Investments in equity securities (Detail) - USD ($) $ in Millions	Dec. 31, 2023	[1]	Dec. 31, 2022	[2]
Summary of Investment Holdings [Line Items]
Cost Basis	$ 109,416		$ 131,610
Net Unrealized Gains	244,426		177,183
Fair Value	353,842		308,793
Banks, insurance and finance [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	27,136		25,893
Net Unrealized Gains	51,176		43,663
Fair Value	78,312		69,556
Consumer products [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	34,248		40,508
Net Unrealized Gains	166,895		112,384
Fair Value	201,143		152,892
Commercial, industrial and other [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	48,032		65,209
Net Unrealized Gains	26,355		21,136
Fair Value	$ 74,387		$ 86,345

[1] Approximately 79% of the aggregate fair value was concentrated in five companies (American Express Company – $28.4 billion; Apple Inc. – $174.3 billion; Bank of America Corporation – $34.8 billion; The Coca-Cola Company – $23.6 billion and Chevron Corporation – $18.8 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).