Income Taxes - Tax Reform (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of Income Tax Expense (Benefit) [Line Items]
Current Income Tax Expense (Benefit)		$ (1,572)	$ (888)	$ (591)
Federal statutory income tax rate		21.00%	21.00%	21.00%	35.00%
Deferred Tax Liabilities, Net		$ 11,775	$ 9,653
Regulatory Liabilities		7,475	7,311
Deferred Income Tax Expense (Benefit)		1,883	296	$ 14
Net income (loss) attributable to parent		6,943	2,950	2,568
Income tax expense (benefit)		308	(598)	(583)
Equity income (loss)		(149)	(44)	43
Reclassification of long-term income tax receivable				609
Long-term income tax receivable adjustments		128	40	17
Related Party Transaction, Cash Received for Income Taxes, Net		1,504	942	884
Deferred Income Tax Charge [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Regulatory Liabilities	[1]	3,600	3,611
Tax Cuts and Jobs Act of 2017 [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory income tax rate					21.00%
Iowa Senate File 2417, Rate Effective Starting 2021 [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Deferred Tax Liabilities, Net		61
Deferred Income Tax Expense (Benefit)		2
Iowa Senate File 2417, Rate Effective Starting 2021 [Member] | Deferred Income Tax Charge [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Increase in Regulatory Liability		59
State and Local Jurisdiction [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Operating Loss Carryforwards	[2]	7,190
State and Local Jurisdiction [Member] | Iowa Senate File 2417, Rate Effective Starting 2021 [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Operating Loss Carryforwards		$ 138	79
Maximum [Member] | IOWA | Tax Year, Current [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Statutory Income Tax Rate, State and Local, Percent		12.00%
Maximum [Member] | IOWA | Iowa Senate File 2417, Rate Effective Starting 2021 [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Statutory Income Tax Rate, State and Local, Percent		9.80%
Long-term income tax receivable [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Reclassification of long-term income tax receivable				609
Long-term income tax receivable adjustments		$ 128	73	$ 152
Long-term income tax receivable [Member] | Iowa Senate File 2417, Rate Effective Starting 2021 [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Reclassification of long-term income tax receivable		609
Long-term income tax receivable adjustments		$ 115
Parent Company [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Related Party Transaction, Cash Received for Income Taxes, Net			$ 90

[1] Amounts primarily represent income tax liabilities related to the federal tax rate change from 35% to 21% that are probable to be passed on to customers, offset by income tax benefits related to certain property-related basis differences and other various differences that were previously passed on to customers and will be included in regulated rates when the temporary differences reverse.

[2] The federal net operating loss carryforwards relate principally to net operating loss carryforwards of subsidiaries that are tax residents in both the United States and the United Kingdom. The federal net operating loss carryforwards were generated prior to Berkshire Hathaway Inc.'s ownership and will begin to expire in 2021.