Exploration License - Additional Information (Detail)	Jul. 09, 2019 USD ($)
Accounting Standards Update 2017-01 [Member]
Business Acquisition [Line Items]
Percent of ownership acquired	79.90%
Bismarck [Member]
Business Acquisition [Line Items]
Annual Fee Due	$ 14,000
Bismarck [Member] \| Accounting Standards Update 2017-01 [Member]
Business Acquisition [Line Items]
Percent of ownership acquired	79.90%

Percentage of voting equity interests acquired at the acquisition date in the business combination.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant