Marketable Securities (Details) - USD ($) $ in Thousands |
Jun. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Schedule of Available-for-sale Securities | ||
| Amortized cost | $ 168,541 | $ 65,146 |
| Gross Unrealized Gains | 221 | 0 |
| Gross Unrealized Losses | (5) | (99) |
| Estimated fair value | 168,757 | 65,047 |
| Corporate debt securities | ||
| Schedule of Available-for-sale Securities | ||
| Amortized cost | 72,592 | 62,151 |
| Gross Unrealized Gains | 43 | 0 |
| Gross Unrealized Losses | (5) | (99) |
| Estimated fair value | 72,630 | 62,052 |
| US Treasury securities | ||
| Schedule of Available-for-sale Securities | ||
| Amortized cost | 87,986 | |
| Gross Unrealized Gains | 178 | |
| Gross Unrealized Losses | 0 | |
| Estimated fair value | 88,164 | |
| Commercial paper | ||
| Schedule of Available-for-sale Securities | ||
| Amortized cost | 7,963 | 2,995 |
| Gross Unrealized Gains | 0 | 0 |
| Gross Unrealized Losses | 0 | 0 |
| Estimated fair value | $ 7,963 | $ 2,995 |