Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross inpatient revenues		$ 9,647,713	$ 8,764,024
Gross outpatient revenues		4,524,160	3,969,842
Total net revenues		2,804,391	2,687,516
Income/(loss) before allocation of corporate overhead and income taxes		296,296	296,238
Allocation of corporate overhead		0	0
Income before income taxes		296,296	296,238
Total assets		11,721,277	11,023,517	$ 11,265,480
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues		7,163,714	6,361,766
Gross outpatient revenues		4,257,614	3,714,661
Total net revenues		1,514,844	1,445,632
Income/(loss) before allocation of corporate overhead and income taxes		192,213	203,711
Allocation of corporate overhead		(57,500)	(49,891)
Income before income taxes		134,713	153,820
Total assets		4,372,628	3,924,302
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]	2,483,999	2,402,258
Gross outpatient revenues	[1]	266,546	255,181
Total net revenues	[1]	1,286,383	1,237,996
Income/(loss) before allocation of corporate overhead and income taxes	[1]	244,168	238,748
Allocation of corporate overhead	[1]	(41,647)	(40,332)
Income before income taxes	[1]	202,521	198,416
Total assets	[1]	6,972,929	6,649,732
Other
Segment Reporting Information [Line Items]
Gross inpatient revenues		0	0
Gross outpatient revenues		0	0
Total net revenues		3,164	3,888
Income/(loss) before allocation of corporate overhead and income taxes		(140,085)	(146,221)
Allocation of corporate overhead		99,147	90,223
Income before income taxes		(40,938)	(55,998)
Total assets		$ 375,720	$ 449,483

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $137 million and $115 million for the three-month periods ended March 31, 2019 and 2018, respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.237 billion and $1.176 billion as of March 31, 2019 and 2018, respectively.