Supplemental Data - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income (loss)		$ 500,285	$ 138,159
Changes in operating and intercompany assets and liabilities and non-cash items included in net income		364,889	290,843
Net cash provided by (used in) operating activities		865,174	429,002
Cash flows from investing activities:
Additions of property and equipment		(214,535)	(173,187)
Acquisitions and divestitures, net		(77,236)
Proceeds from discontinued operations		46,612	4,657
Investments and other items		(4,853)	19,373
Net cash used in investing activities		(250,012)	(554,311)
Cash flows from financing activities:
Long-term debt		(36,141)	(24,571)
Intercompany		0	0
Other items		(22,796)	(308,526)
Net cash (used in) provided by financing activities		(58,937)	(333,097)
Effect of exchange rate changes on cash		2,820	717
Net increase (decrease) in cash		559,045	(457,689)
Cash and cash equivalents at beginning of period		913,187	1,499,116
Cash and cash equivalents at end of period		1,472,232	$ 1,041,427
Physician Groups
Cash flows from operating activities:
Net income (loss)		3,526
Changes in operating and intercompany assets and liabilities and non-cash items included in net income		(14,847)
Net cash provided by (used in) operating activities		(11,321)
Cash flows from investing activities:
Additions of property and equipment		(10)
Investments and other items		(946)
Net cash used in investing activities		(956)
Cash flows from financing activities:
Long-term debt		0
Intercompany		6,672
Net cash (used in) provided by financing activities		6,672
Net increase (decrease) in cash		(5,605)
Cash and cash equivalents at beginning of period		104,691
Cash and cash equivalents at end of period		99,086
Unrestricted Subsidiaries
Cash flows from operating activities:
Net income (loss)		100
Changes in operating and intercompany assets and liabilities and non-cash items included in net income		(100)
Company and Restricted Subsidiaries
Cash flows from operating activities:
Net income (loss)	[1]	496,659
Changes in operating and intercompany assets and liabilities and non-cash items included in net income	[1]	379,836
Net cash provided by (used in) operating activities	[1]	876,495
Cash flows from investing activities:
Additions of property and equipment	[1]	(214,525)
Acquisitions and divestitures, net	[1]	(77,236)
Proceeds from discontinued operations	[1]	46,612
Investments and other items	[1]	(3,907)
Net cash used in investing activities	[1]	(249,056)
Cash flows from financing activities:
Long-term debt	[1]	(36,141)
Intercompany	[1]	(6,672)
Other items	[1]	(22,796)
Net cash (used in) provided by financing activities	[1]	(65,609)
Effect of exchange rate changes on cash	[1]	2,820
Net increase (decrease) in cash	[1]	564,650
Cash and cash equivalents at beginning of period	[1]	808,496
Cash and cash equivalents at end of period	[1]	$ 1,373,146

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