Statement of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Operating Revenue	$ 3,544	$ 3,228
Cost of revenue	2,039	1,871
Selling, administrative, and research and development expenses	566	560
Amortization and impairment of intangible assets	34	36
Operating Income	905	761
Interest expense	(52)	(51)
Other income (expense)	12	25
Income Before Taxes	865	735
Income Taxes	194	169
Net Income	$ 671	$ 566
Net Income Per Share:
Basic (in dollars per share)	$ 2.12	$ 1.78
Diluted (in dollars per share)	$ 2.11	$ 1.77
Shares of Common Stock Outstanding During the Period:
Average (in shares)	316.6	318.3
Average assuming dilution (in shares)	317.9	319.7

Amortization and Impairment of Intangible Assets

No definition available.

Name:	itw_AmortizationandImpairmentofIntangibleAssets
Namespace Prefix:	itw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate total costs related to selling a firm's product and services, as well as all other general, administrative, and research and development expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

+ References

No definition available.