Income Taxes - Additional Information (Detail) - USD ($)
|
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Income Taxes Disclosure [Line Items] |
|
|
|
| Income tax benefit |
$ 0
|
$ 0
|
$ 0
|
| Operating loss carryforwards, federal |
13,100,000
|
|
|
| Operating loss carryforwards, state |
1,900,000
|
|
|
| Uncertain tax position |
0
|
|
|
| Gross deferred tax assets |
97,720,000
|
74,541,000
|
|
| Capitalized research and development expenses |
59,489,000
|
46,568,000
|
|
| Unrecognized tax benefits |
0
|
$ 0
|
|
| Accounting Standards Update 2006 [Member] |
|
|
|
| Income Taxes Disclosure [Line Items] |
|
|
|
| Operating loss carryforwards, federal |
9,400,000
|
|
|
| Operating loss carryforwards, state |
7,200,000
|
|
|
| Capitalized research and development expenses |
3,400,000
|
|
|
| Net operating loss carryforwards tax effected, Federal |
3,200,000
|
|
|
| Net operating loss carryforwards tax effected, State |
400,000
|
|
|
| Capitalized research and development expenses tax effected |
1,300,000
|
|
|
| Accounting Standards Update 2016-09 [Member] |
|
|
|
| Income Taxes Disclosure [Line Items] |
|
|
|
| Operating loss carryforwards, federal |
9,400,000
|
|
|
| Operating loss carryforwards, state |
7,200,000
|
|
|
| Capitalized research and development expenses |
3,400,000
|
|
|
| Net operating loss carryforwards tax effected, Federal |
3,200,000
|
|
|
| Net operating loss carryforwards tax effected, State |
400,000
|
|
|
| Capitalized research and development expenses tax effected |
1,300,000
|
|
|
| Stock Option [Member] |
|
|
|
| Income Taxes Disclosure [Line Items] |
|
|
|
| Operating loss carryforwards, federal |
9,400,000
|
|
|
| Operating loss carryforwards, state |
7,200,000
|
|
|
| Gross deferred tax assets |
12,800,000
|
|
|
| Capitalized research and development expenses |
3,400,000
|
|
|
| Domestic Tax Authority [Member] |
|
|
|
| Income Taxes Disclosure [Line Items] |
|
|
|
| Net operating loss carryforwards |
$ 49,100,000
|
|
|
| Net operating loss carryforwards, beginning of expiration period |
2026
|
|
|
| Research and development tax credit carryforwards, beginning of expiration period |
2026
|
|
|
| State and Local Jurisdiction [Member] |
|
|
|
| Income Taxes Disclosure [Line Items] |
|
|
|
| Net operating loss carryforwards |
$ 35,900,000
|
|
|
| Net operating loss carryforwards, beginning of expiration period |
2030
|
|
|
| Research and development tax credit carryforwards, beginning of expiration period |
2021
|
|
|