Supplemental Guarantor Condensed Consolidating Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended			42 Months Ended
	Jun. 28, 2014		Jun. 29, 2013	Jun. 28, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 175.0		$ 265.4
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(189.1)		(226.4)
Insurance proceeds			7.1
Other, net	(14.9)		40.6
Net cash used in investing activities	(204.0)		(178.7)
Cash Flows from Financing Activities:
Proceeds from the issuance of senior notes	325.0		500.0
Repurchase of senior notes	(327.1)		(72.1)
Payment of debt issuance and other financing costs	(3.8)		(13.4)
Repurchase of common stock	(156.0)		(1,000.1)	(1,700.0)
Dividends paid to Lear Corporation stockholders	(33.6)		(29.6)
Dividends paid to noncontrolling interests	(6.8)		(14.8)
Other	(38.2)		(9.3)
Net cash used in financing activities	(240.5)		(639.3)
Effect of foreign currency translation	(3.1)		(8.5)
Net Change in Cash and Cash Equivalents	(272.6)		(561.1)
Cash and Cash Equivalents as of Beginning of Period	1,137.7		1,402.2
Cash and Cash Equivalents as of End of Period	865.1	[1]	841.1	865.1	[1]
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	25.8		(3.5)
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(4.6)		(6.9)
Other, net	(2.5)		46.9
Net cash used in investing activities	(7.1)		40.0
Cash Flows from Financing Activities:
Proceeds from the issuance of senior notes	325.0		500.0
Repurchase of senior notes	(327.1)		(72.1)
Payment of debt issuance and other financing costs	(3.8)		(13.4)
Repurchase of common stock	(156.0)		(1,000.1)
Dividends paid to Lear Corporation stockholders	(33.6)		(29.6)
Other	(20.4)		(2.7)
Change in intercompany accounts	19.8		254.6
Net cash used in financing activities	(196.1)		(363.3)
Net Change in Cash and Cash Equivalents	(177.4)		(326.8)
Cash and Cash Equivalents as of Beginning of Period	343.5		481.4
Cash and Cash Equivalents as of End of Period	166.1		154.6	166.1
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	16.7		143.0
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(37.5)		(58.5)
Other, net	14.9		0.1
Net cash used in investing activities	(22.6)		(58.4)
Cash Flows from Financing Activities:
Change in intercompany accounts	5.8		(84.6)
Net cash used in financing activities	5.8		(84.6)
Net Change in Cash and Cash Equivalents	(0.1)
Cash and Cash Equivalents as of Beginning of Period	0.1		0.1
Cash and Cash Equivalents as of End of Period			0.1
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	132.5		125.9
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(147.0)		(161.0)
Insurance proceeds			7.1
Other, net	(27.3)		(6.4)
Net cash used in investing activities	(174.3)		(160.3)
Cash Flows from Financing Activities:
Dividends paid to noncontrolling interests	(6.8)		(14.8)
Other	(17.8)		(6.6)
Change in intercompany accounts	(25.6)		(170.0)
Net cash used in financing activities	(50.2)		(191.4)
Effect of foreign currency translation	(3.1)		(8.5)
Net Change in Cash and Cash Equivalents	(95.1)		(234.3)
Cash and Cash Equivalents as of Beginning of Period	794.1		920.7
Cash and Cash Equivalents as of End of Period	$ 699.0		$ 686.4	$ 699.0

[1] Unaudited.