Supplemental Guarantor Condensed Consolidating Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 29, 2012		Jun. 30, 2012	Dec. 31, 2011	Oct. 01, 2011	Jul. 02, 2011	Dec. 31, 2010
CURRENT ASSETS:
Cash and cash equivalents	$ 1,269.6	[1]		$ 1,754.3	$ 1,676.5		$ 1,654.1
Accounts receivable	2,192.8	[1]		1,880.1
Inventories	763.4	[1]		637.8
Other	618.2	[1]		489.3
Total current assets	4,844.0	[1]		4,761.5
LONG-TERM ASSETS:
Property, plant and equipment, net	1,299.6	[1]		1,072.0
Goodwill	728.6	[1]		628.6
Other	590.1	[1]		548.8
Total long-term assets	2,618.3	[1]		2,249.4
Total assets	7,462.3	[1]		7,010.9	7,215.9
CURRENT LIABILITIES:
Accounts payable and drafts	2,264.6	[1]		2,014.3
Accrued liabilities	1,033.1	[1]		1,049.2
Total current liabilities	3,297.7	[1]		3,063.5
LONG-TERM LIABILITIES:
Long-term debt	626.2	[1]		695.4
Other	736.2	[1]		690.9
Total long-term liabilities	1,362.4	[1]		1,386.3
EQUITY:
Lear Corporation stockholders' equity	2,667.4	[1]		2,436.4
Noncontrolling interests	134.8	[1]		124.7
Equity	2,802.2	[1]	2,700.5	2,561.1	2,743.2	2,901.9	2,568.8
Total liabilities and equity	7,462.3	[1]		7,010.9
Lear
CURRENT ASSETS:
Cash and cash equivalents	402.1			820.3	800.8		808.8
Accounts receivable	62.9			56.4
Inventories	5.8			7.7
Other	112.0			99.4
Total current assets	582.8			983.8
LONG-TERM ASSETS:
Property, plant and equipment, net	88.5			90.2
Goodwill	23.5			23.5
Investments in subsidiaries	1,169.0			594.2
Other	108.2			115.2
Total long-term assets	1,389.2			823.1
Total assets	1,972.0			1,806.9
CURRENT LIABILITIES:
Accounts payable and drafts	107.7			92.2
Accrued liabilities	99.4			135.5
Total current liabilities	207.1			227.7
LONG-TERM LIABILITIES:
Long-term debt	626.2			695.4
Intercompany accounts, net	(1,731.4)			(1,754.6)
Other	202.7			202.0
Total long-term liabilities	(902.5)			(857.2)
EQUITY:
Lear Corporation stockholders' equity	2,667.4			2,436.4
Equity	2,667.4			2,436.4
Total liabilities and equity	1,972.0			1,806.9
Guarantors
CURRENT ASSETS:
Cash and cash equivalents	0.5			1.4	0.2		0.4
Accounts receivable	393.8			299.1
Inventories	271.3			234.1
Other	40.7			18.4
Total current assets	706.3			553.0
LONG-TERM ASSETS:
Property, plant and equipment, net	247.1			164.5
Goodwill	370.8			303.9
Investments in subsidiaries	1,235.7			945.3
Other	57.3			30.9
Total long-term assets	1,910.9			1,444.6
Total assets	2,617.2			1,997.6
CURRENT LIABILITIES:
Accounts payable and drafts	582.4			473.7
Accrued liabilities	169.7			171.0
Total current liabilities	752.1			644.7
LONG-TERM LIABILITIES:
Intercompany accounts, net	665.1			675.2
Other	181.1			149.0
Total long-term liabilities	846.2			824.2
EQUITY:
Lear Corporation stockholders' equity	1,018.9			528.7
Equity	1,018.9			528.7
Total liabilities and equity	2,617.2			1,997.6
Non-Guarantors
CURRENT ASSETS:
Cash and cash equivalents	867.0			932.6	875.5		844.9
Accounts receivable	1,736.1			1,524.6
Inventories	486.3			396.0
Other	465.5			371.5
Total current assets	3,554.9			3,224.7
LONG-TERM ASSETS:
Property, plant and equipment, net	964.0			817.3
Goodwill	334.3			301.2
Other	424.6			402.7
Total long-term assets	1,722.9			1,521.2
Total assets	5,277.8			4,745.9
CURRENT LIABILITIES:
Accounts payable and drafts	1,574.5			1,448.4
Accrued liabilities	764.0			742.7
Total current liabilities	2,338.5			2,191.1
LONG-TERM LIABILITIES:
Intercompany accounts, net	1,066.3			1,079.4
Other	352.4			339.9
Total long-term liabilities	1,418.7			1,419.3
EQUITY:
Lear Corporation stockholders' equity	1,385.8			1,010.8
Noncontrolling interests	134.8			124.7
Equity	1,520.6			1,135.5
Total liabilities and equity	5,277.8			4,745.9
Eliminations
LONG-TERM ASSETS:
Investments in subsidiaries	(2,404.7)			(1,539.5)
Total long-term assets	(2,404.7)			(1,539.5)
Total assets	(2,404.7)			(1,539.5)
EQUITY:
Lear Corporation stockholders' equity	(2,404.7)			(1,539.5)
Equity	(2,404.7)			(1,539.5)
Total liabilities and equity	$ (2,404.7)			$ (1,539.5)

[1] Unaudited.