Segment Reporting (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Gross inpatient revenues										$ 27,060,212	$ 24,304,341	$ 21,632,855
Gross outpatient revenues										12,276,200	10,460,630	8,965,578
Total net revenues		$ 2,475,685	$ 2,409,872	$ 2,430,855	$ 2,449,798	$ 2,315,239	$ 2,227,655	$ 2,275,204	$ 2,225,353	9,766,210	9,043,451	8,205,088
Income (loss) before allocation of corporate overhead and income taxes										1,156,358	1,145,901	929,667
Allocation of corporate overhead										0	0	0
Income (loss) after allocation of corporate overhead and before income taxes										1,156,358	1,145,901	929,667
Total assets		10,317,802				9,615,444				10,317,802	9,615,444	8,951,272
Acute Care Hospital Services
Segment Reporting Information [Line Items]
Gross inpatient revenues										19,042,627	16,847,944	14,943,102
Gross outpatient revenues										11,374,098	9,604,952	8,147,031
Total net revenues										5,112,950	4,632,564	4,178,103
Income (loss) before allocation of corporate overhead and income taxes										550,050	519,630	465,328
Allocation of corporate overhead										(170,767)	(197,699)	(178,781)
Income (loss) after allocation of corporate overhead and before income taxes										379,283	321,931	286,547
Total assets		3,723,075				3,413,879				3,723,075	3,413,879	3,362,870
Behavioral Health Services
Segment Reporting Information [Line Items]
Gross inpatient revenues	[1]									8,017,585	7,456,397	6,689,753
Gross outpatient revenues	[1]									902,102	839,884	784,309
Total net revenues	[1]									4,645,007	4,400,335	4,012,216
Income (loss) before allocation of corporate overhead and income taxes	[1]									1,030,734	1,021,823	944,068
Allocation of corporate overhead	[1]									(154,843)	(117,203)	(98,811)
Income (loss) after allocation of corporate overhead and before income taxes	[1]									875,891	904,620	845,257
Total assets	[1]	6,440,195				5,867,088				6,440,195	5,867,088	5,286,960
Other
Segment Reporting Information [Line Items]
Gross outpatient revenues											15,794	34,238
Total net revenues										8,253	10,552	14,769
Income (loss) before allocation of corporate overhead and income taxes										(424,426)	(395,552)	(479,729)
Allocation of corporate overhead										325,610	314,902	277,592
Income (loss) after allocation of corporate overhead and before income taxes										(98,816)	(80,650)	(202,137)
Total assets		$ 154,532				$ 334,477				$ 154,532	$ 334,477	$ 301,442

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $241 million in 2016, $203 million in 2015 and $45 million in 2014.