Marketable Securities (Details Textuals) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Marketable Securities (Textuals) [Abstract]
Marketable securities, net of current portion	$ 140,227	$ 259,317
Equity Securities [Member]
Marketable Securities (Textuals) [Abstract]
Marketable securities, net of current portion	38,300	52,100
Debt Securities [Member]
Marketable Securities (Textuals) [Abstract]
Marketable securities, net of current portion	$ 101,891	$ 207,200

Total debt and equity financial instruments including: (1) securities held-to-maturity and (2) securities available-for-sale that will be held for the long-term.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 17

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant