Lines of Credit and Financing Arrangements (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Eligible amounts available and beneficial interests sold
Eligible amount available under the ASP on qualified accounts receivable	$ 160.0	$ 160.0
Beneficial interest sold	160.0	160.0
Remaining amount available	$ 0	$ 0

Eligible amount available under asset securitization.

No definition available.

Name:	lii_EligibleAmountAvailableUnderAssetSecuritization
Namespace Prefix:	lii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant