Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements Of Comprehensive Income [Abstract]
Net Income	$ 122.1	$ 144.9	$ 143.7
Other Comprehensive Income (Loss)
Foreign currency translation	2.8	4.8	(8.1)
Pension and postretirement benefits liability adjustments (net of tax of $(0.5), $5.2, and $(6.1), respectively)	1.3	(15.0)	17.6
Total Other Comprehensive Income (Loss)	4.1	(10.2)	9.5
Comprehensive Income	126.2	134.7	153.2
Less: Comprehensive income attributable to noncontrolling interests, net of tax	0.5	0.5	0.1
Comprehensive Income attributable to Graybar Electric Company, Inc.	$ 125.7	$ 134.2	$ 153.1