Pre-Production Costs Related to Long-Term Supply Agreements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 29, 2012	Oct. 01, 2011
Pre Production Capitalized Costs and Recoveries Related to Long Term Supply Arrangements [Line Items]
Capitalized pre-production E&D costs	$ 161.0	$ 135.4
Capitalized pre-production tooling costs related to customer-owned tools	121.6	118.8
Cash collected related to E&D and tooling costs	$ 209.4	$ 222.1

Amount of recoverable preproduction engineering and design costs related to long term supply agreements capitalized during the reporting period.

No definition available.

Name:	lea_PreproductionEngineeringAndDevelopmentCostsRelatedToLongTermSupplyArrangementsCostsCapitalized
Namespace Prefix:	lea_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration