Summary of Significant Accounting Policies (MEC) Utility Plant, Net - General (Details) (MidAmerican Energy Company and Subsidiaries [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Regulated electric [Member]
Notes to Consolidated Financial Statements [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.30%	3.20%	3.40%
Regulated gas [Member]
Notes to Consolidated Financial Statements [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.80%	2.90%	3.00%
Depreciable Assets [Member]
Notes to Consolidated Financial Statements [Line Items]
Change in Accounting Estimates, Impact on Period of Change		16
Change in Accounting Estimates, Impact on Future Periods		28
Service Life [Member]
Notes to Consolidated Financial Statements [Line Items]
Change in Accounting Estimates, Impact on Period of Change	5
Change in Accounting Estimates, Impact on Future Periods	11