ACCOUNTING POLICIES (Policies)	12 Months Ended
ACCOUNTING POLICIES (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation. The consolidated financial statements include the accounts of Masco Corporation and all majority-owned subsidiaries. All significant intercompany transactions have been eliminated.
Use of Estimates and Assumptions in the Preparation of Financial Statements	Use of Estimates and Assumptions in the Preparation of Financial Statements. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires us to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of any contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from these estimates and assumptions.
Revenue Recognition	Revenue Recognition. We recognize revenue as title to products and risk of loss is transferred to customers or when services are rendered, net of applicable provisions for discounts, returns and allowances. Amounts billed for shipping and handling are included in net sales, while costs incurred for shipping and handling are included in cost of sales.
Customer Promotion Costs	Customer Promotion Costs. We record estimated reductions to revenue for customer programs and incentive offerings, including special pricing and certain co-operative advertising arrangements, promotions and other volume-based incentives. In-store displays that are owned by us and used to market our products are included in other assets in the consolidated balance sheets and are amortized using the straight-line method over the expected useful life of three to five years; related amortization expense is classified as a selling expense in the consolidated statement of operations.
Foreign Currency	Foreign Currency. The financial statements of our foreign subsidiaries are measured using the local currency as the functional currency. Assets and liabilities of these subsidiaries are translated at exchange rates as of the balance sheet dates. Revenues and expenses are translated at average exchange rates in effect during the year. The resulting cumulative translation adjustments have been recorded in the accumulated other comprehensive loss component of shareholders' equity. Realized foreign currency transaction gains and losses are included in the consolidated statements of operations in other income (expense), net.
Cash and Cash Investments	Cash and Cash Investments. We consider all highly liquid investments with an initial maturity of three months or less to be cash and cash investments.
Short-Term Bank Deposits	Short-Term Bank Deposits. We invest a portion of our foreign excess cash in short-term bank deposits. These highly liquid investments have original maturities between three and twelve months and are valued at cost, which approximates fair value at December 31, 2017 and 2016. These short-term bank deposits are classified in the current assets section of our consolidated balance sheets, and interest income related to short-term bank deposits is recorded in our consolidated statements of operations in other income (expense), net.
Receivables	Receivables. We do significant business with a number of customers, including certain home center retailers and homebuilders. We monitor our exposure for credit losses on our customer receivable balances and the credit worthiness of our customers on an on-going basis and record related allowances for doubtful accounts. Allowances are estimated based upon specific customer balances, where a risk of default has been identified, and also include a provision for non-customer specific defaults based upon historical collection, return and write-off activity. A separate allowance is recorded for customer incentive rebates and is generally based upon sales activity.
Property and Equipment	Property and Equipment. Property and equipment, including significant improvements to existing facilities, are recorded at cost. Upon retirement or disposal, the cost and accumulated depreciation are removed from the accounts and any gain or loss is included in the consolidated statements of operations. Maintenance and repair costs are charged against earnings as incurred. We review our property and equipment as events occur or circumstances change that would more likely than not reduce the fair value of the property and equipment below the carrying amount. If the carrying amount of property and equipment is not recoverable from its undiscounted cash flows, then we would recognize an impairment loss for the difference between the carrying amount and the current fair value. Further, we evaluate the remaining useful lives of property and equipment at each reporting period to determine whether events and circumstances warrant a revision to the remaining depreciation periods.
