Statement of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Operating Revenue	$ 3,676	$ 2,564	$ 7,220	$ 5,792
Cost of revenue	2,163	1,594	4,202	3,465
Selling, administrative, and research and development expenses	588	486	1,154	1,046
Amortization and impairment of intangible assets	32	35	66	71
Operating Income	893	449	1,798	1,210
Interest expense	(52)	(51)	(104)	(102)
Other income (expense)	22	8	34	33
Income Before Taxes	863	406	1,728	1,141
Income Taxes	88	87	282	256
Net Income	$ 775	$ 319	$ 1,446	$ 885
Net Income Per Share:
Basic (in dollars per share)	$ 2.46	$ 1.01	$ 4.58	$ 2.79
Diluted (in dollars per share)	$ 2.45	$ 1.01	$ 4.56	$ 2.78
Shares of Common Stock Outstanding During the Period:
Average (in shares)	315.6	316.1	316.1	317.2
Average assuming dilution (in shares)	316.9	317.4	317.4	318.6

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.