Basis of Presentation and Significant Accounting Policies - Schedule of Revenues from Third Party Payers, Uninsured and Other Payers (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues From Third Party Payers [Line Items]
Revenues	$ 17,492	$ 15,861	$ 34,831	$ 31,452
Revenues ratio from third party payers	100.00%	100.00%	100.00%	100.00%
Medicare [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 2,621	$ 2,567	$ 5,459	$ 5,305
Revenues from third party payers, Ratio	15.00%	16.20%	15.70%	16.90%
Managed Medicare [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 2,913	$ 2,541	$ 5,939	$ 5,100
Revenues from third party payers, Ratio	16.70%	16.00%	17.00%	16.20%
Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 1,108	$ 742	$ 2,108	$ 1,477
Revenues from third party payers, Ratio	6.30%	4.70%	6.10%	4.70%
Managed Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 1,033	$ 894	$ 2,011	$ 1,807
Revenues from third party payers, Ratio	5.90%	5.60%	5.80%	5.70%
Managed Care and Insurers [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 8,549	$ 7,830	$ 17,094	$ 15,453
Revenues from third party payers, Ratio	48.80%	49.40%	49.00%	49.20%
International (Managed Care and Insurers) [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 416	$ 377	$ 828	$ 752
Revenues from third party payers, Ratio	2.40%	2.40%	2.40%	2.40%
Other [Member]
Revenues From Third Party Payers [Line Items]
Revenues	$ 852	$ 910	$ 1,392	$ 1,558
Other, Ratio	4.90%	5.70%	4.00%	4.90%