v2.4.0.6

Segments Of Business (Products And Services) (Details) | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
--- | --- | --- | ---
Segment Reporting Information [Line Items] |  |  |
Products and services | 100.00% | 100.00% | 100.00%
Utility electric operations [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Products and services | 84.00% | 82.00% | 82.00%
Utility gas operations [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Products and services | 13.00% | 15.00% | 15.00%
Utility other [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Products and services | 2.00% | 2.00% | 2.00%
Other [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Products and services | 1.00% | 1.00% | 1.00%

X
- Definition The percentage of net product revenue to total net revenue from the sale of goods as of year end. + References No definition available. + Details
Name: | us-gaap_SalesRevenueGoodsNetPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration