Use of Estimates (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Use Of Estimates [Abstract]
Allowances for contractual adjustments	$ 279,936,000		$ 279,936,000		$ 216,363,000
Allowances for accounts receivable	26,537,000		26,537,000		22,379,000
Bad debt expense included in other operating expenses	$ 5,595,000	$ 4,992,000	$ 16,377,000	$ 14,894,000