Cash and Marketable Securities - Textual (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2010
Cash and Marketable Securities (Textual) [Abstract]
Restricted marketable securities included in other long-term assets		$ 30.2	$ 19.3
Impairment charges related to restricted marketable securities	$ 0.8

Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale which are intended to be held for greater than one year or the normal operating cycle, whichever is longer and that are pledged to one or more secured parties who have the right to buy, sell, or re-pledge the collateral.

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The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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