Common Stock and Warrants - Summary of Warrants Accounted for as Liabilities and Recorded as Derivative Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair value of warrants at beginning of year	$ 6,941	$ 2,857
Issuance of warrants	7,372	3,016
Exercise of warrants	(3,012)	(1,200)
Fair value of previously classified equity warrants	5,049
Fair value of previously classified liability warrants reclassified to additional paid-in capital	(2,478)
Foreign exchange gains	(872)
Change in fair value of warrants during the year	769	2,268
Fair value of warrants at end of year	$ 13,769	$ 6,941

Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 45
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-URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30690-110894

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