Schedule II-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 [Roll Forward]
Balance at beginning of period	$ 10,571		$ 4,500		$ 4,500
Acquired balance	0		9,051		0
Additions charged to costs and expenses	32,829		17,479		22,176
Additions charged to other accounts	0		0		0
Deductions	32,461	[1]	20,459	[1]	22,176	[1]
Balance at end of period	$ 10,939		$ 10,571		$ 4,500

[1] Accounts written off, net of recoveries