Commitments and Contingencies - Additional Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 Boe
Other Commitments [Line Items]
Minimum commitment	$ 86.0
Barrels processing capacity	40,000
Production, barrels of oil equivalents	1,000,000
Minimum commitment, due in first year	35.0
Minimum commitment, due thereafter	$ 48.0
the “Kenya PSCs”
Other Commitments [Line Items]
Production sharing contracts with the Government of the Republic of Kenya	4
the “Gambia Licenses”
Other Commitments [Line Items]
Petroleum Exploration, Development & Production Licenses with the Republic of the Gambia	2