Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves
Balance at Beginning of Year	$ 1,639,198	$ 1,417,188	$ 1,111,131
Acquisitions and Dispositions	(28,954)
Charged to Costs and Expenses	1,766,201	1,588,516	1,460,307
Write-offs	(1,485,111)	(1,366,506)	(1,154,250)
Balance at End of Year	$ 1,891,334	$ 1,639,198	$ 1,417,188