Consolidated Statements Of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements Of Income [Abstract]
Net sales	$ 7,265.7	$ 7,523.9	$ 7,202.5
Cost of merchandise sold	(5,896.2)	(6,094.9)	(5,821.6)
Gross Margin	1,369.5	1,429.0	1,380.9
Selling, general and administrative expenses	(1,098.9)	(1,159.9)	(1,125.0)
Depreciation and amortization	(52.8)	(50.5)	(49.6)
Other income, net	7.0	5.0	3.4
Income from Operations	224.8	223.6	209.7
Non-operating expenses	(58.5)	(23.7)	(30.6)
Income before Provision for Income Taxes	166.3	199.9	179.1
Provision for income taxes	(44.2)	(55.0)	(35.4)
Net Income	122.1	144.9	143.7
Net income attributable to noncontrolling interests	(0.3)	(0.4)	(0.4)
Net Income attributable to Graybar Electric Company, Inc.	$ 121.8	$ 144.5	$ 143.3
Net Income attributable to Graybar Electric Company, Inc. per share of Common Stock	$ 5.38	$ 6.41	$ 6.37