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Short-term Investments (Details) (USD $)
In Thousands |
Jun. 30, 2011
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Dec. 31, 2010
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|---|---|---|
| Schedule of Available-for-sale Securities | ||
| Amortized Cost | $ 299,833 | $ 374,688 |
| Unrealized Gain in Accumulated OCI | 126 | 180 |
| Unrealized Loss in Accumulated OCI | (5) | (6) |
| Aggregate Fair Value | 299,954 | 374,862 |
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Equity securities
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||
| Schedule of Available-for-sale Securities | ||
| Amortized Cost | 7 | 7 |
| Unrealized Gain in Accumulated OCI | 0 | 0 |
| Unrealized Loss in Accumulated OCI | (5) | (6) |
| Aggregate Fair Value | 2 | 1 |
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U.S. Treasury securities
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| Schedule of Available-for-sale Securities | ||
| Amortized Cost | 299,826 | 374,681 |
| Unrealized Gain in Accumulated OCI | 126 | 180 |
| Unrealized Loss in Accumulated OCI | 0 | 0 |
| Aggregate Fair Value | $ 299,952 | $ 374,861 |
| X | ||||||||||
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- Definition
For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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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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| X | ||||||||||
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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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| X | ||||||||||
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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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| X | ||||||||||
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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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