General	9 Months Ended
Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General: References in this Quarterly Report on Form 10-Q to "we," "our," "us," "LII," or the "Company" refer to Lennox International Inc. and its subsidiaries, unless the context requires otherwise. Basis of Presentation The accompanying unaudited Consolidated Balance Sheet as of September 30, 2018, the accompanying unaudited Consolidated Statements of Operations for the three and nine months ended September 30, 2018 and 2017, the accompanying unaudited Consolidated Statements of Comprehensive Income for the three and nine months ended September 30, 2018 and 2017, and the accompanying unaudited Consolidated Statements of Cash Flows for the nine months ended September 30, 2018 and 2017 should be read in conjunction with our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2017. The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The accompanying consolidated financial statements contain all material adjustments, consisting principally of normal recurring adjustments, necessary for a fair presentation of our financial position, results of operations and cash flows. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to applicable rules and regulations, although we believe that the disclosures herein are adequate to make the information presented not misleading. The operating results for the interim periods are not necessarily indicative of the results that may be expected for a full year. Our fiscal quarterly periods are comprised of approximately 13 weeks, but the number of days per quarter may vary year-over-year. Our quarterly reporting periods usually end on the Saturday closest to the last day of March, June and September. Our fourth quarter and fiscal year ends on December 31, regardless of the day of the week on which December 31 falls. Use of Estimates The preparation of financial statements requires us to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangible assets and other long-lived assets, contingencies, guarantee obligations, indemnifications, and assumptions used in the calculation of income taxes, pension and post-retirement medical benefits, and stock-based compensation, among others. These estimates and assumptions are based on our best estimates and judgment. We evaluate these estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment. We believe these estimates and assumptions to be reasonable under the circumstances and will adjust such estimates and assumptions when facts and circumstances dictate. Volatile equity, foreign currency and commodity markets combine to increase the uncertainty inherent in such estimates and assumptions. Future events and their effects cannot be determined with precision and actual results could differ significantly from these estimates. Changes in these estimates will be reflected in the financial statements in future periods. Reclassifications Certain amounts have been reclassified from the prior year presentation to conform to the current year presentation. Recently Adopted Accounting Guidance In August 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-15, Classification of Certain Cash Receipts and Cash Payments. The amendments in this ASU clarify the classification for eight different types of activities, including debt prepayment and extinguishment costs, proceeds from insurance claims and distributions from equity method investees. For public business entities, the standard is effective for financial statements issued for fiscal years beginning after December 15, 2017. This standard did not have a material impact on our consolidated financial statements. We also adopted other new accounting standards during the first quarter of 2018. The impact of these additional standards are discussed in their respective Notes to the Consolidated Financial Statements. Recent Accounting Pronouncements On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842). Lessees will need to recognize almost all leases on their balance sheet as a right-of-use asset and a lease liability. It will be critical to identify leases embedded in a contract to avoid misstating the lessee’s balance sheet. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Classification will be based on criteria that are largely similar to those applied in current lease accounting, but without explicit bright lines. ASU 2016-02 is effective for public companies for annual reporting periods beginning after December 15, 2018, and interim periods within those fiscal years. As a result of the new standard, all of our leases greater than one year in duration will be recognized in our Consolidated Balance Sheets as both operating lease liabilities and right-of-use assets upon adoption of the standard. We will adopt the standard using the prospective approach. We have completed a qualitative and quantitative assessment of our lease portfolio and are in the process of testing our new lease accounting system, collecting data for leases entered into during 2018 and implementing new processes and controls to account for our leases in accordance with the new standard. Upon adoption, we expect to record right-of-use assets and operating lease liabilities between $150 million and $200 million in our Consolidated Balance Sheet. In August 2018, the SEC issued Release No. 33-10532 that amends and clarifies certain financial reporting requirements. The principal change to our financial reporting will be the inclusion of the annual disclosure requirement of changes in stockholders’ equity in Rule 3-04 of Regulation S-X to interim periods. We will adopt this new rule beginning with our financial reporting for the quarter ended March 31, 2019. Upon adoption, we will include our Consolidated Statements of Stockholders' Equity with each quarterly filing on Form 10-Q.

