Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

SUBSEQUENT EVENTS - Appraisal Period (Details) - Guinea Concession - Subsequent Event - m	Sep. 19, 2017	Sep. 08, 2017	Jul. 12, 2017
SUBSEQUENT EVENTS
Interval (in meters)		5
Percentage of appraisal extension (as a percent)	100.00%
Appraisal period			2 years