Supplemental Guarantor Consolidating Financial Statements - Supplemental Guarantor Consolidating Statements of Cash Flows (Detail) - USD ($)	12 Months Ended			72 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	$ 1,619,300,000	$ 1,271,100,000	$ 927,800,000
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(528,300,000)	(485,800,000)	(424,700,000)
Acquisitions, net of cash acquired and use of $350 million restricted cash in 2015 (see non-cash investing activities below) (Note 3)	(155,900,000)	(499,200,000)	0
Cash restricted for use - acquisition of Eagle Ottawa	0	0	(350,000,000)
Intercompany transactions	0	0	0
Other, net	47,100,000	19,700,000	(5,900,000)
Net cash used in investing activities	(637,100,000)	(965,300,000)	(780,600,000)
Cash Flows from Financing Activities:
Credit agreement borrowings	0	500,000,000	0
Credit agreement repayments	(21,900,000)	(9,400,000)	0
Short-term borrowings, net	9,100,000	0	0
Proceeds from the issuance of senior notes	0	0	975,000,000
Repurchase of senior notes, net of use of $250 million restricted cash in 2015 (see non-cash financing activities below) (Note 6)	0	(5,000,000)	(327,100,000)
Payment of debt issuance and other financing costs	0	0	(18,100,000)
Cash restricted for use - repurchase of senior notes	0	0	(250,000,000)
Repurchase of common stock	(658,800,000)	(487,400,000)	(411,400,000)	$ (3,100,000,000)
Dividends paid to Lear Corporation stockholders	(88,800,000)	(78,500,000)	(65,300,000)
Dividends paid to noncontrolling interests	(33,300,000)	(27,800,000)	(25,900,000)
Change in intercompany accounts	0	0	0
Other, net	(79,200,000)	(48,200,000)	(38,000,000)
Net cash used in financing activities	(872,900,000)	(156,300,000)	(160,800,000)
Effect of foreign currency translation	(34,300,000)	(47,000,000)	(30,000,000)
Net Change in Cash and Cash Equivalents	75,000,000	102,500,000	(43,600,000)
Cash and Cash Equivalents as of Beginning of Period	1,196,600,000	1,094,100,000	1,137,700,000
Cash and Cash Equivalents as of End of Period	1,271,600,000	1,196,600,000	1,094,100,000	1,271,600,000
Cash restricted for use - acquisition of Eagle Ottawa	0	(350,000,000)	0
Cash restricted for use - repurchase of senior notes	0	(250,000,000)	0
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	(52,800,000)	(156,300,000)	(12,600,000)
Cash Flows from Investing Activities:
Additions to property, plant and equipment	0	0	0
Acquisitions, net of cash acquired and use of $350 million restricted cash in 2015 (see non-cash investing activities below) (Note 3)	0	0
Cash restricted for use - acquisition of Eagle Ottawa			0
Intercompany transactions	(638,800,000)	(451,600,000)	(337,200,000)
Other, net	0	0	0
Net cash used in investing activities	(638,800,000)	(451,600,000)	(337,200,000)
Cash Flows from Financing Activities:
Credit agreement borrowings		0
Credit agreement repayments	0	0
Short-term borrowings, net	0
Proceeds from the issuance of senior notes			0
Repurchase of senior notes, net of use of $250 million restricted cash in 2015 (see non-cash financing activities below) (Note 6)		0	0
Payment of debt issuance and other financing costs			0
Cash restricted for use - repurchase of senior notes			0
Repurchase of common stock	0	0	0
Dividends paid to Lear Corporation stockholders	0	0	0
Dividends paid to noncontrolling interests	0	0	0
Change in intercompany accounts	691,600,000	607,900,000	349,800,000
Other, net	0	0	0
Net cash used in financing activities	691,600,000	607,900,000	349,800,000
Effect of foreign currency translation	0	0	0
Net Change in Cash and Cash Equivalents	0	0	0
Cash and Cash Equivalents as of Beginning of Period	0	0	0
Cash and Cash Equivalents as of End of Period	0	0	0	0
Cash restricted for use - acquisition of Eagle Ottawa		0
Cash restricted for use - repurchase of senior notes		0
Lear
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	290,900,000	208,300,000	142,400,000
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(77,600,000)	(68,400,000)	(52,400,000)
Acquisitions, net of cash acquired and use of $350 million restricted cash in 2015 (see non-cash investing activities below) (Note 3)	(149,000,000)	(521,100,000)
Cash restricted for use - acquisition of Eagle Ottawa			(350,000,000)
Intercompany transactions	437,400,000	584,600,000	400,500,000
Other, net	(16,800,000)	(6,600,000)	(5,000,000)
Net cash used in investing activities	194,000,000	(11,500,000)	(6,900,000)
Cash Flows from Financing Activities:
Credit agreement borrowings		500,000,000
Credit agreement repayments	(21,900,000)	(9,400,000)
Short-term borrowings, net	0
Proceeds from the issuance of senior notes			975,000,000
