v2.4.0.6

Fair Value Measurements (Tables) | 12 Months Ended
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Dec. 31, 2011
Fair Value Measurements |
Estimated fair values of the financial assets |
|  | Fair Value Measurements at Reporting Date Using |
--- | --- | --- | ---
|  | Quoted Prices in Active Markets for Identical Assets |  | Significant Other Observable Inputs |  | Significant Unobservable Inputs |  |  |
December 31, 2011 (in thousands) |  | Level 1 |  | Level 2 |  | Level 3 |  | Total |
U.S. government securities |  | $ | 66,174 |  | $ | — |  | $ | — |  | $ | 66,174 |
U.S. government agency securities |  |  | 55,901 |  |  | 37,274 |  |  | — |  |  | 93,175 |
U.S. corporate notes |  |  | 2,705 |  |  | — |  |  | — |  |  | 2,705 |
U.S. commercial paper |  |  | — |  |  | 34,976 |  |  | — |  |  | 34,976 |
Money market funds |  |  | 38,721 |  |  | — |  |  | — |  |  | 38,721 |
Total |  | $ | 163,501 |  | $ | 72,250 |  | $ | — |  | $ | 235,751 |
|  | Fair Value Measurements at Reporting Date Using |
--- | --- | --- | ---
|  | Quoted Prices in Active Markets for Identical Assets |  | Significant Other Observable Inputs |  | Significant Unobservable Inputs |  |  |
December 31, 2010 (in thousands) |  | Level 1 |  | Level 2 |  | Level 3 |  | Total |
U.S. government securities |  | $ | 25,976 |  | $ | — |  | $ | — |  | $ | 25,976 |
U.S. government agency securities |  |  | 24,375 |  |  | 30,273 |  |  | — |  |  | 54,648 |
U.S. corporate notes |  |  | 34,695 |  |  | — |  |  | — |  |  | 34,695 |
U.S. commercial paper |  |  | — |  |  | 97,221 |  |  | — |  |  | 97,221 |
Money market funds |  |  | 91,805 |  |  | — |  |  | — |  |  | 91,805 |
Total |  | $ | 176,851 |  | $ | 127,494 |  | $ | — |  | $ | 304,345 |

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- Definition Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19190-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 6 -Footnote 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258 + Details
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