Summary of Significant Accounting Policies (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Concentration of Business
Net revenue	$ 830,274	$ 798,437	$ 805,473	$ 773,213	$ 721,464	$ 686,843	$ 698,338	$ 692,755	$ 3,207,397	$ 2,799,400	$ 2,969,240
Minimum
Concentration of Business
Term of Contract									1 year
Term of renewed contract									1 year
Notice period for termination of contract									60 days
Maximum
Concentration of Business
Term of Contract									3 years
Term of renewed contract									2 years
Notice period for termination of contract									180 days
Pennsylvania Counties
Concentration of Business
Net revenue									354,100	351,600	334,800
Florida Areas
Concentration of Business
Net revenue									$ 133,900	$ 131,800	$ 140,500