Debt (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Line of Credit Facility [Line Items]
Short-term borrowings	$ 41,200,000		$ 41,200,000		$ 124,200,000
Interest expense, net	800,000	$ 600,000	2,300,000	$ 1,000,000.0
Letters of credit outstanding	7,600,000		7,600,000		6,100,000
Minimum
Line of Credit Facility [Line Items]
Short-term borrowings	0	0	0	0
Maximum
Line of Credit Facility [Line Items]
Short-term borrowings	173,100,000	$ 50,000,000.0	173,100,000	$ 50,000,000.0
Amended Credit Agreement
Line of Credit Facility [Line Items]
Remaining borrowing capacity	711,100,000		$ 711,100,000		625,400,000
Credit agreement commitment fee percentage			0.40%
Short-term borrowings	37,000,000.0		$ 37,000,000.0		124,200,000
Letters of credit outstanding	1,900,000		$ 1,900,000		400,000
Prudential Private Placement Shelf Agreement
Line of Credit Facility [Line Items]
Debt maturity date			Aug. 01, 2023
Agreement face amount	100,000,000.0		$ 100,000,000.0
Issuance period			3 years
MetLife Private Placement Shelf Agreement
Line of Credit Facility [Line Items]
Debt maturity date			Jun. 01, 2024
Agreement face amount	150,000,000.0		$ 150,000,000.0
Issuance period			3 years
Prudential Shelf Agreement Or MetLife Shelf Agreement
Line of Credit Facility [Line Items]
Notes issued face amount	0		$ 0		0
Line of credit | Amended Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	750,000,000.0		750,000,000.0		750,000,000.0
Accordion feature, increase limit	375,000,000.0		$ 375,000,000.0		$ 375,000,000.0
Expiration date			Aug. 01, 2026		Aug. 01, 2026
Debt instrument, term			5 years		5 years
Line of credit | Amended Credit Agreement | Letter of Credit Sub-Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	25,000,000.0		$ 25,000,000.0		$ 25,000,000.0
Line of credit | Amended Credit Agreement | Bridge Loan | Graybar Canada [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	100,000,000.0		100,000,000.0		100,000,000.0
Line of credit | Amended Credit Agreement | Bridge Loan | UNITED STATES
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000,000.0		75,000,000.0		75,000,000.0
Line of credit | Amended Credit Agreement | Bridge Loan | CANADA
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 20,000,000.0		$ 20,000,000.0		$ 20,000,000.0