Fair value measurements - Financial assets and liabilities (Detail) - USD ($) $ in Millions		Dec. 31, 2023		Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		$ 23,758		$ 25,128
Investments in equity securities		353,842	[1]	308,793	[2]
Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		23,758		25,128
Investments in equity securities		353,842		308,793
The Kraft Heinz Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, fair value		12,035		13,249
U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		10,269		9,802
Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,805		10,327
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		1,449		2,195
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		235		2,804
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		343,358		296,610
Derivative contract assets	[3]	$ 39		$ 56
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets		Other Assets
Derivative contract liabilities	[3]	$ 7		$ 8
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accounts Payable and Accrued Liabilities		Accounts Payable and Accrued Liabilities
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | The Kraft Heinz Company and Occidental Petroleum Corporation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, fair value		$ 26,587		$ 25,491
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		10,234		9,733
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,559		9,854
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		10		9
Loans and finance receivables		892		1,513
Derivative contract assets	[3]	$ 282		$ 474
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets		Other Assets
Derivative contract liabilities	[3]	$ 111		$ 122
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accounts Payable and Accrued Liabilities		Accounts Payable and Accrued Liabilities
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		$ 81,036		$ 67,651
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		39,153		41,061
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		35		69
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		246		473
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		860		1,546
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		235		2,804
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		10,474		12,174
Loans and finance receivables		23,298		21,915
Derivative contract assets	[3]	$ 13		$ 59
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets		Other Assets
Derivative contract liabilities	[3]	$ 95		$ 112
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accounts Payable and Accrued Liabilities		Accounts Payable and Accrued Liabilities
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		$ 31		$ 900
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		589		649
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		353,842		308,793
Loans and finance receivables		24,681		23,208
Derivative contract assets	[3]	$ 334		$ 589
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets		Other Assets
Derivative contract liabilities	[3]	$ 213		$ 242
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accounts Payable and Accrued Liabilities		Accounts Payable and Accrued Liabilities
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		$ 85,579		$ 76,206
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		42,692		46,538
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | The Kraft Heinz Company and Occidental Petroleum Corporation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, fair value		28,640		24,421
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		10,269		9,802
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,805		10,327
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		1,449		2,195
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		235		2,804
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		353,842		308,793
Loans and finance receivables		24,190		23,428
Derivative contract assets	[3]	$ 334		$ 589
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets		Other Assets
Derivative contract liabilities	[3]	$ 213		$ 242
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accounts Payable and Accrued Liabilities		Accounts Payable and Accrued Liabilities
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		$ 81,036		$ 67,651
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		39,184		41,961
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | The Kraft Heinz Company and Occidental Petroleum Corporation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, fair value		26,587		25,491
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		10,269		9,802
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,805		10,327
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		1,449		2,195
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		$ 235		$ 2,804

[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).

[3] Assets are included in other assets, and liabilities are included in accounts payable, accruals and other liabilities.