Warrants - Summary (Details) - $ / shares	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Class of Warrant or Right [Line Items]
Number of warrants outstanding (shares)	10,417,887
Warrants exercised via cashless exercises (shares)	1,400,025	0
Common stock issued from exercise of warrants (shares)	1,400,000
January 11, 2017 Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (USD per share)	$ 0.001
Number of warrants outstanding (shares)	5,858,238
November 20, 2017 Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (USD per share)	$ 0.001
Number of warrants outstanding (shares)	4,137,999
June 11, 2018 Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (USD per share)	$ 0.001
Number of warrants outstanding (shares)	421,650

Class of Warrant or Right, Number of Warrants Exercised, Noncash

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- Definition

Number of stock issued on warrant exercises during the period.

+ References

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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Number of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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