Guarantor (Cash Flow Statements) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net cash flows provided by operating activities	$ 152,550	$ 143,624
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	(18,346)	(9,972)
Acquisition of property and equipment	(12,472)	(14,569)
Other	55	0
Net cash flows used in investing activities	(30,763)	(24,541)
Cash flows from financing activities:
Proceeds from long-term borrowings	70,922	33,378
Repayment on long-term borrowings	(96,222)	(72,517)
Distributions to noncontrolling interests	(91,526)	(82,759)
Net cash flows provided by (used in) financing activities	(128,262)	(122,152)
Net increase (decrease) in cash and cash equivalents	(6,475)	(3,069)
Cash and cash equivalents, beginning of period	46,398	40,718
Cash and cash equivalents, end of period	39,923	37,649
Parent Company [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	32,189	35,844
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	0	0
Acquisition of property and equipment	(1,189)	(1,391)
Other	0	0
Net cash flows used in investing activities	(1,189)	(1,391)
Cash flows from financing activities:
Proceeds from long-term borrowings	66,700	32,000
Repayment on long-term borrowings	(89,224)	(67,000)
Distributions to noncontrolling interests	0	0
Changes In Intercompany Balances	1,431	(1,195)
Other financing activities, net	(12,371)	(1,773)
Net cash flows provided by (used in) financing activities	(33,464)	(37,968)
Net increase (decrease) in cash and cash equivalents	(2,464)	(3,515)
Cash and cash equivalents, beginning of period	7,259	8,530
Cash and cash equivalents, end of period	4,795	5,015
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	102,630	91,782
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	(18,424)	(10,040)
Acquisition of property and equipment	0	0
Other	55	0
Net cash flows used in investing activities	(18,369)	(10,040)
Cash flows from financing activities:
Proceeds from long-term borrowings	0	0
Repayment on long-term borrowings	0	0
Distributions to noncontrolling interests	(84,863)	(82,801)
Changes In Intercompany Balances	0	0
Other financing activities, net	602	1,059
Net cash flows provided by (used in) financing activities	(84,261)	(81,742)
Net increase (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
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	205,224	175,182
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	0	0
Acquisition of property and equipment	(11,283)	(13,178)
Other	0	0
Net cash flows used in investing activities	(11,283)	(13,178)
Cash flows from financing activities:
Proceeds from long-term borrowings	4,222	1,378
Repayment on long-term borrowings	(6,998)	(5,517)
Distributions to noncontrolling interests	(194,156)	(159,142)
Changes In Intercompany Balances	(1,431)	1,195
Other financing activities, net	411	528
Net cash flows provided by (used in) financing activities	(197,952)	(161,558)
Net increase (decrease) in cash and cash equivalents	(4,011)	446
Cash and cash equivalents, beginning of period	39,139	32,188
Cash and cash equivalents, end of period	35,128	32,634
Consolidation, Eliminations [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	(187,493)	(159,184)
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	78	68
Acquisition of property and equipment	0	0
Other	0	0
Net cash flows used in investing activities	78	68
Cash flows from financing activities:
Proceeds from long-term borrowings	0	0
Repayment on long-term borrowings	0	0
Distributions to noncontrolling interests	187,493	159,184
Changes In Intercompany Balances	0	0
Other financing activities, net	(78)	(68)
Net cash flows provided by (used in) financing activities	187,415	159,116
Net increase (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
Consolidated Entities [Member]
Cash flows from financing activities:
Other financing activities, net	$ (11,436)	$ (254)