Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.1
Nature of Operations and Summary of Significant Accounting Policies - Clinics in Operation Under Franchise Agreements or Company-owned or Managed (Details) - clinic
 3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Product Information, Franchised Clinics, Company-Owned Or Managed Clinics, Activity [Roll Forward]    
Clinics in operation at the end of the period 592 530
Clinic licenses sold but not yet developed 223 176
Executed letters of intent for future clinic licenses 37 36
Franchised Clinics    
Product Information, Franchised Clinics, Company-Owned Or Managed Clinics, Activity [Roll Forward]    
Clinics open at beginning of period 515 453
Opened during the period 12 16
Sold during the period 0 0
Closed during the period 0 0
Clinics in operation at the end of the period 527 469
Company-owned or Managed Clinics    
Product Information, Franchised Clinics, Company-Owned Or Managed Clinics, Activity [Roll Forward]    
Clinics open at beginning of period 64 60
Opened during the period 1 1
Acquired during the period 0 0
Closed during the period 0 0
Clinics in operation at the end of the period 65 61