Short-term Investments (Details) (USD $) In Thousands | Sep. 30, 2011 | Dec. 31, 2010 |
|---|---|---|
| Schedule of Available-for-sale Securities | ||
| Amortized Cost | $ 299,917 | $ 374,688 |
| Unrealized Gain in Accumulated OCI | 70 | 180 |
| Unrealized Loss in Accumulated OCI | (6) | (6) |
| Aggregate Fair Value | 299,981 | 374,862 |
Equity securities | ||
| Schedule of Available-for-sale Securities | ||
| Amortized Cost | 7 | 7 |
| Unrealized Gain in Accumulated OCI | 0 | 0 |
| Unrealized Loss in Accumulated OCI | (6) | (6) |
| Aggregate Fair Value | 1 | 1 |
U.S. Treasury securities | ||
| Schedule of Available-for-sale Securities | ||
| Amortized Cost | 299,910 | 374,681 |
| Unrealized Gain in Accumulated OCI | 70 | 180 |
| Unrealized Loss in Accumulated OCI | 0 | 0 |
| Aggregate Fair Value | $ 299,980 | $ 374,861 |
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- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Investments in debt and equity securities which are categorized neither as trading securities nor held-to-maturity securities and which are intended be sold or mature within one year from the balance sheet date or the normal operating cycle, whichever is longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This item represents the gross unrealized losses for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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