Debt (Narrative) (Details) - USD ($)		3 Months Ended
	Aug. 10, 2018	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Aug. 13, 2021
Line of Credit Facility [Line Items]
Remaining borrowing capacity		$ 679,600,000		$ 625,400,000
Credit agreement commitment fee percentage		0.40%
Short-term borrowings		$ 70,000,000.0		124,200,000
Interest expense, net		800,000	$ 200,000
Letters of credit outstanding		6,100,000		6,100,000
Minimum
Line of Credit Facility [Line Items]
Short-term borrowings		33,100,000	0
Maximum
Line of Credit Facility [Line Items]
Short-term borrowings		173,100,000	$ 50,000,000.0
Amended Credit Agreement
Line of Credit Facility [Line Items]
Letters of credit outstanding		$ 400,000		400,000
Prudential Private Placement Shelf Agreement
Line of Credit Facility [Line Items]
Agreement face amount	$ 100,000,000.0
Issuance period		3 years
Notes issued face amount		$ 0		0
MetLife Private Placement Shelf Agreement
Line of Credit Facility [Line Items]
Agreement face amount		150,000,000.0
Notes issued face amount		$ 0		$ 0
Line of credit | Amended Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 750,000,000.0
Accordion feature, increase limit					$ 375,000,000.0
Expiration date		Aug. 13, 2026
Debt instrument, term	5 years
Line of credit | Amended Credit Agreement | Letter of Credit Sub-Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity					25,000,000.0
Line of credit | Amended Credit Agreement | Bridge Loan | Graybar Canada
Line of Credit Facility [Line Items]
Maximum borrowing capacity					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
Line of credit | Amended Credit Agreement | Bridge Loan | CANADA
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 20,000,000.0