Debt Instrument, Percentage Of Principal, Discount

No definition available.

Name:	bxc_DebtInstrumentPercentageOfPrincipalDiscount
Namespace Prefix:	bxc_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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Balance Type:	na
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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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+ Details

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

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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+ Details

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
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- Details

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- Details

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Long-Term Debt - Narrative (Details) - USD ($)	9 Months Ended
Long-Term Debt - Narrative (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022	Oct. 01, 2022	Oct. 31, 2021
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Letters of credit outstanding	$ 350,000,000
Outstanding principal balance	0	$ 0
Qualified accounts	816,300,000	645,400,000
Line of credit facility, remaining borrowing capacity	$ 346,500,000	346,500,000
Weighted average interest rate	0.00%		0.00%
Line of Credit \| Revolving Credit Facility \| SOFR
Debt Instrument [Line Items]
Credit agreement interest rate	0.10%
Line of Credit \| Revolving Credit Facility \| Minimum \| SOFR
Debt Instrument [Line Items]
Credit agreement interest rate	1.25%
Line of Credit \| Revolving Credit Facility \| Minimum \| Base Rate
Debt Instrument [Line Items]
Credit agreement interest rate	0.25%
Line of Credit \| Revolving Credit Facility \| Maximum \| SOFR
Debt Instrument [Line Items]
Credit agreement interest rate	1.75%
Line of Credit \| Revolving Credit Facility \| Maximum \| Base Rate
Debt Instrument [Line Items]
Credit agreement interest rate	0.75%
6.0% Senior Secured Notes Due 2029 \| Senior Notes
Debt Instrument [Line Items]
Debt instrument face amount				$ 300,000,000
Stated interest rate				6.00%
Percentage of principal, discount				98.625%
Long-term debt fair value	$ 271,500,000	$ 283,600,000