BASIS OF PRESENTATION (Policies)	6 Months Ended
BASIS OF PRESENTATION (Policies)	Jun. 30, 2017
Basis of Consolidation	Basis of Consolidation Watsco, Inc. (collectively with its subsidiaries, “Watsco,” “we,” “us” or “our”) was incorporated in Florida in 1956 and is the largest distributor of air conditioning, heating and refrigeration equipment and related parts and supplies (“HVAC/R”) in the HVAC/R distribution industry in North America. The accompanying June 30, 2017 interim condensed consolidated unaudited financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures normally included in the annual financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to those rules and regulations, but we believe the disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments, consisting of normal and recurring adjustments, necessary for a fair presentation have been included in the condensed consolidated unaudited financial statements included herein. These statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our 2016 Annual Report on Form 10-K. The condensed consolidated unaudited financial statements contained in this report include the accounts of Watsco, all of its wholly owned subsidiaries and the accounts of three joint ventures with Carrier Corporation (“Carrier”), in each of which Watsco maintains a controlling interest. All significant intercompany balances and transactions have been eliminated in consolidation. The results of operations for the quarter and six months ended June 30, 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2017. Sales of residential central air conditioners, heating equipment and parts and supplies are seasonal. Furthermore, results of operations can be impacted favorably or unfavorably based on weather patterns, primarily during the Summer and Winter selling seasons. Demand related to the residential central air conditioning replacement market is typically highest in the second and third quarters, and demand for heating equipment is usually highest in the fourth quarter. Demand related to the new construction market is fairly consistent during the year, subject to weather and economic conditions, including their effect on the number of housing completions.
Equity Method Investments	Equity Method Investments Investments in which we have the ability to exercise significant influence, but do not control, are accounted for under the equity method of accounting and are included in other assets in our consolidated balance sheets. Under this method of accounting, our proportionate share of the net income or loss of the investee is included in our consolidated statements of income.
Reclassifications	Reclassifications Certain reclassifications of prior year amounts have been made to conform to the 2017 presentation. These reclassifications had no effect on net income or earnings per share as previously reported.
Use of Estimates	Use of Estimates The preparation of condensed consolidated unaudited financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated unaudited financial statements and the reported amounts of revenues and expenses for the reporting period. Significant estimates include valuation reserves for accounts receivable, inventories and income taxes, reserves related to self-insurance programs and the valuation of goodwill and indefinite lived intangible assets. While we believe that these estimates are reasonable, actual results could differ from such estimates.
New Accounting Standards	New Accounting Standards Revenue Recognition In May 2014, the Financial Accounting Standards Board (the “FASB”) issued a standard on revenue recognition that provides a single, comprehensive revenue recognition model for all contracts with customers. The standard is principle-based and provides a five-step model to determine the measurement of revenue and timing of when it is recognized. This standard will be applied using either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients or (ii) a modified retrospective approach with the cumulative effect of initially adopting the standard recognized at the date of adoption, which requires additional footnote disclosures. This standard is effective for our interim and annual reporting periods beginning after December 15, 2017, with early adoption permitted for annual reporting periods beginning after December 15, 2016. We will adopt this guidance on January 1, 2018. While we are currently evaluating the method of adoption and the impact of the provisions of this standard, we expect similar performance obligations to result under this guidance as compared with deliverables and separate units of accounting currently identified. As a result, we expect the timing of our revenue recognition to generally remain the same. Measurement of Inventory In July 2015, the FASB issued guidance that simplifies the measurement of inventory by replacing the lower of cost or market test with a lower of cost and net realizable value test. The guidance applies to all inventory that is measured using first-in, first-out or average cost methods. This guidance must be applied prospectively and became effective for interim and annual reporting periods beginning after December 15, 2016. The adoption of this guidance did not have an impact on our consolidated financial statements. Classification of Deferred Taxes In November 2015, the FASB issued guidance that requires deferred tax assets and liabilities to be classified as noncurrent in a classified balance sheet. This guidance may be applied either prospectively or retrospectively and became effective for interim and annual reporting periods beginning after December 15, 2016. The adoption of this guidance on January 1, 2017 using the prospective approach did not have a material impact on our consolidated financial statements. Leases In February 2016, the FASB issued guidance on accounting for leases, which requires lessees to recognize most leases on their balance sheets for the rights and obligations created by those leases. The guidance requires enhanced disclosures regarding the amount, timing and uncertainty of cash flows arising from leases. This guidance will be applied using a modified retrospective approach and is effective for interim and annual periods beginning after December 15, 2018 with early adoption permitted. We will adopt this guidance on January 1, 2019. While we are still evaluating the impact of adopting this guidance on our consolidated financial statements, including the option to elect certain practical expedients, we expect that, upon adoption, the right-of-use assets and lease liabilities recorded could be material to our consolidated balance sheets. However, we do not expect a material impact to our consolidated statements of income. Intangibles – Goodwill and Other In January 2017, the FASB issued guidance to simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. Under this updated standard, an entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, but the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. An entity also should consider income tax effects from any tax-deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if any. This guidance is effective prospectively and is effective for interim and annual periods beginning after December 15, 2019 with early adoption permitted. We do not expect the adoption of this guidance to have a material impact to our consolidated financial statements. Stock Compensation In May 2017, the FASB issued guidance to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. This guidance is effective prospectively and is effective for interim and annual periods beginning after December 15, 2017 with early adoption permitted. We do not expect the adoption of this guidance to have a material impact to our consolidated financial statements.
Self-Insurance	Self-Insurance Self-insurance reserves are maintained relative to company-wide casualty insurance and health benefit programs. The level of exposure from catastrophic events is limited by the purchase of stop-loss and aggregate liability reinsurance coverage. When estimating the self-insurance liabilities and related reserves, management considers a number of factors, which include historical claims experience, demographic factors, severity factors and valuations provided by independent third-party actuaries. Management reviews its assumptions with its independent third-party actuaries to evaluate whether the self-insurance reserves are adequate. If actual claims or adverse development of loss reserves occur and exceed these estimates, additional reserves may be required. Reserves in the amounts of $2,815 and $2,951 at June 30, 2017 and December 31, 2016, respectively, were established related to such programs and are included in accrued expenses and other current liabilities in our condensed consolidated unaudited balance sheets.