Use of Estimates (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Accounting Policies [Abstract]
Allowances for contractual adjustments	$ 291,434		$ 291,434		$ 289,937
Allowances for accounts receivable	30,414		30,414		27,862
Bad debt expense included in other operating expenses	$ 5,554	$ 4,844	$ 10,762	$ 10,744