Commodity Price Risk Management (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
Sep. 30, 2012 bbl
Current Asset [Member] \| Crude oil costless collars [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	635
Current Liability [Member] \| Crude oil costless collars [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value	0
Commodity Contract [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Number of commodity derivative contracts	3
Crude Oil Costless Collar 01/01/12 - 12/31/12 [Member]
Derivative [Line Items]
Counterparty	BNP Parabis
Basis	WTI
Quantity (barrels per day)	200
Crude Oil Costless Collar 01/01/12 - 12/31/12 [Member] \| Put Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	90.00
Crude Oil Costless Collar 01/01/12 - 12/31/12 [Member] \| Call Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	106.50
Crude Oil Costless Collar 10/01/12 - 03/31/13 [Member]
Derivative [Line Items]
Counterparty	Wells Fargo
Basis	WTI
Quantity (barrels per day)	200
Crude Oil Costless Collar 10/01/12 - 03/31/13 [Member] \| Put Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	85.00
Crude Oil Costless Collar 10/01/12 - 03/31/13 [Member] \| Call Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	101.00
Crude Oil Costless Collar 01/01/13 - 06/30/13 [Member]
Derivative [Line Items]
Counterparty	Wells Fargo
Basis	WTI
Quantity (barrels per day)	200
Crude Oil Costless Collar 01/01/13 - 06/30/13 [Member] \| Put Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	90.00
Crude Oil Costless Collar 01/01/13 - 06/30/13 [Member] \| Call Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	105.75
Crude Oil Costless Collar 10/01/12 - 09/30/13 [Member]
Derivative [Line Items]
Counterparty	BNP Parabis
Basis	WTI
Quantity (barrels per day)	200
Crude Oil Costless Collar 10/01/12 - 09/30/13 [Member] \| Put Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	95.00
Crude Oil Costless Collar 10/01/12 - 09/30/13 [Member] \| Call Option [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	116.60
Crude Oil Costless Collar 04/01/13 - 06/30/13 [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Counterparty	Wells Fargo
Basis	WTI
Quantity (barrels per day)	200
Crude Oil Costless Collar 04/01/13 - 06/30/13 [Member] \| Put Option [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	90.00
Crude Oil Costless Collar 04/01/13 - 06/30/13 [Member] \| Call Option [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	97.50
Crude Oil Costless Collar 06/01/13 - 09/30/13 [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Counterparty	Wells Fargo
Basis	WTI
Quantity (barrels per day)	400
Crude Oil Costless Collar 06/01/13 - 09/30/13 [Member] \| Put Option [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	90.00
Crude Oil Costless Collar 06/01/13 - 09/30/13 [Member] \| Call Option [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	97.50
Crude Oil Costless Collar 10/01/13 - 12/31/13 [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Counterparty	Wells Fargo
Basis	WTI
Quantity (barrels per day)	600
Crude Oil Costless Collar 10/01/13 - 12/31/13 [Member] \| Put Option [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	90.00
Crude Oil Costless Collar 10/01/13 - 12/31/13 [Member] \| Call Option [Member] \| Subsequent Event [Member]
Derivative [Line Items]
Strike Price (in dollars per barrel)	97.50

Identification of the name or type of counterparty to the derivative instrument.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column A

-Footnote 1

+ Details

Name:	invest_DerivativeCounterparty
Namespace Prefix:	invest_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 205G

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph a

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

+ Details

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

- Definition

Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

+ Details

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

- Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

+ Details

Name:	us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The strike price on the price risk option contract such as a put option or a call option.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativePriceRiskOptionStrikePrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativesFairValueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Reference to the index or unit of measurement for the underlying which establishes the pricing terms of the derivative instrument. For example, the basis on the underlying for a natural gas futures contract might be the NYMEX price per million British thermal units (MMBtu).

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeUnderlyingBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The quantity of future oil and gas production being hedged.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 360

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 12.D.3(b))

-URI http://asc.fasb.org/extlink&oid=6601679&loc=d3e516453-122869

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 12

-Section D

-Paragraph b

-Subsection 3

+ Details

Name:	us-gaap_PortionOfFutureOilAndGasProductionBeingHedged
Namespace Prefix:	us-gaap_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant