Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross inpatient revenues		$ 9,599,551	$ 8,612,904	$ 19,247,264	$ 17,376,928
Gross outpatient revenues		4,671,001	4,027,863	9,195,161	7,997,705
Total net revenues		2,855,168	2,681,353	5,659,559	5,368,869
Income/(loss) before allocation of corporate overhead and income taxes		310,808	301,770	607,104	598,008
Allocation of corporate overhead		0	0	0	0
Income before income taxes		310,808	301,770	607,104	598,008
Total assets		11,752,650	11,069,417	11,752,650	11,069,417	$ 11,265,480
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues		7,051,925	6,164,010	14,215,639	12,525,776
Gross outpatient revenues		4,402,308	3,760,326	8,659,922	7,474,987
Total net revenues		1,531,709	1,403,991	3,046,553	2,849,623
Income/(loss) before allocation of corporate overhead and income taxes		188,157	162,015	380,370	365,726
Allocation of corporate overhead		(57,528)	(49,902)	(115,028)	(99,793)
Income before income taxes		130,629	112,113	265,342	265,933
Total assets		4,413,509	3,971,106	4,413,509	3,971,106
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]	2,547,626	2,448,894	5,031,625	4,851,152
Gross outpatient revenues	[1]	268,693	267,537	535,239	522,718
Total net revenues	[1]	1,320,241	1,274,083	2,606,624	2,512,079
Income/(loss) before allocation of corporate overhead and income taxes	[1]	265,986	261,444	510,154	500,192
Allocation of corporate overhead	[1]	(41,638)	(40,246)	(83,285)	(80,578)
Income before income taxes	[1]	224,348	221,198	426,869	419,614
Total assets	[1]	6,933,825	6,746,272	6,933,825	6,746,272
Other
Segment Reporting Information [Line Items]
Gross inpatient revenues		0	0	0	0
Gross outpatient revenues		0	0	0	0
Total net revenues		3,218	3,279	6,382	7,167
Income/(loss) before allocation of corporate overhead and income taxes		(143,335)	(121,689)	(283,420)	(267,910)
Allocation of corporate overhead		99,166	90,148	198,313	180,371
Income before income taxes		(44,169)	(31,541)	(85,107)	(87,539)
Total assets		$ 405,316	$ 352,039	$ 405,316	$ 352,039

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $144 million and $119 million for the three-month periods ended June 30, 2019 and 2018, respectively, and approximately $281 million and $234 million for the six-month periods ended June 30, 2019 and 2018, respectively.  Total assets at our U.K. behavioral health care facilities were approximately $1.217 billion and $1.123 billion as of June 30, 2019 and 2018, respectively.