Commitments and Contingencies - Future Delivery Commitments (Detail)	12 Months Ended
	Dec. 31, 2013 Mcfe
2014 | Natural Gas
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	145,500
2014 | Ethane
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	15,000
2015 | Natural Gas
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	140,538
2015 | Ethane
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	15,000
2016 | Natural Gas
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	102,598
2016 | Ethane
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	15,000
2017 | Natural Gas
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	52,055
2017 | Ethane
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	15,000
2018-2028 | Ethane
Contingencies And Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Daily Production	15,000