Fair Value Measurements - Schedule of Reconciliation of Preferred Stock Warrant Liability Measured at Fair Value Using Significant Unobservable Inputs (Details) - Preferred Stock Warrant Liability $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Balance as of December 31, 2015	$ 414
Changes in fair value of underlying warrant securities, recorded to interest expense	202
Conversion of warrant, recorded to additional paid-in capital	$ (616)