SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for doubtful accounts
Movement in reserves
Balance at beginning of year	$ 22,028	$ 16,686	$ 10,526
Additions Charged to Costs and Expenses	19,773	22,101	20,276
Write-offs	20,422	16,759	14,116
Balance at end of year	21,379	22,028	16,686
Deferred tax asset
Movement in reserves
Balance at beginning of year	1,374	828	11,359
Generated	12	547	23
Utilized/Released	167	1	10,554
Balance at end of year	$ 1,219	$ 1,374	$ 828