Accounting Policies - Schedule of Revenues from Third Party Payers, Uninsured and Other Payers (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenues From Third Party Payers [Line Items]
Revenues	$ 70,603	$ 64,968	$ 60,233
Revenues ratio from third party payers	100.00%	100.00%	100.00%
Medicare [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 10,780	$ 10,585	$ 10,447
Revenues from third party payers, Ratio	15.30%	16.30%	17.30%
Managed Medicare [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 11,987	$ 10,496	$ 9,201
Revenues from third party payers, Ratio	17.00%	16.20%	15.30%
Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 4,678	$ 3,606	$ 2,636
Revenues from third party payers, Ratio	6.60%	5.60%	4.40%
Managed Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 3,980	$ 3,879	$ 3,998
Revenues from third party payers, Ratio	5.60%	6.00%	6.60%
Managed Care and Other Insurers [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 34,954	$ 31,819	$ 29,120
Revenues from third party payers, Ratio	49.50%	49.00%	48.30%
International (Managed Care and Other Insurers) [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 1,682	$ 1,509	$ 1,317
Revenues from third party payers, Ratio	2.40%	2.30%	2.20%
Other [Member]
Revenues From Third Party Payers [Line Items]
Revenues	$ 2,542	$ 3,074	$ 3,514
Other, Ratio	3.60%	4.60%	5.90%