Condensed Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Consolidated Statements Of Income [Abstract]
Net sales		$ 1,763.0	$ 1,948.0	$ 3,536.2	$ 3,725.8
Cost of merchandise sold		(1,429.7)	(1,580.3)	(2,862.5)	(3,019.4)
Gross Margin		333.3	367.7	673.7	706.4
Selling, general and administrative expenses		(261.2)	(284.5)	(551.3)	(558.0)
Depreciation and amortization		(13.3)	(12.6)	(26.5)	(25.1)
Other income, net		0.4	0.5	1.0	1.8
Income from Operations		59.2	71.1	96.9	125.1
Non-operating expenses		(8.6)	(6.3)	(16.1)	(12.9)
Income before Provision for Income Taxes		50.6	64.8	80.8	112.2
Provision for income taxes		(13.5)	(17.8)	(22.2)	(30.8)
Net Income		37.1	47.0	58.6	81.4
Net income attributable to noncontrolling interests				(0.1)	(0.1)
Net Income attributable to Graybar Electric Company, Inc.		$ 37.1	$ 47.0	$ 58.5	$ 81.3
Net Income attributable to Graybar Electric Company, Inc. per share of Common Stock	[1]	$ 1.64	$ 2.08	$ 2.58	$ 3.59
Cash Dividends per share of Common Stock		$ 0.30	$ 0.30	$ 0.60	$ 0.60
Average common shares outstanding	[1]	22.7	22.6	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 and 21.6 million for the three and six months ended June 30, 2019, respectively.