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Fair Value Measurements (Tables) | 3 Months Ended
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Aug. 31, 2011
Fair Value Measurements |
Schedule of fair value of financial instruments measured on a recurring basis |
(In thousands) |  |  | As of August 31, 2011
|  |  | Level 1 |  | Level 2 |  | Level 3 |  | Fair Value |
Cash and cash equivalents |  |  | $ | 150,312 |  | $ | — |  | $ | — |  | $ | 150,312 |
Marketable securities: |  |  |  |  |  |  |  |  |  |
Canadian treasury securities |  |  | 98,873 |  | 27,855 |  | — |  | 126,728 |
Total assets at fair value |  |  | $ | 249,185 |  | $ | 27,855 |  | $ | — |  | $ | 277,040 |
Current accrued liabilities |  |  | $ | — |  | $ | 548 |  | $ | — |  | $ | 548 |
Total liabilities at fair value |  |  | $ | — |  | $ | 548 |  | $ | — |  | $ | 548 |
(In thousands) |  | As of May 31, 2011
|  |  | Level 1 |  | Level 2 |  | Level 3 |  | Fair Value |
Cash and cash equivalents |  |  | $ | 438,106 |  | $ | — |  | $ | — |  | $ | 438,106 |
Marketable securities: |  |  |  |  |  |  |  |  |  |
Canadian treasury securities |  |  | 61,142 |  | 26,078 |  | — |  | 87,220 |
Total assets at fair value |  |  | $ | 499,248 |  | $ | 26,078 |  | $ | — |  | $ | 525,326 |
Current accrued liabilities |  |  | $ | — |  | $ | 869 |  | $ | — |  | $ | 869 |
Total liabilities at fair value |  |  | $ | — |  | $ | 869 |  | $ | — |  | $ | 869 |

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- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, 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 -Topic 820 -SubTopic 10 -Publisher FASB -Number -Article -Subparagraph -Name Accounting Standards Codification -Paragraph 1 -Section 50 -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19190-110258 + Details
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