Business segment data - Reconciliations of Revenues and Earnings before income taxes (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Revenues	$ 89,725	$ 89,869
Investment gains (losses)	(6,435)	1,876
Equity method investments	126	493
Earnings before income taxes	5,148	15,706
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Revenues	88,959	89,785
Earnings before income taxes	11,615	12,486
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment gains (losses)	(6,435)	1,876
Equity method investments	126	493
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Revenues	766	84
Earnings before income taxes from operating businesses	$ (158)	$ 851