Fair Value Measurements (Reconciliation Of Marketable Securities Measured At Fair Value Using Significant Unobservable Inputs (Level 3)) (Details) (USD $) In Thousands | 3 Months Ended | 9 Months Ended | ||
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Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010 | |
| Fair Value Measurements [Abstract] | ||||
| Balance, beginning of period | $ 104,145 | $ 94,062 | $ 80,365 | $ 105,662 |
| Total realized and unrealized gains (losses) included in interest and other income, net | 1,707 | 4,578 | 115 | |
| Total realized and unrealized gains (losses) included in other comprehensive income, net | (22,681) | 2,299 | (28,375) | 4,066 |
| Sales of marketable securities | (1,350) | (8,050) | (28,630) | (21,532) |
| Transfers into Level 3 | 53,883 | |||
| Balance, end of period | 81,821 | 88,311 | 81,821 | 88,311 |
| Total losses included in interest and other income, net attributable to the change in unrealized losses relating to assets still held at the reporting date | ||||
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- Definition This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in other income. Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to assets measured at fair value on a recurring basis using unobservable inputs (Level 3). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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