Inventories, net - Schedule of Mine site period costs (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Inventory Disclosure [Abstract]
Production related costs	$ 10,956	$ 13,394	$ 23,341	$ 32,024
Capitalized depreciation and amortization	511	836	1,104	2,268
Total	$ 11,467	$ 14,230	$ 24,445	$ 34,292

The amount of mine site costs, including depreciation and amortization, incurred during the reporting period.

No definition available.

Name:	hymc_MineSitePeriodCostsGross
Namespace Prefix:	hymc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration