Commitments - Additional Information (Detail) (Forward Contracts [Member])	3 Months Ended
	Mar. 31, 2014 bbl
Heavy Oil [Member]
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day	4,000
Underlying derivative, volume	55.14
April through December 2014 Deliveries [Member] | Natural Gas [Member]
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day	110
Underlying derivative, volume	4.04
January through December 2015 Deliveries [Member] | Natural Gas [Member]
Commitments and Contingencies Disclosure [Line Items]
Notional amount, per day	65
Underlying derivative, volume	4.13