Inventories - Schedule of inventory, Ore on leach pads (Details) $ in Thousands	Dec. 31, 2020 USD ($) oz	Dec. 31, 2019 USD ($) oz
Amount
Ore on leach pads, current \| $	$ 38,041	$ 22,062
Ore on leach pads, non-current \| $	7,243	0
Total \| $	$ 45,284	$ 22,062
Gold Ounces
Ore on leach pads, current \| oz	21,869	17,019
Ore on leach pads, non-current \| oz	4,164	0
Total \| oz	26,033	17,019

Amount before valuation reserves of gold ore material contained on a leach pad.

No definition available.

Name:	hymc_InventoryOreOnLeachPads
Namespace Prefix:	hymc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant