Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 MBbls acre	Dec. 31, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]
Lease of facilities, maturity year	2025
Payments related to lease obligations	$ 966	$ 597	$ 894
Contingent liability to surety insurance company	78,070
Commitments to use drilling rigs and acquisition of seismic data, value	352,660
Commitments to use drilling rigs and acquisition of seismic data, period	4 years
Minimum barrels of oil spill to impose financial responsibility under Oil Pollution Act	1,000
Minimum financial responsibility in amounts if oil spill exceeds minimum quantity of barrels of oil in specified state	10,000
Minimum financial responsibility in amounts if oil spill exceeds minimum quantity of barrels of oil Outer Continental	35,000
Maximum financial responsibility in amounts if oil spill exceeds minimum quantity of barrels of oil	150,000
Legal settlement	18,373
Net mineral acres	33,000
Brokerage fee unpaid	1,119
Acquisition amount owed	17,254
Litigation settlement amount	2,119
Minimum potential range contingency loss	0
Maximum potential range contingency loss	2,119
Second Claim [Member]
Loss Contingencies [Line Items]
Litigation settlement amount	$ 1,000