Supplemental Data - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income (loss)	$ 201,688	$ (96,668)	$ 718,332	$ 434,883
Changes in operating and intercompany assets and liabilities and non-cash items included in net income			673,493	947,365
Net cash provided by operating activities			1,391,825	1,382,248
Cash flows from investing activities:
Additions of property and equipment	(173,265)	(231,682)	(547,183)	(705,659)
Acquisitions			(77,348)
Proceeds from asset and business sales			3,863,619	135,268
Investments and other items			(105,063)	22,598
Net cash used in investing activities			3,134,025	(661,319)
Cash flows from financing activities:
Long-term debt			(2,050,012)	845,836
Intercompany			0	0
Other items			(1,953,752)	(1,269,175)
Net cash used in financing activities			(4,003,764)	(423,339)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(4,178)	(5,790)
Net increase in cash, cash equivalents and restricted cash			517,908	291,800
Cash, cash equivalents and restricted cash of continuing operations at beginning of the year			415,420	518,920
Cash, cash equivalents and restricted cash of continuing operations at end of the period	1,357,141	$ 540,155	1,357,141	540,155
Physician Groups
Cash flows from operating activities:
Net income (loss)			12,706
Changes in operating and intercompany assets and liabilities and non-cash items included in net income			(4,607)
Net cash provided by operating activities			8,099
Cash flows from investing activities:
Additions of property and equipment			(846)
Acquisitions			0
Cash divested from asset and business sales			0
Investments and other items			(1,882)
Net cash used in investing activities			(2,728)
Cash flows from financing activities:
Long-term debt			0
Intercompany			(247,175)
Other items			0
Net cash used in financing activities			(247,175)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			0
Net increase in cash, cash equivalents and restricted cash			(241,804)
Cash, cash equivalents and restricted cash of continuing operations at beginning of the year			0
Cash, cash equivalents and restricted cash of continuing operations at end of the period	0		0
Unrestricted Subsidiaries
Cash flows from operating activities:
Net income (loss)			249
Changes in operating and intercompany assets and liabilities and non-cash items included in net income			(249)
Net cash provided by operating activities			0
Cash flows from investing activities:
Additions of property and equipment			0
Acquisitions			0
Proceeds from asset and business sales			0
Investments and other items			0
Net cash used in investing activities			0
Cash flows from financing activities:
Long-term debt			0
Intercompany			0
Other items			0
Net cash used in financing activities			0
Effect of exchange rate changes on cash, cash equivalents and restricted cash			0
Net increase in cash, cash equivalents and restricted cash			0
Cash, cash equivalents and restricted cash of continuing operations at beginning of the year			0
Cash, cash equivalents and restricted cash of continuing operations at end of the period	0		0
Company and Restricted Subsidiaries
Cash flows from operating activities:
Net income (loss)			705,377
Changes in operating and intercompany assets and liabilities and non-cash items included in net income			678,349
Net cash provided by operating activities			1,383,726
Cash flows from investing activities:
Additions of property and equipment			(546,337)
Acquisitions			(77,348)
Proceeds from asset and business sales			3,863,619
Investments and other items			(103,181)
Net cash used in investing activities			3,136,753
Cash flows from financing activities:
Long-term debt			(2,050,012)
Intercompany			247,175
Other items			(1,953,752)
Net cash used in financing activities			(3,756,589)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(4,178)
Net increase in cash, cash equivalents and restricted cash			759,712
Cash, cash equivalents and restricted cash of continuing operations at beginning of the year			415,420
Cash, cash equivalents and restricted cash of continuing operations at end of the period	$ 1,357,141		1,357,141
Discontinued Operations
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			(423,813)	270,565
Discontinued Operations | Physician Groups
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			(241,804)
Discontinued Operations | Unrestricted Subsidiaries
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			0
Discontinued Operations | Company and Restricted Subsidiaries
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			(182,009)
Continuing Operations
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			941,721	$ 21,235
Continuing Operations | Physician Groups
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			0
Continuing Operations | Unrestricted Subsidiaries
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			0
Continuing Operations | Company and Restricted Subsidiaries
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			$ 941,721