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Investment in ATC (Tables) | 3 Months Ended
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Mar. 31, 2013
Investment in ATC (Tables) [Abstract] |
ATC's Summarized Financial Data |
|  |  | Three Months Ended |
|  |  | March 31, |
| (In thousands) |  | 2013 |  | 2012 |
| Operating revenues | $ | 151,737 | $ | 147,662 |
| Operating expenses |  | (69,770) |  | (69,566) |
| Other expense, net |  | (448) |  | (500) |
| Interest expense, net |  | (21,044) |  | (19,501) |
| Earnings before members' income taxes | $ | 60,475 | $ | 58,095 |

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- Definition Tabular disclosure of the summarized income statement reported by an equity method investment of the entity. + References No definition available. + Details
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