SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) (Allowance for doubtful accounts, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for doubtful accounts
Changes in valuation and qualifying accounts
Balance at Beginning of Year	$ 18,484	$ 7,644	$ 5,605
Charged to Costs and Expenses	27,099	18,779	3,672
Deductions	(28,689)	(7,939)	(1,633)
Balance at End of Year	$ 16,894	$ 18,484	$ 7,644