Segment Reporting (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Gross inpatient revenues									$ 24,304,341	$ 21,632,855	$ 19,763,315
Gross outpatient revenues									10,460,630	8,965,578	7,613,277
Total net revenues	$ 2,315,239	$ 2,227,655	$ 2,275,204	$ 2,225,353	$ 2,176,291	$ 2,038,717	$ 2,051,766	$ 1,938,314	9,043,451	8,205,088	7,367,873
Income (loss) before allocation of corporate overhead and income taxes									1,145,901	929,667	869,332
Allocation of corporate overhead									0	0	0
Income (loss) after allocation of corporate overhead and before income taxes									1,145,901	929,667	869,332
Total assets	9,634,113				8,974,443				9,634,113	8,974,443	8,311,723
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues									16,847,944	14,943,102	13,469,269
Gross outpatient revenues									9,604,952	8,147,031	6,828,307
Total net revenues									4,632,564	4,178,103	3,602,874
Income (loss) before allocation of corporate overhead and income taxes									519,630	465,328	342,191
Allocation of corporate overhead									(197,699)	(178,781)	(184,444)
Income (loss) after allocation of corporate overhead and before income taxes									321,931	286,547	157,747
Total assets	3,413,879				3,362,870				3,413,879	3,362,870	3,125,626
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues									7,456,397	6,689,753	6,294,046
Gross outpatient revenues									839,884	784,309	744,510
Total net revenues									4,400,335	4,012,216	3,725,513
Income (loss) before allocation of corporate overhead and income taxes									1,021,823	944,068	895,869
Allocation of corporate overhead									(117,203)	(98,811)	(89,447)
Income (loss) after allocation of corporate overhead and before income taxes									904,620	845,257	806,422
Total assets	5,867,088				5,286,960				5,867,088	5,286,960	4,966,182
Other
Segment Reporting Information [Line Items]
Gross outpatient revenues									15,794	34,238	40,460
Total net revenues									10,552	14,769	39,486
Income (loss) before allocation of corporate overhead and income taxes									(395,552)	(479,729)	(368,728)
Allocation of corporate overhead									314,902	277,592	273,891
Income (loss) after allocation of corporate overhead and before income taxes									(80,650)	(202,137)	(94,837)
Total assets	$ 353,146				$ 324,613				$ 353,146	$ 324,613	$ 219,915