Acquisitions (Narrative) (Details)			3 Months Ended		6 Months Ended
	Jul. 16, 2014 USD ($) shares	Jul. 02, 2014 shares	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) physician_practice center	Jun. 30, 2014 USD ($) center	Dec. 31, 2014 USD ($)	Jul. 15, 2014 USD ($)
Business Acquisition [Line Items]
Transaction costs			$ 1,982,000	$ 3,579,000	$ 3,453,000	$ 3,579,000
Acquisitions and related expenses, net					196,032,000	24,437,000
Net change in fair value of contingent consideration			6,410,000	$ 0	6,410,000	0
Sheridan Healthcare [Member]
Business Acquisition [Line Items]
Cash paid to acquire business	$ 2,100,000,000
Value of common stock issued for acquisition	$ 272,000,000
Common Stock [Member]
Business Acquisition [Line Items]
Issuance of common stock (in shares) | shares		9,775,000
Common Stock [Member] | Sheridan Healthcare [Member]
Business Acquisition [Line Items]
Shares of common stock issued for acquisition | shares	5,713,909
Mandatory Convertible Preferred Stock [Member]
Business Acquisition [Line Items]
Issuance of common stock (in shares) | shares		1,725,000
Senior Secured Credit Facility - Term Loan [Member]
Business Acquisition [Line Items]
Maximum borrowing capacity	$ 870,000,000.0
Revolving Credit Facility [Member]
Business Acquisition [Line Items]
Maximum borrowing capacity	300,000,000.0							$ 475,000,000.0
Senior Notes [Member] | 2022 Senior Unsecured Notes [Member]
Business Acquisition [Line Items]
Face amount	$ 1,100,000,000.0
Interest rate	5.625%
Ambulatory Services [Member]
Business Acquisition [Line Items]
Acquisitions and related expenses, net					$ 95,400,000	$ 24,400,000
Ambulatory Services [Member] | Controlling Interest [Member]
Business Acquisition [Line Items]
Number of business acquisitions | center					4	2
Physician Services [Member]
Business Acquisition [Line Items]
Net change in fair value of contingent consideration					$ 6,410,000
Physician Services [Member] | Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Cash paid to acquire business			100,600,000
Business Combination, Contingent Consideration, Liability			31,300,000		$ 31,300,000		$ 20,700,000
Number of business acquisitions | physician_practice					4
Contingent consideration arrangements, low			30,000,000		$ 30,000,000
Contingent consideration arrangements, high			$ 33,000,000		$ 33,000,000