Summary of Significant Accounting Policies Summary of Unearned Income (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Oct. 02, 2014
Contract Liabilities
Deferred Revenue Recognized	$ 15,887,000	$ 16,226,000	$ 16,702,000
Palmarejo gold production royalty
Contract Liabilities
Aggregate deposit to be received				$ 22,000,000
Price per ounce under agreement				$ 800
Production to be sold, percent				50.00%
Franco-Nevada
Contract Liabilities
Opening Balance	8,150,000	9,376,000	11,061,000
Deferred Revenue Recognized	(739,000)	(1,226,000)	(1,685,000)
Closing Balance	7,411,000	8,150,000	9,376,000
Kensington
Contract Liabilities
Opening Balance	15,016,000	15,003,000	15,009,000
Deferred Revenue, Additions	36,020,000	30,013,000	30,177,000
Deferred Revenue Recognized	(26,020,000)	(30,000,000)	(30,183,000)
Closing Balance	25,016,000	15,016,000	$ 15,003,000
Kensington | December 2020 Prepayment [Member]
Contract Liabilities
Opening Balance	15,000,000
Closing Balance		$ 15,000,000
Kensington | June 2021 Prepayment
Contract Liabilities
Closing Balance	10,000,000
Kensington | December 2021 Prepayment
Contract Liabilities
Closing Balance	$ 25,000,000