Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Apr. 02, 2016
Accounting Policies [Abstract]
Consolidation	The accompanying condensed consolidated financial statements include the accounts of Lear, a Delaware corporation, and the wholly owned and less than wholly owned subsidiaries controlled by Lear. In addition, Lear consolidates all entities, including variable interest entities, in which it has a controlling financial interest. Investments in affiliates in which Lear does not have control, but does have the ability to exercise significant influence over operating and financial policies, are accounted for under the equity method.
Fiscal period reporting	The Company’s annual financial results are reported on a calendar year basis, and quarterly interim results are reported using a thirteen week reporting calendar.
Reclassifications	Certain amounts in the prior period’s financial statements have been reclassified to conform to the presentation used in the quarter ended April 2, 2016.
Cost of sales	Cost of sales includes material, labor and overhead costs associated with the manufacture and distribution of the Company’s products. Distribution costs include inbound freight costs, purchasing and receiving costs, inspection costs, warehousing costs and other costs of the Company’s distribution network.
Selling, general and administrative expenses	Selling, general and administrative expenses include selling, engineering and development and administrative costs not directly associated with the manufacture and distribution of the Company’s products.
Inventories	Inventories are stated at the lower of cost or market. Cost is determined using the first-in, first-out method. Finished goods and work-in-process inventories include material, labor and manufacturing overhead costs.
Pre-production costs related to long-term supply arrangement	The Company incurs pre-production engineering and development ("E&D") and tooling costs related to the products produced for its customers under long-term supply agreements. The Company expenses all pre-production E&D costs for which reimbursement is not contractually guaranteed by the customer. In addition, the Company expenses all pre-production tooling costs related to customer-owned tools for which reimbursement is not contractually guaranteed by the customer or for which the Company does not have a non-cancelable right to use the tooling.
Property, plant and equipment	Property, plant and equipment is stated at cost. Costs associated with the repair and maintenance of the Company’s property, plant and equipment are expensed as incurred. Costs associated with improvements which extend the life, increase the capacity or improve the efficiency or safety of the Company’s property, plant and equipment are capitalized and depreciated over the remaining useful life of the related asset. Depreciable property is depreciated over the estimated useful lives of the assets, using principally the straight-line method.
Impairment of long-lived assets	The Company monitors its long-lived assets for impairment indicators on an ongoing basis in accordance with GAAP. If impairment indicators exist, the Company performs the required impairment analysis by comparing the undiscounted cash flows expected to be generated from the long-lived assets to the related net book values. If the net book value exceeds the undiscounted cash flows, an impairment loss is measured and recognized. The Company does not believe that there were any indicators that would have resulted in long-lived asset impairment charges as of April 2, 2016. The Company will, however, continue to assess the impact of any significant industry events and long-term automotive production estimates on the realization of its long-lived assets.
Impairment of goodwill	Goodwill is not amortized but is tested for impairment on at least an annual basis. Impairment testing is required more often than annually if an event or circumstance indicates that an impairment is more likely than not to have occurred. In conducting its annual impairment testing, the Company may first perform a qualitative assessment of whether it is more likely than not that a reporting unit’s fair value is less than its carrying amount. If not, no further goodwill impairment testing is required. If it is more likely than not that a reporting unit’s fair value is less than its carrying amount, or if the Company elects not to perform a qualitative assessment of a reporting unit, the Company then compares the fair value of the reporting unit to the related net book value. If the net book value of a reporting unit exceeds its fair value, an impairment loss is measured and recognized. The Company conducts its annual impairment testing as of the first day of its fourth quarter.
Net income per share attributable to Lear	Basic net income per share attributable to Lear is computed by dividing net income attributable to Lear by the average number of common shares outstanding during the period. Common shares issuable upon the satisfaction of certain conditions pursuant to a contractual agreement are considered common shares outstanding and are included in the computation of basic net income per share attributable to Lear. Diluted net income per share attributable to Lear is computed using the treasury stock method by dividing net income attributable to Lear by the average number of common shares outstanding, including the dilutive effect of common stock equivalents using the average share price during the period.
Marketable equity securities	Included in other current assets in the accompanying condensed consolidated balance sheets as of April 2, 2016 and December 31, 2015, are $25.0 million and $23.0 million, respectively, of marketable equity securities, which the Company accounts for under the fair value option. Accordingly, unrealized gains and losses arising from changes in the fair value of the marketable equity securities are recognized in the condensed consolidated statement of income as a component of other expense, net. The fair value of the marketable equity securities is determined by reference to quoted market prices in active markets (Level 1 input based on the GAAP fair value hierarchy).
