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