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v3.21.1

Commitments and Contingencies (Details) | 3 Months Ended
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Apr. 03, 2021 employee Agreement
Commitments and Contingencies Disclosure [Abstract] |
Entity number of employees | employee | 2,100
Percentage of employees for part time | 1.00%
Percentage of employees represented by various labor unions | 23.00%
Number of CBAs up for renewal, next fiscal year agreement | 5
Percentage of employees covered by CBAs | 5.00%
Number of CBAs renewed | 1

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- Definition Entity percentage of employees for part time + References No definition available. + Details
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Namespace Prefix: | bxc_
Data Type: | num:percentItemType
Balance Type: | na
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- Definition Number Of Collective Bargaining Agreements, Number Of Renewals + References No definition available. + Details
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Namespace Prefix: | bxc_
Data Type: | xbrli:integerItemType
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- Definition Number Of Collective Bargaining Agreements, Renewals In Next Fiscal Year + References No definition available. + Details
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Namespace Prefix: | bxc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage Of Employees Covered By CBAs, Or Expired And Under Negotiation + References No definition available. + Details
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Namespace Prefix: | bxc_
Data Type: | num:percentItemType
Balance Type: | na
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- Definition Percentage of employees represented by various labor unions. + References No definition available. + Details
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Namespace Prefix: | bxc_
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Balance Type: | na
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- Definition Number of persons employed by the Entity + References No definition available. + Details
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Namespace Prefix: | dei_
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Balance Type: | na
Period Type: | instant

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- References No definition available. + Details
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