Marketable Securities (Details 1) (USD $) In Thousands	6 Months Ended
Jun. 30, 2011
Estimated fair values and gross unrealized losses for the Company's investments
Estimated Fair Value, Less than 12 Months	$ 140,227
Unrealized Losses, Less than 12 Months	(12,070)
Estimated Fair Value, More than 12 Months	0
Unrealized Losses, More than 12 Months	$ 0

This item represents the excess of [amortized] cost over fair value of securities that have been in a loss position for twelve months or longer for those securities which are categorized neither as held-to-maturity nor trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 03-1
-Paragraph 21
-Subparagraph a(2)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 17
-Subparagraph a(1)

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- Definition

This item represents the excess of [amortized] cost over fair value of securities that have been in a loss position for less than twelve months for those securities which are categorized neither as held-to-maturity nor trading securities.

+ References

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+ References

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