CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 2,837	$ 2,893	$ 5,838	$ 5,692
Cost of goods sold	1,821	1,772	3,701	3,476
Gross profit	1,016	1,121	2,137	2,216
Selling, general and administrative expenses	811	741	1,773	1,473
Operating earnings	205	380	364	743
Other (income) expense:
Interest expense, net	28	21	49	40
Other, net	(7)	(7)	(11)	(14)
Total other expense, net	21	14	38	26
Earnings before income taxes	184	366	326	717
Income tax provision	55	94	12	183
Net earnings	129	272	314	534
Less: Net earnings attributable to noncontrolling interest	15	12	27	21
Net earnings attributable to W.W. Grainger, Inc.	$ 114	$ 260	$ 287	$ 513
Earnings per share:
Basic (in dollars per share)	$ 2.11	$ 4.69	$ 5.31	$ 9.19
Diluted (in dollars per share)	$ 2.10	$ 4.67	$ 5.29	$ 9.14
Weighted average number of shares outstanding:
Basic (in shares)	53.5	55.1	53.6	55.4
Diluted (in shares)	53.7	55.4	53.8	55.7
Cash dividends paid per share (in dollars per share)	$ 1.44	$ 1.44	$ 2.88	$ 2.80