Investments in debt and equity securities which are categorized neither as trading securities nor held-to-maturity securities and which are intended be sold or mature within one year from the balance sheet date or the normal operating cycle, whichever is longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income.

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-Name Accounting Research Bulletin (ARB)

-Number 43

-Chapter 3

-Section A

-Paragraph 4, 5

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+ Details

- Definition

Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 2

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

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+ Details

- Definition

Includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits are not generally reported as cash and cash equivalents. Includes cash and cash equivalents associated with the entity's continuing operations. Excludes cash and cash equivalents associated with the disposal group (and discontinued operation).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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-Number 95

-Paragraph 7

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-Name Accounting Standards Codification

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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-Name Statement of Financial Accounting Standard (FAS)

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-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

+ Details

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References+ Details

Fair Value Measurements (Assets And Liabilities Subject To Fair Value Measurements On Recurring Basis) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009
Cash and cash equivalents	$ 37,660	$ 155,691	$ 230,359	$ 567,667
Marketable securities	502,137	282,016
Marketable securities, non-current		416,165
Restricted investments	79,921	79,510
Corporate Debt Securities [Member] \| Marketable Securities [Member]
Marketable securities	329,662	127,344
Investments, Fair Value Disclosure	329,662
Corporate Debt Securities [Member] \| Marketable Securities [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure
Corporate Debt Securities [Member] \| Marketable Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	329,662
Corporate Debt Securities [Member] \| Marketable Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Government-Sponsored Enterprise Securities [Member] \| Marketable Securities [Member]
Marketable securities	15,313	86,966
Investments, Fair Value Disclosure	15,313
Government-Sponsored Enterprise Securities [Member] \| Marketable Securities [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure
Government-Sponsored Enterprise Securities [Member] \| Marketable Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	15,313
Government-Sponsored Enterprise Securities [Member] \| Marketable Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Marketable Securities [Member]
Marketable securities	502,137	282,016
Marketable Securities [Member] \| Level 1 [Member] \| Residential Mortgage-Backed Securities [Member]
Investments, Fair Value Disclosure
Marketable Securities [Member] \| Level 1 [Member] \| Asset-Backed Securities [Member]
Investments, Fair Value Disclosure
Marketable Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Investments, Fair Value Disclosure	91,830
Marketable Securities [Member] \| Residential Mortgage-Backed Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	91,830
Marketable Securities [Member] \| Residential Mortgage-Backed Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Marketable Securities [Member] \| Asset-Backed Securities [Member]
Investments, Fair Value Disclosure	65,332
Marketable Securities [Member] \| Asset-Backed Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	65,332
Marketable Securities [Member] \| Asset-Backed Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Level 1 [Member] \| Marketable Securities [Member]
Investments, Fair Value Disclosure
Marketable Securities [Member]
Investments, Fair Value Disclosure	502,137
Marketable Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	502,137
Marketable Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Corporate Debt Securities [Member] \| Restricted Investments [Member]
Investments, Fair Value Disclosure	50,284
Corporate Debt Securities [Member] \| Restricted Investments [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure
Corporate Debt Securities [Member] \| Restricted Investments [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	50,284
Corporate Debt Securities [Member] \| Restricted Investments [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Government-Sponsored Enterprise Securities [Member] \| Restricted Investments [Member]
Investments, Fair Value Disclosure	8,560
Government-Sponsored Enterprise Securities [Member] \| Restricted Investments [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure
Government-Sponsored Enterprise Securities [Member] \| Restricted Investments [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	8,560
Government-Sponsored Enterprise Securities [Member] \| Restricted Investments [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member]
Investments, Fair Value Disclosure	79,921
Restricted Investments [Member] \| Level 1 [Member]
Investments, Fair Value Disclosure	10,149
Restricted Investments [Member] \| Level 1 [Member] \| Money Market Funds [Member]
Investments, Fair Value Disclosure	8,844
Restricted Investments [Member] \| Level 1 [Member] \| U.S. Treasury Securities [Member]
Investments, Fair Value Disclosure	1,305
Restricted Investments [Member] \| Level 1 [Member] \| Residential Mortgage-Backed Securities [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| Level 1 [Member] \| Asset-Backed Securities [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| Money Market Funds [Member]
Investments, Fair Value Disclosure	8,844
Restricted Investments [Member] \| Money Market Funds [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| Money Market Funds [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| U.S. Treasury Securities [Member]
Investments, Fair Value Disclosure	1,305
Restricted Investments [Member] \| U.S. Treasury Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| U.S. Treasury Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| Residential Mortgage-Backed Securities [Member]
Investments, Fair Value Disclosure	7,801
Restricted Investments [Member] \| Residential Mortgage-Backed Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	7,801
Restricted Investments [Member] \| Residential Mortgage-Backed Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| Asset-Backed Securities [Member]
Investments, Fair Value Disclosure	3,127
Restricted Investments [Member] \| Asset-Backed Securities [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	3,127
Restricted Investments [Member] \| Asset-Backed Securities [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Restricted Investments [Member] \| Level 2 [Member]
Investments, Fair Value Disclosure	69,772
Restricted Investments [Member] \| Level 3 [Member]
Investments, Fair Value Disclosure
Level 1 [Member]
Cash and cash equivalents	37,660
Level 2 [Member]
Cash and cash equivalents
Level 3 [Member]
Cash and cash equivalents