Commitments and Contingencies - Contract Liability (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Business Acquisition [Line Items]
Revenue Recognized	$ 143	$ 10,167	$ 25,358	$ 10,723
Franco-Nevada
Business Acquisition [Line Items]
Opening Balance	7,196	7,742	7,411	8,150
Revenue Recognized	(145)	(167)	(360)	(575)
Closing Balance	7,051	7,575	7,051	7,575
Kensington
Business Acquisition [Line Items]
Opening Balance	45,012	25,012	25,016	15,016
Additions	30,311	361	75,307	10,811
Revenue Recognized	(31,000)	(10,000)	(56,000)	(10,454)
Closing Balance	$ 44,323	$ 15,373	$ 44,323	$ 15,373