SUBSEQUENT EVENTS (Details)	Aug. 19, 2016 USD ($) km² item m	Aug. 15, 2016	Jun. 30, 2016	Dec. 31, 2012	Dec. 30, 2012	Mar. 25, 2010 mi²	Mar. 25, 2010 km²
Guinea concession
SUBSEQUENT EVENTS
Ownership interest (as a percent)			37.00%	37.00%	77.00%
Contract area retained (in square kilometers/square miles)						9,650	25,000
Subsequent event | Tullow and Dana | Settlement Agreement
SUBSEQUENT EVENTS
Ownership interest (as a percent)		100.00%
Subsequent event | Guinea concession
SUBSEQUENT EVENTS
Ownership interest (as a percent)	100.00%
Extension period for second exploration (in years)	1 year
Number of exploratory well in extension period | item	1
Depth below seabed required to be drilled of an exploration well (in meters) | m	2,500
Amount receivable, if extension well not drilled	$ 46,000,000
Contract area retained (in square kilometers/square miles) | km²	5,000
Notice period for termination (in days)	30 days
Mutually acceptable security	$ 5,000,000
Estimated amount to limit cost recovery to share of expenditures	150,000,000
Agreed amount in training budget	250,000
Estimated amount of unused portion of training program	$ 500,000