Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 MBbls	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies Disclosure [Line Items]
Lease of facilities, maturity year	2018
Payments related to lease obligations	$ 894	$ 446	$ 703
Contingent liability to surety insurance company	90,789
Commitments to use drilling rigs and acquisition of seismic data, value	52,299
Commitments to use drilling rigs and acquisition of seismic data, period	3 years
Minimum barrels of oil spill to impose financial responsibility under Oil Pollution Act	1
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
Approximate asserted claims plus accrued interest assessed by Louisiana Department of Revenue	29,581
Additional estimated assessments including interest by Louisiana Department of Revenue	2,440
Minimum potential range contingency loss	0
Maximum potential range contingency loss	$ 32,021