Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net Income	$ 47.3	$ 21.5
Other Comprehensive Income
Foreign currency translation	1.5	(9.2)
Pension and postretirement benefits liability adjustment (net of tax of $(2.3), and $(1.9), respectively)	6.6	5.5
Total Other Comprehensive Income (Loss)	8.1	(3.7)
Comprehensive Income	55.4	17.8
Less: Comprehensive income (loss) attributable to noncontrolling interests, net of tax	0.2	(0.2)
Comprehensive Income attributable to Graybar Electric Company, Inc.	$ 55.2	$ 18.0