Condensed Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Condensed Consolidated Statements Of Income [Abstract]
Net sales	$ 2,313.4	$ 1,877.9	$ 6,446.3	$ 5,414.1
Cost of merchandise sold	(1,877.0)	(1,522.7)	(5,226.2)	(4,385.2)
Gross Margin	436.4	355.2	1,220.1	1,028.9
Selling, general and administrative expenses	(309.0)	(270.4)	(884.2)	(821.7)
Depreciation and amortization	(12.3)	(13.1)	(36.7)	(39.6)
Other income, net	8.3		10.7	1.0
Income from Operations	123.4	71.7	309.9	168.6
Non-operating expenses	(24.5)	(25.3)	(39.6)	(41.4)
Income before Provision for Income Taxes	98.9	46.4	270.3	127.2
Provision for income taxes	(24.4)	(11.8)	(68.2)	(34.0)
Net Income	74.5	34.6	202.1	93.2
Net income attributable to noncontrolling interests	(0.2)	(0.1)	(0.5)	(0.2)
Net Income attributable to Graybar Electric Company, Inc.	$ 74.3	$ 34.5	$ 201.6	$ 93.0
Net Income attributable to Graybar Electric Company, Inc. per share of Common Stock	$ 3.27	$ 1.52	$ 8.85	$ 4.10
Cash Dividends per share of Common Stock	$ 0.30	$ 0.30	$ 0.90	$ 0.90
Average Common Shares Outstanding	22.8	22.6	22.8	22.7