Supplemental Data - Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 189,487	$ 225,229
Changes in operating and intercompany assets and liabilities and non-cash items included in net income	(48,183)	137,310
Net cash provided by operating activities	141,304	362,539
Cash flows from investing activities:
Additions of property and equipment	(198,878)	(232,443)
Acquisitions	(11,274)
Proceeds from asset and business sales	13,903	18,535
Investments and other items	(4,109)	30,362
Net cash used in investing activities	(200,358)	(200,128)
Cash flows from financing activities:
Long-term debt	357,197	104,673
Intercompany	0	0
Other items	(32,246)	(327,220)
Net cash used in financing activities	324,951	(222,547)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(921)	6,668
Net increase (decrease) in cash, cash equivalents and restricted cash	264,976	(53,468)
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	561,434	447,618
Physician Groups
Cash flows from operating activities:
Net income	9,237
Changes in operating and intercompany assets and liabilities and non-cash items included in net income	9,696
Net cash provided by operating activities	18,933
Cash flows from investing activities:
Additions of property and equipment	(229)
Acquisitions	0
Proceeds from asset and business sales	0
Investments and other items	(1,355)
Net cash used in investing activities	(1,584)
Cash flows from financing activities:
Long-term debt	0
Intercompany	28,965
Other items	0
Net cash used in financing activities	28,965
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0
Net increase (decrease) in cash, cash equivalents and restricted cash	46,314
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
Unrestricted Subsidiaries
Cash flows from operating activities:
Net income	463
Changes in operating and intercompany assets and liabilities and non-cash items included in net income	(463)
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 (decrease) 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
Company and Restricted Subsidiaries
Cash flows from operating activities:
Net income	179,787
Changes in operating and intercompany assets and liabilities and non-cash items included in net income	(57,416)
Net cash provided by operating activities	122,371
Cash flows from investing activities:
Additions of property and equipment	(198,649)
Acquisitions	(11,274)
Proceeds from asset and business sales	13,903
Investments and other items	(2,754)
Net cash used in investing activities	(198,774)
Cash flows from financing activities:
Long-term debt	357,197
Intercompany	(28,965)
Other items	(32,246)
Net cash used in financing activities	295,986
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(921)
Net increase (decrease) in cash, cash equivalents and restricted cash	218,662
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	561,434
Discontinued Operations
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	118,962	17,834
Discontinued Operations | Physician Groups
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	46,314
Discontinued Operations | Unrestricted Subsidiaries
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	0
Discontinued Operations | Company and Restricted Subsidiaries
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	72,648
Continuing Operations
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	146,014	$ (71,302)
Continuing Operations | Physician Groups
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	0
Continuing Operations | Unrestricted Subsidiaries
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	0
Continuing Operations | Company and Restricted Subsidiaries
Cash flows from financing activities:
Net increase (decrease) in cash, cash equivalents and restricted cash	$ 146,014