| Assets and Liabilities Carried at Fair Value on a Recurring Basis |
| | | | | | | | | | | | | | | | | | Level 1 | | Level 2 | | Level 3 | | Total Fair Value | June 30, 2015 | (In thousands) | Assets | | | | | | | | Corporate bonds | $ | — |
| | $ | 36,869 |
| | $ | — |
| | $ | 36,869 |
| Commercial paper | — |
| | 36,788 |
| | — |
| | 36,788 |
| U.S. Treasury notes | — |
| | 26,284 |
| | — |
| | 26,284 |
| Mortgage-backed securities | — |
| | 79,277 |
| | — |
| | 79,277 |
| Municipal bonds | — |
| | 2,188 |
| | — |
| | 2,188 |
| Asset-backed securities | — |
| | 17,773 |
| | — |
| | 17,773 |
| Total assets | $ | — |
| | $ | 199,179 |
| | $ | — |
| | $ | 199,179 |
| | | | | | | | | Liabilities | | | | | | | | Contingent consideration | $ | — |
| | $ | — |
| | $ | 14,976 |
| | $ | 14,976 |
| | | | | | | | | December 31, 2014 | | | | | | | | Assets | | | | | | | | Corporate bonds | $ | — |
| | $ | 40,389 |
| | $ | — |
| | $ | 40,389 |
| Commercial paper | — |
| | 7,649 |
| | — |
| | 7,649 |
| U.S. Treasury notes | — |
| | 14,771 |
| | — |
| | 14,771 |
| Agency securities | — |
| | 2,950 |
| | — |
| | 2,950 |
| Mortgage-backed securities | — |
| | 35,362 |
| | — |
| | 35,362 |
| Municipal bonds | — |
| | 5,595 |
| | — |
| | 5,595 |
| Asset-backed securities | — |
| | 13,715 |
| | — |
| | 13,715 |
| Total assets | $ | — |
| | $ | 120,431 |
| | $ | — |
| | $ | 120,431 |
| | | | | | | | | Liabilities | | | | | | | | Contingent consideration | $ | — |
| | $ | — |
| | $ | 23,160 |
| | $ | 23,160 |
|
|
| Change in Contingent Consideration Payable |
The following table presents changes in our contingent consideration payable for the three and six months ended June 30, 2015, which is categorized in Level 3 of the fair value hierarchy. | | | | | | | | | | Three Months Ended June 30, 2015 | | Six Months Ended June 30, 2015 | | (In thousands) | Balance, beginning of period | $ | 15,375 |
| | $ | 23,160 |
| Payments of contingent consideration | (499 | ) | | (668 | ) | Change in fair value of contingent consideration | 100 |
| | (7,516 | ) | Balance, end of period | $ | 14,976 |
| | $ | 14,976 |
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