Quarterly report pursuant to Section 13 or 15(d)

Segment Information - Summarized Financial Information (Detail)

v2.4.0.8
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]
       
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