Condensed Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Condensed Consolidated Statements Of Income [Abstract]
Net sales		$ 1,877.9	$ 1,981.4	$ 5,414.1	$ 5,707.2
Cost of merchandise sold		(1,522.7)	(1,603.6)	(4,385.2)	(4,623.0)
Gross Margin		355.2	377.8	1,028.9	1,084.2
Selling, general and administrative expenses		(270.4)	(293.0)	(821.7)	(851.0)
Depreciation and amortization		(13.1)	(12.6)	(39.6)	(37.7)
Other income, net			0.6	1.0	2.4
Income from Operations		71.7	72.8	168.6	197.9
Non-operating expenses		(25.3)	(5.9)	(41.4)	(18.8)
Income before Provision for Income Taxes		46.4	66.9	127.2	179.1
Provision for income taxes		(11.8)	(17.9)	(34.0)	(48.7)
Net Income		34.6	49.0	93.2	130.4
Net income attributable to noncontrolling interests		(0.1)	(0.2)	(0.2)	(0.3)
Net Income attributable to Graybar Electric Company, Inc.		$ 34.5	$ 48.8	$ 93.0	$ 130.1
Net Income attributable to Graybar Electric Company, Inc. per share of Common Stock	[1]	$ 1.52	$ 2.17	$ 4.10	$ 5.76
Cash Dividends per share of Common Stock		$ 0.30	$ 0.30	$ 0.90	$ 0.90
Average common shares outstanding	[1]	22.6	22.5	22.7	22.6

[1] Adjusted for the declaration of a 5% stock dividend in 2019, shares related to which were issued in February 2020.  Prior to the adjustment, the average common shares outstanding were 21.5 million for the three and nine months ended September 30, 2019, respectively.