Financial Information for the Company and Its Subsidiaries (Cash Flow Statements) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net cash flows provided by operating activities	$ 195,105	$ 251,395
Cash flows from investing activities:
Acquisitions and related expenses	(281,113)	(196,032)
Acquisition of property and equipment	(37,618)	(32,665)
Proceeds from sale of interests in surgery centers	25	0
Purchases of marketable securities	(498)	(1,245)
Maturities of marketable securities	2,738	2,988
Other	(8,749)	(1,987)
Net cash flows used in investing activities	(325,215)	(228,941)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	317,151	7,795
Repayment on long-term borrowings and revolving credit facility	(98,763)	(10,288)
Distributions to owners, including noncontrolling interests	(115,589)	(101,033)
Capital contributions	0	0
Changes in intercompany balances with affiliates, net	0	0
Other, net	(5,244)	(718)
Net cash flows provided by (used in) financing activities	97,555	(104,244)
Net decrease in cash and cash equivalents	(32,555)	(81,790)
Cash and cash equivalents, beginning of period	106,660	208,079
Cash and cash equivalents, end of period	74,105	126,289
Consolidation, Eliminations [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	(230,713)	(126,382)
Cash flows from investing activities:
Acquisitions and related expenses	268,155	53,538
Acquisition of property and equipment	0	0
Proceeds from sale of interests in surgery centers	0
Purchases of marketable securities	0	0
Maturities of marketable securities	0	0
Other	0	0
Net cash flows used in investing activities	268,155	53,538
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	0	0
Repayment on long-term borrowings and revolving credit facility	0	0
Distributions to owners, including noncontrolling interests	230,713	126,382
Capital contributions	(265,258)	(51,852)
Changes in intercompany balances with affiliates, net	0	0
Other, net	(2,897)	(1,686)
Net cash flows provided by (used in) financing activities	(37,442)	72,844
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Parent Company [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	39,294	(27,553)
Cash flows from investing activities:
Acquisitions and related expenses	(265,258)	(51,852)
Acquisition of property and equipment	(1,676)	(4,490)
Proceeds from sale of interests in surgery centers	0
Purchases of marketable securities	0	0
Maturities of marketable securities	0	0
Other	0	0
Net cash flows used in investing activities	(266,934)	(56,342)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	313,000	0
Repayment on long-term borrowings and revolving credit facility	(92,350)	(4,350)
Distributions to owners, including noncontrolling interests	0	0
Capital contributions	0	0
Changes in intercompany balances with affiliates, net	(2,657)	444
Other, net	(6,199)	(2,892)
Net cash flows provided by (used in) financing activities	211,794	(6,798)
Net decrease in cash and cash equivalents	(15,846)	(90,693)
Cash and cash equivalents, beginning of period	20,437	134,351
Cash and cash equivalents, end of period	4,591	43,658
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	131,227	172,907
Cash flows from investing activities:
Acquisitions and related expenses	(284,010)	(197,718)
Acquisition of property and equipment	(19,916)	(9,424)
Proceeds from sale of interests in surgery centers	25
Purchases of marketable securities	0	0
Maturities of marketable securities	0	0
Other	(4,057)	(1,441)
Net cash flows used in investing activities	(307,958)	(208,583)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	0	0
Repayment on long-term borrowings and revolving credit facility	(9)	0
Distributions to owners, including noncontrolling interests	(102,330)	(15,108)
Capital contributions	265,258	51,852
Changes in intercompany balances with affiliates, net	0	0
Other, net	2,520	2,573
Net cash flows provided by (used in) financing activities	165,439	39,317
Net decrease in cash and cash equivalents	(11,292)	3,641
Cash and cash equivalents, beginning of period	27,507	23,471
Cash and cash equivalents, end of period	16,215	27,112
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	255,297	232,423
Cash flows from investing activities:
Acquisitions and related expenses	0	0
Acquisition of property and equipment	(16,026)	(18,751)
Proceeds from sale of interests in surgery centers	0
Purchases of marketable securities	(498)	(1,245)
Maturities of marketable securities	2,738	2,988
Other	(4,692)	(546)
Net cash flows used in investing activities	(18,478)	(17,554)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	4,151	7,795
Repayment on long-term borrowings and revolving credit facility	(6,404)	(5,938)
Distributions to owners, including noncontrolling interests	(243,972)	(212,307)
Capital contributions	0	0
Changes in intercompany balances with affiliates, net	2,657	(444)
Other, net	1,332	1,287
Net cash flows provided by (used in) financing activities	(242,236)	(209,607)
Net decrease in cash and cash equivalents	(5,417)	5,262
Cash and cash equivalents, beginning of period	58,716	50,257
Cash and cash equivalents, end of period	$ 53,299	$ 55,519