Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Gross inpatient revenues		$ 10,624,832	$ 9,541,336	$ 29,993,979	$ 28,788,600
Gross outpatient revenues		4,372,149	4,734,967	12,924,483	13,930,128
Total net revenues		2,912,541	2,822,453	8,471,962	8,482,012
Income/(loss) before allocation of corporate overhead and income taxes		323,264	138,075	849,705	745,179
Allocation of corporate overhead		0	0	0	0
Income before income taxes		323,264	138,075	849,705	745,179
Total assets		12,975,758	11,594,401	12,975,758	11,594,401	$ 11,668,250
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues		8,137,264	7,004,832	22,695,513	21,220,471
Gross outpatient revenues		4,128,549	4,477,277	12,204,970	13,137,199
Total net revenues		1,610,003	1,528,535	4,598,558	4,575,088
Income/(loss) before allocation of corporate overhead and income taxes		177,606	148,085	464,139	528,455
Allocation of corporate overhead		(55,980)	(57,578)	(167,936)	(172,606)
Income before income taxes		121,626	90,507	296,203	355,849
Total assets		4,666,917	4,395,259	4,666,917	4,395,259
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]	2,487,568	2,536,504	7,298,466	7,568,129
Gross outpatient revenues	[1]	243,600	257,690	719,513	792,929
Total net revenues	[1]	1,299,591	1,291,816	3,864,823	3,898,440
Income/(loss) before allocation of corporate overhead and income taxes	[1]	252,532	138,019	746,980	648,173
Allocation of corporate overhead	[1]	(42,667)	(41,651)	(128,147)	(124,936)
Income before income taxes	[1]	209,865	96,368	618,833	523,237
Total assets	[1]	6,898,757	6,919,100	6,898,757	6,919,100
Other
Segment Reporting Information [Line Items]
Gross inpatient revenues			0	0	0
Gross outpatient revenues			0	0	0
Total net revenues		2,947	2,102	8,581	8,484
Income/(loss) before allocation of corporate overhead and income taxes		(106,874)	(148,029)	(361,414)	(431,449)
Allocation of corporate overhead		98,647	99,229	296,083	297,542
Income before income taxes		(8,227)	(48,800)	(65,331)	(133,907)
Total assets		$ 1,410,084	$ 280,042	$ 1,410,084	$ 280,042

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $156 million and $135 million for the three-month periods ended September 30, 2020 and 2019, respectively, and approximately $429 million and $415 million for the nine-month periods ended September 30, 2020 and 2019, respectively.  Total assets at our U.K. behavioral health care facilities were approximately $1.257 billion and $1.175 billion as of September 30, 2020 and 2019, respectively.