INCOME AND MINING TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deductible temporary differences relating to:
Marketable securities	$ 634	$ 0
Inventories	0	3,245
Reclamation liabilities	27,608	20,117
Lease liabilities	23,895	24,307
Deductibility of other taxes	9,299	10,770
Stock-based compensation	7,247	11,410
Other items	16,595	7,873
Deferred tax assets, gross	85,278	77,722
Investment incentive tax credits	46,354	168,447
Tax loss carryforwards	25,395	22,597
Less: Valuation allowance	(38,496)	(37,410)
Total deferred income tax assets	118,531	231,356
Taxable temporary differences relating to:
Marketable securities	(270)	(2,041)
Inventories	(17,768)	(47,484)
Mineral properties, plant and equipment	(365,793)	(566,922)
Convertible notes	(359)	(414)
Mineral tax	(38,452)	(39,575)
Foreign withholding tax	(17,080)	(32,875)
Other items	(9,096)	0
Total deferred income tax liabilities	(448,818)	(689,311)
Balance sheet presentation
Deferred income tax assets	8,501	15,072
Deferred income tax liabilities	(338,788)	(473,027)
Deferred income tax liabilities, net	$ (330,287)	$ (457,955)

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