Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Gross inpatient revenues										$ 38,531,825	$ 34,550,480	$ 30,838,191
Gross outpatient revenues										18,733,333	15,993,034	14,109,290
Total net revenues		$ 2,896,247	$ 2,822,453	$ 2,855,168	$ 2,804,391	$ 2,754,496	$ 2,648,913	$ 2,681,353	$ 2,687,516	11,378,259	10,772,278	10,409,865
Income (loss) before allocation of corporate overhead and income taxes										1,066,337	1,034,525	1,135,009
Allocation of corporate overhead										0	0	0
Income before income taxes										1,066,337	1,034,525	1,135,009
Total assets		11,668,250				11,265,480				11,668,250	11,265,480	10,761,828
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues										28,430,922	24,814,959	21,888,207
Gross outpatient revenues										17,666,629	14,967,313	13,115,881
Total net revenues										6,164,560	5,719,905	5,484,683
Income (loss) before allocation of corporate overhead and income taxes										713,410	708,680	641,857
Allocation of corporate overhead										(230,166)	(199,823)	(182,713)
Income before income taxes										483,244	508,857	459,144
Total assets		4,405,643				4,094,537				4,405,643	4,094,537	3,849,214
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]									10,100,903	9,735,521	8,949,984
Gross outpatient revenues	[1]									1,066,704	1,025,721	993,409
Total net revenues	[1]									5,210,063	5,038,874	4,906,719
Income (loss) before allocation of corporate overhead and income taxes	[1]									900,965	915,517	968,974
Allocation of corporate overhead	[1]									(166,571)	(161,282)	(158,735)
Income before income taxes	[1]									734,394	754,235	810,239
Total assets	[1]	6,910,790				6,786,369				6,910,790	6,786,369	6,648,818
Other
Segment Reporting Information [Line Items]
Total net revenues										3,636	13,499	18,463
Income (loss) before allocation of corporate overhead and income taxes										(548,038)	(589,672)	(475,822)
Allocation of corporate overhead										396,737	361,105	341,448
Income before income taxes										(151,301)	(228,567)	(134,374)
Total assets		$ 351,817				$ 384,574				$ 351,817	$ 384,574	$ 263,796

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $554 million in 2019, $505 million in 2018 and $429 million in 2017.  Total assets at our U.K. behavioral health care facilities were approximately $1.270 billion as of December 31, 2019, $1.224 billion as of December 31, 2018 and $1.098 billion as of December 31, 2017. In addition, included in our 2019 Behavioral Health Services operating segment Income (loss) before allocation of corporate overhead and income taxes is a pre-tax $98 million provision for asset impairment to reduce the carrying value of a tradename intangible asset and real property assets. Included in our 2018 Behavioral Health Services operating segment Income (loss) before allocation of corporate overhead and income taxes is a pre-tax $49 million provision for asset impairment to reduce the carrying value of a tradename intangible asset.