Short-term and Other Investments - Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Other Investments
Proceeds from Sale and Maturity of Marketable Securities			$ 954
Other investments, at fair value	$ 2,692		$ 2,692		$ 3,676
Midas Gold Shares [Member]
Other Investments
Shares owned	4,667,615		4,667,615		6,882,115
Marketable Securities Cumulative Gain (Loss)	$ (4,730)		$ (4,730)		$ (4,850)
Number Marketable Securities Sold	1,572,500	0	2,214,500	0
Proceeds from Sale and Maturity of Marketable Securities	$ 654		$ 954
Marketable Securities, Realized Gain (Loss)	$ 135		$ 120
Nusantara Resources
Other Investments
Shares owned	1,333,334		1,333,334		1,333,334