Derivative instruments and hedging activities	The Company has used derivative financial instruments, including forwards, futures, options, swaps and other derivative contracts to reduce the effects of fluctuations in foreign exchange rates, interest rates and commodity prices and the resulting variability of the Company’s operating results. The Company is not a party to leveraged derivatives. The Company’s derivative financial instruments are subject to master netting arrangements that provide for the net settlement of contracts, by counterparty, in the event of default or termination. On the date that a derivative contract for a hedging instrument is entered into, the Company designates the derivative as either (1) a hedge of the exposure to changes in the fair value of a recognized asset or liability or of an unrecognized firm commitment (a fair value hedge), (2) a hedge of the exposure of a forecasted transaction or of the variability in the cash flows of a recognized asset or liability (a cash flow hedge) or (3) a hedge of a net investment in a foreign operation (a net investment hedge). For a fair value hedge, both the effective and ineffective portions of the change in the fair value of the derivative are recorded in earnings and reflected in the condensed consolidated statement of income on the same line as the gain or loss on the hedged item attributable to the hedged risk. For a cash flow hedge, the effective portion of the change in the fair value of the derivative is recorded in accumulated other comprehensive loss in the condensed consolidated balance sheet. When the underlying hedged transaction is realized, the gain or loss included in accumulated other comprehensive loss is recorded in earnings and reflected in the condensed consolidated statement of income on the same line as the gain or loss on the hedged item attributable to the hedged risk. For a net investment hedge, the effective portion of the change in the fair value of the derivative is recorded in cumulative translation adjustment, which is a component of accumulated other comprehensive loss in the condensed consolidated balance sheet. In addition, for both cash flow and net investment hedges, changes in the fair value of the derivative that are excluded from the Company’s effectiveness assessments and the ineffective portion of changes in the fair value of the derivative are recorded in earnings and reflected in the condensed consolidated statement of income as other expense, net. The Company uses forwards, swaps and other derivative contracts to reduce the effects of fluctuations in foreign exchange rates on known foreign currency exposures. Gains and losses on the derivative instruments are intended to offset gains and losses on the hedged transaction in an effort to reduce exposure to fluctuations in foreign exchange rates. The Company determines the fair value of its derivative contracts using quoted market prices to calculate the forward values and then discounts such forward values to the present value. The discount rates used are based on quoted bank deposit or swap interest rates. If a derivative contract is in a net liability position, the Company adjusts these discount rates, if required, by an estimate of the credit spread that would be applied by market participants purchasing these contracts from the Company’s counterparties. To estimate this credit spread, the Company uses significant assumptions and factors other than quoted market rates, which would result in the classification of its derivative liabilities within Level 3 of the fair value hierarchy.
Fair value of financial instruments	The Company measures certain assets and liabilities at fair value on a non-recurring basis, which are not included in the table above. As these non-recurring fair value measurements are generally determined using unobservable inputs, these fair value measurements are classified within Level 3 of the fair value hierarchy. As of April 2, 2016 and December 31, 2015, pretax net losses of approximately $43.6 million and $46.4 million, respectively, related to the Company’s derivative instruments and hedging activities were recorded in accumulated other comprehensive loss. During the next twelve month period, the Company expects to reclassify into earnings net losses of approximately $43.8 million recorded in accumulated other comprehensive loss as of April 2, 2016. Such losses will be reclassified at the time that the underlying hedged transactions are realized. During the three months ended April 2, 2016 and March 28, 2015, amounts recognized in the accompanying condensed consolidated statements of comprehensive income related to changes in the fair value of cash flow and fair value hedges excluded from the Company’s
New accounting pronouncements	Revenue Recognition The Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, "Revenue from Contracts with Customers (Topic 606)," ASU 2015-14, "Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date," ASU 2016-08, "Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net)," and ASU 2016-10, "Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing," all of which amend existing revenue recognition guidance and require additional financial statement disclosures. The provisions of these updates are effective as of January 1, 2018, and may be applied through either a full retrospective or a modified retrospective approach. The Company is currently evaluating the impact of these updates. Going Concern The FASB issued ASU 2014-15, "Presentation of Financial Statements — Going Concern," which requires management to make a going concern assessment for 24 months after the financial statement date. Previously, this assessment was made by the Company's independent registered public accounting firm. The provisions of this update are effective as of December 31, 2016, and are not expected to significantly