Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Income Statement [Abstract]
Gross Sales	$ 1,840,417	$ 1,720,842		$ 3,485,393		$ 3,258,711
Cash discounts	(8,085)	(7,962)		(15,409)		(15,260)
Net Sales	1,832,332	1,712,880		3,469,984		3,243,451
Cost of merchandise sold	(1,481,176)	(1,389,987)		(2,807,409)		(2,620,729)
Gross Margin	351,156	322,893		662,575		622,722
Selling, general and administrative expenses	(270,768)	(252,107)		(534,129)		(505,102)
Depreciation and amortization	(12,358)	(12,144)		(24,415)		(24,020)
Other income, net	652	3,521		1,416		4,129
Income from Operations	68,682	62,163		105,447		97,729
Non-operating expenses	(7,527)	(6,299)		(15,013)		(12,146)
Income before Provision for Income Taxes	61,155	55,864		90,434		85,583
Provision for income taxes	(16,574)	(22,463)		(24,689)		(34,459)
Net Income	44,581	33,401		65,745		51,124
Less: Net income attributable to noncontrolling interests	(89)	(67)		(160)		(109)
Net Income attributable to Graybar Electric Company, Inc.	$ 44,492	$ 33,334		$ 65,585		$ 51,015
Net Income per share of Common Stock (in dollars per share)	$ 2.28	$ 1.72	[1]	$ 3.36	[1]	$ 2.63	[1]
Cash Dividends per share of Common Stock (in dollars per share)	$ 0.30	$ 0.30		$ 0.60		$ 0.60
Average Common Shares Outstanding (Shares)	19,501	19,406		19,516		19,394

[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 17,642 and 17,631 for the three and six months ended June 30, 2017, respectively.