Acquisitions (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended			0 Months Ended		12 Months Ended	3 Months Ended	6 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 16, 2014	Jul. 02, 2014	Dec. 31, 2011 center	Dec. 31, 2014 physician_practice	Dec. 31, 2014 physician_practice	Jul. 15, 2014
Business Acquisition [Line Items]
Proceeds from common stock offering		$ 439,875,000	$ 0	$ 0
Proceeds from preferred stock offering		172,500,000	0	0
Payments of equity issuance costs		(24,494,000)	0	0
Transaction costs	25,100,000	33,890,000	300,000	700,000
Debt extinguishment costs	(16,900,000)	(16,887,000)	0	0
Acquisitions and related expenses, net		2,184,058,000	73,594,000	277,388,000
Contingent purchase price payable		8,470,000	0					8,470,000	8,470,000
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
Fees and expenses associated with acquisition		139,100,000						139,100,000	139,100,000
Deferred financing costs		53,000,000						53,000,000	53,000,000
Transaction costs		31,900,000
Common Stock [Member]
Business Acquisition [Line Items]
Issuance of common stock (in shares)						9,775,000
Proceeds from common stock offering					421,300,000
Common Stock [Member] | Sheridan Healthcare [Member]
Business Acquisition [Line Items]
Shares of common stock issued for acquisition					5,713,909
Mandatory Convertible Preferred Stock [Member]
Business Acquisition [Line Items]
Issuance of common stock (in shares)						1,725,000
Proceeds from preferred stock offering					166,600,000
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
Debt extinguishment costs		4,500,000
Senior Notes [Member] | 2022 Senior Unsecured Notes [Member]
Business Acquisition [Line Items]
Face amount					1,100,000,000.0
Interest rate					5.625%
Bridge Loan [Member] | Interest Expense [Member] | Sheridan Healthcare [Member]
Business Acquisition [Line Items]
Fees paid to obtain a commitment for financing		12,800,000
Ambulatory Services [Member]
Business Acquisition [Line Items]
Acquisitions and related expenses, net		50,900,000	73,600,000
Ambulatory Services [Member] | Controlling Interest [Member]
Business Acquisition [Line Items]
Number of business acquisitions		8	5
Ambulatory Services [Member] | Sheridan Healthcare [Member] | Controlling Interest [Member]
Business Acquisition [Line Items]
Number of business acquisitions		3
Ambulatory Services [Member] | Series of Individually Immaterial Business Acquisitions [Member] | Controlling Interest [Member]
Business Acquisition [Line Items]
Number of business acquisitions		5
Ambulatory Services [Member] | National Surgical Care, Inc. [Member]
Business Acquisition [Line Items]
Number of business acquisitions							17
Final settlement of contingent earn out fee			2,700,000
Physician Services [Member] | Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Cash paid to acquire business									19,000,000
Number of business acquisitions								2	2
Contingent purchase price payable		20,700,000						20,700,000	20,700,000
Estimate contingent consideration payment, low		18,000,000						18,000,000	18,000,000
Estimate contingent consideration payment, high		$ 23,000,000						$ 23,000,000	$ 23,000,000
Contingent consideration payment period, low									1 year
Contingent consideration payment period, high									3 years