Schedule of Basic and Diluted Earnings per Common Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Watsco, Inc. shareholders	$ 45,699	$ 41,005	$ 110,402	$ 88,575
Less: distributed and undistributed earnings allocated to non-vested (restricted) common stock - basic	3,251	2,822	7,813	6,119
Earnings allocated to Watsco, Inc. shareholders - basic	42,448	38,183	102,589	82,456
Weighted-average Common and Class B common shares outstanding for basic earnings per share	32,206,448	32,107,701	32,182,430	31,529,296
Basic earnings per share for Common and Class B common stock	$ 1.32	$ 1.19	$ 3.19	$ 2.62
Net income attributable to Watsco, Inc. shareholders	45,699	41,005	110,402	88,575
Less: distributed and undistributed earnings allocated to non-vested (restricted) common stock - diluted	3,246	2,820	7,801	6,115
Earnings allocated to Watsco, Inc. shareholders	42,453	38,185	102,601	82,460
Weighted-average Common and Class B common shares outstanding for basic earnings per share	32,206,448	32,107,701	32,182,430	31,529,296
Effect of dilutive stock options	69,665	60,465	63,936	68,242
Weighted-average Common and Class B common shares outstanding for diluted earnings per share	32,276,113	32,168,166	32,246,366	31,597,538
Diluted earnings per share for Common and Class B common stock	$ 1.32	$ 1.19	$ 3.18	$ 2.61
Anti-dilutive stock options not included in above	620	2,283	4,963	11,445
Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings allocated to Watsco, Inc. shareholders - basic	38,880	34,789	93,960	74,992
Class B Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings allocated to Watsco, Inc. shareholders - basic	$ 3,568	$ 3,394	$ 8,629	$ 7,464