Debt Instrument, Covenant, Net Leverage Ratio

No definition available.

Name:	lii_DebtInstrumentCovenantNetLeverageRatio
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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Covenant, Net Leverage Ratio Following Material Acquisition

+ References

No definition available.

+ Details

Name:	lii_DebtInstrumentCovenantNetLeverageRatioFollowingMaterialAcquisition
Namespace Prefix:	lii_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Revolving credit facility committed to stand by letters of credit.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

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Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lii_A2025NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lii_A2027NotesMember
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Period Type:

Lines of Credit and Financing Arrangements (Domestic Credit Facility) (Details)	3 Months Ended
	Mar. 31, 2022 USD ($)	Jul. 31, 2021	Jul. 30, 2020 USD ($)	Nov. 01, 2016
Medium-term Notes \| Domestic Credit Facility
Line of Credit Facility [Line Items]
Face amount of debt			$ 750,000,000
Senior Notes [Member]
Line of Credit Facility [Line Items]
Minimum principal amount accelerated	$ 75,000,000
Debt instrument, interest rate, stated percentage				3.00%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Outstanding borrowings	347,500,000
Committed standby letters of credit	2,000,000
Available for future borrowings	$ 400,500,000
Debt instrument, covenant, net leverage ratio		3.50
Debt instrument, covenant, net leverage ratio following material acquisition		4.00
2025 Notes [Member] \| Senior Notes [Member]
Line of Credit Facility [Line Items]
Face amount of debt			$ 300,000,000
Debt instrument, interest rate, stated percentage			1.35%
2027 Notes [Member] \| Senior Notes [Member]
Line of Credit Facility [Line Items]
Face amount of debt			$ 300,000,000
Debt instrument, interest rate, stated percentage			1.70%