Depreciation	Depreciation. Depreciation expense is computed principally using the straight-line method over the estimated useful lives of the assets. Annual depreciation rates are as follows: buildings and land improvements, 2 to 10 percent, computer hardware and software, 17 to 33 percent, and machinery and equipment, 5 to 33 percent.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets. We perform our annual impairment testing of goodwill in the fourth quarter of each year, or as events occur or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. We have defined our reporting units and completed the impairment testing of goodwill at the operating segment level. Our operating segments are reporting units that engage in business activities, for which discrete financial information, including five-year forecasts, are available. We compare the fair value of the reporting units to the carrying value of the reporting units for goodwill impairment testing. Fair value is determined using a discounted cash flow method, which includes significant unobservable inputs (Level 3 inputs), and requires us to make significant estimates and assumptions, including long-term projections of cash flows, market conditions and appropriate discount rates. Our judgments are based upon historical experience, current market trends, consultations with external valuation specialists and other information. While we believe that the estimates and assumptions underlying the valuation methodology are reasonable, different estimates and assumptions could result in different outcomes. In estimating future cash flows, we rely on internally generated five-year forecasts for sales and operating profits, including capital expenditures, and, currently, a two percent long-term assumed annual growth rate of cash flows for periods after the five-year forecast. We utilize our weighted average cost of capital of approximately 8.0 percent as the basis to determine the discount rate to apply to the estimated future cash flows. In 2017, based upon our assessment of the risks impacting each of our businesses, we applied a risk premium to increase the discount rate to a range of 10.0 percent to 13.0 percent for our reporting units. If the carrying amount of a reporting unit exceeds its fair value, an impairment loss is recognized to the extent that a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill in that reporting unit. We review our other indefinite-lived intangible assets for impairment annually, in the fourth quarter, or as events occur or circumstances change that indicate the assets may be impaired without regard to the business unit. We consider the implications of both external (e.g., market growth, competition and local economic conditions) and internal (e.g., product sales and expected product growth) factors and their potential impact on cash flows related to the intangible asset in both the near- and long-term. Intangible assets with finite useful lives are amortized using the straight-line method over their estimated useful lives. We evaluate the remaining useful lives of amortizable intangible assets at each reporting period to determine whether events and circumstances warrant a revision to the remaining periods of amortization. Refer to Note G to the consolidated financial statements for additional information regarding goodwill and other intangible assets.
Fair Value Accounting	Fair Value Accounting. We use derivative financial instruments to manage certain exposure to fluctuations in earnings and cash flows resulting from changes in foreign currency exchange rates, and occasionally from changes in commodity costs and interest rate exposures. Derivative financial instruments are recorded in the consolidated balance sheets as either an asset or liability measured at fair value, netted by counterparty, where the right of offset exists. The gain or loss is recognized in determining current earnings during the period of the change in fair value.
Warranty	Warranty. We offer full and limited warranties on certain products with warranty periods ranging up to the lifetime of the product to the original consumer purchaser. At the time of sale, we accrue a warranty liability for the estimated future cost to provide products, parts or services to repair or replace products to satisfy our warranty obligations. Our estimate of future costs to service our warranty obligations is based upon the information available and includes a number of factors, such as the warranty coverage, the warranty period, historical experience specific to the nature, frequency and average cost to service the claim, along with industry and demographic trends. Certain factors and related assumptions in determining our warranty liability involve judgments and estimates and are sensitive to changes in the factors described above. We believe that the warranty accrual is appropriate; however, actual claims incurred could differ from our original estimates which would require us to adjust our previously established accruals. Refer to Note S to the consolidated financial statements for additional information on our warranty accrual. A. ACCOUNTING POLICIES (Continued) A significant portion of our business is at the consumer retail level through home center retailers and other major retailers. A consumer may return a product to a retail outlet that is a warranty return. However, certain retail outlets do not distinguish between warranty and other types of returns when they claim a return deduction from us. Our revenue recognition policy takes into account this type of return when recognizing revenue, and an estimate of these amounts is recorded as a deduction to net sales at the time of sale.
Insurance Reserves	Insurance Reserves. We provide for expenses associated with workers' compensation and product liability obligations when such amounts are probable and can be reasonably estimated. The accruals are adjusted as new information develops or circumstances change that would affect the estimated liability. Any obligations expected to be settled within 12 months are recorded in accrued liabilities; all other obligations are recorded in other liabilities.
Stock-Based Compensation	Stock-Based Compensation. We measure compensation expense for stock awards at the market price of our common stock at the grant date. Such expense is recognized ratably over the shorter of the vesting period of the stock awards, typically 5 or 10 years, or the length of time until the grantee becomes retirement-eligible at age 65. We measure compensation expense for stock options using a Black-Scholes option pricing model. Such expense is recognized ratably over the shorter of the vesting period of the stock options, typically five years, or the length of time until the grantee becomes retirement-eligible at age 65.
Noncontrolling Interest	Noncontrolling Interest. We owned 68 percent of Hansgrohe SE at both December 31, 2017 and 2016. The aggregate noncontrolling interest, net of dividends, at December 31, 2017 and 2016 has been recorded as a component of equity on our consolidated balance sheets.
