Investments in equity securities (Detail) - USD ($) $ in Millions	Dec. 31, 2022	[1]	Dec. 31, 2021	[2]
Summary of Investment Holdings [Line Items]
Cost Basis	$ 131,610		$ 104,605
Net Unrealized Gains	177,183		246,114
Fair Value	308,793		350,719
Banks, insurance and finance [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	25,893		26,822
Net Unrealized Gains	43,663		62,236
Fair Value	69,556		89,058
Consumer products [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	40,508		36,076
Net Unrealized Gains	112,384		154,945
Fair Value	152,892		191,021
Commercial, industrial and other [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	65,209		41,707
Net Unrealized Gains	21,136		28,933
Fair Value	$ 86,345		$ 70,640

[1] 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).

[2] Approximately 73% of the aggregate fair value was concentrated in four companies (American Express Company – $24.8 billion; Apple Inc. – $161.2 billion; Bank of America Corporation – $46.0 billion and The Coca-Cola Company – $23.7 billion).