Segment Information (MEC) (Details) (MidAmerican Energy Company and Subsidiaries [Member], USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 TheNumberOfReportableSegments	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Number of Reportable Segments									3
Regulated electric									$ 1,694	$ 1,662	$ 1,779
Regulated gas									659	769	852
Nonregulated energy									889	1,070	1,179
Total operating revenue	834	825	709	874	852	866	804	979	3,242	3,501	3,810
Total depreciation and amortization									392	336	344
Total operating income	58	139	81	92	82	148	86	113	370	429	459
Total fixed charges									138	151	154
Income tax expense (benefit)									(99)	(17)	(49)
Earnings on common stock	60	140	80	74	89	107	48	74	354	318	357
Total utility construction expenditures									645	565	337
Total assets	11,232				10,310				11,232	10,310	9,010
Regulated electric [Member]
Segment Reporting Information [Line Items]
Regulated electric									1,694	1,662	1,779
Total depreciation and amortization									356	301	309
Total operating income									270	294	319
Total fixed charges									123	133	136
Income tax expense (benefit)									(129)	(61)	(84)
Earnings on common stock									297	243	268
Total utility construction expenditures									588	505	295
Total assets	9,898				9,016				9,898	9,016	7,780
Regulated gas [Member]
Segment Reporting Information [Line Items]
Regulated gas									659	769	852
Total depreciation and amortization									36	35	35
Total operating income									47	66	64
Total fixed charges									15	18	18
Income tax expense (benefit)									7	16	5
Earnings on common stock									28	36	45
Total utility construction expenditures									57	60	42
Total assets	1,202				1,159				1,202	1,159	1,033
Nonregulated Energy [Member]
Segment Reporting Information [Line Items]
Nonregulated energy									889	1,070	1,179
Total operating income									53	69	76
Income tax expense (benefit)									23	28	30
Earnings on common stock									29	39	44
Total assets	$ 132				$ 135				$ 132	$ 135	$ 197