Investments in Unconsolidated Affiliates (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) equity_method_investment center	Sep. 30, 2015 USD ($) equity_method_investment center	Dec. 31, 2015 USD ($)
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 111,006		$ 111,006		$ 169,170
Equity in earnings of unconsolidated affiliates	4,445	$ 4,935	18,375	$ 11,575
Net gain (loss) on deconsolidation	(700)	9,100	$ (700)	$ 5,900
Joint Venture [Member] | Ambulatory Services [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Consolidated Entities Contributed To Joint Venture | center			1	3
Joint Venture [Member] | Ambulatory Services [Member] | Noncontrolling Interest In Centers [Member]
Schedule of Equity Method Investments [Line Items]
Number of separate equity method investments | equity_method_investment			1	2
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 1,800	$ 26,900	$ 1,800	$ 26,900
Controlling Interest [Member] | Joint Venture [Member] | Physician Services [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Consolidated Entities Contributed To Joint Venture | center			0	2