Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 143.7	$ 71.9	$ 93.3
Other Comprehensive Income
Foreign currency translation	(8.1)	5.9	2.2
Pension and postretirement benefits liability adjustment (net of tax of $(6.1), $10.0, and $5.2, respectively)	17.6	(15.7)	(8.2)
Total Other Comprehensive Income (Loss)	9.5	(9.8)	(6.0)
Comprehensive Income	153.2	62.1	87.3
Less: comprehensive income attributable to noncontrolling interests, net of tax	0.1	0.5	0.4
Comprehensive Income attributable to Graybar Electric Company, Inc.	$ 153.1	$ 61.6	$ 86.9