Fair Value Measurements - MidAmerican Funding - Debt (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, carrying value	$ 37,916	$ 36,250
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	42,154	38,874
MidAmerican Funding, LLC and Subsidiaries [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, carrying value	6,581	5,619
Long-term debt, fair value		$ 5,941
MidAmerican Funding, LLC and Subsidiaries [Domain] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 7,236