Pension plans - Projected benefit obligation, plan assets and net funded status (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Benefit obligations
Balance at the beginning of the year	$ 12,738	$ 18,792
Service cost	111	181	$ 257
Interest cost	$ 640	$ 482	410
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense	Interest Expense
Benefits paid	$ (852)	$ (835)
Settlements paid	(448)	(842)
Actuarial (gains) losses and other	578	(5,040)
Balance at the end of the year	12,767	12,738	18,792
Plan assets
Balance at the beginning of the year	12,592	18,620
Employer contributions	145	162
Benefits paid	(852)	(835)
Settlements paid	(448)	(842)
Actual return on plan assets	1,783	(4,133)
Other	159	(380)
Balance at the end of the year	13,379	12,592	18,620
Funded status - net (asset) liability	(612)	146
Berkshire Hathaway Energy ("BHE") [Member]
Benefit obligations
Balance at the beginning of the year	3,215	4,780
Service cost	21	36
Interest cost	$ 167	$ 118
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense	Interest Expense
Benefits paid	$ (274)	$ (250)
Settlements paid		(164)
Actuarial (gains) losses and other	140	(1,305)
Balance at the end of the year	3,269	3,215	4,780
Plan assets
Balance at the beginning of the year	3,376	5,158
Employer contributions	27	29
Benefits paid	(274)	(250)
Settlements paid		(164)
Actual return on plan assets	271	(1,162)
Other	71	(235)
Balance at the end of the year	3,471	3,376	5,158
Funded status - net (asset) liability	(202)	(161)
Other [Member]
Benefit obligations
Balance at the beginning of the year	9,523	14,012
Service cost	90	145
Interest cost	$ 473	$ 364
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense	Interest Expense
Benefits paid	$ (578)	$ (585)
Settlements paid	(448)	(678)
Actuarial (gains) losses and other	438	(3,735)
Balance at the end of the year	9,498	9,523	14,012
Plan assets
Balance at the beginning of the year	9,216	13,462
Employer contributions	118	133
Benefits paid	(578)	(585)
Settlements paid	(448)	(678)
Actual return on plan assets	1,512	(2,971)
Other	88	(145)
Balance at the end of the year	9,908	9,216	$ 13,462
Funded status - net (asset) liability	$ (410)	$ 307