Summary of Comprehensive Income (Loss) and Reconciliations of Equity (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 28, 2014		Jun. 29, 2013	Jun. 28, 2014		Jun. 29, 2013
Stockholders Equity Note [Line Items]
Beginning equity balance	$ 3,242.5		$ 3,485.8	$ 3,149.5		$ 3,612.2
Stock-based compensation transactions	16.3		14.4	16.6		21.8
Repurchase of common stock	(156.0)		(800.0)	(156.0)		(1,000.1)
Dividends declared to Lear Corporation stockholders	(16.7)		(14.1)	(33.9)		(30.6)
Dividends paid to noncontrolling interests	(1.0)		(9.5)	(6.8)		(14.8)
Acquisition of noncontrolling interests	(15.9)			(18.0)		(6.6)
Sale of controlling interest	(11.5)			(11.5)
Comprehensive income:
Net income	157.8		142.3	286.4		259.2
Other comprehensive income (loss), net of tax:
Defined benefit plan adjustments	0.1		1.8	0.1		3.7
Derivative instruments and hedging activities	2.8		(16.1)	4.7		(8.8)
Foreign currency translation adjustments	2.8		(14.3)	(9.9)		(45.7)
Other comprehensive income (loss)	5.7		(28.6)	(5.1)		(50.8)
Comprehensive income	163.5		113.7	281.3		208.4
Ending equity balance	3,221.2	[1]	2,790.3	3,221.2	[1]	2,790.3
Parent
Stockholders Equity Note [Line Items]
Beginning equity balance	3,142.3		3,360.6	3,045.9		3,487.1
Stock-based compensation transactions	16.3		14.4	16.6		21.8
Repurchase of common stock	(156.0)		(800.0)	(156.0)		(1,000.1)
Dividends declared to Lear Corporation stockholders	(16.7)		(14.1)	(33.9)		(30.6)
Acquisition of noncontrolling interests	5.4			5.7		(3.2)
Comprehensive income:
Net income	148.5		137.3	270.5		245.8
Other comprehensive income (loss), net of tax:
Defined benefit plan adjustments	0.1		1.8	0.1		3.7
Derivative instruments and hedging activities	2.8		(16.1)	4.7		(8.8)
Foreign currency translation adjustments	3.1		(14.6)	(7.8)		(46.4)
Other comprehensive income (loss)	6.0		(28.9)	(3.0)		(51.5)
Comprehensive income	154.5		108.4	267.5		194.3
Ending equity balance	3,145.8		2,669.3	3,145.8		2,669.3
Noncontrolling Interest
Stockholders Equity Note [Line Items]
Beginning equity balance	100.2		125.2	103.6		125.1
Dividends paid to noncontrolling interests	(1.0)		(9.5)	(6.8)		(14.8)
Acquisition of noncontrolling interests	(21.3)			(23.7)		(3.4)
Sale of controlling interest	(11.5)			(11.5)
Comprehensive income:
Net income	9.3		5.0	15.9		13.4
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(0.3)		0.3	(2.1)		0.7
Other comprehensive income (loss)	(0.3)		0.3	(2.1)		0.7
Comprehensive income	9.0		5.3	13.8		14.1
Ending equity balance	$ 75.4		$ 121.0	$ 75.4		$ 121.0

[1] Unaudited.