Consolidated Statements of Operations and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Operating revenues	$ 724,265		$ 745,607		$ 1,360,402		$ 1,364,161
Operating expenses
Operation and maintenance	323,320		327,577		635,523		637,581
Depreciation and amortization	101,366		92,329		201,015		184,433
General taxes	57,806		55,282		117,952		112,403
Gain on asset dispositions and purchases	(114)		(213)		(208)		(626)
Total operating expenses, net	482,378		474,975		954,282		933,791
Operating income	241,887		270,632		406,120		430,370
Other income (expenses)
Interest, net	(77,757)		(79,730)		(155,871)		(159,384)
Allowance for other funds used during construction	3,699		5,076		7,095		9,438
Allowance for borrowed funds used during construction	1,770		2,313		3,423		4,394
Amortization of debt expense	(1,624)		(1,361)		(3,205)		(2,627)
Other, net	(256)		335		(1,032)		(281)
Total other income (expenses)	(74,168)		(73,367)		(149,590)		(148,460)
Income from continuing operations before income taxes	167,719		197,265		256,530		281,910
Provision for income taxes	66,456		80,602		97,624		115,995
Income from continuing operations	101,263		116,663		158,906		165,915
Loss from discontinued operations, net of tax	0		(9,637)		0		(17,135)
Net income	101,263		107,026		158,906		148,780
Pension plan amortized to periodic benefit cost:
Prior service cost, net of tax of $27 and $28 for the three months and $55 and $56 for the six months ended, respectively	44		44		87		88
Actuarial loss, net of tax of $1,425 and $1,167 for the three months and $2,849 and $2,334 for the six months ended, respectively	2,227		1,826		4,455		3,651
Foreign currency translation adjustment	(453)		(211)		(819)		48
Other comprehensive income	1,818		1,659		3,723		3,787
Comprehensive income	$ 103,081		$ 108,685		$ 162,629		$ 152,567
Basic earnings per common share:
Income from continuing operations	$ 0.57	[1]	$ 0.66	[1]	$ 0.89	[1]	$ 0.94	[1]
Loss from discontinued operations, net of tax	$ 0.00	[1]	$ (0.05)	[1]	$ 0.00	[1]	$ (0.10)	[1]
Net income	$ 0.57	[1]	$ 0.61	[1]	$ 0.89	[1]	$ 0.84	[1]
Diluted earnings per common share:
Income from continuing operations	$ 0.57	[1]	$ 0.66	[1]	$ 0.89	[1]	$ 0.94	[1]
Loss from discontinued operations, net of tax	$ 0.00	[1]	$ (0.05)	[1]	$ 0.00	[1]	$ (0.10)	[1]
Net income	$ 0.57	[1]	$ 0.60	[1]	$ 0.89	[1]	$ 0.84	[1]
Average common shares outstanding during the period:
Basic	177,716		176,331		177,522		176,122
Diluted	178,910		177,491		178,716		177,296
Dividends per common share	$ 0.28		$ 0.25		$ 0.28		$ 0.48

[1] Amounts may not sum due to rounding.