Fair Value Measurements and Financial Instruments - Debt Excluding Capital Leases (Detail) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument fair value	$ 141,217	$ 141,665
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument fair value	137,015	137,016
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument fair value	82,646	81,552
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument fair value	54,369	55,464
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument fair value	$ 0	$ 0