Commitments and Contingencies - Contract Liability (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Business Acquisition [Line Items]
Revenue Recognized	$ 15,100	$ 241	$ 25,215	$ 556
Franco-Nevada
Business Acquisition [Line Items]
Opening Balance	7,296	7,835	7,411	8,150
Revenue Recognized	(100)	(93)	(215)	(408)
Closing Balance	7,196	7,742	7,196	7,742
Kensington
Business Acquisition [Line Items]
Opening Balance	15,127	25,155	25,016	15,016
Additions	44,885	311	44,996	10,450
Revenue Recognized	(15,000)	(454)	(25,000)	(454)
Closing Balance	$ 45,012	$ 25,012	$ 45,012	$ 25,012