Repurchase of senior notes, net of use of $250 million restricted cash in 2015 (see non-cash financing activities below) (Note 6)		(5,000,000)	(327,100,000)
Payment of debt issuance and other financing costs			(18,100,000)
Cash restricted for use - repurchase of senior notes			(250,000,000)
Repurchase of common stock	(658,800,000)	(487,400,000)	(411,400,000)
Dividends paid to Lear Corporation stockholders	(88,800,000)	(78,500,000)	(65,300,000)
Dividends paid to noncontrolling interests	0	0	0
Change in intercompany accounts	283,300,000	82,700,000	15,900,000
Other, net	(44,700,000)	(50,600,000)	(20,200,000)
Net cash used in financing activities	(530,900,000)	(48,200,000)	(101,200,000)
Effect of foreign currency translation	0	0	0
Net Change in Cash and Cash Equivalents	(46,000,000)	148,600,000	34,300,000
Cash and Cash Equivalents as of Beginning of Period	526,400,000	377,800,000	343,500,000
Cash and Cash Equivalents as of End of Period	480,400,000	526,400,000	377,800,000	480,400,000
Cash restricted for use - acquisition of Eagle Ottawa		(350,000,000)
Cash restricted for use - repurchase of senior notes		(250,000,000)
Guarantors
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	345,300,000	329,500,000	211,800,000
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(111,000,000)	(91,500,000)	(61,400,000)
Acquisitions, net of cash acquired and use of $350 million restricted cash in 2015 (see non-cash investing activities below) (Note 3)	0	1,200,000
Cash restricted for use - acquisition of Eagle Ottawa			0
Intercompany transactions	214,800,000	(267,900,000)	(17,000,000)
Other, net	(1,400,000)	7,300,000	13,300,000
Net cash used in investing activities	102,400,000	(350,900,000)	(65,100,000)
Cash Flows from Financing Activities:
Credit agreement borrowings		0
Credit agreement repayments	0	0
Short-term borrowings, net	0
Proceeds from the issuance of senior notes			0
Repurchase of senior notes, net of use of $250 million restricted cash in 2015 (see non-cash financing activities below) (Note 6)		0	0
Payment of debt issuance and other financing costs			0
Cash restricted for use - repurchase of senior notes			0
Repurchase of common stock	0	0	0
Dividends paid to Lear Corporation stockholders	0	0	0
Dividends paid to noncontrolling interests	0	0	0
Change in intercompany accounts	(447,800,000)	21,800,000	(146,800,000)
Other, net	0	0	0
Net cash used in financing activities	(447,800,000)	21,800,000	(146,800,000)
Effect of foreign currency translation	0	0	0
Net Change in Cash and Cash Equivalents	(100,000)	400,000	(100,000)
Cash and Cash Equivalents as of Beginning of Period	400,000	0	100,000
Cash and Cash Equivalents as of End of Period	300,000	400,000	0	300,000
Cash restricted for use - acquisition of Eagle Ottawa		0
Cash restricted for use - repurchase of senior notes		0
Non- guarantors
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	1,035,900,000	889,600,000	586,200,000
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(339,700,000)	(325,900,000)	(310,900,000)
Acquisitions, net of cash acquired and use of $350 million restricted cash in 2015 (see non-cash investing activities below) (Note 3)	(6,900,000)	20,700,000
Cash restricted for use - acquisition of Eagle Ottawa			0
Intercompany transactions	(13,400,000)	134,900,000	(46,300,000)
Other, net	65,300,000	19,000,000	(14,200,000)
Net cash used in investing activities	(294,700,000)	(151,300,000)	(371,400,000)
Cash Flows from Financing Activities:
Credit agreement borrowings		0
Credit agreement repayments	0	0
Short-term borrowings, net	9,100,000
Proceeds from the issuance of senior notes			0
Repurchase of senior notes, net of use of $250 million restricted cash in 2015 (see non-cash financing activities below) (Note 6)		0	0
Payment of debt issuance and other financing costs			0
Cash restricted for use - repurchase of senior notes			0
Repurchase of common stock	0	0	0
Dividends paid to Lear Corporation stockholders	0	0	0
Dividends paid to noncontrolling interests	(33,300,000)	(27,800,000)	(25,900,000)
Change in intercompany accounts	(527,100,000)	(712,400,000)	(218,900,000)
Other, net	(34,500,000)	2,400,000	(17,800,000)
Net cash used in financing activities	(585,800,000)	(737,800,000)	(262,600,000)
Effect of foreign currency translation	(34,300,000)	(47,000,000)	(30,000,000)
Net Change in Cash and Cash Equivalents	121,100,000	(46,500,000)	(77,800,000)
Cash and Cash Equivalents as of Beginning of Period	669,800,000	716,300,000	794,100,000
Cash and Cash Equivalents as of End of Period	$ 790,900,000	669,800,000	$ 716,300,000	$ 790,900,000
Cash restricted for use - acquisition of Eagle Ottawa		0
Cash restricted for use - repurchase of senior notes		$ 0