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Segment Information - Summarized Financial Information (Detail) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2012
|
Sep. 30, 2012
|
Jun. 30, 2012
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Mar. 31, 2012
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Dec. 31, 2011
|
Sep. 30, 2011
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Jun. 30, 2011
|
Mar. 31, 2011
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Dec. 31, 2012
|
Dec. 31, 2011
|
Dec. 31, 2010
|
|
| Segment Reporting Information [Line Items] | |||||||||||
| Revenues | $ 1,673,342 | $ 1,532,001 | $ 1,386,162 | $ 1,328,764 | $ 1,393,004 | $ 1,112,674 | $ 904,781 | $ 783,305 | $ 5,920,269 | $ 4,193,764 | $ 3,629,433 |
| Operating income (loss) | 465,122 | 194,842 | 243,991 | ||||||||
| Depreciation | 120,303 | 109,874 | 101,199 | ||||||||
|
Electric Power [Member]
|
|||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenues | 4,206,509 | 3,022,659 | 2,028,734 | ||||||||
| Operating income (loss) | 520,834 | 337,726 | 204,088 | ||||||||
| Depreciation | 55,205 | 49,038 | 40,249 | ||||||||
|
Natural Gas and Pipeline [Member]
|
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| Segment Reporting Information [Line Items] | |||||||||||
| Revenues | 1,534,713 | 1,011,248 | 1,392,824 | ||||||||
| Operating income (loss) | 55,410 | (78,307) | 118,816 | ||||||||
| Depreciation | 43,285 | 41,051 | 43,407 | ||||||||
|
Fiber Optic Licensing and Other [Member]
|
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| Segment Reporting Information [Line Items] | |||||||||||
| Revenues | 179,047 | 159,857 | 207,875 | ||||||||
| Operating income (loss) | 61,299 | 53,476 | 52,952 | ||||||||
| Depreciation | 15,173 | 14,736 | 13,749 | ||||||||
|
Corporate and non-allocated costs [Member]
|
|||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Operating income (loss) | (172,421) | (118,053) | (131,865) | ||||||||
| Depreciation | $ 6,640 | $ 5,049 | $ 3,794 | ||||||||