Derivative Financial Instruments - Summary of Derivative Cash Flow Hedges (Details) - Designated as Hedging Instrument $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) oz $ / oz Rate
Gold Put Options - 2020
Derivative [Line Items]
Average gold strike price per ounce | $ / oz	1,457
Notional ounces | oz	105,000
Gold Call Options - 2020
Derivative [Line Items]
Average gold strike price per ounce | $ / oz	1,825
Notional ounces | oz	105,000
Gold Put Options - 2021
Derivative [Line Items]
Average gold strike price per ounce | $ / oz	1,600
Notional ounces | oz	202,800
Gold Call Options - 2021
Derivative [Line Items]
Average gold strike price per ounce | $ / oz	1,892
Notional ounces | oz	202,800
Mexican peso forward exchange contracts 2020
Derivative [Line Items]
Derivative, forward exchange rate | Rate	2422.00%
Derivative, notional amount | $	$ 30,000
Mexican peso forward exchange contracts 2021
Derivative [Line Items]
Derivative, forward exchange rate | Rate	2500.00%
Derivative, notional amount | $	$ 60,000
Canadian Forward Exchange Contracts 2020
Derivative [Line Items]
Derivative, forward exchange rate | Rate	144.00%
Derivative, notional amount | $	$ 15,000
Canadian Dollar Forward Purchase Contracts 2021
Derivative [Line Items]
Derivative, forward exchange rate | Rate	0.00%
Derivative, notional amount | $	$ 0