Investments in equity securities (Detail) - USD ($) $ in Millions	Jun. 30, 2022		Dec. 31, 2021
Summary of Investment Holdings [Line Items]
Cost Basis	$ 149,722		$ 104,605
Net Unrealized Gains	177,940		246,114
Fair Value	327,662	[1]	350,719	[2]
Banks, insurance and finance [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	36,837		26,822
Net Unrealized Gains	39,655		62,236
Fair Value	76,492		89,058
Consumer products [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	41,785		36,076
Net Unrealized Gains	118,294		154,945
Fair Value	160,079		191,021
Commercial, industrial and other [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	71,100		41,707
Net Unrealized Gains	19,991		28,933
Fair Value	$ 91,091		$ 70,640

[1] Approximately 69% of the aggregate fair value was concentrated in five companies (American Express Company – $21.0 billion; Apple Inc. – $125.1 billion; Bank of America Corporation – $32.2 billion; The Coca-Cola Company – $25.2 billion and Chevron Corporation – $23.7 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).