Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,907,604	$ 3,548,138	$ 7,751,186	$ 7,015,656
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 414,408	$ 409,770	$ 840,311	$ 815,760
Percentage of Net Revenue		11.00%	12.00%	11.00%	12.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 472,692	$ 430,586	$ 942,167	$ 849,695
Percentage of Net Revenue		12.00%	12.00%	12.00%	12.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 532,968	$ 349,850	$ 1,016,193	$ 666,332
Percentage of Net Revenue		14.00%	10.00%	13.00%	9.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 568,997	$ 569,213	$ 1,151,664	$ 1,160,462
Percentage of Net Revenue		15.00%	16.00%	15.00%	17.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,127,197	$ 1,088,876	$ 2,230,155	$ 2,134,968
Percentage of Net Revenue		29.00%	31.00%	29.00%	30.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 212,706	$ 190,114	$ 420,502	$ 357,903
Percentage of Net Revenue		5.00%	5.00%	5.00%	5.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 284,295	$ 210,448	$ 551,759	$ 453,082
Percentage of Net Revenue		7.00%	6.00%	7.00%	6.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 294,341	$ 299,281	$ 598,435	$ 577,454
Percentage of Net Revenue		8.00%	8.00%	8.00%	8.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,173,409	$ 2,003,079	$ 4,358,490	$ 3,976,611
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 338,077	$ 334,073	$ 687,164	$ 663,519
Percentage of Net Revenue		16.00%	17.00%	16.00%	17.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 369,288	$ 344,975	$ 742,689	$ 689,007
Percentage of Net Revenue		17.00%	17.00%	17.00%	17.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 239,470	$ 134,521	$ 474,332	$ 244,530
Percentage of Net Revenue		11.00%	7.00%	11.00%	6.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 152,760	$ 171,824	$ 312,119	$ 364,122
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		$ 705,318	$ 702,499	$ 1,404,103	$ 1,357,294
Percentage of Net Revenue		32.00%	35.00%	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		$ 134,149	$ 74,290	$ 257,482	$ 195,247
Percentage of Net Revenue		6.00%	4.00%	6.00%	5.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 234,347	$ 240,897	$ 480,601	$ 462,892
Percentage of Net Revenue		11.00%	12.00%	11.00%	12.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,731,309	$ 1,542,194	$ 3,387,376	$ 3,032,683
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 76,331	$ 75,697	$ 153,147	$ 152,241
Percentage of Net Revenue		4.00%	5.00%	5.00%	5.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 103,404	$ 85,611	$ 199,478	$ 160,688
Percentage of Net Revenue		6.00%	6.00%	6.00%	5.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 293,498	$ 215,329	$ 541,861	$ 421,802
Percentage of Net Revenue		17.00%	14.00%	16.00%	14.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 416,237	$ 397,389	$ 839,545	$ 796,340
Percentage of Net Revenue		24.00%	26.00%	25.00%	26.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 421,879	$ 386,377	$ 826,052	$ 777,674
Percentage of Net Revenue		24.00%	25.00%	24.00%	26.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 212,706	$ 190,114	$ 420,502	$ 357,903
Percentage of Net Revenue		12.00%	12.00%	12.00%	12.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 150,146	$ 136,158	$ 294,277	$ 257,835
Percentage of Net Revenue		9.00%	9.00%	9.00%	9.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 57,108	$ 55,519	$ 112,514	$ 108,200
Percentage of Net Revenue		3.00%	4.00%	3.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,886	$ 2,865	$ 5,320	$ 6,362
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,886	$ 2,865	$ 5,320	$ 6,362

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $213 million and $190 million for the three-month periods ended June 30, 2024 and 2023, respectively, and approximately $421 million and $358 million for the six-month periods ended June 30, 2024 and 2023, respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.36 billion and $1.295 billion as of June 30, 2024 and 2023, respectively.