Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Common Stock Warrants (Detail)	Mar. 31, 2019 $ / shares $ / shares	Dec. 31, 2018 $ / shares $ / shares
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value of common stock	$ 0.67	$ 0.57
Exercise Price
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation assumptions measurement input	55.00	55.00
Expected Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation assumptions measurement input	179.0	134.0
Expected Term
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation assumptions expected term	2 years 1 month 9 days	2 years 4 months 6 days
Risk-free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation assumptions measurement input	2.3	2.5
Expected Dividend Yield
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation assumptions measurement input	0	0

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.

No definition available.

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- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

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- Definition

Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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