Goodwill (Summary Of Changes In Goodwill) (Details) (USD $)
In Thousands | 9 Months Ended |
|---|
Sep. 30, 2011 | Sep. 30, 2010 |
|---|
| Goodwill [Line Items] | | |
| Cost, beginning balance | $ 3,635,874 | $ 3,635,563 |
| Accumulated impairment, beginning balance | (2,440,289) | (2,440,289) |
| Total net, beginning balance | 1,195,585 | 1,195,274 |
| Reclassifications and other activity, cost | (75) | 311 |
| Reclassifications and other activity, accumulated impairment | 0 | 0 |
| Cost, ending balance | 3,635,799 | 3,635,874 |
| Accumulated impairment, ending balance | (2,440,289) | (2,440,289) |
| Total net, ending balance | 1,195,510 | 1,195,585 |
Regulated Unit [Member] | | |
| Goodwill [Line Items] | | |
| Cost, beginning balance | 3,399,884 | 3,399,848 |
| Accumulated impairment, beginning balance | (2,332,670) | (2,332,670) |
| Reclassifications and other activity, cost | (75) | 36 |
| Reclassifications and other activity, accumulated impairment | 0 | 0 |
| Cost, ending balance | 3,399,809 | 3,399,884 |
| Accumulated impairment, ending balance | (2,332,670) | (2,332,670) |
Market-Based Unit [Member] | | |
| Goodwill [Line Items] | | |
| Cost, beginning balance | 235,990 | 235,715 |
| Accumulated impairment, beginning balance | (107,619) | (107,619) |
| Reclassifications and other activity, cost | 0 | 275 |
| Reclassifications and other activity, accumulated impairment | 0 | 0 |
| Cost, ending balance | 235,990 | 235,990 |
| Accumulated impairment, ending balance | $ (107,619) | $ (107,619) |