Investments in equity securities (Detail) - USD ($) $ in Millions	Mar. 31, 2023	[1]	Dec. 31, 2022	[2]
Summary of Investment Holdings [Line Items]
Cost Basis	$ 121,342		$ 131,610
Net Unrealized Gains	206,819		177,183
Fair Value	328,161		308,793
Banks, insurance and finance [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	24,023		25,893
Net Unrealized Gains	41,292		43,663
Fair Value	65,315		69,556
Consumer products [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	40,003		40,508
Net Unrealized Gains	144,506		112,384
Fair Value	184,509		152,892
Commercial, industrial and other [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	57,316		65,209
Net Unrealized Gains	21,021		21,136
Fair Value	$ 78,337		$ 86,345

[1] Approximately 77% of the aggregate fair value was concentrated in five companies (American Express Company – $25.0 billion; Apple Inc. – $151.0 billion; Bank of America Corporation – $29.5 billion; The Coca-Cola Company – $24.8 billion and Chevron Corporation – $21.6 billion).

[2] Approximately 75% of the aggregate fair value was concentrated in five companies (American Express Company – $22.4 billion; Apple Inc. – $119.0 billion; Bank of America Corporation – $34.2 billion; The Coca-Cola Company – $25.4 billion and Chevron Corporation – $30.0 billion).