Line of Credit Facility, Accordion Feature, Increase Limit

No definition available.

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Namespace Prefix:	c402_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Private Placement After Issuance Successive Period

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Private Placement Issuance Period

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Amount of short-term and long-term debt and lease obligation.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Amount of interest income (expense) classified as operating.

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Balance Type:	credit
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Date the credit facility terminates, in YYYY-MM-DD format.

+ References

+ Details

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Data Type:	xbrli:dateItemType
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Period Type:	instant

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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Debt (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
Debt (Narrative) (Details) - USD ($)	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Line of Credit Facility [Line Items]
Total debt	$ 1,400,000		$ 1,400,000		$ 1,900,000
Long-term debt	800,000		800,000		1,000,000.0
Short-term borrowings	0		0		0
Interest income (expense), net	200,000	$ 100,000	1,000,000.0	$ 400,000
Letters of credit outstanding	10,200,000		10,200,000		$ 10,600,000
Minimum [Member]
Line of Credit Facility [Line Items]
Short-term borrowings	0	0	0	0
Maximum [Member]
Line of Credit Facility [Line Items]
Short-term borrowings	39,000,000.0	$ 37,000,000.0	$ 39,000,000.0	$ 37,000,000.0
Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt instrument, term			5 years		5 years
Maximum borrowing capacity	750,000,000.0		$ 750,000,000.0		$ 750,000,000.0
Expiration date			Jun. 01, 2030		Jun. 01, 2030
Accordion feature, increase limit	375,000,000.0		$ 375,000,000.0		$ 375,000,000.0
Remaining borrowing capacity	744,800,000		$ 744,800,000		744,400,000
Credit agreement commitment fee percentage			0.40%
Credit Agreement [Member] \| Graybar Canada [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	100,000,000.0		$ 100,000,000.0		100,000,000.0
Letters of credit outstanding	5,200,000		5,200,000		5,600,000
Credit Agreement [Member] \| Letter of Credit Sub Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	35,000,000.0		35,000,000.0		35,000,000.0
Credit Agreement [Member] \| Swing-Line Loan [Member] \| United States [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000,000.0		75,000,000.0		75,000,000.0
Credit Agreement [Member] \| Swing-Line Loan [Member] \| Canada [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	20,000,000.0		20,000,000.0		20,000,000.0
Prudential Private Placement Shelf Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	200,000,000.0		$ 200,000,000.0
Expiration date			Aug. 02, 2029
Issuance period			3 years
Notes issued face amount	0		$ 0		0
MetLife Private Placement Shelf Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	200,000,000.0		$ 200,000,000.0
Expiration date			Jun. 01, 2027
Issuance period			3 years
Successive issuance period			3 years
Notes issued face amount	$ 0		$ 0		$ 0