Summary of Comprehensive Income (Loss) and Reconciliations of Equity (Detail) (USD $) In Millions	3 Months Ended			9 Months Ended
	Oct. 01, 2011		Oct. 02, 2010	Oct. 01, 2011		Oct. 02, 2010
Stockholders Equity Note [Line Items]
Beginning equity balance	$ 2,901.9		$ 2,322.5	$ 2,568.8		$ 2,181.8
Stock-based compensation transactions and other	10.3		4.0	25.8		13.1
Repurchase of common stock	(94.2)			(194.2)
Dividends declared to Lear Corporation stockholders	(13.2)			(40.0)
Dividends paid to noncontrolling interests	(0.3)		(9.3)	(18.5)		(13.9)
Addition to noncontrolling interests				2.4
Transaction with affiliates						6.5
Comprehensive income:
Net income	108.1		98.5	456.5		337.6
Other comprehensive income (loss), net of tax:
Defined benefit plan adjustments	0.1		(1.9)	0.3		(2.1)
Derivative instruments and hedging activities	(51.9)		3.5	(45.0)		3.7
Foreign currency translation adjustments	(117.6)		120.7	(12.9)		11.3
Other comprehensive income (loss)	(169.4)		122.3	(57.6)		12.9
Comprehensive income (loss)	(61.3)		220.8	398.9		350.5
Ending equity balance	2,743.2	[1]	2,538.0	2,743.2	[1]	2,538.0
Attributable to Lear Corporation Stockholders
Stockholders Equity Note [Line Items]
Beginning equity balance	2,792.7		2,214.5	2,460.2		2,089.1
Stock-based compensation transactions and other	10.3		4.0	25.8		13.1
Repurchase of common stock	(94.2)			(194.2)
Dividends declared to Lear Corporation stockholders	(13.2)			(40.0)
Comprehensive income:
Net income	100.7		95.3	434.2		321.2
Other comprehensive income (loss), net of tax:
Defined benefit plan adjustments	0.1		(1.9)	0.3		(2.1)
Derivative instruments and hedging activities	(51.9)		3.5	(45.0)		3.7
Foreign currency translation adjustments	(118.0)		119.0	(14.8)		9.4
Other comprehensive income (loss)	(169.8)		120.6	(59.5)		11.0
Comprehensive income (loss)	(69.1)		215.9	374.7		332.2
Ending equity balance	2,626.5		2,434.4	2,626.5		2,434.4
Non-controlling Interests
Stockholders Equity Note [Line Items]
Beginning equity balance	109.2		108.0	108.6		92.7
Dividends paid to noncontrolling interests	(0.3)		(9.3)	(18.5)		(13.9)
Addition to noncontrolling interests				2.4
Transaction with affiliates						6.5
Comprehensive income:
Net income	7.4		3.2	22.3		16.4
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	0.4		1.7	1.9		1.9
Other comprehensive income (loss)	0.4		1.7	1.9		1.9
Comprehensive income (loss)	7.8		4.9	24.2		18.3
Ending equity balance	$ 116.7		$ 103.6	$ 116.7		$ 103.6

[1] Unaudited.