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Valuation And Qualifying Accounts (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Valuation And Qualifying Accounts [Abstract]      
Balance at beginning of year $ 421,977 $ 377,506 $ 369,446
Amount charged against operating revenue 3,362,081 2,825,827 2,444,222
Accounts receivable contractual adjustments and write-offs (net of recoveries) (3,208,028) (2,781,356) (2,436,162)
Balance at end of year $ 576,030 $ 421,977 $ 377,506