Consolidated Statements of Operations and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Operating revenues	$ 3,011,328		$ 2,878,936		$ 2,853,926
Operating expenses
Operation and maintenance	1,349,864		1,289,081		1,329,500
Depreciation and amortization	424,084		406,717		380,402
General taxes	236,732		234,198		220,758
(Gain) loss on asset dispositions and purchases	(1,928)		624		(838)
Total operating expenses, net	2,008,752		1,930,620		1,929,822
Operating income	1,002,576		948,316		924,104
Other income (expenses)
Interest, net	(297,818)		(308,164)		(310,794)
Loss on extinguishment of debt			(40,583)
Amortization of debt expense	(7,026)		(6,603)		(5,358)
Other, net	(3,196)		(4,045)		(926)
Total other income (expenses)	(292,762)		(340,379)		(293,715)
Income from continuing operations before income taxes	709,814		607,937		630,389
Provision for income taxes	279,973		237,093		256,787
Income from continuing operations	429,841		370,844		373,602
Loss from discontinued operations, net of tax	(6,733)		(1,580)		(15,532)
Net income	423,108		369,264		358,070
Other comprehensive income (loss), net of tax:
Change in employee benefit plan funded status, net of tax of $(29,487), $46,974 and $(16,894), respectively	(46,119)		73,472		(26,425)
Pension amortized to periodic benefit cost:
Prior service cost, net of tax of $106, $111 and $113, respectively	166		174		176
Actuarial (gain) loss, net of tax of $(19), $5,697 and $4,668, respectively	(31)		8,911		7,301
Foreign currency translation adjustment	(458)		(1,001)		434
Unrealized loss on cash flow hedge, net of tax of $(428)	(791)
Other comprehensive income (loss)	(47,233)		81,556		(18,514)
Comprehensive income	375,875		450,820		339,556
Basic earnings per share:
Income from continuing operations	$ 2.40	[1],[2]	$ 2.08	[1],[2]	$ 2.12	[1],[2]
Loss from discontinued operations, net of tax	$ (0.04)	[1],[2]	$ (0.01)	[1],[2]	$ (0.09)	[1],[2]
Net income	$ 2.36	[1],[2]	$ 2.08	[1],[2]	$ 2.03	[1],[2]
Diluted earnings per share:
Income from continuing operations	$ 2.39	[1],[2]	$ 2.07	[1],[2]	$ 2.10	[1],[2]
Loss from discontinued operations, net of tax	$ (0.04)	[1],[2]	$ (0.01)	[1],[2]	$ (0.09)	[1],[2]
Net income	$ 2.35	[1],[2]	$ 2.06	[1],[2]	$ 2.01	[1],[2]
Average common shares outstanding during the period
Basic	178,888		177,814		176,445
Diluted	179,806		179,056		177,671
Dividends declared per common share	$ 1.24		$ 1.12		$ 0.98
Other Funds
Other income (expenses)
Allowance for funds used during construction	9,440		12,639		15,592
Borrowed Funds
Other income (expenses)
Allowance for funds used during construction	$ 5,838		$ 6,377		$ 7,771

[1] Amounts may not sum due to rounding

[2] Earnings per share amounts are computed independently for income from continuing operations, loss from discontinued operations and net income. As a result, the sum of per-share amounts from continuing operations and discontinued operations may not equal the total per-share amount for net income.