Deferred Consideration - Schedule of Deferred Consideration (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Contractual gold payments	$ 4,450	$ 4,270
Contractual gold payments – gold ounces paid	2,375	2,375
(Loss)/gain on revaluation of deferred consideration – gold payments	$ (17,018)	$ 2,832