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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	$ (2,982)	$ (7,097)	$ 24,376	$ (6,891)
Gains (losses) reclassified from AOCI into net income - effective portion:	(3,061)	(679)	(5,783)	(679)
Gold zero cost collars
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	(4,571)	(14,490)	23,976	(14,349)
Gains (losses) reclassified from AOCI into net income - effective portion:	437	0	828	0
Foreign Exchange Forward
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gains (losses) recognized in OCI - effective portion:	1,589	7,393	400	7,458
Gains (losses) reclassified from AOCI into net income - effective portion:	$ (3,498)	$ (679)	$ (6,611)	$ (679)