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, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Revenues From Third Party Payers [Line Items]
Revenues	$ 20,230	$ 18,605	$ 39,339	$ 36,926
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	$ 2,927	$ 2,803	$ 5,985	$ 5,698
Revenues from third party payers, Ratio	14.50%	15.10%	15.20%	15.40%
Managed Medicare [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 3,424	$ 3,352	$ 6,932	$ 6,651
Revenues from third party payers, Ratio	16.90%	18.00%	17.60%	18.00%
Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 2,789	$ 1,440	$ 4,233	$ 2,630
Revenues from third party payers, Ratio	13.80%	7.70%	10.80%	7.10%
Managed Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 997	$ 899	$ 1,936	$ 1,778
Revenues from third party payers, Ratio	4.90%	4.80%	4.90%	4.80%
Managed Care and Insurers [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 9,013	$ 9,124	$ 18,097	$ 18,165
Revenues from third party payers, Ratio	44.60%	49.10%	46.00%	49.20%
International (Managed Care and Insurers) [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 491	$ 461	$ 990	$ 906
Revenues from third party payers, Ratio	2.40%	2.50%	2.50%	2.50%
Other [Member]
Revenues From Third Party Payers [Line Items]
Revenues	$ 589	$ 526	$ 1,166	$ 1,098
Other, Ratio	2.90%	2.80%	3.00%	3.00%