|
Segment Information - Summarized Financial Information (Detail) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
|
Jun. 30, 2013
|
Jun. 30, 2012
|
Jun. 30, 2013
|
Jun. 30, 2012
|
|
| Segment Reporting Information [Line Items] | ||||
| Revenues | $ 1,474,377 | $ 1,386,162 | $ 3,060,087 | $ 2,714,926 |
| Operating income (loss) | 117,174 | 98,345 | 236,465 | 177,136 |
| Depreciation | 33,040 | 29,376 | 64,920 | 58,402 |
|
Electric Power [Member]
|
||||
| Segment Reporting Information [Line Items] | ||||
| Revenues | 1,046,379 | 1,006,073 | 2,227,362 | 1,938,286 |
| Operating income (loss) | 120,809 | 110,735 | 253,359 | 224,949 |
| Depreciation | 15,776 | 13,342 | 30,699 | 26,710 |
|
Natural Gas and Pipeline [Member]
|
||||
| Segment Reporting Information [Line Items] | ||||
| Revenues | 385,942 | 337,595 | 744,874 | 694,562 |
| Operating income (loss) | 27,644 | 15,055 | 38,001 | 4,520 |
| Depreciation | 11,335 | 10,634 | 22,600 | 20,990 |
|
Fiber Optic Licensing and Other [Member]
|
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| Segment Reporting Information [Line Items] | ||||
| Revenues | 42,056 | 42,494 | 87,851 | 82,078 |
| Operating income (loss) | 14,301 | 15,423 | 31,184 | 29,963 |
| Depreciation | 4,230 | 3,727 | 8,281 | 7,402 |
|
Corporate and Non-Allocated Costs [Member]
|
||||
| Segment Reporting Information [Line Items] | ||||
| Operating income (loss) | (45,580) | (42,868) | (86,079) | (82,296) |
| Depreciation | $ 1,699 | $ 1,673 | $ 3,340 | $ 3,300 |