Segment Reporting (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Gross inpatient revenues	$ 6,925,107	$ 6,152,192
Gross outpatient revenues	2,988,972	2,497,108
Total net revenues	2,449,798	2,225,353
Income/(loss) before allocation of corporate overhead and income taxes	326,724	297,017
Allocation of corporate overhead	0	0
Income/(loss) after allocation of corporate overhead and before income taxes	326,724	297,017
Total assets	9,565,009	9,062,403	$ 9,615,444
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	4,965,537	4,328,767
Gross outpatient revenues	2,767,329	2,284,712
Total net revenues	1,287,147	1,145,940
Income/(loss) before allocation of corporate overhead and income taxes	185,918	155,200
Allocation of corporate overhead	(42,649)	(49,426)
Income/(loss) after allocation of corporate overhead and before income taxes	143,269	105,774
Total assets	3,498,240	3,431,688
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	1,959,570	1,823,425
Gross outpatient revenues	221,643	204,569
Total net revenues	1,161,046	1,076,345
Income/(loss) before allocation of corporate overhead and income taxes	265,577	253,442
Allocation of corporate overhead	(38,716)	(29,666)
Income/(loss) after allocation of corporate overhead and before income taxes	226,861	223,776
Total assets	5,929,802	5,315,270
Other
Segment Reporting Information [Line Items]
Gross outpatient revenues		7,827
Total net revenues	1,605	3,068
Income/(loss) before allocation of corporate overhead and income taxes	(124,771)	(111,625)
Allocation of corporate overhead	81,365	79,092
Income/(loss) after allocation of corporate overhead and before income taxes	(43,406)	(32,533)
Total assets	$ 136,967	$ 315,445