Condensed Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Condensed Consolidated Statements Of Income [Abstract]
Net sales	$ 2,232.4	$ 1,763.0	$ 4,132.9	$ 3,536.2
Cost of merchandise sold	(1,809.6)	(1,429.7)	(3,349.2)	(2,862.5)
Gross Margin	422.8	333.3	783.7	673.7
Selling, general and administrative expenses	(297.3)	(261.2)	(575.2)	(551.3)
Depreciation and amortization	(12.2)	(13.3)	(24.4)	(26.5)
Other income, net	1.9	0.4	2.4	1.0
Income from Operations	115.2	59.2	186.5	96.9
Non-operating expenses	(7.3)	(8.6)	(15.1)	(16.1)
Income before Provision for Income Taxes	107.9	50.6	171.4	80.8
Provision for income taxes	(27.6)	(13.5)	(43.8)	(22.2)
Net Income	80.3	37.1	127.6	58.6
Net income attributable to noncontrolling interests	(0.2)		(0.3)	(0.1)
Net Income attributable to Graybar Electric Company, Inc.	$ 80.1	$ 37.1	$ 127.3	$ 58.5
Net Income attributable to Graybar Electric Company, Inc. per share of Common Stock	$ 3.51	$ 1.64	$ 5.58	$ 2.58
Cash Dividends per share of Common Stock	$ 0.30	$ 0.30	$ 0.60	$ 0.60
Average Common Shares Outstanding	22.8	22.7	22.8	22.7