Loan Agreements - Additional Information (Detail) | Jan. 08, 2015USD ($)Tranches$ / sharesshares | Jan. 31, 2015USD ($) | Aug. 31, 2012USD ($) | Mar. 31, 2012USD ($) | Dec. 31, 2011USD ($)$ / sharesshares | Mar. 31, 2016USD ($) | Mar. 31, 2015USD ($) | Aug. 31, 2012USD ($) | Dec. 31, 2015USD ($) | Dec. 15, 2015USD ($) | Nov. 24, 2015USD ($) | Apr. 30, 2014shares |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Proceeds from sale of common stock | | | | | | $ 41,000 | $ 2,411,000 | | | | | |
Proceeds from loan payable | | | | | | | $ 15,000,000 | | | | | |
Hercules Loan Agreement [Member] | Term Loan [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Prior written notice period to prepay term loan | | | | | | 7 days | | | | | | |
Loan and Security Agreement with Lighthouse Capital [Member] | Loans payable [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Loan and security agreement, maximum borrowing capacity | | | | | $ 10,000,000 | | | | | | | |
Proceeds from loan payable | | | $ 5,000,000 | $ 5,000,000 | | | | $ 10,000,000 | | | | |
Loan and security agreement, borrowings repayment period | | | | | 36 months | | | | | | | |
Debt instrument stated interest rate | | | | | 8.25% | | | | | | | |
Loan and security agreement, borrowings repayment start date | | | | | Dec. 1, 2012 | | | | | | | |
Line of credit facility, additional interest payment | | | | | | $ 600,000 | | | | | | |
Repayments of notes payable | | $ 3,600,000 | | | | | | | | | | |
Unamortized discount on debt, relating to warrants | | 200,000 | | | | | | | | | | |
Loan and Security Agreement with Lighthouse Capital [Member] | Loans payable [Member] | Series D Convertible Preferred Stock [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Exercise price of warrant | $ / shares | | | | | $ 12.04 | | | | | | | |
Warrant expiration date | | | | | 2021-12 | | | | | | | |
Warrant expiration period | | | | | 10 years | | | | | | | |
Loan and Security Agreement with Lighthouse Capital [Member] | Loans payable [Member] | Common Stock [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Warrant to purchase stock, number of securities called by warrants or rights | shares | | | | | | | | | | | | 66,436 |
Loan and Security Agreement with Lighthouse Capital [Member] | Maximum [Member] | Loans payable [Member] | Series D Convertible Preferred Stock [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Warrant to purchase stock, number of securities called by warrants or rights | shares | | | | | 66,436 | | | | | | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Stock Purchase Agreement [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Issuance of common stock, shares | shares | 135,501 | | | | | | | | | | | |
Issuance/sale of stock, price per share | $ / shares | $ 7.38 | | | | | | | | | | | |
Proceeds from sale of common stock | $ 1,000,000 | | | | | | | | | | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Loan and security agreement, maximum borrowing capacity | $ 26,000,000 | | | | | | | | | | | |
Amount outstanding under the Term Loan | | | | | | $ 19,100,000 | | | $ 21,000,000 | | | |
Term loan facility, maturity date | Jul. 1, 2018 | | | | | | | | | | | |
Term loan facility, interest rate terms | | | | | | The Term Loan will mature on July 1, 2018. Each advance under the Term Loan accrues interest at a floating per annum rate equal to the greater of (i) 7.30% or (ii) the sum of 7.30% plus the prime rate minus 5.75%. The Term Loan provided for interest-only payments on a monthly basis until December 31, 2015. | | | | | | |
Additional interest rate during an event of default | 5.00% | | | | | | | | | | | |
Final payment as percentage of aggregate original principal amount | 6.70% | | | | | | | | | | | |
Term loan facility, interest rate | 7.30% | | | | | | | | | | | |
Debt prepayment charge, after twelve months | 2.00% | | | | | | | | | | | |
Debt prepayment charge, after twenty-four months | 1.00% | | | | | | | | | | | |
Class of warrant or right, date until which warrants exercisable | Jan. 8, 2020 | | | | | | | | | | | |
Estimated fair value of warrant | | $ 824,000 | | | | | | | | | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | Common Stock [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Exercise price of warrant | $ / shares | $ 6.05 | | | | | | | | | | | |
Warrant to purchase stock, number of securities called by warrants or rights | shares | 171,901 | | | | | | | | | | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | Prime Rate [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Term loan facility, interest rate spread | 5.75% | | | | | | | | | | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | Borrowing One [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Loan and security agreement, maximum borrowing capacity | $ 15,000,000 | | | | | | | | | | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | Second Tranche [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Loan and security agreement, maximum borrowing capacity | | | | | | | | | | | $ 6,000,000 | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | Up on Meeting Certain Clinical Milestone on or Prior to Dec. 15, 2015 [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Loan and security agreement, maximum borrowing capacity | | | | | | | | | | $ 5,000,000 | | |
Hercules Technology Growth Capital, Inc. [Member] | Hercules Loan Agreement [Member] | Term Loan [Member] | Maximum [Member] | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | |
Number of tranches | Tranches | 3 | | | | | | | | | | | |