Capitalization - Schedule of Mandatory Conversion of Convertible Promissory Notes into Preferred Stock (Detail) $ / shares in Units, $ in Thousands	Aug. 08, 2017 USD ($) $ / shares shares
Debt Conversion [Line Items]
Principal	$ 4,142
Accrued Interest	112
Total	4,254
Loss on Extinguishment of Convertible Promissory Notes	(3,159)
Convertible Promissory Notes [Member] | Note Purchase Agreement [Member]
Debt Conversion [Line Items]
Principal	2,444
Accrued Interest	72
Total	$ 2,516
Conversion Price Per Share | $ / shares	$ 4.14
Fair Value Date of Conversion | $ / shares	$ 7.66
Loss on Extinguishment of Convertible Promissory Notes	$ (2,138)
Convertible Promissory Notes [Member] | Note Purchase Agreement - Related Parties [Member]
Debt Conversion [Line Items]
Principal	948
Accrued Interest	32
Total	$ 980
Conversion Price Per Share | $ / shares	$ 4.14
Fair Value Date of Conversion | $ / shares	$ 7.66
Loss on Extinguishment of Convertible Promissory Notes	$ (832)
Convertible Promissory Notes [Member] | Second Note Purchase Agreement - Related Parties [Member]
Debt Conversion [Line Items]
Principal	750
Accrued Interest	8
Total	$ 758
Conversion Price Per Share | $ / shares	$ 6.13
Fair Value Date of Conversion | $ / shares	$ 7.66
Loss on Extinguishment of Convertible Promissory Notes	$ (189)
Convertible Promissory Notes [Member] | Agreements - Related Parties [Member]
Debt Conversion [Line Items]
Principal	1,698
Accrued Interest	40
Total	1,738
Loss on Extinguishment of Convertible Promissory Notes	$ (1,021)
Series A 1 Preferred Stock [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	844,362
Fair Value Preferred Stock	$ 6,466
Series A 1 Preferred Stock [Member] | Convertible Promissory Notes [Member] | Note Purchase Agreement [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	607,743
Fair Value Preferred Stock	$ 4,654
Series A 1 Preferred Stock [Member] | Convertible Promissory Notes [Member] | Note Purchase Agreement - Related Parties [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	236,619
Fair Value Preferred Stock	$ 1,812
Series A 1 Preferred Stock [Member] | Convertible Promissory Notes [Member] | Agreements - Related Parties [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	236,619
Fair Value Preferred Stock	$ 1,812
Series A 2 Preferred Stock [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	123,691
Fair Value Preferred Stock	$ 947
Series A 2 Preferred Stock [Member] | Convertible Promissory Notes [Member] | Second Note Purchase Agreement - Related Parties [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	123,691
Fair Value Preferred Stock	$ 947
Series A 2 Preferred Stock [Member] | Convertible Promissory Notes [Member] | Agreements - Related Parties [Member]
Debt Conversion [Line Items]
Shares of Preferred Stock | shares	123,691
Fair Value Preferred Stock	$ 947