Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,012,987	$ 2,829,667
Percentage of Net Revenue		100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 424,005	$ 445,642
Percentage of Net Revenue		14.00%	16.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 333,102	$ 281,229
Percentage of Net Revenue		11.00%	10.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 264,781	$ 302,977
Percentage of Net Revenue		9.00%	11.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 470,256	$ 426,012
Percentage of Net Revenue		16.00%	15.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 947,554	$ 881,424
Percentage of Net Revenue		31.00%	31.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 164,666	$ 136,850
Percentage of Net Revenue		5.00%	5.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 214,533	$ 187,659
Percentage of Net Revenue		7.00%	7.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 194,090	$ 167,874
Percentage of Net Revenue		6.00%	6.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,694,542	$ 1,521,049
Percentage of Net Revenue		100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 335,513	$ 326,025
Percentage of Net Revenue		20.00%	21.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 275,560	$ 221,991
Percentage of Net Revenue		16.00%	15.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 111,641	$ 127,959
Percentage of Net Revenue		7.00%	8.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 135,498	$ 123,455
Percentage of Net Revenue		8.00%	8.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 598,810	$ 540,737
Percentage of Net Revenue		35.00%	36.00%
Acute Care Hospital Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 0	$ 0
Percentage of Net Revenue		0.00%	0.00%
Acute Care Hospital Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 94,250	$ 64,599
Percentage of Net Revenue		6.00%	4.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 143,270	$ 116,283
Percentage of Net Revenue		8.00%	8.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,315,337	$ 1,306,109
Percentage of Net Revenue		100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 88,492	$ 119,617
Percentage of Net Revenue		7.00%	9.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 57,542	$ 59,238
Percentage of Net Revenue		4.00%	5.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 153,140	$ 175,018
Percentage of Net Revenue		12.00%	13.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 334,758	$ 302,557
Percentage of Net Revenue		25.00%	23.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 348,744	$ 340,687
Percentage of Net Revenue		27.00%	26.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 164,666	$ 136,850
Percentage of Net Revenue		13.00%	10.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 120,283	$ 123,060
Percentage of Net Revenue		9.00%	9.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 47,712	$ 49,082
Percentage of Net Revenue		4.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,108	$ 2,509
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,108	$ 2,509

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $165 million and $137 million for the three-month periods ended March 31, 2021 and 2020, respectively.  Total assets at our U.K. behavioral health care facilities were approximately $1.355 billion and $1.197 billion as of March 31, 2021 and 2020, respectively.