Income Taxes Income Taxes - Related Party Income Taxes (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Long-term income tax receivable		$ (530)	$ (457)
Parent Company [Member]
Related Party Transaction [Line Items]
Income Taxes Receivable From (Payable To) Related Parties Current		(90)	76
Long-term income tax receivable		530	457
State and Local Jurisdiction [Member]
Related Party Transaction [Line Items]
Operating Loss Carryforwards	[1]	5,819
Iowa Senate File 2417, Rate Effective Starting 2021 [Member] | State and Local Jurisdiction [Member]
Related Party Transaction [Line Items]
Operating Loss Carryforwards		$ 79	$ 53

[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 2020.