General:

References in this Quarterly Report on Form 10-Q to "we," "our," "us," "LII," or the "Company" refer to Lennox International Inc. and its subsidiaries, unless the context requires otherwise.

Basis of Presentation

The accompanying unaudited Consolidated Balance Sheet as of September 30, 2018, the accompanying unaudited Consolidated Statements of Operations for the three and nine months ended September 30, 2018 and 2017, the accompanying unaudited Consolidated Statements of Comprehensive Income for the three and nine months ended September 30, 2018 and 2017, and the accompanying unaudited Consolidated Statements of Cash Flows for the nine months ended September 30, 2018 and 2017 should be read in conjunction with our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2017. The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The accompanying consolidated financial statements contain all material adjustments, consisting principally of normal recurring adjustments, necessary for a fair presentation of our financial position, results of operations and cash flows. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to applicable rules and regulations, although we believe that the disclosures herein are adequate to make the information presented not misleading. The operating results for the interim periods are not necessarily indicative of the results that may be expected for a full year.

Our fiscal quarterly periods are comprised of approximately 13 weeks, but the number of days per quarter may vary year-over-year. Our quarterly reporting periods usually end on the Saturday closest to the last day of March, June and September. Our fourth quarter and fiscal year ends on December 31, regardless of the day of the week on which December 31 falls.

Use of Estimates

The preparation of financial statements requires us to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangible assets and other long-lived assets, contingencies, guarantee obligations, indemnifications, and assumptions used in the calculation of income taxes, pension and post-retirement medical benefits, and stock-based compensation, among others. These estimates and assumptions are based on our best estimates and judgment.

We evaluate these estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment. We believe these estimates and assumptions to be reasonable under the circumstances and will adjust such estimates and assumptions when facts and circumstances dictate. Volatile equity, foreign currency and commodity markets combine to increase the uncertainty inherent in such estimates and assumptions. Future events and their effects cannot be determined with precision and actual results could differ significantly from these estimates. Changes in these estimates will be reflected in the financial statements in future periods.

Reclassifications

Certain amounts have been reclassified from the prior year presentation to conform to the current year presentation.

Recently Adopted Accounting Guidance

In August 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-15, Classification of Certain Cash Receipts and Cash Payments. The amendments in this ASU clarify the classification for eight different types of activities, including debt prepayment and extinguishment costs, proceeds from insurance claims and distributions from equity method investees. For public business entities, the standard is effective for financial statements issued for fiscal years beginning after December 15, 2017. This standard did not have a material impact on our consolidated financial statements.

We also adopted other new accounting standards during the first quarter of 2018. The impact of these additional standards are discussed in their respective Notes to the Consolidated Financial Statements.

Recent Accounting Pronouncements

On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842). Lessees will need to recognize almost all leases on their balance sheet as a right-of-use asset and a lease liability. It will be critical to identify leases embedded in a contract to avoid misstating the lessee’s balance sheet. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Classification will be based on criteria that are largely similar to those applied in current lease accounting, but without explicit bright lines. ASU 2016-02 is effective for public companies for annual reporting periods beginning after December 15, 2018, and interim periods within those fiscal years. As a result of the new standard, all of our leases greater than one year in duration will be recognized in our Consolidated Balance Sheets as both operating lease liabilities and right-of-use assets upon adoption of the standard. We will adopt the standard using the prospective approach. We have completed a qualitative and quantitative assessment of our lease portfolio and are in the process of testing our new lease accounting system, collecting data for leases entered into during 2018 and implementing new processes and controls to account for our leases in accordance with the new standard. Upon adoption, we expect to record right-of-use assets and operating lease liabilities between $150 million and $200 million in our Consolidated Balance Sheet.

In August 2018, the SEC issued Release No. 33-10532 that amends and clarifies certain financial reporting requirements. The principal change to our financial reporting will be the inclusion of the annual disclosure requirement of changes in stockholders’ equity in Rule 3-04 of Regulation S-X to interim periods. We will adopt this new rule beginning with our financial reporting for the quarter ended March 31, 2019. Upon adoption, we will include our Consolidated Statements of Stockholders' Equity with each quarterly filing on Form 10-Q.