INVESTMENT IN OIL AND GAS PROPERTIES - Guinea Concession - General Information (Details)											12 Months Ended
	Oct. 08, 2017 USD ($)	Sep. 19, 2017	Sep. 08, 2017 m	Jul. 12, 2017	Jun. 12, 2017 USD ($)	Jun. 05, 2017 USD ($)	Jun. 02, 2017 USD ($)	Jan. 29, 2017 USD ($)	Sep. 15, 2016 USD ($) km²	Mar. 25, 2010 km² m	Jun. 30, 2017 USD ($) item m $ / km²	Jun. 30, 2016 USD ($) km²	Jun. 30, 2012 km²	Apr. 21, 2017 km²
INVESTMENT IN OIL AND GAS PROPERTIES
Contract area retained as percentage of original contract area, required to be relinquished under PSC										25.00%
Additional participating interest (as a percent)											2.00%
Guinea Concession
INVESTMENT IN OIL AND GAS PROPERTIES
Contract area retained (in square kilometers/square miles) | km²									5,000	25,000
Contract area retained as percentage of original contract area										30.00%
Current contract area | km²												18,750
Area of 3D seismic required to be acquired (in square kilometers) | km²													3,600
Amount spent for work obligations												$ 200,000,000
Guinea's participating interest in development of discovery as percentage of costs, maximum (as a percent)											15.00%
Guinea's share of cost and profit oil (as a percent)											62.50%
Annual surface tax, obligated to pay (in dollars per square kilometers) | $ / km²											2.00
Extension of exploration period Additionally allowable to completion of appraisal of discovery made									1 year
Number of exploratory well in extension period | item											1
Minimum depth to be seabed | m											2,500
Notice period for termination (in days)											30 days
Estimated amount to limit cost recovery to share of expenditures									$ 165,000,000		$ 165,000,000
Agreed amount in training budget								$ 250,000			250,000
Estimated amount of unused portion of training program								$ 200,000			221,000
Maximum total budget											120,000
Estimated Unused portion of Budget											$ 22,000
Guinea Concession | Minimum
INVESTMENT IN OIL AND GAS PROPERTIES
Minimum depth to be reached to satisfy work requirement | m										2,500
Area of 3D seismic required to be acquired (in square kilometers) | km²										2,000
Guinea Concession | Subsequent Event
INVESTMENT IN OIL AND GAS PROPERTIES
Percentage of appraisal extension (as a percent)		100.00%
Appraisal period				2 years
Interval (in meters) | m			5
SAPETRO | Guinea Concession
INVESTMENT IN OIL AND GAS PROPERTIES
Ownership interest sold (as a percent)							50.00%
Preliminary closing statement						$ 4,100,000
Payment for legal settlement					$ 300,000
SAPETRO | Guinea Concession | Subsequent Event
INVESTMENT IN OIL AND GAS PROPERTIES
Settlement amount	$ 4,924,000
SAPETRO | Guinea Concession | Farm-out Agreement
INVESTMENT IN OIL AND GAS PROPERTIES
Contract area retained (in square kilometers/square miles) | km²														5,000
Ownership interest sold (as a percent)							50.00%
Participation interest in joint venture (as a percent)							100.00%
Estimated total drilling preparation cost							$ 4,400,000
Settlement amount					$ 700,000
Additional participating interest (as a percent)											2.00%
Threshold amount for additional assigned 2% participating interest											$ 1,000,000