Supplemental Guarantor Condensed Consolidating Statements of Income (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
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 4,585.1	$ 4,113.1	$ 8,944.9	$ 8,060.2
Cost of sales	4,206.0	3,775.4	8,205.3	7,410.1
Selling, general and administrative expenses	138.0	127.9	274.7	257.5
Amortization of intangible assets	8.3	8.6	16.8	17.2
Interest expense	14.6	17.4	31.4	34.1
Other expense, net	16.8	10.3	46.0	21.0
Consolidated income before provision for income taxes and equity in net income of affiliates	201.4	173.5	370.7	320.3
Provision for income taxes	52.8	41.1	105.5	79.0
Equity in net income of affiliates	(9.2)	(9.9)	(21.2)	(17.9)
Consolidated net income	157.8	142.3	286.4	259.2
Less: Net income attributable to noncontrolling interests	9.3	5.0	15.9	13.4
Net income attributable to Lear	148.5	137.3	270.5	245.8
Consolidated comprehensive income	163.5	113.7	281.3	208.4
Less: Comprehensive income attributable to noncontrolling interests	9.0	5.3	13.8	14.1
Comprehensive income attributable to Lear	154.5	108.4	267.5	194.3
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net sales	127.7	125.6	230.8	247.2
Cost of sales	177.3	144.2	330.6	297.3
Selling, general and administrative expenses	52.8	38.3	115.4	78.7
Intercompany operating (income) expense, net	(119.0)	(70.1)	(248.2)	(124.4)
Amortization of intangible assets	0.4	0.4	0.8	0.8
Interest expense	10.7	9.1	24.2	24.1
Other expense, net	2.6	1.8	19.9	6.2
Consolidated income before provision for income taxes and equity in net income of affiliates	2.9	1.9	(11.9)	(35.5)
Provision for income taxes	1.3	4.2	(5.3)	(12.4)
Equity in net income of affiliates	0.5	(0.7)	0.6	(0.7)
Equity in net income of subsidiaries	(147.4)	(138.9)	(277.7)	(268.2)
Consolidated net income	148.5	137.3	270.5	245.8
Net income attributable to Lear	148.5	137.3	270.5	245.8
Consolidated comprehensive income	154.5	108.4	267.5	194.3
Comprehensive income attributable to Lear	154.5	108.4	267.5	194.3
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	1,815.2	1,615.8	3,449.8	3,143.5
Cost of sales	1,662.9	1,479.3	3,146.9	2,866.2
Selling, general and administrative expenses	14.7	14.2	20.0	31.9
Intercompany operating (income) expense, net	69.6	33.1	139.3	64.4
Amortization of intangible assets	1.2	1.2	2.4	2.4
Interest expense	6.4	8.8	11.2	12.1
Other expense, net	0.7	0.3	0.4	0.8
Consolidated income before provision for income taxes and equity in net income of affiliates	59.7	78.9	129.6	165.7
Provision for income taxes	22.9	28.7	53.1	60.6
Equity in net income of affiliates		(0.4)	(0.5)	(0.1)
Equity in net income of subsidiaries	(81.0)	(43.4)	(133.0)	(85.9)
Consolidated net income	117.8	94.0	210.0	191.1
Net income attributable to Lear	117.8	94.0	210.0	191.1
Consolidated comprehensive income	121.7	70.2	215.0	184.1
Comprehensive income attributable to Lear	121.7	70.2	215.0	184.1
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	3,894.6	3,537.8	7,685.7	6,975.1
Cost of sales	3,618.2	3,318.0	7,149.2	6,552.2
Selling, general and administrative expenses	70.5	75.4	139.3	146.9
Intercompany operating (income) expense, net	49.4	37.0	108.9	60.0
Amortization of intangible assets	6.7	7.0	13.6	14.0
Interest expense	(2.5)	(0.5)	(4.0)	(2.1)
Other expense, net	13.5	8.2	25.7	14.0
Consolidated income before provision for income taxes and equity in net income of affiliates	138.8	92.7	253.0	190.1
Provision for income taxes	28.6	8.2	57.7	30.8
Equity in net income of affiliates	(9.7)	(8.8)	(21.3)	(17.1)
Consolidated net income	119.9	93.3	216.6	176.4
Less: Net income attributable to noncontrolling interests	9.3	5.0	15.9	13.4
Net income attributable to Lear	110.6	88.3	200.7	163.0
Consolidated comprehensive income	122.0	82.3	206.4	131.9
Less: Comprehensive income attributable to noncontrolling interests	9.0	5.3	13.8	14.1
Comprehensive income attributable to Lear	113.0	77.0	192.6	117.8
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(1,252.4)	(1,166.1)	(2,421.4)	(2,305.6)
Cost of sales	(1,252.4)	(1,166.1)	(2,421.4)	(2,305.6)
Equity in net income of subsidiaries	228.4	182.3	410.7	354.1
Consolidated net income	(228.4)	(182.3)	(410.7)	(354.1)
Net income attributable to Lear	(228.4)	(182.3)	(410.7)	(354.1)
Consolidated comprehensive income	(234.7)	(147.2)	(407.6)	(301.9)
Comprehensive income attributable to Lear	$ (234.7)	$ (147.2)	$ (407.6)	$ (301.9)