Schedule of Disaggregates Revenue by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation Of Revenue [Line Items]
Net revenues	$ 4,495,245	$ 3,963,027	$ 12,878,781	$ 11,714,213
Percentage of Net Revenue	100.00%	100.00%	100.00%	100.00%
Medicare
Disaggregation Of Revenue [Line Items]
Net revenues	$ 460,583	$ 403,614	$ 1,377,869	$ 1,243,925
Percentage of Net Revenue	10.00%	10.00%	11.00%	11.00%
Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues	$ 516,611	$ 469,714	$ 1,556,082	$ 1,411,881
Percentage of Net Revenue	11.00%	12.00%	12.00%	12.00%
Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues	$ 766,265	$ 559,359	$ 1,937,293	$ 1,575,552
Percentage of Net Revenue	17.00%	14.00%	15.00%	13.00%
Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues	$ 627,932	$ 577,325	$ 1,850,369	$ 1,728,989
Percentage of Net Revenue	14.00%	15.00%	14.00%	15.00%
Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues	$ 1,241,821	$ 1,126,018	$ 3,654,475	$ 3,356,173
Percentage of Net Revenue	28.00%	28.00%	28.00%	29.00%
UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues	$ 264,486	$ 230,153	$ 738,460	$ 650,655
Percentage of Net Revenue	6.00%	6.00%	6.00%	6.00%
Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues	$ 319,015	$ 273,011	$ 939,142	$ 824,770
Percentage of Net Revenue	7.00%	7.00%	7.00%	7.00%
Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues	$ 298,532	$ 323,833	$ 825,091	$ 922,268
Percentage of Net Revenue	7.00%	8.00%	6.00%	8.00%
Acute Care Hospital Services
Disaggregation Of Revenue [Line Items]
Net revenues	$ 2,630,065	$ 2,253,819	$ 7,380,328	$ 6,617,586
Percentage of Net Revenue	100.00%	100.00%	100.00%	100.00%
Acute Care Hospital Services \| Medicare
Disaggregation Of Revenue [Line Items]
Net revenues	$ 374,814	$ 323,015	$ 1,141,829	$ 1,010,737
Percentage of Net Revenue	14.00%	14.00%	15.00%	15.00%
Acute Care Hospital Services \| Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues	$ 404,619	$ 362,961	$ 1,236,634	$ 1,106,470
Percentage of Net Revenue	15.00%	16.00%	17.00%	17.00%
Acute Care Hospital Services \| Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues	$ 451,867	$ 299,147	$ 983,889	$ 774,586
Percentage of Net Revenue	17.00%	13.00%	13.00%	12.00%
Acute Care Hospital Services \| Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues	$ 180,592	$ 157,435	$ 509,186	$ 471,344
Percentage of Net Revenue	7.00%	7.00%	7.00%	7.00%
Acute Care Hospital Services \| Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues	$ 831,058	$ 726,227	$ 2,421,837	$ 2,131,280
Percentage of Net Revenue	32.00%	32.00%	33.00%	32.00%
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	$ 151,144	$ 118,193	$ 447,484	$ 375,727
Percentage of Net Revenue	6.00%	5.00%	6.00%	6.00%
Acute Care Hospital Services \| Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues	$ 235,971	$ 266,841	$ 639,469	$ 747,442
Percentage of Net Revenue	9.00%	12.00%	9.00%	11.00%
Behavioral Health Services
Disaggregation Of Revenue [Line Items]
Net revenues	$ 1,860,259	$ 1,706,612	$ 5,487,984	$ 5,088,711
Percentage of Net Revenue	100.00%	100.00%	100.00%	100.00%
Behavioral Health Services \| Medicare
Disaggregation Of Revenue [Line Items]
Net revenues	$ 85,769	$ 80,599	$ 236,040	$ 233,188
Percentage of Net Revenue	5.00%	5.00%	4.00%	5.00%
Behavioral Health Services \| Managed Medicare
Disaggregation Of Revenue [Line Items]
Net revenues	$ 111,992	$ 106,753	$ 319,448	$ 305,411
Percentage of Net Revenue	6.00%	6.00%	6.00%	6.00%
Behavioral Health Services \| Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues	$ 314,398	$ 260,212	$ 953,404	$ 800,966
Percentage of Net Revenue	17.00%	15.00%	17.00%	16.00%
Behavioral Health Services \| Managed Medicaid
Disaggregation Of Revenue [Line Items]
Net revenues	$ 447,340	$ 419,890	$ 1,341,183	$ 1,257,645
Percentage of Net Revenue	24.00%	25.00%	24.00%	25.00%
Behavioral Health Services \| Managed Care (HMO and PPOs)
Disaggregation Of Revenue [Line Items]
Net revenues	$ 410,763	$ 399,791	$ 1,232,638	$ 1,224,893
Percentage of Net Revenue	22.00%	23.00%	22.00%	24.00%
Behavioral Health Services \| UK Revenue
Disaggregation Of Revenue [Line Items]
Net revenues	$ 264,486	$ 230,153	$ 738,460	$ 650,655
Percentage of Net Revenue	14.00%	13.00%	13.00%	13.00%
Behavioral Health Services \| Other Patient Revenue and Adjustments, Net
Disaggregation Of Revenue [Line Items]
Net revenues	$ 167,871	$ 154,818	$ 491,658	$ 449,043
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	$ 57,640	$ 54,396	$ 175,153	$ 166,910
Percentage of Net Revenue	3.00%	3.00%	3.00%	3.00%
Other
Disaggregation Of Revenue [Line Items]
Net revenues	$ 4,921	$ 2,596	$ 10,469	$ 7,916
Other \| Other Non-patient Revenue
Disaggregation Of Revenue [Line Items]
Net revenues	$ 4,921	$ 2,596	$ 10,469	$ 7,916