v3.19.3
Document and Entity Information
Oct. 17, 2019
Document And Entity Information [Line Items]  
Entity Registrant Name WATSCO INC
Amendment Flag false
Entity Central Index Key 0000105016
Document Type 8-K
Document Period End Date Oct. 17, 2019
Entity Incorporation State Country Code FL
Entity File Number 1-5581
Entity Tax Identification Number 59-0778222
Entity Address, Address Line One 2665 South Bayshore Drive
Entity Address, Address Line Two Suite 901
Entity Address, City or Town Miami
Entity Address, State or Province FL
Entity Address, Postal Zip Code 33133
City Area Code (305)
Local Phone Number 714-4100
Written Communications false
Soliciting Material false
Pre Commencement Tender Offer false
Pre Commencement Issuer Tender Offer false
Entity Emerging Growth Company false
Common Stock [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Common stock, $0.50 par value
Trading Symbol WSO
Security Exchange Name NYSE
Common Class B [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Class B common stock, $0.50 par value
Trading Symbol WSOB
Security Exchange Name NYSE