Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net Income	$ 37.1	$ 47.0	$ 58.6	$ 81.4
Other Comprehensive Income
Foreign currency translation	4.1	2.1	(5.1)	4.2
Pension and postretirement benefits liability adjustment (net of tax of $(2.0), $(1.2), $(3.9) and $(2.5), respectively)	5.7	3.5	11.2	7.2
Total Other Comprehensive Income	9.8	5.6	6.1	11.4
Comprehensive Income	46.9	52.6	64.7	92.8
Less: Comprehensive income attributable to noncontrolling interests, net of tax	0.2	0.1		0.3
Comprehensive Income attributable to Graybar Electric Company, Inc.	$ 46.7	$ 52.5	$ 64.7	$ 92.5