Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,804,391	$ 2,687,516
Percentage of Net Revenue		100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 473,365	$ 485,245
Percentage of Net Revenue		17.00%	18.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 261,362	$ 221,952
Percentage of Net Revenue		9.00%	8.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 277,426	$ 283,302
Percentage of Net Revenue		10.00%	11.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 401,004	$ 342,053
Percentage of Net Revenue		14.00%	13.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 918,265	$ 855,842
Percentage of Net Revenue		33.00%	32.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 136,702	$ 114,741
Percentage of Net Revenue		5.00%	4.00%
Other Patient Revenue and Adjustments,Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 175,361	$ 229,555
Percentage of Net Revenue		6.00%	9.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 160,906	$ 154,826
Percentage of Net Revenue		6.00%	6.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,514,844	$ 1,445,632
Percentage of Net Revenue		100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 335,909	$ 342,718
Percentage of Net Revenue		22.00%	24.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 209,103	$ 176,957
Percentage of Net Revenue		14.00%	12.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 104,510	$ 105,966
Percentage of Net Revenue		7.00%	7.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 133,731	$ 111,277
Percentage of Net Revenue		9.00%	8.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 570,383	$ 497,780
Percentage of Net Revenue		38.00%	34.00%
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		$ 51,883	$ 112,570
Percentage of Net Revenue		3.00%	8.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 109,325	$ 98,364
Percentage of Net Revenue		7.00%	7.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,286,383	$ 1,237,996
Percentage of Net Revenue		100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 137,456	$ 142,527
Percentage of Net Revenue		11.00%	12.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 52,259	$ 44,995
Percentage of Net Revenue		4.00%	4.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 172,916	$ 177,336
Percentage of Net Revenue		13.00%	14.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 267,273	$ 230,776
Percentage of Net Revenue		21.00%	19.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 347,882	$ 358,062
Percentage of Net Revenue		27.00%	29.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 136,702	$ 114,741
Percentage of Net Revenue		11.00%	9.00%
Behavioral Health Services | Other Patient Revenue and Adjustments,Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 123,478	$ 116,985
Percentage of Net Revenue		10.00%	9.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 48,417	$ 52,574
Percentage of Net Revenue		4.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,164	$ 3,888
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,164	$ 3,888

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $137 million and $115 million for the three-month periods ended March 31, 2019 and 2018, respectively. Total assets at our U.K. behavioral health care facilities were approximately $1.237 billion and $1.176 billion as of March 31, 2019 and 2018, respectively.