Significant Accounting Policies - Percentage of Net Service Revenue Earned by Type of Ownership or Relationship with Operating Entity (Detail)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Health Care Organization, Revenue [Abstract]
Percentage of net service revenue	100.00%	100.00%
Wholly-owned subsidiaries
Health Care Organization, Revenue [Abstract]
Percentage of net service revenue	56.70%	54.60%
Equity joint ventures
Health Care Organization, Revenue [Abstract]
Percentage of net service revenue	41.60%	43.20%
License leasing arrangements
Health Care Organization, Revenue [Abstract]
Percentage of net service revenue	0.90%	1.30%
Management services
Health Care Organization, Revenue [Abstract]
Percentage of net service revenue	0.80%	0.90%