Revolving Credit Facility Credit Agreement (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 500,000	$ 200,000
Line of Credit Facility, Expiration Date	September 2016	May 2012
Combined Letter of Credit Sub-Facility	50,000
US Swing Line Loan Facility	50,000
Canadian Swing Line Loan Facility	20,000
Sublimit for Borrowings by Graybar Canada	100,000
Aggregate Borrowing Commitments	$ 200,000