Annual report pursuant to Section 13 and 15(d)

Segment Reporting - Narrative (Details)

v3.20.4
Segment Reporting - Narrative (Details)
12 Months Ended
Dec. 31, 2020
segment
clinic
Dec. 31, 2019
clinic
Dec. 31, 2018
clinic
Segment Reporting Information [Line Items]      
Number of operating segments | segment 2    
Number of stores 579 513  
Entity Operated Units      
Segment Reporting Information [Line Items]      
Number of stores 64 60 48
Franchised Units      
Segment Reporting Information [Line Items]      
Number of stores 515 453 394