impact the Company. Extraordinary Items The FASB issued ASU 2015-01, "Income Statement — Extraordinary and Unusual Items," which eliminates the concept of extraordinary items. The provisions of this update were effective as of January 1, 2016. The effects of adoption were not significant. Consolidation The FASB issued ASU 2015-02, "Amendments to the Consolidation Analysis," which provides guidance related to the application of both the variable interest and voting interest consolidation models. The provisions of this update were effective as of January 1, 2016. The effects of adoption were not significant. Inventory The FASB issued ASU 2015-11, "Simplifying the Measurement of Inventory," which requires entities to measure inventory at the lower of cost or net realizable value rather than at the lower of cost or market. The provisions of this update are effective as of January 1, 2017 (with early adoption permitted) and are not expected to significantly impact the Company. Business Combinations The FASB issued ASU 2015-16, "Simplifying the Accounting for Measurement-Period Adjustments," which eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. The provisions of this update were effective as of January 1, 2016. The effects of adoption were not significant. Financial Instruments The FASB issued ASU 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities," which requires equity investments in unconsolidated entities (other than those accounted for using the equity method of accounting) to be measured at fair value through earnings. A practicability exception exists for equity investments without readily determinable fair values. The provisions of this update are effective as of January 1, 2018 (with early adoption of certain provisions permitted) and are not expected to significantly impact the Company. The Company accounts for its investments in certain marketable equity securities under the fair value option (Note 15, "Financial Instruments"). Leases The FASB issued ASU 2016-02, "Leases,” which generally requires that a lessee recognize on its balance sheet right-of-use assets and corresponding liabilities resulting from leasing transactions, as well as additional required financial statement disclosures. Currently, U.S. GAAP only requires such balance sheet recognition for leases classified as capital leases. The provisions of this update apply to substantially all leased assets, with certain permitted exceptions, and are effective as of January 1, 2019. ASU 2016-02 must be adopted using a modified retrospective approach, which requires adoption as of the beginning of the earliest comparative financial statement period presented. The Company’s leases cover principally buildings and transportation equipment, and the Company incurred related rental expense of $126.2 million for the year ended December 31, 2015. The Company is currently evaluating the impact of this update. For additional information on the Company’s operating lease commitments, see Note 11, "Commitments and Contingencies," to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. Derivatives and Hedging The FASB issued ASU 2016-05, "Derivatives and Hedging (Topic 815): Effects of Derivative Contract Novations on Existing Hedge Accounting Relationships," and ASU 2016-06, "Derivatives and Hedging (Topic 815): Contingent Put and Call Options in Debt Instruments." The ASUs provide clarification when there is a change in a counterparty to a derivative hedging instrument and the steps required when assessing the economic characteristics of embedded put or call options. The provisions of these updates are effective as of January 1, 2017 (with early adoption permitted) and are not expected to significantly impact the Company. Equity Method of Accounting The FASB issued ASU 2016-07, "Investments-Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to Equity Method of Accounting," which eliminates the retroactive application when investments become qualified for the equity method of accounting as a result of an increase in the level of ownership or degree of influence. The provisions of this update are effective as of January 1, 2017 (with early adoption permitted) and are not expected to significantly impact the Company. Stock-Based Compensation The FASB issued ASU 2016-09, "Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” which simplifies several aspects of the accounting for share-based payment awards to employees and includes provisions related to income taxes, the liability or equity classification of share-based payment awards and statement of cash flow presentation. The income tax related provisions of this update are expected to significantly impact the Company and must be adopted through a cumulative effect adjustment to retained earnings as of the beginning of the period in which the update is adopted. Specifically, this update requires that income tax effects associated with share-based payment awards be recognized in the income statement when such awards vest or settle. Currently, certain of these income tax effects are required to be recorded in additional paid-in-capital to the extent that such tax benefits are realized through a reduction to current income tax payable. Tax benefits that do not result in a reduction to current income tax payable are recorded as a reduction to long-term deferred tax assets. As of December 31, 2015, the Company had tax benefits related to share-based payment awards of $45.4 million, recorded as a reduction to long-term deferred tax assets, and $3.9 million, recorded in additional paid-in-capital. Adoption of this update would result in the elimination of such amounts from other long-term assets and additional paid-in-capital, with a corresponding $49.3 million increase to retained earnings. The provisions of this update are effective as of January 1, 2017 (with early adoption permitted).