Lines of Credit and Financing Arrangements (Details 3)	Mar. 31, 2012	Dec. 31, 2011
Weighted average borrowing rate on the facility
Weighted average borrowing rate	1.49%	1.53%

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