XML 104 R1.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Cover Page - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Feb. 25, 2020
Jun. 28, 2019
Document Information [Line Items]      
Document Type 10-K    
Document Period End Date Dec. 31, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Current Fiscal Year End Date --12-31    
Amendment Flag false    
Entity Registrant Name WATSCO INC    
Entity Central Index Key 0000105016    
Entity Filer Category Large Accelerated Filer    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Shell Company false    
Entity File Number 1-5581    
Entity Small Business false    
Entity Incorporation, State or Country Code FL    
Entity Emerging Growth Company false    
Document Annual Report true    
Document Transition Report false    
Entity Tax Identification Number 59-0778222    
Entity Address, Address Line One 2665 South Bayshore Drive    
Entity Address, State or Province FL    
Entity Address, Address Line Two Suite 901    
Entity Address, City or Town Miami    
Entity Address, Postal Zip Code 33133    
City Area Code 305    
Local Phone Number 714-4100    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Public Float     $ 5,328
Common Stock [Member]      
Document Information [Line Items]      
Trading Symbol WSO    
Security Exchange Name NYSE    
Title of 12(b) Security Common stock, $0.50 par value    
Entity Common Stock, Shares Outstanding   32,717,924  
Common Class B [Member]      
Document Information [Line Items]      
Trading Symbol WSOB    
Security Exchange Name NYSE    
Title of 12(b) Security Class B common stock, $0.50 par value    
Entity Common Stock, Shares Outstanding   5,564,890