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Marketable Securities (Tables) | 9 Months Ended
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Sep. 30, 2011
Marketable Securities |
Cash equivalents and marketable securities classified as available-for-sale |
|  | September 30, 2011 |
(Dollars in thousands) |  | Fair Value |  | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Weighted Rate of Return |
Money market funds |  | $ | 132,721 |  | $ | 132,721 |  | $ | — |  | $ | — |  | 0.01 | %
U.S. government sponsored obligations |  | 35,668 |  | 35,668 |  | 3 |  | (3 | ) | 0.25 | %
Corporate notes, bonds and commercial paper |  | 96,241 |  | 96,359 |  | — |  | (118 | ) | 0.43 | %
Total cash equivalents and marketable securities |  | 264,630 |  | 264,748 |  | 3 |  | (121 | ) |  |
Cash |  | 28,123 |  | 28,123 |  | — |  | — |  |  |
Total cash, cash equivalents and marketable securities |  | $ | 292,753 |  | $ | 292,871 |  | $ | 3 |  | $ | (121 | ) |  |
|  | December 31, 2010 |
(Dollars in thousands) |  | Fair Value |  | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Weighted Rate of Return |
Money market funds |  | $ | 132,364 |  | $ | 132,364 |  | $ | — |  | $ | — |  | 0.04 | %
U.S. government sponsored obligations |  | 266,817 |  | 266,840 |  | 29 |  | (52 | ) | 0.26 | %
Corporate notes, bonds and commercial paper |  | 95,724 |  | 95,773 |  | 8 |  | (57 | ) | 0.39 | %
Total cash equivalents and marketable securities |  | 494,905 |  | 494,977 |  | 37 |  | (109 | ) |  |
Cash |  | 17,104 |  | 17,104 |  | — |  | — |  |  |
Total cash, cash equivalents and marketable securities |  | $ | 512,009 |  | $ | 512,081 |  | $ | 37 |  | $ | (109 | ) |  |
Available-for-sale securities reported at fair value |
(Dollars in thousands) |  | September 30, 2011 |  | December 31, 2010 |
Cash equivalents |  | $ | 132,721 |  | $ | 198,158 |
Short term marketable securities |  | 131,909 |  | 296,747 |
Total cash equivalents and marketable securities |  | 264,630 |  | 494,905 |
Cash |  | 28,123 |  | 17,104 |
Total cash, cash equivalents and marketable securities |  | $ | 292,753 |  | $ | 512,009 |
Estimated fair value of cash equivalents and marketable securities classified by date of contractual maturity and the associated unrealized gain, net |
|  | As of |  | Unrealized Loss, net |
(Dollars in thousands) |  | September 30, 2011 |  | December 31, 2010 |  | September 30, 2011 |  | December 31, 2010 |
Contractual maturity: |  |  |  |  |  |  |  |  |
Due within one year |  | $ | 264,630 |  | $ | 494,905 |  | $ | (118 | ) | $ | (72 | )

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