Risk Management and Hedging Activities - MEC - Designated as Hedging Contracts (Details) - Commodity derivative [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive (Income) Loss, Net, Derivatives [Roll Forward]
Accumulated other comprehensive income (loss), net, cummulative net gain (loss) from cash flow hedges, effect before taxes	$ (46)	$ (32)
Changes in fair value recognized in OCI	48	(8)
Accumulated other comprehensive income (loss), net, cummulative net gain (loss) from cash flow hedges, effect before taxes	(72)	(27)
MidAmerican Energy Company [Member]
Accumulated Other Comprehensive (Income) Loss, Net, Derivatives [Roll Forward]
Accumulated other comprehensive income (loss), net, cummulative net gain (loss) from cash flow hedges, effect before taxes	(45)	(34)
Cumulative Net Gain (Loss) From Cash Flow Hedges, Before Taxes Transferred to Affiliate	(45)	0
Changes in fair value recognized in OCI	0	(6)
Cash Flow Hedge Gain (Loss) Reclassified To Cost Of Sales Nonregulated	0	2
Accumulated other comprehensive income (loss), net, cummulative net gain (loss) from cash flow hedges, effect before taxes	$ 0	$ (30)