Note 9 - Third-party Long-term Debt - Accrued Interest (Details) - Nonrelated Party [Member] - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Interest payable	$ 189	$ 235
Less: Accrued interest payable, current portion	(189)	(235)
Long-term interest payable, net of current portion	0	0
Small Business Administration SBA [Member] \| BDEC Term Loan Due 2051 [Member]
Interest payable	59	93
Small Business Administration SBA [Member] \| LE Term Loan Due 2050 [Member]
Interest payable	5	8
Small Business Administration SBA [Member] \| NPS Term Loan Due 2053 [Member]
Interest payable	5	8
Veritex Community Bank [Member] \| LE Term Loan Due 2034 [Member]
Interest payable	45	48
Veritex Community Bank [Member] \| LRM Term Loan Due 2034 [Member]
Interest payable	57	61
Greater Nevada Credit Union (GNCU) [Member] \| NPS Term Loan Due 2031 [Member]
Interest payable	18	17
Texas First Rentals, LLC [Member] \| Equipment Loan Due 2025 [Member]
Interest payable	$ 0	$ 0

Amount of interest payable on debt, including, but not limited to, trade payables, classified as noncurrent.

No definition available.

Name:	bdco_InterestPayableNoncurrent
Namespace Prefix:	bdco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

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

- Definition

Amount of interest payable on debt, including, but not limited to, trade payables.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(15)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(15)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_NonrelatedPartyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=bdco_SmallBusinessAdministrationSbaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_BDECTermLoanDue2051Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_LETermLoanDue2050Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_NpsTermLoanDue2053Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=bdco_VeritexCommunityBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_LETermLoanDue2034Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_LRMTermLoanDue2034Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=bdco_GreaterNevadaCreditUnionGncuMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_NPSTermLoanDue2031Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=bdco_TexasFirstRentalsLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bdco_EquipmentLoanDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: