Financial Information for the Company and Its Subsidiaries (Cash Flow Statements) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net cash flows provided by operating activities	$ 537,959	$ 412,371	$ 332,824
Cash flows from investing activities:
Acquisitions and related transactions	(962,689)	(2,184,058)	(73,594)
Acquisition of property and equipment	(60,305)	(40,217)	(28,856)
Proceeds from sale of interests in surgery centers	7,114	7,069	3,553
Purchases of marketable securities	(3,984)	(6,474)	0
Maturities of marketable securities	4,233	3,486	0
Other	(1,194)	(4,941)	159
Net cash flows used in investing activities	(1,016,825)	(2,225,135)	(98,738)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	560,133	2,048,958	162,204
Repayment on long-term borrowings and revolving credit facility	(392,586)	(408,475)	(202,083)
Distributions to owners, including noncontrolling interests	(214,899)	(190,097)	(184,149)
Capital contributions	0	0
Proceeds from preferred stock offering	0	172,500	0
Proceeds from common stock offering	466,777	439,875	0
Payments of equity issuance costs	(19,058)	(24,494)	0
Financing costs incurred	(1,111)	(65,811)	(1,322)
Changes in intercompany balances with affiliates, net	0	0	0
Other financing activities, net	(21,809)	(2,453)	(5,616)
Net cash flows provided by (used in) financing activities	377,447	1,970,003	(229,644)
Net increase (decrease) in cash and cash equivalents	(101,419)	157,239	4,442
Cash and cash equivalents, beginning of period	208,079	50,840	46,398
Cash and cash equivalents, end of period	106,660	208,079	50,840
Consolidating Adjustments [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	(346,225)	(413,605)	(347,648)
Cash flows from investing activities:
Acquisitions and related transactions	764,345	2,126,737	694
Acquisition of property and equipment	0	0	0
Proceeds from sale of interests in surgery centers	0	0	0
Purchases of marketable securities	0	0
Maturities of marketable securities	0	0
Other	0	0	0
Net cash flows used in investing activities	764,345	2,126,737	694
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	0	0	0
Repayment on long-term borrowings and revolving credit facility	0	0	0
Distributions to owners, including noncontrolling interests	346,225	413,605	347,648
Capital contributions	(757,775)	(2,124,124)
Proceeds from preferred stock offering		0
Proceeds from common stock offering	0	0
Payments of equity issuance costs	0	0
Financing costs incurred	0	0
Changes in intercompany balances with affiliates, net	0	0	0
Other financing activities, net	(6,570)	(2,613)	(694)
Net cash flows provided by (used in) financing activities	(418,120)	(1,713,132)	346,954
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of period	0	0	0
Cash and cash equivalents, end of period	0	0	0
Parent Company [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	40,432	96,681	45,127
Cash flows from investing activities:
Acquisitions and related transactions	(757,775)	(2,124,124)	0
Acquisition of property and equipment	(5,876)	(7,877)	(3,693)
Proceeds from sale of interests in surgery centers	0	0	0
Purchases of marketable securities	0	0
Maturities of marketable securities	0	0
Other	0	(3,068)	0
Net cash flows used in investing activities	(763,651)	(2,135,069)	(3,693)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	546,000	2,040,000	152,700
Repayment on long-term borrowings and revolving credit facility	(379,700)	(396,493)	(188,081)
Distributions to owners, including noncontrolling interests	0	0	0
Capital contributions	0	0
Proceeds from preferred stock offering		172,500
Proceeds from common stock offering	466,777	439,875
Payments of equity issuance costs	(19,058)	(24,494)
Financing costs incurred	(1,101)	(65,811)
Changes in intercompany balances with affiliates, net	5,016	2,965	88
Other financing activities, net	(8,629)	(2,513)	(6,690)
Net cash flows provided by (used in) financing activities	609,305	2,166,029	(41,983)
Net increase (decrease) in cash and cash equivalents	(113,914)	127,641	(549)
Cash and cash equivalents, beginning of period	134,351	6,710	7,259
Cash and cash equivalents, end of period	20,437	134,351	6,710
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	353,932	298,415	208,773
Cash flows from investing activities:
Acquisitions and related transactions	(969,259)	(2,188,191)	(74,288)
Acquisition of property and equipment	(22,988)	(9,933)	0
Proceeds from sale of interests in surgery centers	7,114	7,069	3,553
Purchases of marketable securities	0	0
Maturities of marketable securities	0	0
Other	(2,927)	(6,594)	159
Net cash flows used in investing activities	(988,060)	(2,197,649)	(70,576)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	0	0	0
Repayment on long-term borrowings and revolving credit facility	0	0	0
Distributions to owners, including noncontrolling interests	(109,862)	(202,247)	(138,875)
Capital contributions	757,775	2,124,124
Proceeds from preferred stock offering		0
Proceeds from common stock offering	0	0
Payments of equity issuance costs	0	0
Financing costs incurred	0	0
Changes in intercompany balances with affiliates, net	0	0	0
Other financing activities, net	(9,749)	828	678
Net cash flows provided by (used in) financing activities	638,164	1,922,705	(138,197)
Net increase (decrease) in cash and cash equivalents	4,036	23,471	0
Cash and cash equivalents, beginning of period	23,471	0	0
Cash and cash equivalents, end of period	27,507	23,471	0
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	489,820	430,880	426,572
Cash flows from investing activities:
Acquisitions and related transactions	0	1,520	0
Acquisition of property and equipment	(31,441)	(22,407)	(25,163)
Proceeds from sale of interests in surgery centers	0	0	0
Purchases of marketable securities	(3,984)	(6,474)
Maturities of marketable securities	4,233	3,486
Other	1,733	4,721	0
Net cash flows used in investing activities	(29,459)	(19,154)	(25,163)
Cash flows from financing activities:
Proceeds from long-term borrowings and revolving credit facility	14,133	8,958	9,504
Repayment on long-term borrowings and revolving credit facility	(12,886)	(11,982)	(14,002)
Distributions to owners, including noncontrolling interests	(451,262)	(401,455)	(392,922)
Capital contributions	0	0
Proceeds from preferred stock offering		0
Proceeds from common stock offering	0	0
Payments of equity issuance costs	0	0
Financing costs incurred	(10)	0
Changes in intercompany balances with affiliates, net	(5,016)	(2,965)	(88)
Other financing activities, net	3,139	1,845	1,090
Net cash flows provided by (used in) financing activities	(451,902)	(405,599)	(396,418)
Net increase (decrease) in cash and cash equivalents	8,459	6,127	4,991
Cash and cash equivalents, beginning of period	50,257	44,130	39,139
Cash and cash equivalents, end of period	$ 58,716	$ 50,257	$ 44,130