Lines of Credit and Financing Arrangements (Details Textual 3) (Line of Credit [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Line of Credit [Member]
Lines of Credit and Financing Arrangements (Textual) [Abstract]
Minimum amount of principal or interest due on indebtedness or receivable securitization	$ 75.0

Minimum amount of principal or interest due on indebtedness or receivable securitization.

No definition available.

Name:	lii_MinimumAmountOfPrincipalOrInterestDueOnIndebtednessOrReceivableSecuritization
Namespace Prefix:	lii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration