Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Net revenues		$ 2,729,754	$ 2,855,168	$ 5,559,421	$ 5,659,559
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 370,881	$ 458,308	$ 816,523	$ 931,673
Percentage of Net Revenue		14.00%	16.00%	15.00%	16.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 242,750	$ 265,812	$ 523,979	$ 527,174
Percentage of Net Revenue		9.00%	9.00%	9.00%	9.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 285,542	$ 322,245	$ 588,519	$ 599,671
Percentage of Net Revenue		10.00%	11.00%	11.00%	11.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 389,201	$ 421,222	$ 815,213	$ 822,226
Percentage of Net Revenue		14.00%	15.00%	15.00%	15.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 725,819	$ 912,882	$ 1,607,243	$ 1,831,147
Percentage of Net Revenue		27.00%	32.00%	29.00%	32.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 136,622	$ 143,800	$ 273,472	$ 280,502
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		$ 199,331	$ 163,064	$ 386,990	$ 338,425
Percentage of Net Revenue		7.00%	6.00%	7.00%	6.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 379,608	$ 167,835	$ 547,482	$ 328,741
Percentage of Net Revenue		14.00%	6.00%	10.00%	6.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues		$ 1,467,506	$ 1,531,709	$ 2,988,555	$ 3,046,553
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Acute Care Hospital Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 264,310	$ 319,060	$ 590,335	$ 654,969
Percentage of Net Revenue		18.00%	21.00%	20.00%	21.00%
Acute Care Hospital Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 182,771	$ 211,660	$ 404,762	$ 420,763
Percentage of Net Revenue		12.00%	14.00%	14.00%	14.00%
Acute Care Hospital Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 131,452	$ 138,682	$ 259,411	$ 243,192
Percentage of Net Revenue		9.00%	9.00%	9.00%	8.00%
Acute Care Hospital Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 108,336	$ 145,970	$ 231,791	$ 279,701
Percentage of Net Revenue		7.00%	10.00%	8.00%	9.00%
Acute Care Hospital Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 432,695	$ 566,165	$ 973,432	$ 1,136,548
Percentage of Net Revenue		29.00%	37.00%	33.00%	37.00%
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		$ 78,196	$ 36,161	$ 142,795	$ 88,044
Percentage of Net Revenue		5.00%	2.00%	5.00%	3.00%
Acute Care Hospital Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 269,746	$ 114,011	$ 386,029	$ 223,336
Percentage of Net Revenue		18.00%	7.00%	13.00%	7.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	[1]	$ 1,259,123	$ 1,320,241	$ 2,565,232	$ 2,606,624
Percentage of Net Revenue		100.00%	100.00%	100.00%	100.00%
Behavioral Health Services | Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 106,571	$ 139,248	$ 226,188	$ 276,704
Percentage of Net Revenue		8.00%	11.00%	9.00%	11.00%
Behavioral Health Services | Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues		$ 59,979	$ 54,152	$ 119,217	$ 106,411
Percentage of Net Revenue		5.00%	4.00%	5.00%	4.00%
Behavioral Health Services | Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 154,090	$ 183,563	$ 329,108	$ 356,479
Percentage of Net Revenue		12.00%	14.00%	13.00%	14.00%
Behavioral Health Services | Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues		$ 280,865	$ 275,252	$ 583,422	$ 542,525
Percentage of Net Revenue		22.00%	21.00%	23.00%	21.00%
Behavioral Health Services | Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues		$ 293,124	$ 346,717	$ 633,811	$ 694,599
Percentage of Net Revenue		23.00%	26.00%	25.00%	27.00%
Behavioral Health Services | UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 136,622	$ 143,800	$ 273,472	$ 280,502
Percentage of Net Revenue		11.00%	11.00%	11.00%	11.00%
Behavioral Health Services | Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues		$ 121,135	$ 126,903	$ 244,195	$ 250,381
Percentage of Net Revenue		10.00%	10.00%	10.00%	10.00%
Behavioral Health Services | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 106,737	$ 50,606	$ 155,819	$ 99,023
Percentage of Net Revenue		8.00%	4.00%	6.00%	4.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,125	$ 3,218	$ 5,634	$ 6,382
Other | Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues		$ 3,125	$ 3,218	$ 5,634	$ 6,382

[1] Includes net revenues generated from our behavioral health care facilities located in the U.K. amounting to approximately $136 million and $144 million for the three-month periods ended June 30, 2020 and 2019, respectively, and approximately $273 million and $281 million for the six-month periods ended June 30, 2020 and 2019, respectively.  Total assets at our U.K. behavioral health care facilities were approximately $1.192 billion and $1.217 billion as of June 30, 2020 and 2019, respectively.