Short-term and Other Investments - Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Other Investments
Proceeds from Sale and Maturity of Marketable Securities			$ 5,788
Other investments, at fair value	$ 295		$ 295		$ 3,676
Midas Gold Shares [Member]
Other Investments
Shares owned	0		0		6,882,115
Marketable Securities Cumulative Gain (Loss)	$ (11,841)		$ (11,841)		$ (14,415)
Number Marketable Securities Sold	4,667,615	0	6,882,115	0
Proceeds from Sale and Maturity of Marketable Securities	$ 4,835		$ 5,788
Marketable Securities, Realized Gain (Loss)	$ 2,454		$ 2,574
Nusantara Resources
Other Investments
Shares owned	1,333,334		1,333,334		1,333,334