Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net Income	$ 21.5	$ 34.4
Other Comprehensive Income
Foreign currency translation	(9.2)	2.1
Pension and postretirement benefits liability adjustment (net of tax of $(1.9), and $(1.3), respectively)	5.5	3.7
Total Other Comprehensive (Loss) Income	(3.7)	5.8
Comprehensive Income	17.8	40.2
Less: Comprehensive (loss) income attributable to noncontrolling interests, net of tax	(0.2)	0.2
Comprehensive Income attributable to Graybar Electric Company, Inc.	$ 18.0	$ 40.0