Fair Value Measurements (MEC) Level 3 (Details) - MidAmerican Energy Company [Member] - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Commodity Derivative [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ 9	$ (2)	$ 12	$ (3)
Changes included in earnings	[1]	2	2	4	(4)
Changes in fair value recognized in OCI		(4)	1	(3)	4
Changes in fair value recognized in net regulatory assets		(15)	(4)	(15)	(1)
Purchases		1		1
Settlements		0	1	(6)	2
Ending balance		(7)	(2)	(7)	(2)
Net unrealized gains (losses) included in earnings		1	2	4	1
Auction rate securities [Member]
Fair Value, Assets and Liabilities, Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		26	25	26	23
Changes included in earnings	[1]	0	0	0	0
Changes in fair value recognized in OCI		1	0	1	2
Changes in fair value recognized in net regulatory assets		0	0	0	0
Purchases		0		0
Settlements		0	0	0	0
Ending balance		$ 27	$ 25	$ 27	$ 25

[1] Changes included in earnings are reported as nonregulated operating revenue on the Statements of Operations. For commodity derivatives held as of June 30, 2015 and 2014, net unrealized gains included in earnings for the three-month periods ended June 30, 2015 and 2014, totaled $1 million and $2 million, respectively, and for the six-month periods ended June 30, 2015 and 2014, totaled $4 million and $1 million, respectively .