Lines of Credit and Financing Arrangements (Details 4)	Mar. 31, 2013	Dec. 31, 2012
Summary of weighted average borrowing rate facility
Weighted average borrowing rate	1.20%	1.46%

Line of credit facility weighted average borrowing rate.

No definition available.

Name:	lii_LineOfCreditFacilityWeightedAverageBorrowingRate
Namespace Prefix:	lii_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant