Capital Stock (Details)	Jun. 30, 2012
Schedule of Ownership Held in Voting Trust [Line Items]
Percentage Ownership in Voting Trust	82.00%

The percentage of common stock held in the Voting Trust

No definition available.

Name:	graybar_PercentageOwnershipInVotingTrust
Namespace Prefix:	graybar_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant