Revenue Recognition	3 Months Ended
Mar. 31, 2013
Revenue Recognition
Revenue Recognition	(3) Revenue Recognition Center revenues consist of billing for the use of the centers' facilities (the “facility fee”) directly to the patient or third-party payor and, at certain of our centers (primarily centers that perform gastrointestinal endoscopy procedures), billing for anesthesia services provided by medical professionals employed or contracted by our centers. Such revenues are recognized when the related surgical procedures are performed. Revenues exclude any amounts billed for physicians' surgical services, which are billed separately by the physicians to the patient or third-party payor. Revenues from centers are recognized on the date of service, net of estimated contractual adjustments from third-party medical service payors including Medicare and Medicaid. During the three months ended March 31, 2013 and 2012, the Company derived approximately 25% and 27%, respectively, of its revenues from governmental healthcare programs, primarily Medicare and Medicare managed programs. Concentration of credit risk with respect to other payors is limited due to the large number of such payors.

Revenue Recognition

3 Months Ended

Mar. 31, 2013

(3) Revenue Recognition

Center revenues consist of billing for the use of the centers' facilities (the “facility fee”) directly to the patient or third-party payor and, at certain of our centers (primarily centers that perform gastrointestinal endoscopy procedures), billing for anesthesia services provided by medical professionals employed or contracted by our centers. Such revenues are recognized when the related surgical procedures are performed. Revenues exclude any amounts billed for physicians' surgical services, which are billed separately by the physicians to the patient or third-party payor.

Revenues from centers are recognized on the date of service, net of estimated contractual adjustments from third-party medical service payors including Medicare and Medicaid. During the three months ended March 31, 2013 and 2012, the Company derived approximately 25% and 27%, respectively, of its revenues from governmental healthcare programs, primarily Medicare and Medicare managed programs. Concentration of credit risk with respect to other payors is limited due to the large number of such payors.