Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016
Income Statement [Abstract]
Gross Sales	$ 1,708,638	$ 1,697,037		$ 4,967,349		$ 4,806,245
Cash discounts	(7,795)	(7,418)		(23,055)		(20,625)
Net Sales	1,700,843	1,689,619		4,944,294		4,785,620
Cost of merchandise sold	(1,378,859)	(1,370,861)		(3,999,588)		(3,881,616)
Gross Margin	321,984	318,758		944,706		904,004
Selling, general and administrative expenses	(260,752)	(254,969)		(776,135)		(750,266)
Depreciation and amortization	(12,211)	(12,283)		(36,231)		(35,158)
Other income, net	1,511	629		5,640		3,438
Income from Operations	50,532	52,135		137,980		122,018
Interest expense, net	(1,217)	(1,215)		(3,082)		(2,635)
Income before Provision for Income Taxes	49,315	50,920		134,898		119,383
Provision for income taxes	(19,761)	(20,724)		(54,220)		(48,396)
Net Income	29,554	30,196		80,678		70,987
Less: Net income attributable to noncontrolling interests	(120)	(67)		(229)		(178)
Net Income attributable to Graybar Electric Company, Inc.	$ 29,434	$ 30,129		$ 80,449		$ 70,809
Net Income per share of Common Stock (in dollars per share)	$ 1.68	$ 1.73	[1]	$ 4.57	[1]	$ 4.07	[1]
Cash Dividends per share of Common Stock (in dollars per share)	$ 0.30	$ 0.30		$ 0.90		$ 0.90
Average Common Shares Outstanding (Shares)	17,611	17,402		17,618		17,386

[1] (A)Adjusted for the declaration of a 5% stock dividend in 2016, shares related to which were issued in February 2017. Prior to the adjustment, the average common shares outstanding were 16,573 and 16,558 for the three and nine months ended September 30, 2016, respectively.