Pre-Production Costs Related to Long-Term Supply Agreements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 28, 2014	Jun. 29, 2013
Preproduction Costs Related To Long Term Supply Arrangements [Abstract]
Capitalized pre-production E&D costs	$ 103.6	$ 98.6
Capitalized pre-production tooling costs related to customer-owned tools	91.5	101.7
Cash collected related to E&D and tooling costs	$ 202.6	$ 198.3

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