Organization and Basis of Presentation - Additional Information (Detail) - USD ($) |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Jun. 30, 2014 |
Mar. 31, 2014 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] | |||||||||||
| Date of incorporation | Jan. 29, 2007 | ||||||||||
| Net loss | $ (2,624,152) | $ (2,735,400) | $ (3,241,163) | $ (3,520,748) | $ (2,919,803) | $ (3,825,354) | $ (3,547,040) | $ (2,955,484) | $ (12,121,463) | $ (13,247,681) | |
| Accumulated deficit | (48,060,612) | (35,939,149) | (48,060,612) | (35,939,149) | |||||||
| Cash and cash equivalents | 8,691,155 | 14,155,809 | 8,691,155 | 14,155,809 | $ 24,196,691 | ||||||
| Square 1 Bank [Member] | Loan and security agreement [Member] | |||||||||||
| Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] | |||||||||||
| Borrowings under bank credit facility | $ 4,500,000 | $ 4,500,000 | $ 4,500,000 | $ 4,500,000 | |||||||