Derivative Financial Instruments - Summary of Classification of Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Prepaid expenses and other
Fair value of the derivative instruments
Other derivative instruments, net	$ 553	$ 914
Accrued liabilities and other
Fair value of the derivative instruments
Fair value of derivative liability	112	644
Silver and Gold Concentrate Sales Agreements \| Prepaid expenses and other
Fair value of the derivative instruments
Other derivative instruments, net	550	784
Silver and Gold Concentrate Sales Agreements \| Accrued liabilities and other
Fair value of the derivative instruments
Fair value of derivative liability	161	644
Zinc Put and Call Options [Member] \| Prepaid expenses and other
Fair value of the derivative instruments
Other derivative instruments, net		113
Interest rate swap \| Prepaid expenses and other
Fair value of the derivative instruments
Other derivative instruments, net	3	$ 17
Interest rate swap \| Accrued liabilities and other
Fair value of the derivative instruments
Fair value of derivative liability	$ (49)

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=SL51823488-111719

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

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Balance Type:	credit
Period Type:	instant