Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Gross Sales	$ 1,786.1	$ 1,645.0
Cash discounts	(8.3)	(7.3)
Net Sales	1,777.8	1,637.7
Cost of merchandise sold	(1,439.1)	(1,326.3)
Gross Margin	338.7	311.4
Selling, general and administrative expenses	(273.5)	(263.3)
Depreciation and amortization	(12.5)	(12.1)
Other income, net	1.3	0.8
Income from Operations	54.0	36.8
Non-operating expenses	(6.6)	(7.5)
Income before Provision for Income Taxes	47.4	29.3
Provision for income taxes	(13.0)	(8.1)
Net Income	34.4	21.2
Less: Net income attributable to noncontrolling interests	(0.1)	(0.1)
Net Income attributable to Graybar Electric Company, Inc.	$ 34.3	$ 21.1
Net Income per share of Common Stock (in dollars per share)	$ 1.59	$ 0.98	[1]
Cash Dividends per share of Common Stock (in dollars per share)	$ 0.30	$ 0.30
Average Common Shares Outstanding (Shares)	21.6	21.5

[1] (A)Adjusted for the declaration of a 10% stock dividend in 2018, shares related to which were issued in February 2019. Prior to the adjustment, the average common shares outstanding were 19.5 million for the three months ended March 31, 2018.