NEW ACCOUNTING STANDARDS	3 Months Ended
Mar. 31, 2018
Accounting Policies [Abstract]
NEW ACCOUNTING STANDARDS	NEW ACCOUNTING STANDARDS Revenue Recognition In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606) as modified by subsequently issued ASUs 2015-14, 2016-08, 2016-10, 2016-12, 2016-20 and 2017-05. The core principle of these ASUs, among other changes, is that an entity should recognize revenue when it transfers promised products or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those products or services. The Company elected the modified retrospective method and adopted the new revenue guidance effective January 1, 2018, with no impact to the opening retained earnings. Grainger assessed the impact of the new standard on the Company's process of evaluating customer contracts which primarily resulted in the reclassification of certain service-related costs from Warehousing, marketing and administrative expenses to Cost of merchandise sold to reflect certain Company customer contracts with dual performance obligations. The new standard also expanded the Company's qualitative and quantitative disclosures related to revenue recognition. The timing of revenue recognition under the new revenue recognition standard was consistent with the Company’s prior revenue recognition model, whereby revenue is recognized primarily on the date products are shipped to, or picked up by the customer. See Note 3 to the Condensed Consolidated Financial Statements (Financial Statements). Adoption of the new standard did not and is not expected to have an ongoing material impact on the Company's Financial Statements. Other In January 2016, the FASB issued ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities. This change to the financial instrument model primarily affects the accounting for equity investments, financial liabilities under the fair value options and the presentation and disclosure requirements for financial instruments. In February 2018, the FASB issued ASU 2018-03, Technical Corrections and Improvements to Financial Instruments. This ASU provides technical corrections and improvements intended to clarify certain aspects of recognizing and measuring financial assets and liabilities. The effective date of these ASUs was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted these ASUs as of January 1, 2018, and they did not have a material impact on the Company's Financial Statements. In February 2016, the FASB issued ASU 2016-02, Leases. This ASU improves transparency and comparability related to the accounting and reporting of leasing arrangements, including balance sheet recognition for assets and liabilities associated with rights and obligations created by leases with terms greater than twelve months, among other changes. In January 2018, the FASB issued ASU 2018-01, Leases: Land Easement Practical Expedient for Transition. This ASU clarifies the accounting and reporting of land easements. The effective date of these ASUs is for fiscal years and interim periods beginning after December 15, 2018 and early adoption is permitted. The Company is evaluating the impact of these ASUs. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments. This ASU addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The effective date of this ASU was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018, and it did not have a material impact on the Company's Financial Statements. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This ASU clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The effective date of this ASU was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018, and it did not have a material impact on the Company's Financial Statements. In March 2017, the FASB issued ASU 2017-07, Compensation Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. This ASU improves the presentation of net periodic pension cost and net periodic postretirement benefit cost. The effective date of this ASU was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018. This ASU was applied retrospectively for the presentation of the net periodic postretirement cost components in the Condensed Consolidated Statement of Earnings for the quarter ended March 31, 2017 and prospectively, after the effective date. The guidance limiting the capitalization of net periodic benefit cost in assets to the service cost component will be applied prospectively. The impact of the ASU for the three months ended March 31, 2017 was an increase of $3.0 million in Warehousing, marketing and administrative expense offset by a reduction in Total other expense, net of $3.0 million related to the reclassification of interest cost, expected return on plan assets and amortization of unrecognized gains and prior service credits. See Note 7 to the Financial Statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in this ASU were effective for public entities for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018, and it did not have a material impact on the Company's Financial Statements. In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This ASU allows a reclassification from Accumulated other comprehensive earnings to Retained earnings for stranded tax effects resulting from the 2017 Tax Cuts and Jobs Act. The effective date of this ASU is for fiscal years and interim periods beginning after December 15, 2018, and early adoption is permitted. The Company is evaluating the impact of this ASU.

NEW ACCOUNTING STANDARDS

Revenue Recognition

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606) as modified by subsequently issued ASUs 2015-14, 2016-08, 2016-10, 2016-12, 2016-20 and 2017-05. The core principle of these ASUs, among other changes, is that an entity should recognize revenue when it transfers promised products or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those products or services. The Company elected the modified retrospective method and adopted the new revenue guidance effective January 1, 2018, with no impact to the opening retained earnings.

Grainger assessed the impact of the new standard on the Company's process of evaluating customer contracts which primarily resulted in the reclassification of certain service-related costs from Warehousing, marketing and administrative expenses to Cost of merchandise sold to reflect certain Company customer contracts with dual performance obligations.

The new standard also expanded the Company's qualitative and quantitative disclosures related to revenue recognition. The timing of revenue recognition under the new revenue recognition standard was consistent with the Company’s prior revenue recognition model, whereby revenue is recognized primarily on the date products are shipped to, or picked up by the customer. See Note 3 to the Condensed Consolidated Financial Statements (Financial Statements).

Adoption of the new standard did not and is not expected to have an ongoing material impact on the Company's Financial Statements.

Other

In January 2016, the FASB issued ASU 2016-01, Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities. This change to the financial instrument model primarily affects the accounting for equity investments, financial liabilities under the fair value options and the presentation and disclosure requirements for financial instruments. In February 2018, the FASB issued ASU 2018-03, Technical Corrections and Improvements to Financial Instruments. This ASU provides technical corrections and improvements intended to clarify certain aspects of recognizing and measuring financial assets and liabilities. The effective date of these ASUs was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted these ASUs as of January 1, 2018, and they did not have a material impact on the Company's Financial Statements.

In February 2016, the FASB issued ASU 2016-02, Leases. This ASU improves transparency and comparability related to the accounting and reporting of leasing arrangements, including balance sheet recognition for assets and liabilities associated with rights and obligations created by leases with terms greater than twelve months, among other changes. In January 2018, the FASB issued ASU 2018-01, Leases: Land Easement Practical Expedient for Transition. This ASU clarifies the accounting and reporting of land easements. The effective date of these ASUs is for fiscal years and interim periods beginning after December 15, 2018 and early adoption is permitted. The Company is evaluating the impact of these ASUs.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments. This ASU addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The effective date of this ASU was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018, and it did not have a material impact on the Company's Financial Statements.

In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This ASU clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The effective date of this ASU was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018, and it did not have a material impact on the Company's Financial Statements.

In March 2017, the FASB issued ASU 2017-07, Compensation Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. This ASU improves the presentation of net periodic pension cost and net periodic postretirement benefit cost. The effective date of this ASU

was for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018. This ASU was applied retrospectively for the presentation of the net periodic postretirement cost components in the Condensed Consolidated Statement of Earnings for the quarter ended March 31, 2017 and prospectively, after the effective date. The guidance limiting the capitalization of net periodic benefit cost in assets to the service cost component will be applied prospectively. The impact of the ASU for the three months ended March 31, 2017 was an increase of $3.0 million in Warehousing, marketing and administrative expense offset by a reduction in Total other expense, net of $3.0 million related to the reclassification of interest cost, expected return on plan assets and amortization of unrecognized gains and prior service credits. See Note 7 to the Financial Statements.

In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in this ASU were effective for public entities for fiscal years and interim periods beginning after December 15, 2017. The Company adopted this ASU as of January 1, 2018, and it did not have a material impact on the Company's Financial Statements.

In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This ASU allows a reclassification from Accumulated other comprehensive earnings to Retained earnings for stranded tax effects resulting from the 2017 Tax Cuts and Jobs Act. The effective date of this ASU is for fiscal years and interim periods beginning after December 15, 2018, and early adoption is permitted. The Company is evaluating the impact of this ASU.