Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Sales Revenue, Goods, Gross	$ 1,878,894	$ 1,708,638		$ 5,364,287	$ 4,967,349
Sales Discounts, Goods	8,643	7,795		24,052	23,055
Sales Revenue, Goods, Net	1,870,251	1,700,843		5,340,235	4,944,294
Cost of merchandise sold	(1,516,849)	(1,378,859)		(4,324,258)	(3,999,588)
Gross Margin	353,402	321,984		1,015,977	944,706
Selling, general and administrative expenses	(276,345)	(255,612)		(810,474)	(760,714)
Depreciation and amortization	(12,517)	(12,211)		(36,932)	(36,231)
Other income, net	979	1,511		2,395	5,640
Income from Operations	65,519	55,672		170,966	153,401
Non-operating expenses	(7,828)	(6,357)		(22,841)	(18,503)
Income before Provision for Income Taxes	57,691	49,315		148,125	134,898
Provision for income taxes	(4,019)	(19,761)		(28,708)	(54,220)
Net Income	53,672	29,554		119,417	80,678
Less: Net income attributable to noncontrolling interests	(110)	(120)		(270)	(229)
Net Income attributable to Graybar Electric Company, Inc.	$ 53,562	$ 29,434		$ 119,147	$ 80,449
Net Income per share of Common Stock (in dollars per share)	$ 2.75	$ 1.52	[1]	$ 6.11	$ 4.15	[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)	19,465	19,372		19,496	19,380

[1] (A)Adjusted for the declaration of a 10% stock dividend in 2017, shares related to which were issued in February 2018. Prior to the adjustment, the average common shares outstanding were 17,611 and 17,618 for the three and nine months ended September 30, 2017, respectively.