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Fair Value Measurements - MEC - Level 3 (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Derivative [Member] | MidAmerican Energy Company [Member]        
Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance $ 1 $ (4) $ (2) $ (6)
Fair value, level 3, transferred to affiliate   0   (4)
Changes in fair value recognized in other comprehensive income   0   0
Changes in fair value recognized in net regulatory assets (2) (3) 0 (4)
Fair value, level 3, asset, sales   0   0
Settlements 0 5 1 12
Ending balance (1) (2) (1) (2)
Auction rate securities [Member]        
Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 0 26 0 44
Changes included in earnings 0 0 0 0
Changes in fair value recognized in other comprehensive income 0 2 0 6
Changes in fair value recognized in net regulatory assets 0 0 0 0
Purchases 0   0  
Fair value, level 3, asset, sales   (10)   (32)
Settlements 0 (26) 0 0
Ending balance 0 18 0 18
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 0 26
Fair value, level 3, transferred to affiliate   0   0
Changes in fair value recognized in other comprehensive income   2   3
Changes in fair value recognized in net regulatory assets 0 0 0 0
Fair value, level 3, asset, sales   (10)   (11)
Settlements 0 0 0 0
Ending balance $ 0 $ 18 $ 0 $ 18