Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,963,027	$ 3,562,774	$ 11,714,213	$ 10,578,430
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 403,614	$ 379,810	$ 1,243,925	$ 1,195,570
Percentage of Net Revenue		10.00%	11.00%	11.00%	11.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 469,714	$ 419,580	$ 1,411,881	$ 1,269,275
Percentage of Net Revenue		12.00%	12.00%	12.00%	12.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 559,359	$ 405,302	$ 1,575,552	$ 1,071,634
Percentage of Net Revenue		14.00%	11.00%	13.00%	10.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 577,325	$ 569,026	$ 1,728,989	$ 1,729,488
Percentage of Net Revenue		15.00%	16.00%	15.00%	16.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,126,018	$ 1,034,962	$ 3,356,173	$ 3,169,930
Percentage of Net Revenue		28.00%	29.00%	29.00%	30.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 230,153	$ 202,994	$ 650,655	$ 560,897
Percentage of Net Revenue		6.00%	6.00%	6.00%	5.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 273,011	$ 238,168	$ 824,770	$ 691,250
Percentage of Net Revenue		7.00%	7.00%	7.00%	7.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 323,833	$ 312,932	$ 922,268	$ 890,386
Percentage of Net Revenue		8.00%	9.00%	8.00%	8.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,245,517	$ 2,017,288	$ 6,604,007	$ 5,993,899
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 322,466	$ 298,121	$ 1,009,630	$ 961,640
Percentage of Net Revenue		14.00%	15.00%	15.00%	16.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 361,804	$ 324,486	$ 1,104,493	$ 1,013,493
Percentage of Net Revenue		16.00%	16.00%	17.00%	17.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 296,966	$ 201,148	$ 771,298	$ 445,678
Percentage of Net Revenue		13.00%	10.00%	12.00%	7.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 154,762	$ 181,051	$ 466,881	$ 545,173
Percentage of Net Revenue		7.00%	9.00%	7.00%	9.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 725,014	$ 651,816	$ 2,129,117	$ 2,009,110
Percentage of Net Revenue		32.00%	32.00%	32.00%	34.00%
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		$ 117,679	$ 108,676	$ 375,161	$ 303,923
Percentage of Net Revenue		5.00%	5.00%	6.00%	5.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 266,826	$ 251,990	$ 747,427	$ 714,882
Percentage of Net Revenue		12.00%	12.00%	11.00%	12.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,714,914	$ 1,542,695	$ 5,102,290	$ 4,575,378
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 81,148	$ 81,689	$ 234,295	$ 233,930
Percentage of Net Revenue		5.00%	5.00%	5.00%	5.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 107,910	$ 95,094	$ 307,388	$ 255,782
Percentage of Net Revenue		6.00%	6.00%	6.00%	6.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 262,393	$ 204,154	$ 804,254	$ 625,956
Percentage of Net Revenue		15.00%	13.00%	16.00%	14.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 422,563	$ 387,975	$ 1,262,108	$ 1,184,315
Percentage of Net Revenue		25.00%	25.00%	25.00%	26.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 401,004	$ 383,146	$ 1,227,056	$ 1,160,820
Percentage of Net Revenue		23.00%	25.00%	24.00%	25.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 230,153	$ 202,994	$ 650,655	$ 560,897
Percentage of Net Revenue		13.00%	13.00%	13.00%	12.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 155,332	$ 129,492	$ 449,609	$ 387,327
Percentage of Net Revenue		9.00%	8.00%	9.00%	8.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 54,411	$ 58,151	$ 166,925	$ 166,351
Percentage of Net Revenue		3.00%	4.00%	3.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,596	$ 2,791	$ 7,916	$ 9,153
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,596	$ 2,791	$ 7,916	$ 9,153

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $230 million and $203 million for the three-month periods ended September 30, 2024 and 2023, respectively, and approximately $651 million and $561 million for the nine-month periods ended September 30, 2024 and 2023, respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.442 billion and $1.260 billion as of September 30, 2024 and 2023, respectively.