Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,896,247	$ 2,822,453	$ 2,855,168	$ 2,804,391	$ 2,754,496	$ 2,648,913	$ 2,681,353	$ 2,687,516	$ 11,378,259	$ 10,772,278	$ 10,409,865
Percentage of Net Revenue										100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,889,245	$ 1,875,875	$ 1,816,840
Percentage of Net Revenue										17.00%	17.00%	17.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,047,759	$ 929,390	$ 791,403
Percentage of Net Revenue										9.00%	9.00%	8.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,207,649	$ 1,183,618	$ 1,206,364
Percentage of Net Revenue										11.00%	11.00%	12.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,678,641	$ 1,530,005	$ 1,388,751
Percentage of Net Revenue										15.00%	14.00%	13.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues										$ 3,634,817	$ 3,489,870	$ 3,361,521
Percentage of Net Revenue										32.00%	32.00%	32.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 553,831	$ 504,721	$ 426,575
Percentage of Net Revenue										5.00%	5.00%	4.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues										$ 696,566	$ 650,987	$ 717,971
Percentage of Net Revenue										6.00%	6.00%	7.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 669,751	$ 607,812	$ 700,440
Percentage of Net Revenue										6.00%	6.00%	7.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues										$ 6,164,560	$ 5,719,905	$ 5,484,683
Percentage of Net Revenue										100.00%	100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,336,200	$ 1,296,152	$ 1,223,150
Percentage of Net Revenue										22.00%	23.00%	22.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues										$ 827,216	$ 730,387	$ 630,083
Percentage of Net Revenue										13.00%	13.00%	11.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues										$ 519,508	$ 487,197	$ 482,820
Percentage of Net Revenue										8.00%	9.00%	9.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues										$ 560,029	$ 554,438	$ 511,844
Percentage of Net Revenue										9.00%	10.00%	9.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues										$ 2,271,002	$ 2,093,890	$ 1,949,435
Percentage of Net Revenue										37.00%	37.00%	36.00%
Acute Care Hospital Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 0	$ 0	$ 0
Percentage of Net Revenue										0.00%	0.00%	0.00%
Acute Care Hospital Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues										$ 191,422	$ 167,570	$ 219,056
Percentage of Net Revenue										3.00%	3.00%	4.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 459,183	$ 390,271	$ 468,295
Percentage of Net Revenue										7.00%	7.00%	9.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]									$ 5,210,063	$ 5,038,874	$ 4,906,719
Percentage of Net Revenue										100.00%	100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues										$ 553,045	$ 579,723	$ 593,690
Percentage of Net Revenue										11.00%	12.00%	12.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues										$ 220,543	$ 199,003	$ 161,320
Percentage of Net Revenue										4.00%	4.00%	3.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues										$ 688,141	$ 696,421	$ 723,544
Percentage of Net Revenue										13.00%	14.00%	15.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,118,612	$ 975,567	$ 876,907
Percentage of Net Revenue										21.00%	19.00%	18.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues										$ 1,363,815	$ 1,395,980	$ 1,412,086
Percentage of Net Revenue										26.00%	28.00%	29.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 553,831	$ 504,721	$ 426,575
Percentage of Net Revenue										11.00%	10.00%	9.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues										$ 505,144	$ 483,417	$ 498,915
Percentage of Net Revenue										10.00%	10.00%	10.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 206,932	$ 204,042	$ 213,682
Percentage of Net Revenue										4.00%	4.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues										$ 3,636	$ 13,499	$ 18,463
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues										$ 3,636	$ 13,499	$ 18,463

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $554 million in 2019, $505 million in 2018 and $429 million in 2017.  Total assets at our U.K. behavioral health care facilities were approximately $1.270 billion as of December 31, 2019, $1.224 billion as of December 31, 2018 and $1.098 billion as of December 31, 2017. In addition, included in our 2019 Behavioral Health Services operating segment Income (loss) before allocation of corporate overhead and income taxes is a pre-tax $98 million provision for asset impairment to reduce the carrying value of a tradename intangible asset and real property assets. Included in our 2018 Behavioral Health Services operating segment Income (loss) before allocation of corporate overhead and income taxes is a pre-tax $49 million provision for asset impairment to reduce the carrying value of a tradename intangible asset.