clinics, Activity [Roll Forward]    
Clinics open at beginning of period 515 453
Opened during the period 110 70
Sold during the period (12) (1)
Closed during the period (3) (7)
Clinics in operation at the end of the period 610 515
Entity Operated Units    
Product Information, Franchised Clinics, Company-Owned Or Managed Clinics, Activity [Roll Forward]    
Clinics open at beginning of period 64 60
Opened during the period 20 3
Acquired during the period 12 1
Closed during the period 0 0
Clinics in operation at the end of the period 96 64