WTI Open Contracts (Detail)	Mar. 31, 2014 bbl
April to June 2014 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of barrels	24,000
Natural gas deliveries contract average price per thousand cubic feet	96.41
July to September 2014 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of barrels	20,000
Natural gas deliveries contract average price per thousand cubic feet	94.32
October to December 2014 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of barrels	12,000
Natural gas deliveries contract average price per thousand cubic feet	91.72