Supplemental Data - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 327,157	$ 306,322	$ 516,644	$ 531,551
Changes in operating and intercompany assets and liabilities and non-cash items included in net income			234,471	393,024
Net cash provided by operating activities			751,115	924,575
Cash flows from investing activities:
Additions of property and equipment	(175,040)	(241,534)	(373,918)	(473,977)
Acquisitions			(65,970)
Proceeds from asset and business sales			3,851,381	116,241
Investments and other items			(8,801)	23,137
Net cash used in investing activities			3,402,692	(424,064)
Cash flows from financing activities:
Long-term debt			(1,164,109)	573,981
Intercompany			0	0
Other items			(146,444)	(879,890)
Net cash used in financing activities			(1,310,553)	(305,909)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(77)	(3,473)
Net increase in cash, cash equivalents and restricted cash			2,843,177	191,129
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	3,682,410	$ 480,148	3,682,410	480,148
Physician Groups
Cash flows from operating activities:
Net income			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			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			503,689
Changes in operating and intercompany assets and liabilities and non-cash items included in net income			239,327
Net cash provided by operating activities			743,016
Cash flows from investing activities:
Additions of property and equipment			(373,072)
Acquisitions			(65,970)
Proceeds from asset and business sales			3,851,381
Investments and other items			(6,919)
Net cash used in investing activities			3,405,420
Cash flows from financing activities:
Long-term debt			(1,164,109)
Intercompany			247,175
Other items			(146,444)
Net cash used in financing activities			(1,063,378)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(77)
Net increase in cash, cash equivalents and restricted cash			3,084,981
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	$ 3,682,410		3,682,410
Discontinued Operations
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash			(423,813)	229,901
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			3,266,990	$ (38,772)
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			$ 3,266,990