Assets measured at fair value on a recurring basis as of September 30, 2014 are as follows (in thousands): | | | | | | | | | | | | | | | | | | Balance as of September 30, 2014 | | Quoted Prices in Active Markets for Identical Assets (Level 1) | | Significant Other Observable Inputs (Level 2) | | Significant Unobservable Inputs (Level 3) | Assets: | | | | | | | | Money market funds | $ | 7,445 |
| | $ | 7,445 |
| | $ | — |
| | $ | — |
| Commercial paper | 5,250 |
| | — |
| | 5,250 |
| | — |
| Corporate debt securities | 42,053 |
| | — |
| | 42,053 |
| | — |
| Total assets | $ | 54,748 |
| | $ | 7,445 |
| | $ | 47,303 |
| | $ | — |
|
Assets measured at fair value on a recurring basis as of December 31, 2013 are as follows (in thousands): | | | | | | | | | | | | | | | | | | Balance as of December 31, 2013 | | Quoted Prices in Active Markets for Identical Assets (Level 1) | | Significant Other Observable Inputs (Level 2) | | Significant Unobservable Inputs (Level 3) | Assets: | | | | | | | | Money market funds | $ | 5,774 |
| | $ | 5,774 |
| | $ | — |
| | $ | — |
| Commercial paper | 15,246 |
| | — |
| | 15,246 |
| | — |
| Corporate debt securities | 20,884 |
| | — |
| | 20,884 |
| | — |
| Total assets | $ | 41,904 |
| | $ | 5,774 |
| | $ | 36,130 |
| | $ | — |
|
|