| Available-for-sale Securities |
Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at June 30, 2016, were as follows: | | | | | | | | | | | | | | | | | | Amortized Cost | | Gross Unrealized | | Estimated Fair Market Value | (In thousands) | | Gains | | Losses | | Investments due in less than 3 months: | | | | | | | | Commercial paper | $ | 8,189 |
| | $ | — |
| | $ | — |
| | $ | 8,189 |
| Corporate securities | 14,027 |
| | — |
| | (3 | ) | | 14,024 |
| Total | 22,216 |
| | — |
| | (3 | ) | | 22,213 |
| Investments due in 4-12 months: | | | | | | | | Commercial paper | 8,309 |
| | — |
| | — |
| | 8,309 |
| Corporate securities | 33,591 |
| | 50 |
| | — |
| | 33,641 |
| Total | 41,900 |
| | 50 |
| | — |
| | 41,950 |
| Investments due between 12 months and 5 years: | | | | | | | | Corporate securities | 32,611 |
| | 117 |
| | — |
| | 32,728 |
| Total | 32,611 |
| | 117 |
| | — |
| | 32,728 |
| Total marketable securities | $ | 96,727 |
| | $ | 167 |
| | $ | (3 | ) | | $ | 96,891 |
|
Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2015, were as follows: | | | | | | | | | | | | | | | | | | Amortized Cost | | Gross Unrealized | | Estimated Fair Market Value | (In thousands) | | Gains | | Losses | | Investments due in less than 3 months: | | | | | | | | Corporate securities | $ | 38,586 |
| | $ | 7 |
| | $ | (10 | ) | | $ | 38,583 |
| Total | 38,586 |
| | 7 |
| | (10 | ) | | 38,583 |
| Investments due in 4-12 months: | | | | | | | | Corporate securities | 33,654 |
| | 1 |
| | (36 | ) | | 33,619 |
| Total | 33,654 |
| | 1 |
| | (36 | ) | | 33,619 |
| Investments due between 12 months and 5 years: | | | | | | | | Corporate securities | 11,626 |
| | — |
| | (59 | ) | | 11,567 |
| Total | 11,626 |
| | — |
| | (59 | ) | | 11,567 |
| Total marketable securities | $ | 83,866 |
| | $ | 8 |
| | $ | (105 | ) | | $ | 83,769 |
|
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