Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Gross inpatient revenues		$ 8,764,024	$ 7,780,852
Gross outpatient revenues		3,969,842	3,540,637
Total net revenues		2,687,516	2,612,858
Income/(loss) before allocation of corporate overhead and income taxes		296,238	318,426
Allocation of corporate overhead		0	0
Income/(loss) after allocation of corporate overhead and before income taxes		296,238	318,426
Total assets		11,023,517	10,448,259	$ 10,761,828
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues		6,361,766	5,597,850
Gross outpatient revenues		3,714,661	3,294,177
Total net revenues		1,445,632	1,389,547
Income/(loss) before allocation of corporate overhead and income taxes		203,711	187,804
Allocation of corporate overhead		(49,891)	(45,676)
Income/(loss) after allocation of corporate overhead and before income taxes		153,820	142,128
Total assets		3,924,302	3,757,311
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]	2,402,258	2,183,002
Gross outpatient revenues	[1]	255,181	246,460
Total net revenues	[1]	1,237,996	1,218,122
Income/(loss) before allocation of corporate overhead and income taxes	[1]	238,748	251,931
Allocation of corporate overhead	[1]	(40,332)	(39,661)
Income/(loss) after allocation of corporate overhead and before income taxes	[1]	198,416	212,270
Total assets	[1]	6,649,732	6,517,608
Other
Segment Reporting Information [Line Items]
Gross inpatient revenues		0	0
Gross outpatient revenues		0	0
Total net revenues		3,888	5,189
Income/(loss) before allocation of corporate overhead and income taxes		(146,221)	(121,309)
Allocation of corporate overhead		90,223	85,337
Income/(loss) after allocation of corporate overhead and before income taxes		(55,998)	(35,972)
Total assets		$ 449,483	$ 173,340

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $115 million and $100 million for the three-month periods ended March 31, 2018 and 2017, respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.176 billion and $992 million as of March 31, 2018 and 2017, respectively.