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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	$ 1,349	$ (21,248)	$ 25,723	$ (28,139)
Gains (losses) reclassified from AOCI into net income - effective portion:	(3,902)	2,642	(9,683)	1,963
Gold zero cost collars
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	1,614	(24,003)	25,590	(38,353)
Gains (losses) reclassified from AOCI into net income - effective portion:	23	4,563	853	4,563
Foreign Exchange Forward
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	(265)	2,755	133	10,214
Gains (losses) reclassified from AOCI into net income - effective portion:	$ (3,925)	$ (1,921)	$ (10,536)	$ (2,600)