Disposal Group, Including Discontinued Operation, AOCI Reclassification Adjustment

No definition available.

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

- Definition

Disposal Group, Including Discontinued Operation, Asset Sold, Net

+ References

No definition available.

+ Details

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

- Definition

Disposal Group, Including Discontinued Operation, Gain (Loss)

+ References

No definition available.

+ Details

Name:	lii_DisposalGroupIncludingDiscontinuedOperationGainLoss
Namespace Prefix:	lii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Disposal Group, Including Discontinued Operation, Selling Expenses

+ References

No definition available.

+ Details

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

- Definition

Gain (Loss) on Disposition of Business and Related Property

+ References

No definition available.

+ Details

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

- Definition

Gain (loss) from sale or disposal of an organization or integrated set of activities (for example, but not limited to, a partnership or corporation) engaged in providing a product or service in a commercial, industrial, or professional environment.

+ References

No definition available.

+ Details

Name:	us-gaap_GainLossOnSaleOfBusiness
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow associated with the deconsolidation of a previously consolidated subsidiary or the sale of investment in consolidated subsidiaries (generally greater than 50 percent).

+ References

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfInterestInConsolidatedSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=lii_AustraliaNewZealandandAsiaBusinessesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsDisposedOfBySaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=lii_MilperraPropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=lii_BrazilBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Divestitures (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
Divestitures (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of business						$ 0.0
Loss (gain), net on sale of businesses and related property	$ (6.2)			$ 0.0	$ (25.8)	0.0
Net proceeds from sale of business and related property					115.9	$ 0.0
Australia, New Zealand and Asia Businesses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of business					13.0
Australia, New Zealand and Asia Businesses \| Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash received from the buyer					82.9
Net assets sold					(87.2)
AOCI reclassification adjustments, primarily foreign currency translation					(3.2)
Direct costs to sell					(5.5)
Loss on sale of business					(13.0)
Impairment reserve		$ 1.2	$ 10.3
Milperra Property \| Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Direct costs to sell					(1.5)
Loss on sale of business					(23.8)
Net proceeds from sale of business and related property					37.2
Brazil Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of business					36.6
Brazil Business \| Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash received from the buyer					4.2
Net assets sold					(13.2)
AOCI reclassification adjustments, primarily foreign currency translation					(24.7)
Direct costs to sell					(2.9)
Loss on sale of business					$ (36.6)