Debt (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Aug. 13, 2021
Line of Credit Facility [Line Items]
Fixed rate debt carrying amount in excess of fair value	$ 900,000	$ 1,300,000
Short-term borrowings	124,200,000	50,000,000.0
Interest expense, net	$ 1,000,000.0	3,800,000	$ 6,100,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Weighted average interest rate	1.11%
Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding	$ 6,100,000	6,300,000
Amended Credit Agreement
Line of Credit Facility [Line Items]
Letters of credit outstanding	$ 400,000	400,000
Amended Credit Agreement | Minimum | Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.00%
Amended Credit Agreement | Minimum | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Amended Credit Agreement | Maximum | Base Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.60%
Amended Credit Agreement | Maximum | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.60%
Amended Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Short-term borrowings	$ 124,200,000	50,000,000.0
Short-term debt average amount outstanding	10,600,000	$ 191,600,000
Interest rate during the period		1.55%
Debt instrument interest expense	1,000,000.0	$ 3,600,000	$ 5,500,000
Unused Commitments, Extend Credit	625,400,000	699,600,000
Amended Credit Agreement | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Short-term borrowings	0	50,000,000.0
Amended Credit Agreement | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Short-term borrowings	$ 124,200,000	370,000,000.0
Amended Credit Agreement | Revolving Credit Facility | Weighted Average
Line of Credit Facility [Line Items]
Interest rate during the period	1.15%
Prudential Private Placement Shelf Agreement
Line of Credit Facility [Line Items]
Agreement face amount	$ 100,000,000.0
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
Prudential Shelf Agreement Or MetLife Shelf Agreement
Line of Credit Facility [Line Items]
Issuance period	3 years
Line of credit | Amended Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 750,000,000.0
Debt instrument, term	5 years
Line of credit | Amended Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Accordian feature, increase limit	$ 375,000,000.0
Line of credit | Amended Credit Agreement | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Credit agreement commitment fee percentage	0.25%
Line of credit | Amended Credit Agreement | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Credit agreement commitment fee percentage	0.40%
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
Line of credit | Amended Credit Agreement | Letter of Credit | Minimum
Line of Credit Facility [Line Items]
Credit agreement commitment fee percentage	1.00%
Line of credit | Amended Credit Agreement | Letter of Credit | Maximum
Line of Credit Facility [Line Items]
Credit agreement commitment fee percentage	1.60%
Line of credit | Fourth Amended Credit Agreement [Member] | Revolving Credit Facility
Line of Credit Facility [Line Items]
Accordian feature, increase limit				$ 375,000,000.0
Line of credit | Fourth Amended Credit Agreement [Member] | Letter of Credit Sub-Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity				25,000,000.0
Line of credit | Fourth Amended Credit Agreement [Member] | Bridge Loan | Graybar Canada
Line of Credit Facility [Line Items]
Maximum borrowing capacity				100,000,000.0
Line of credit | Fourth Amended Credit Agreement [Member] | Bridge Loan | UNITED STATES
Line of Credit Facility [Line Items]
Maximum borrowing capacity				75,000,000.0
Line of credit | Fourth Amended Credit Agreement [Member] | Bridge Loan | CANADA
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 20,000,000.0