Summary of Significant Accounting Policies - Percentage of Net Service Revenue Earned by Type of Ownership or relationship with Operating Entity (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Health Care organization, Revenue [Abstract]
Percentage of Net Service Revenue	100.00%	100.00%	100.00%
Wholly-owned Subsidiaries [Member]
Health Care organization, Revenue [Abstract]
Percentage of Net Service Revenue	55.20%	53.50%	48.80%
Equity Joint Ventures [Member]
Health Care organization, Revenue [Abstract]
Percentage of Net Service Revenue	42.90%	43.90%	48.50%
License Leasing Arrangements [Member]
Health Care organization, Revenue [Abstract]
Percentage of Net Service Revenue	1.00%	1.80%	1.90%
Management Services [Member]
Health Care organization, Revenue [Abstract]
Percentage of Net Service Revenue	0.90%	0.80%	0.80%