Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,562,774	$ 3,336,027	$ 10,578,430	$ 9,952,390
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 379,810	$ 400,910	$ 1,195,570	$ 1,219,047
Percentage of Net Revenue		11.00%	12.00%	11.00%	12.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 419,580	$ 383,793	$ 1,269,275	$ 1,157,353
Percentage of Net Revenue		12.00%	12.00%	12.00%	12.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 405,302	$ 396,312	$ 1,071,634	$ 1,095,560
Percentage of Net Revenue		11.00%	12.00%	10.00%	11.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 569,026	$ 587,179	$ 1,729,488	$ 1,619,244
Percentage of Net Revenue		16.00%	18.00%	16.00%	16.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,034,962	$ 995,112	$ 3,169,930	$ 3,002,698
Percentage of Net Revenue		29.00%	30.00%	30.00%	30.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 202,994	$ 166,843	$ 560,897	$ 516,166
Percentage of Net Revenue		6.00%	5.00%	5.00%	5.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 238,168	$ 154,396	$ 691,250	$ 567,357
Percentage of Net Revenue		7.00%	5.00%	7.00%	6.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 312,932	$ 251,482	$ 890,386	$ 774,965
Percentage of Net Revenue		9.00%	8.00%	8.00%	8.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,017,288	$ 1,919,678	$ 5,993,899	$ 5,707,510
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 298,121	$ 314,785	$ 961,640	$ 970,060
Percentage of Net Revenue		15.00%	16.00%	16.00%	17.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 324,486	$ 305,239	$ 1,013,493	$ 944,072
Percentage of Net Revenue		16.00%	16.00%	17.00%	17.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 201,148	$ 200,656	$ 445,678	$ 540,590
Percentage of Net Revenue		10.00%	10.00%	7.00%	9.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 181,051	$ 213,723	$ 545,173	$ 547,452
Percentage of Net Revenue		9.00%	11.00%	9.00%	10.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 651,816	$ 631,670	$ 2,009,110	$ 1,898,040
Percentage of Net Revenue		32.00%	33.00%	34.00%	33.00%
Acute Care Hospital Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 0	$ 0	$ 0	$ 0
Percentage of Net Revenue		0.00%	0.00%	0.00%	0.00%
Acute Care Hospital Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 108,676	$ 38,427	$ 303,923	$ 204,660
Percentage of Net Revenue		5.00%	2.00%	5.00%	4.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 251,990	$ 215,178	$ 714,882	$ 602,636
Percentage of Net Revenue		12.00%	11.00%	12.00%	11.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,542,695	$ 1,434,828	$ 4,575,378	$ 4,235,215
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 81,689	$ 86,125	$ 233,930	$ 248,987
Percentage of Net Revenue		5.00%	6.00%	5.00%	6.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 95,094	$ 78,554	$ 255,782	$ 213,281
Percentage of Net Revenue		6.00%	5.00%	6.00%	5.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 204,154	$ 195,656	$ 625,956	$ 554,970
Percentage of Net Revenue		13.00%	14.00%	14.00%	13.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 387,975	$ 373,456	$ 1,184,315	$ 1,071,792
Percentage of Net Revenue		25.00%	26.00%	26.00%	25.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 383,146	$ 363,442	$ 1,160,820	$ 1,104,658
Percentage of Net Revenue		25.00%	25.00%	25.00%	26.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 202,994	$ 166,843	$ 560,897	$ 516,166
Percentage of Net Revenue		13.00%	12.00%	12.00%	12.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 129,492	$ 115,969	$ 387,327	$ 362,697
Percentage of Net Revenue		8.00%	8.00%	8.00%	9.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 58,151	$ 54,783	$ 166,351	$ 162,664
Percentage of Net Revenue		4.00%	4.00%	4.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,791	$ (18,479)	$ 9,153	$ 9,665
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,791	$ (18,479)	$ 9,153	$ 9,665

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $203 million and $167 million for the three-month periods ended September 30, 2023 and 2022, respectively, and approximately $561 million and $516 million for the nine-month periods ended September 30, 2023 and 2022, respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.260 billion and $1.119 billion as of September 30, 2023 and 2022, respectively.