Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level1 and Level 3 Financial Instruments (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) shares
Series A Warrant [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the end of period, in shares | shares	2,425,605
Common stock warrant liability [Member] | Series A Warrant [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares | shares	2,425,605
Balance at the beginning of period	$ 194
Change in value of Warrant	$ 221
Balance at the end of period, in shares | shares	2,425,605
Balance at end of period	$ 415
Common stock warrant liability [Member] | Series C Warrant [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares | shares	590,415
Balance at the beginning of period	$ 86
Change in value of Warrant	$ (62)
Balance at the end of period, in shares | shares	590,415
Balance at end of period	$ 24