Significant Accounting Policies	6 Months Ended
Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant Accounting Policies	Significant Accounting PoliciesFinancial Statements— The unaudited financial statements included herein have been prepared by Illinois Tool Works Inc. and Subsidiaries (the "Company"). In the opinion of management, the interim financial statements reflect all adjustments of a normal recurring nature necessary for a fair statement of the results for interim periods. It is suggested that these financial statements be read in conjunction with the financial statements and notes to financial statements included in the Company's 2020 Annual Report on Form 10-K. Certain reclassifications of prior year data have been made to conform with current year reporting.

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-URI http://asc.fasb.org/topic&trid=2122149

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-URI http://asc.fasb.org/topic&trid=2197479

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