FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details) (USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2011
|
Dec. 31, 2010
|
---|---|---|
Put options related to auction rate securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | $ 3,000 | |
Level 1
|
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Fair value of certain assets | ||
Cash | 81,879 | 50,202 |
Assets measured at fair value | 319,942 | 377,724 |
Level 1 | Money market funds
|
||
Fair value of certain assets | ||
Assets measured at fair value | 230,029 | 242,001 |
Level 1 | U.S. Treasuries
|
||
Fair value of certain assets | ||
Assets measured at fair value | 8,034 | 85,521 |
Level 2
|
||
Fair value of certain assets | ||
Assets measured at fair value | 438,013 | 197,704 |
Level 2 | Certificates of deposit
|
||
Fair value of certain assets | ||
Assets measured at fair value | 69,078 | 40,010 |
Level 2 | Corporate bonds
|
||
Fair value of certain assets | ||
Assets measured at fair value | 2,022 | |
Level 2 | Municipal securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | 291,984 | 81,899 |
Level 2 | U.S. government agency securities.
|
||
Fair value of certain assets | ||
Assets measured at fair value | 16,005 | 19,688 |
Level 2 | Variable rate demand notes
|
||
Fair value of certain assets | ||
Assets measured at fair value | 58,924 | 56,107 |
Level 3
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Fair value of certain assets | ||
Assets measured at fair value | 38,893 | 72,020 |
Level 3 | Auction rate securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | 35,852 | 68,252 |
Level 3 | Put options related to auction rate securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | 3,041 | 3,768 |
Total fair value
|
||
Fair value of certain assets | ||
Cash | 81,879 | 50,202 |
Assets measured at fair value | 796,848 | 647,448 |
Total fair value | Money market funds
|
||
Fair value of certain assets | ||
Assets measured at fair value | 230,029 | 242,001 |
Total fair value | U.S. Treasuries
|
||
Fair value of certain assets | ||
Assets measured at fair value | 8,034 | 85,521 |
Total fair value | Certificates of deposit
|
||
Fair value of certain assets | ||
Assets measured at fair value | 69,078 | 40,010 |
Total fair value | Corporate bonds
|
||
Fair value of certain assets | ||
Assets measured at fair value | 2,022 | |
Total fair value | Municipal securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | 291,984 | 81,899 |
Total fair value | U.S. government agency securities.
|
||
Fair value of certain assets | ||
Assets measured at fair value | 16,005 | 19,688 |
Total fair value | Variable rate demand notes
|
||
Fair value of certain assets | ||
Assets measured at fair value | 58,924 | 56,107 |
Total fair value | Auction rate securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | 35,852 | 68,252 |
Total fair value | Put options related to auction rate securities
|
||
Fair value of certain assets | ||
Assets measured at fair value | $ 3,041 | $ 3,768 |