The following table summarizes the gross unrealized losses on available for sale securities in an unrealized loss position as of September 30, 2013 and December 31, 2012: | | | | | | | | | | | | | | | | | | September 30, 2013 | | Less Than or Equal to One Year | | More Than One Year | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | U.S. Treasury securities and obligations of U.S. government authorities and agencies | $ | 3,754 |
| | $ | (52 | ) | | $ | 287 |
| | $ | (4 | ) | Corporate securities | 2,233 |
| | (44 | ) | | — |
| | — |
| Asset-backed securities | — |
| | — |
| | 2 |
| | — |
| Total | $ | 5,987 |
| | $ | (96 | ) | | $ | 289 |
| | $ | (4 | ) |
| | | | | | | | | | | | | | | | | | December 31, 2012 | | Less Than or Equal to One Year | | More Than One Year | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | U.S. Treasury securities and obligations of U.S. government authorities and agencies | $ | 612 |
| | $ | (3 | ) | | $ | — |
| | $ | — |
| Corporate securities | 540 |
| | (3 | ) | | 149 |
| | (2 | ) | Asset-backed securities | — |
| | — |
| | 194 |
| | (8 | ) | Total | $ | 1,152 |
| | $ | (6 | ) | | $ | 343 |
| | $ | (10 | ) |
|