Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,336,027	$ 3,155,999	$ 9,952,390	$ 9,366,866
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 400,910	$ 406,702	$ 1,219,047	$ 1,231,645
Percentage of Net Revenue		12.00%	13.00%	12.00%	13.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 383,793	$ 346,923	$ 1,157,353	$ 1,015,950
Percentage of Net Revenue		12.00%	11.00%	12.00%	11.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 396,312	$ 283,270	$ 1,095,560	$ 945,280
Percentage of Net Revenue		12.00%	9.00%	11.00%	10.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 587,179	$ 503,286	$ 1,619,244	$ 1,469,005
Percentage of Net Revenue		18.00%	16.00%	16.00%	16.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 995,112	$ 1,023,671	$ 3,002,698	$ 2,932,177
Percentage of Net Revenue		30.00%	32.00%	30.00%	31.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 166,843	$ 173,728	$ 516,166	$ 510,614
Percentage of Net Revenue		5.00%	6.00%	5.00%	5.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 154,396	$ 187,377	$ 567,357	$ 615,011
Percentage of Net Revenue		5.00%	6.00%	6.00%	7.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 251,482	$ 231,042	$ 774,965	$ 647,184
Percentage of Net Revenue		8.00%	7.00%	8.00%	7.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,919,678	$ 1,822,027	$ 5,707,510	$ 5,271,000
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 314,785	$ 310,483	$ 970,060	$ 954,207
Percentage of Net Revenue		16.00%	17.00%	17.00%	18.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 305,239	$ 280,674	$ 944,072	$ 830,627
Percentage of Net Revenue		16.00%	15.00%	17.00%	16.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 200,656	$ 136,989	$ 540,590	$ 418,335
Percentage of Net Revenue		10.00%	8.00%	9.00%	8.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 213,723	$ 176,497	$ 547,452	$ 473,256
Percentage of Net Revenue		11.00%	10.00%	10.00%	9.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 631,670	$ 674,396	$ 1,898,040	$ 1,862,012
Percentage of Net Revenue		33.00%	37.00%	33.00%	35.00%
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		$ 38,427	$ 69,935	$ 204,660	$ 248,342
Percentage of Net Revenue		2.00%	4.00%	4.00%	5.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 215,178	$ 173,053	$ 602,636	$ 484,221
Percentage of Net Revenue		11.00%	9.00%	11.00%	9.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,434,828	$ 1,328,293	$ 4,235,215	$ 4,075,127
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 86,125	$ 96,219	$ 248,987	$ 277,438
Percentage of Net Revenue		6.00%	7.00%	6.00%	7.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 78,554	$ 66,249	$ 213,281	$ 185,323
Percentage of Net Revenue		5.00%	5.00%	5.00%	5.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 195,656	$ 146,281	$ 554,970	$ 526,945
Percentage of Net Revenue		14.00%	11.00%	13.00%	13.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 373,456	$ 326,789	$ 1,071,792	$ 995,749
Percentage of Net Revenue		26.00%	25.00%	25.00%	24.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 363,442	$ 349,275	$ 1,104,658	$ 1,070,165
Percentage of Net Revenue		25.00%	26.00%	26.00%	26.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 166,843	$ 173,728	$ 516,166	$ 510,614
Percentage of Net Revenue		12.00%	13.00%	12.00%	13.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 115,969	$ 117,442	$ 362,697	$ 366,669
Percentage of Net Revenue		8.00%	9.00%	9.00%	9.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 54,783	$ 52,310	$ 162,664	$ 142,224
Percentage of Net Revenue		4.00%	4.00%	4.00%	3.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ (18,479)	$ 5,679	$ 9,665	$ 20,739
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ (18,479)	$ 5,679	$ 9,665	$ 20,739

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $167 million and $174 million for the three-month periods ended September 30, 2022 and 2021, respectively, and approximately $516 million and $511 million for the nine-month periods ended September 30, 2022 and 2021, respectively.  Total assets at our U.K. behavioral health care facilities were approximately $1.119 billion and $1.338 billion as of September 30, 2022 and 2021, respectively.