Segment Reporting (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Gross inpatient revenues	$ 6,678,674	$ 6,054,003	$ 13,603,781	$ 12,206,195
Gross outpatient revenues	3,068,095	2,628,341	6,057,067	5,125,449
Total net revenues	2,430,855	2,275,204	4,880,653	4,500,557
Income/(loss) before allocation of corporate overhead and income taxes	302,846	307,708	629,570	604,725
Allocation of corporate overhead	0	0	0	0
Income/(loss) after allocation of corporate overhead and before income taxes	302,846	307,708	629,570	604,725
Total assets	9,540,930	9,057,880	9,540,930	9,057,880	$ 9,615,444
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	4,682,682	4,188,933	9,648,219	8,517,700
Gross outpatient revenues	2,838,852	2,403,044	5,606,181	4,687,756
Total net revenues	1,253,328	1,164,516	2,540,475	2,310,456
Income/(loss) before allocation of corporate overhead and income taxes	137,372	140,584	323,290	295,784
Allocation of corporate overhead	(42,691)	(49,422)	(85,340)	(98,848)
Income/(loss) after allocation of corporate overhead and before income taxes	94,681	91,162	237,950	196,936
Total assets	3,497,571	3,425,974	3,497,571	3,425,974
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	1,995,992	1,865,070	3,955,562	3,688,495
Gross outpatient revenues	229,243	217,013	450,886	421,582
Total net revenues	1,174,755	1,106,860	2,335,801	2,183,205
Income/(loss) before allocation of corporate overhead and income taxes	272,916	268,413	538,501	521,855
Allocation of corporate overhead	(38,726)	(29,721)	(77,442)	(59,387)
Income/(loss) after allocation of corporate overhead and before income taxes	234,190	238,692	461,059	462,468
Total assets	5,920,483	5,320,163	5,920,483	5,320,163
Other
Segment Reporting Information [Line Items]
Gross outpatient revenues		8,284		16,111
Total net revenues	2,772	3,828	4,377	6,896
Income/(loss) before allocation of corporate overhead and income taxes	(107,442)	(101,289)	(232,221)	(212,914)
Allocation of corporate overhead	81,417	79,143	162,782	158,235
Income/(loss) after allocation of corporate overhead and before income taxes	(26,025)	(22,146)	(69,439)	(54,679)
Total assets	$ 122,876	$ 311,743	$ 122,876	$ 311,743