Accounting Policies - Schedule of Revenues from Third Party Payers, Uninsured and Other Payers (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues From Third Party Payers [Line Items]
Revenues	$ 64,968	$ 60,233	$ 58,752
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	$ 10,585	$ 10,447	$ 10,447
Revenues from third party payers, Ratio	16.30%	17.30%	17.80%
Managed Medicare [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 10,496	$ 9,201	$ 8,424
Revenues from third party payers, Ratio	16.20%	15.30%	14.30%
Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 3,606	$ 2,636	$ 2,290
Revenues from third party payers, Ratio	5.60%	4.40%	3.90%
Managed Medicaid [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 3,879	$ 3,998	$ 3,124
Revenues from third party payers, Ratio	6.00%	6.60%	5.30%
Managed Care and Other Insurers [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 31,819	$ 29,120	$ 30,295
Revenues from third party payers, Ratio	49.00%	48.30%	51.60%
International (Managed Care and Other Insurers) [Member]
Revenues From Third Party Payers [Line Items]
Revenues from third party payers	$ 1,509	$ 1,317	$ 1,336
Revenues from third party payers, Ratio	2.30%	2.20%	2.30%
Other [Member]
Revenues From Third Party Payers [Line Items]
Revenues	$ 3,074	$ 3,514	$ 2,836
Other, Ratio	4.60%	5.90%	4.80%