Pre-Production Costs Related to Long-Term Supply Agreements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 27, 2014	Sep. 28, 2013
Preproduction Costs Related to Long-term Supply Arrangements [Abstract]
Capitalized pre-production E&D costs	$ 143.0	$ 139.8
Capitalized pre-production tooling costs related to customer-owned tools	118.2	164.3
Cash collected related to E&D and tooling costs	$ 247.2	$ 296.5

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