Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Assets: |
|
|
| Marketable securities |
$ 74,280
|
$ 37,435
|
| Recurring Basis [Member] |
|
|
| Assets: |
|
|
| Total assets at fair value |
104,159
|
74,137
|
| Recurring Basis [Member] | United States Treasury Notes [Member] |
|
|
| Assets: |
|
|
| Marketable securities |
44,534
|
10,026
|
| Recurring Basis [Member] | Agency Bonds [Member] |
|
|
| Assets: |
|
|
| Cash equivalents |
|
7,599
|
| Marketable securities |
29,746
|
27,409
|
| Money Market Funds [Member] | Recurring Basis [Member] |
|
|
| Assets: |
|
|
| Cash equivalents |
29,879
|
29,103
|
| Level 2 [Member] | Recurring Basis [Member] |
|
|
| Assets: |
|
|
| Total assets at fair value |
104,159
|
74,137
|
| Level 2 [Member] | Recurring Basis [Member] | United States Treasury Notes [Member] |
|
|
| Assets: |
|
|
| Marketable securities |
44,534
|
10,026
|
| Level 2 [Member] | Recurring Basis [Member] | Agency Bonds [Member] |
|
|
| Assets: |
|
|
| Cash equivalents |
|
7,599
|
| Marketable securities |
29,746
|
27,409
|
| Level 2 [Member] | Money Market Funds [Member] | Recurring Basis [Member] |
|
|
| Assets: |
|
|
| Cash equivalents |
$ 29,879
|
$ 29,103
|