Inventories (Summary) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Finished products	$ 24,424	$ 20,378
In-process	10,310	8,111
Raw materials	12,346	11,904
Fine and fabricated precious metals in various stages of completion	17,094us-gaap_OtherInventoryNetOfReserves	19,802us-gaap_OtherInventoryNetOfReserves
Inventory, before LIFO reserve	64,174hnh_InventoryNetBeforeLifoReserves	60,195hnh_InventoryNetBeforeLifoReserves
LIFO reserve	(245)us-gaap_InventoryLIFOReserve	(1,025)us-gaap_InventoryLIFOReserve
Inventory, Net	$ 63,929us-gaap_InventoryNet	$ 59,170us-gaap_InventoryNet

Inventory, Net, Before LIFO Reserves

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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Carrying amount, net of valuation reserves and allowances, as of the balance sheet date of inventories not otherwise specified in the taxonomy.

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