Subsequent Events (MEC) Subsequent Events - MEC (Details) - USD ($) $ in Millions	Feb. 28, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Par value		$ 35,376
MidAmerican Energy Company [Member]
Subsequent Event [Line Items]
Par value		5,080
MidAmerican Energy Company [Member] | MEC First Mortgage Bonds, 3.95%, Due 2047 [Member]
Subsequent Event [Line Items]
Par value		475
MidAmerican Energy Company [Member] | MEC Notes, 5.95% Series, due 2017 [Member]
Subsequent Event [Line Items]
Par value		$ 0
Debt Instrument, Interest Rate, Stated Percentage		5.95%	5.95%
MidAmerican Energy Company [Member] | Subsequent Event [Member] | MidAmerican Energy Company [Member] | MEC First Mortgage Bonds, 3.65%, Due August 2048 [Member]
Subsequent Event [Line Items]
Par value	$ 700
Debt Instrument, Interest Rate, Stated Percentage	3.65%