Statement of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Operating Revenue	$ 3,556	$ 3,307	$ 10,776	$ 9,099
Cost of revenue	2,096	1,910	6,298	5,375
Selling, administrative, and research and development expenses	581	560	1,735	1,606
Amortization and impairment of intangible assets	34	48	100	119
Operating Income	845	789	2,643	1,999
Interest expense	(49)	(52)	(153)	(154)
Other income (expense)	10	2	44	35
Income Before Taxes	806	739	2,534	1,880
Income Taxes	167	157	449	413
Net Income	$ 639	$ 582	$ 2,085	$ 1,467
Net Income Per Share:
Basic (in dollars per share)	$ 2.03	$ 1.84	$ 6.61	$ 4.63
Diluted (in dollars per share)	$ 2.02	$ 1.83	$ 6.58	$ 4.61
Shares of Common Stock Outstanding During the Period:
Average (in shares)	314.6	316.5	315.6	316.9
Average assuming dilution (in shares)	315.9	317.9	316.9	318.3

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.