Commitments and Contingencies (Details) - USD ($)		12 Months Ended
	Apr. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
Contingencies
Loss contingency		$ 0
Velardena properties
Leases and Purchase Commitments
2019		80,000
2020		80,000
2021		80,000
2022		80,000
2023		80,000
Thereafter		80,000
Lease payments		78,000	$ 69,000
Surface right agreement with local ejido
Leases and Purchase Commitments
Lease payments		33,000
El Quevar Project
Leases and Purchase Commitments
2019		60,000
2020		60,000
2021		60,000
2022		60,000
2023		60,000
Thereafter		60,000
Lease payments		57,000	111,000
Office space
Leases and Purchase Commitments
2019		224,000
2020		157,000
2021		160,000
2022		163,000
2023		166,000
Thereafter		154,000
Lease payments		$ 237,000	$ 226,000
Reduction in space (as a percent)	45.00%
Reduction in cost (as a percent)	45.00%