Note 6 - Inventory (Details) - Inventory (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 bbl	Dec. 31, 2013 bbl
Inventory [Abstract]
Tubular goods, accessories and spare parts	$ 9,854	$ 15,534
Crude oil	2,024us-gaap_EnergyRelatedInventoryPetroleum	1,834us-gaap_EnergyRelatedInventoryPetroleum
Inventory	$ 11,878us-gaap_InventoryNet	$ 17,368us-gaap_InventoryNet
Crude oil (barrels) (in Barrels (of Oil))	42,087bpz_CrudeOilBarrels	24,866bpz_CrudeOilBarrels
Crude oil (cost per barrel) (in Dollars per Barrel (of Oil))	48.09	73.77

Crude oil barrels included in inventory.

No definition available.

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Namespace Prefix:	bpz_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

- Details

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- Definition

Production costs incurred in lifting the oil and gas to the surface during the reporting period divided by the number of barrels of oil equivalents (BOE) produced. Production (or lifting costs) are costs incurred in lifting the oil and gas to the surface and generally include gathering, treating, primary processing, field storage, property taxes and insurance on proved properties, but do not include depreciation, depletion, accretion, amortization, royalties, income taxes, interest, general and administrative and other expenses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 2

-Paragraph 3

-Subparagraph A

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of petroleum or crude oil.

+ References

+ Details

Name:	us-gaap_EnergyRelatedInventoryPetroleum
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(4),(5))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	debit
Period Type:	instant