Derivative Financial Instruments - Summary of Pre-tax Gains (Losses) On Derivatives Designated as Cash Flow Hedges (Details) - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	$ 27,357	$ 228
Gains (losses) reclassified from AOCI into net income - effective portion:	(2,721)	0
Gold zero cost collars
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	28,547	163
Gains (losses) reclassified from AOCI into net income - effective portion:	392	0
Foreign Exchange Forward
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	(1,190)	65
Gains (losses) reclassified from AOCI into net income - effective portion:	$ (3,113)	$ 0