Guarantor (Cash Flow Statements) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net cash flows provided by operating activities	$ 73,865	$ 69,145
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	(252)	(9,857)
Acquisition of property and equipment	(6,110)	(6,046)
Net cash flows used in investing activities	(6,362)	(15,903)
Cash flows from financing activities:
Proceeds from long-term borrowings	30,870	19,600
Repayment on long-term borrowings	(48,211)	(30,877)
Distributions to noncontrolling interests	(43,914)	(39,009)
Net cash flows provided by (used in) financing activities	(71,488)	(49,640)
Net increase (decrease) in cash and cash equivalents	(3,985)	3,602
Cash and cash equivalents, beginning of period	46,398	40,718
Cash and cash equivalents, end of period	42,413	44,320
Parent Company [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	23,940	10,211
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	0	0
Acquisition of property and equipment	(853)	(751)
Net cash flows used in investing activities	(853)	(751)
Cash flows from financing activities:
Proceeds from long-term borrowings	29,700	19,600
Repayment on long-term borrowings	(45,024)	(28,100)
Distributions to noncontrolling interests	0	0
Changes In Intercompany Balances	533	(460)
Other financing activities, net	(10,792)	(223)
Net cash flows provided by (used in) financing activities	(25,583)	(9,183)
Net increase (decrease) in cash and cash equivalents	(2,496)	277
Cash and cash equivalents, beginning of period	7,259	8,530
Cash and cash equivalents, end of period	4,763	8,807
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	49,577	43,158
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	(242)	(9,925)
Acquisition of property and equipment	0	0
Net cash flows used in investing activities	(242)	(9,925)
Cash flows from financing activities:
Proceeds from long-term borrowings	0	0
Repayment on long-term borrowings	0	0
Distributions to noncontrolling interests	(49,486)	(34,042)
Changes In Intercompany Balances	0	0
Other financing activities, net	151	809
Net cash flows provided by (used in) financing activities	(49,335)	(33,233)
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	99,411	92,976
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	0	0
Acquisition of property and equipment	(5,257)	(5,295)
Net cash flows used in investing activities	(5,257)	(5,295)
Cash flows from financing activities:
Proceeds from long-term borrowings	1,170	0
Repayment on long-term borrowings	(3,187)	(2,777)
Distributions to noncontrolling interests	(93,491)	(82,167)
Changes In Intercompany Balances	(533)	460
Other financing activities, net	398	128
Net cash flows provided by (used in) financing activities	(95,643)	(84,356)
Net increase (decrease) in cash and cash equivalents	(1,489)	3,325
Cash and cash equivalents, beginning of period	39,139	32,188
Cash and cash equivalents, end of period	37,650	35,513
Consolidation, Eliminations [Member]
Cash flows from operating activities:
Net cash flows provided by operating activities	(99,063)	(77,200)
Cash flows from investing activities:
Acquisition of interests in surgery centers and related transactions	(10)	68
Acquisition of property and equipment	0	0
Net cash flows used in investing activities	(10)	68
Cash flows from financing activities:
Proceeds from long-term borrowings	0	0
Repayment on long-term borrowings	0	0
Distributions to noncontrolling interests	99,063	77,200
Changes In Intercompany Balances	0	0
Other financing activities, net	10	(68)
Net cash flows provided by (used in) financing activities	99,073	77,132
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	$ (10,233)	$ 646