Property, Plant and Equipment - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Development Expenses [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 60,000	$ 0
Australia [Member]
Property, Plant and Equipment [Line Items]
Reserves	0
Depletion	$ 0