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Fair Value Measurements - MEC - Level 3 (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Derivative [Member] | MidAmerican Energy Company [Member]    
Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance $ (2) $ (6)
Fair value, level 3, transferred to affiliate   (4)
Changes in fair value recognized in other comprehensive income   0
Changes in fair value recognized in net regulatory assets 2 (1)
Fair value, level 3, asset, sales   0
Settlements 1 7
Ending balance 1 (4)
Auction rate securities [Member]    
Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Changes included in earnings 0 0
Changes in fair value recognized in other comprehensive income 0 4
Changes in fair value recognized in net regulatory assets 0 0
Purchases 0  
Fair value, level 3, asset, sales   (22)
Settlements 0 (18)
Ending balance 0 26
Auction rate securities [Member] | MidAmerican Energy Company [Member]    
Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 0 26
Fair value, level 3, transferred to affiliate   0
Changes in fair value recognized in other comprehensive income   1
Changes in fair value recognized in net regulatory assets 0 0
Fair value, level 3, asset, sales   (1)
Settlements 0 0
Ending balance $ 0 $ 26