Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross inpatient revenues		$ 9,541,336	$ 8,468,381	$ 28,788,600	$ 25,845,309
Gross outpatient revenues		4,734,967	3,936,556	13,930,128	11,934,261
Total net revenues		2,822,453	2,648,913	8,482,012	8,017,782
Income/(loss) before allocation of corporate overhead and income taxes		138,075	229,067	745,179	827,075
Allocation of corporate overhead		0	0	0	0
Income before income taxes		138,075	229,067	745,179	827,075
Total assets		11,594,401	11,273,585	11,594,401	11,273,585	$ 11,265,480
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues		7,004,832	6,009,303	21,220,471	18,535,079
Gross outpatient revenues		4,477,277	3,694,389	13,137,199	11,169,376
Total net revenues		1,528,535	1,383,050	4,575,088	4,232,673
Income/(loss) before allocation of corporate overhead and income taxes		148,085	147,448	528,455	513,174
Allocation of corporate overhead		(57,578)	(49,967)	(172,606)	(149,760)
Income before income taxes		90,507	97,481	355,849	363,414
Total assets		4,395,259	4,027,573	4,395,259	4,027,573
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]	2,536,504	2,459,078	7,568,129	7,310,230
Gross outpatient revenues	[1]	257,690	242,167	792,929	764,885
Total net revenues	[1]	1,291,816	1,262,472	3,898,440	3,774,551
Income/(loss) before allocation of corporate overhead and income taxes	[1]	138,019	234,170	648,173	734,362
Allocation of corporate overhead	[1]	(41,651)	(40,244)	(124,936)	(120,822)
Income before income taxes	[1]	96,368	193,926	523,237	613,540
Total assets	[1]	6,919,100	6,871,765	6,919,100	6,871,765
Other
Segment Reporting Information [Line Items]
Gross inpatient revenues		0	0	0	0
Gross outpatient revenues		0	0	0	0
Total net revenues		2,102	3,391	8,484	10,558
Income/(loss) before allocation of corporate overhead and income taxes		(148,029)	(152,551)	(431,449)	(420,461)
Allocation of corporate overhead		99,229	90,211	297,542	270,582
Income before income taxes		(48,800)	(62,340)	(133,907)	(149,879)
Total assets		$ 280,042	$ 374,247	$ 280,042	$ 374,247

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $135 million and $130 million for the three-month periods ended September 30, 2019 and 2018, respectively, and approximately $415 million and $364 million for the nine-month periods ended September 30, 2019 and 2018, respectively.  Total assets at our U.K. behavioral health care facilities were approximately $1.175 billion and $1.231 billion as of September 30, 2019 and 2018, respectively.