Fair value measurements - Financial assets and liabilities (Detail) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		$ 15,364	$ 23,758
Investments in equity securities		271,588	353,842
Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		15,364	23,758
Investments in equity securities		271,588	353,842
The Kraft Heinz Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, fair value		9,994	12,035
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		4,459	10,269
Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		9,362	11,805
Corporate and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		1,543	1,684
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		261,910	343,358
Derivative contract assets	[1]	$ 33	$ 39
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets	Other Assets
Derivative contract liabilities	[1]	$ 15	$ 7
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		$ 23,047	$ 26,587
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		4,425	10,234
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		9,199	11,559
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	10
Loans and finance receivables		810	892
Derivative contract assets	[1]	$ 158	$ 282
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets	Other Assets
Derivative contract liabilities	[1]	$ 143	$ 111
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		$ 72,506	$ 75,239
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		40,158	44,950
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		34	35
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		163	246
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		1,041	1,095
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		9,668	10,474
Loans and finance receivables		26,769	23,298
Derivative contract assets	[1]	$ 10	$ 13
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets	Other Assets
Derivative contract liabilities	[1]	$ 76	$ 95
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		$ 23	$ 31
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		502	589
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		271,588	353,842
Loans and finance receivables		27,798	24,681
Derivative contract assets	[1]	$ 201	$ 334
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets	Other Assets
Derivative contract liabilities	[1]	$ 234	$ 213
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		$ 79,877	$ 79,803
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		44,885	48,468
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		30,682	28,640
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		4,459	10,269
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		9,362	11,805
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Corporate and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		1,543	1,684
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		271,588	353,842
Loans and finance receivables		27,579	24,190
Derivative contract assets	[1]	$ 201	$ 334
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets	Other Assets
Derivative contract liabilities	[1]	$ 234	$ 213
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		$ 72,506	$ 75,239
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		40,181	44,981
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		23,047	26,587
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		4,459	10,269
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		9,362	11,805
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Corporate and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		$ 1,543	$ 1,684

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