Derivative Instruments and Hedging Activities - Hedging Positions (Detail) - Subsequent Event [Member] - Designated as Hedging Instrument [Member]	Nov. 03, 2015 MMBTU MBbls $ / MMBTU $ / bbl
Fixed Price Swaps [Member] \| 2015 Hedging Position One [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	89.00
Fixed Price Swaps [Member] \| 2015 Hedging Position One [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.005
Fixed Price Swaps [Member] \| 2015 Hedging Position Two [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	90.00
Fixed Price Swaps [Member] \| 2015 Hedging Position Two [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.120
Fixed Price Swaps [Member] \| 2015 Hedging Position Three [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	90.25
Fixed Price Swaps [Member] \| 2015 Hedging Position Three [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.150
Fixed Price Swaps [Member] \| 2015 Hedging Position Four [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	90.40
Fixed Price Swaps [Member] \| 2015 Hedging Position Four [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.165
Fixed Price Swaps [Member] \| 2015 Hedging Position Five [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	91.05
Fixed Price Swaps [Member] \| 2015 Hedging Position Five [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.220
Fixed Price Swaps [Member] \| 2015 Hedging Position Six [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	93.28
Fixed Price Swaps [Member] \| 2015 Hedging Position Six [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.255
Fixed Price Swaps [Member] \| 2015 Hedging Position Seven [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	93.37
Fixed Price Swaps [Member] \| 2015 Hedging Position Eight [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	94.85
Fixed Price Swaps [Member] \| 2015 Hedging Position Nine [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	95.00
Fixed Price Swaps [Member] \| 2016 Hedging Position One [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	49.75
Fixed Price Swaps [Member] \| 2016 Hedging Position One [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.110
Fixed Price Swaps [Member] \| 2016 Hedging Position Two [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	52.78
Fixed Price Swaps [Member] \| 2016 Hedging Position Two [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU	10,000
Swap Price \| $ / MMBTU	4.120
Fixed Price Swaps [Member] \| 2016 Hedging Position Three [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Swap Price \| $ / bbl	90.00
Fixed Price Swaps [Member] \| 2016 Hedging Position Three [Member] \| Natural Gas (MMcfe) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume \| MMBTU
Swap Price \| $ / MMBTU
Costless Collar [Member] \| 2016 Hedging Position Four [Member] \| Oil (MBbls) [Member]
Derivatives, Fair Value [Line Items]
Daily Volume	1,000
Floor Price ($) \| $ / MMBTU	45.00
Ceiling Price ($) \| $ / MMBTU	54.75

- Definition

Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

Name:	invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

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

- Definition

Floor rate on a price risk derivative such as a floor or a collar. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

+ Details

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

- Definition

Fixed price related to the price risk swap derivative.

+ References

No definition available.

+ Details

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

- 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.

+ References

No definition available.

+ Details

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