Warrants - Summary of Key Assumptions Used in Calculating Marketability Discount (Detail)	Dec. 31, 2018 yr
Expected Term (Years) [Member]
Class of Warrant or Right [Line Items]
Measurement input	0.03
Risk-free Interest Rate [Member]
Class of Warrant or Right [Line Items]
Measurement input	1.77
Dividend Yield [Member]
Class of Warrant or Right [Line Items]
Measurement input	0
Expected Volatility [Member]
Class of Warrant or Right [Line Items]
Measurement input	109.9

Value of input used to measure debt instrument, including, but not limited to, convertible and non-convertible debt.

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=117815213&loc=d3e19207-110258

Name:	us-gaap_DebtInstrumentMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant