Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 144.9	$ 143.7	$ 71.9
Other Comprehensive Income
Foreign currency translation	4.8	(8.1)	5.9
Pension and postretirement benefits liability adjustment (net of tax of $5.2, $(6.1), and $10.0, respectively)	(15.0)	17.6	(15.7)
Total Other Comprehensive Income (Loss)	(10.2)	9.5	(9.8)
Comprehensive Income	134.7	153.2	62.1
Less: comprehensive income attributable to noncontrolling interests, net of tax	0.5	0.1	0.5
Comprehensive Income attributable to Graybar Electric Company, Inc.	$ 134.2	$ 153.1	$ 61.6