Components of Accumulated Other Comprehensive Loss, Net - MEC (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - Accumulated other comprehensive loss, net			$ (1,511)
Other comprehensive income (loss), unrealized gains on available-for-sale securities	$ 423	$ 80	542	$ 151
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges	1	(3)	(5)	(2)
Other comprehensive income (loss)	666	(39)	1,088	(110)
Ending balance - Accumulated other comprehensive loss, net	(423)		(423)
Accumulated Other Comprehensive (Loss) Income, Net [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - unrealized gains (losses) on available-for-sale securities			585	615
Beginning balance - unrealized gains (losses) on cash flow hedges			26	7
Beginning balance - Accumulated other comprehensive loss, net			(1,511)	(908)
Other comprehensive income (loss), unrealized gains on available-for-sale securities			542	151
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges			(5)	(2)
Other comprehensive income (loss)			1,088	(110)
Ending balance - unrealized gains (losses) on available-for-sale securities	1,127	766	1,127	766
Ending balance - unrealized gains (losses) on cash flow hedges	21	5	21	5
Ending balance - Accumulated other comprehensive loss, net	$ (423)	(1,018)	$ (423)	(1,018)
MidAmerican Energy Company [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss)				2
Dividend, unrealized losses on cash flow hedges, transfer of operations				(90)
MidAmerican Energy Company [Member] | Accumulated Other Comprehensive (Loss) Income, Net [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - unrealized gains (losses) on available-for-sale securities				(3)
Beginning balance - unrealized gains (losses) on cash flow hedges				(27)
Beginning balance - Accumulated other comprehensive loss, net				(30)
Other comprehensive income (loss), unrealized gains on available-for-sale securities				2
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges				0
Other comprehensive income (loss)				2
Dividend, unrealized losses on cash flow hedges, transfer of operations				(27)
Ending balance - unrealized gains (losses) on available-for-sale securities		(1)		(1)
Ending balance - unrealized gains (losses) on cash flow hedges		0		0
Ending balance - Accumulated other comprehensive loss, net		$ (1)		$ (1)