Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Equity securities	$ 161,894	$ 132,197
Fair Value, Recurring
Assets:
Assets	164,588	132,283
Liabilities:
Total liabilities	1,878	1,374
Provisional metal sales contracts | Fair Value, Recurring
Assets:
Fair value of other derivative instruments, net	461	86
Liabilities:
Fair value of derivative liability	46	162
Gold Forwards | Fair Value, Recurring
Liabilities:
Fair value of derivative liability	1,832
Gold zero cost collars | Fair Value, Recurring
Liabilities:
Fair value of derivative liability		1,212
Equity Securities | Fair Value, Recurring
Assets:
Equity securities		132,197
Liabilities:
Marketable securities including warrants	164,127
Level 1 | Fair Value, Recurring
Assets:
Assets	161,894	132,197
Liabilities:
Total liabilities	0	0
Level 1 | Provisional metal sales contracts | Fair Value, Recurring
Assets:
Fair value of other derivative instruments, net	0	0
Liabilities:
Fair value of derivative liability	0	0
Level 1 | Gold Forwards | Fair Value, Recurring
Liabilities:
Fair value of derivative liability	0
Level 1 | Gold zero cost collars | Fair Value, Recurring
Liabilities:
Fair value of derivative liability		0
Level 1 | Equity Securities | Fair Value, Recurring
Assets:
Equity securities		132,197
Liabilities:
Marketable securities including warrants	161,894
Level 2 | Fair Value, Recurring
Assets:
Assets	2,694	86
Liabilities:
Total liabilities	1,878	1,374
Level 2 | Provisional metal sales contracts | Fair Value, Recurring
Assets:
Fair value of other derivative instruments, net	461	86
Liabilities:
Fair value of derivative liability	46	162
Level 2 | Gold Forwards | Fair Value, Recurring
Liabilities:
Fair value of derivative liability	1,832
Level 2 | Gold zero cost collars | Fair Value, Recurring
Liabilities:
Fair value of derivative liability		1,212
Level 2 | Equity Securities | Fair Value, Recurring
Assets:
Equity securities		0
Liabilities:
Marketable securities including warrants	2,233
Level 3   | Fair Value, Recurring
Assets:
Assets	0	0
Liabilities:
Total liabilities	0	0
Level 3   | Provisional metal sales contracts | Fair Value, Recurring
Assets:
Fair value of other derivative instruments, net	0	0
Liabilities:
Fair value of derivative liability	0	0
Level 3   | Gold Forwards | Fair Value, Recurring
Liabilities:
Fair value of derivative liability	0
Level 3   | Gold zero cost collars | Fair Value, Recurring
Liabilities:
Fair value of derivative liability		0
Level 3   | Equity Securities | Fair Value, Recurring
Assets:
Equity securities		$ 0
Liabilities:
Marketable securities including warrants	$ 0