Income Taxes - Summary of Operating Loss Carryforwards (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Current Income Tax Expense (Benefit)		$ 591	$ 573	$ 687
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	[1]	284
Deferred Tax Assets, Operating Loss Carryforwards		60
Deferred Tax Assets, Tax Credit Carryforwards		45
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	[1]	5,577
Deferred Tax Assets, Operating Loss Carryforwards		312
Deferred Tax Assets, Tax Credit Carryforwards		28
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	[1]	562
Deferred Tax Assets, Operating Loss Carryforwards		151
Deferred Tax Assets, Tax Credit Carryforwards		0
Income Tax Authority, Name [Domain]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	[1]	6,423
Deferred Tax Assets, Operating Loss Carryforwards		523
Deferred Tax Assets, Tax Credit Carryforwards		$ 73
Minimum [Member] | Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2023
Tax Credit Carryforward, Expiration Date		Dec. 31, 2023
Minimum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2019
Tax Credit Carryforward, Expiration Date		Dec. 31, 2019
Maximum [Member] | Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2026
Maximum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2038
Tax Cuts and Jobs Act of 2017 [Member]
Operating Loss Carryforwards [Line Items]
Current Income Tax Expense (Benefit)		$ (68)
Deferred Income Tax Charge [Member] | Tax Cuts and Jobs Act of 2017 [Member]
Operating Loss Carryforwards [Line Items]
Increase in Regulatory Liability		$ 27

[1] 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 2023.