Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Trade Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	$ 269,416	$ 358,713	$ 401,027	$ 332,541
Valuation Allowances and Reserves, Charged to Cost and Expense	99,407	98,552	136,630
Valuation Allowances and Reserves, Adjustments	(188,704)	(140,866)	(68,144)
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	21,037	20,502	18,418	22,594
Valuation Allowances and Reserves, Charged to Cost and Expense	3,765	4,151	(3,723)
Valuation Allowances and Reserves, Adjustments	$ (3,230)	$ (2,067)	$ (453)