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Loan Agreements - Additional Information (Detail) - Hercules Loan Agreement [Member] - Hercules Technology Growth Capital, Inc. [Member] - USD ($)		3 Months Ended
	Mar. 20, 2017	Mar. 31, 2017	Dec. 31, 2016	Jan. 31, 2015	Jan. 08, 2015
Debt Instrument [Line Items]
Loan and security agreement, maximum borrowing capacity					$ 26,000,000
Pay off loan agreement, amount paid	$ 12,400,000
Pay off loan agreement, final end of term charge amount	$ 1,400,000
Final payment as percentage of aggregate original principal amount	6.70%
Amount outstanding under the loan and security agreement			$ 12,800,000
Accrued end of term charge			$ 1,100,000
Class of warrant or right, date until which warrants exercisable		Jan. 08, 2020
Estimated fair value of warrant				$ 824,000
Loans Payable [Member]
Debt Instrument [Line Items]
Unamortized discount on debt, relating to warrants				$ 200,000
Common Stock [Member]
Debt Instrument [Line Items]
Exercise price of warrant					$ 6.05
Warrant to purchase stock, number of securities called by warrants or rights					171,901

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