Supplemental Data - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income		$ 207,777	$ 181,421	$ 131,629	$ 393,158
Changes in operating and intercompany assets and liabilities and non-cash items included in net income				309,902	288,340
Net cash provided by operating activities				441,531	681,498
Cash flows from investing activities:
Additions of property and equipment		(169,452)	(152,031)	(290,873)	(278,593)
Acquisitions				(45,059)	(98,442)
Proceeds from discontinued operations				3,415	215
Investments and other items				(614,820)	(66,035)
Net cash used in investing activities				(947,337)	(442,855)
Cash flows from financing activities:
Long-term debt				667,992	348,436
Other items				(192,899)	(111,788)
Net cash provided by financing activities				475,093	236,648
Effect of exchange rate changes on cash				(793)	(567)
Net (decrease) increase in cash and cash equivalents				(31,506)	474,724
Cash and cash equivalents at beginning of the year				965,241	946,249
Cash and cash equivalents at end of the period		933,735	$ 1,420,973	933,735	$ 1,420,973
Physician Groups
Cash flows from operating activities:
Net income				14,237
Changes in operating and intercompany assets and liabilities and non-cash items included in net income				(19,648)
Net cash provided by operating activities				(5,411)
Cash flows from investing activities:
Additions of property and equipment				(24)
Investments and other items				(1,581)
Net cash used in investing activities				(1,605)
Cash flows from financing activities:
Intercompany				(8,223)
Net cash provided by financing activities				(8,223)
Net (decrease) increase in cash and cash equivalents				(15,239)
Cash and cash equivalents at beginning of the year				112,448
Cash and cash equivalents at end of the period		97,209		97,209
Unrestricted Subsidiaries
Cash flows from operating activities:
Net income				196
Changes in operating and intercompany assets and liabilities and non-cash items included in net income				(196)
Company and Restricted Subsidiaries
Cash flows from operating activities:
Net income	[1]			117,196
Changes in operating and intercompany assets and liabilities and non-cash items included in net income	[1]			329,746
Net cash provided by operating activities	[1]			446,942
Cash flows from investing activities:
Additions of property and equipment	[1]			(290,849)
Acquisitions	[1]			(45,059)
Proceeds from discontinued operations	[1]			3,415
Investments and other items	[1]			(613,239)
Net cash used in investing activities	[1]			(945,732)
Cash flows from financing activities:
Long-term debt	[1]			667,992
Intercompany	[1]			8,223
Other items	[1]			(192,899)
Net cash provided by financing activities	[1]			483,316
Effect of exchange rate changes on cash	[1]			(793)
Net (decrease) increase in cash and cash equivalents	[1]			(16,267)
Cash and cash equivalents at beginning of the year	[1]			852,793
Cash and cash equivalents at end of the period	[1]	$ 836,526		$ 836,526

[1] (1) After the elimination of the unrestricted subsidiaries and the physician groups