Interest and Penalties on Uncertain Tax Positions	Interest and Penalties on Uncertain Tax Positions. We record interest and penalties on our uncertain tax positions in income tax expense (benefit). Accounting for Global Intangible Low-taxed Income ("GILTI"). We record the tax effects of GILTI related to our foreign operations as a component of income tax expense (benefit) in the period the tax arises.
Reclassifications	Reclassifications. Certain prior year amounts have been reclassified to conform to the 2017 presentation in the consolidated financial statements. In our consolidated statements of cash flows, the cash flows from discontinued operations are not separately classified.
Recently Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements. In May 2014, the FASB issued a new standard for revenue recognition, Accounting Standards Codification ("ASC") 606. The purpose of ASC 606 is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability across industries. The standard allows for either a full retrospective or modified retrospective method of adoption. We will adopt this standard on its effective date, January 1, 2018, under the full retrospective method of adoption. The adoption of the standard will not have a material impact on our financial position or results of operations. We have finalized our accounting policy, trained our business units on the new standard and finalized our internal controls under the new standard. We did not experience significant issues in our implementation process. In January 2016, the FASB issued ASU 2016-01, “Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities,” which primarily affects the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. ASU 2016-01 is effective for us for annual periods beginning January 1, 2018. The adoption of this standard will not have a material impact on our financial position or results of operations. In February 2016, the FASB issued a new standard for leases, ASC 842, which changes the accounting model for identifying and accounting for leases. ASC 842 is effective for us for annual periods beginning January 1, 2019 and currently requires retrospective application. We expect this standard to increase our total assets and total liabilities; however, we are currently evaluating the magnitude of the impact the adoption of this new standard will have on our financial position and results of operations. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments," which modifies the methodology for recognizing loss impairments on certain types of financial instruments. The new methodology requires an entity to estimate the credit losses expected over the life of an exposure. Additionally, ASU 2016-13 amends the current available-for-sale security other-than-temporary impairment model for debt securities. ASU 2016-13 is effective for us for annual periods beginning January 1, 2020. We are currently evaluating the impact the adoption of this new standard will have on our financial position and results of operations. In October 2016, the FASB issued ASU 2016-16, "Income Taxes (Topic 740): Intra-Entity Asset Transfers of Assets Other than Inventory," which no longer allows the tax effects of intra-entity asset transfers (intercompany sales) of assets other than inventory to be deferred until the transferred asset is sold to a third party or otherwise recovered through use. The new standard requires the tax expense from the sale of the asset in the seller’s tax jurisdiction and the corresponding basis differences in the buyer’s jurisdiction to be recognized when the transfer occurs even though the pre-tax effects of the transaction are eliminated in consolidation. ASU 2016-16 is effective for us for annual periods beginning January 1, 2018. The adoption of this standard will not have a material impact on our financial position or results of operations. In March 2017, the FASB issued ASU 2017-07, "Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost," which modifies the presentation of net periodic pension and post-retirement benefit cost ("net benefit cost") in the income statement and the components eligible for capitalization as assets. ASU 2017-07 is effective for us for annual periods beginning January 1, 2018. The adoption of the new standard will not have a material impact on our financial position or results of operations. For full year 2017 and 2016, we expect $26 million and $32 million of expense to be retrospectively reclassified from operating profit to other income (expense), net, within our results of operations. In May 2017, the FASB issued ASU 2017-09, "Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting," which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. ASU 2017-09 is effective for us for annual periods beginning January 1, 2018, and is applied prospectively. Upon adoption, 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. A. ACCOUNTING POLICIES (Concluded) In August 2017, the FASB issued ASU 2017-12, "Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities," which improves and simplifies accounting rules around hedge accounting and better portrays the economic results of an entity’s risk management activities in its financial statements. ASU 2017-12 is effective for us for annual periods beginning January 1, 2019. We are currently evaluating the impact the adoption of this new standard will have on our financial position and results of operations.
Inventories	Inventories, which include purchased parts, materials, direct labor and applied overhead, are stated at the lower of cost or net realizable value, with cost determined by use of the first-in, first-out method.
Derivatives	The fair value of all foreign currency and metals derivative contracts is estimated on a recurring basis, quarterly, using Level 2 inputs (significant other observable inputs).