Consolidated Statements of 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:
Electric, natural gas distribution and pipeline and energy services	$ 1,366,356		$ 1,264,574		$ 1,131,626
Exploration and production, construction materials and contracting, construction services and other	3,304,202		3,197,830		2,943,805
Total operating revenues	4,670,558		4,462,404		4,075,431
Operating expenses:
Fuel and purchased power	89,312		83,528		72,380
Purchased natural gas sold	570,041		505,065		425,220
Operation and maintenance:
Electric, natural gas distribution and pipeline and energy services	303,822		269,825		254,194
Exploration and production, construction materials and contracting, construction services and other	2,625,228		2,535,872		2,377,285
Depreciation, depletion and amortization	401,368		386,856		359,205
Taxes, other than income	192,562		188,359		176,140
Write-downs of oil and natural gas properties (Note 1)	0		0		391,800
Total operating expenses	4,182,333		3,969,505		4,056,224
Operating income	488,225		492,899		19,207
Earnings (loss) from equity method investments	(41)		(132)		5,383
Other income	9,962		6,768		6,642
Interest expense	87,016		83,917		76,699
Income (loss) before income taxes	411,130		415,618		(45,467)
Income taxes	119,969		136,736		(31,146)
Income (loss) from continuing operations	291,161		278,882		(14,321)
Income (loss) from discontinued operations, net of tax (Note 3)	3,177	[1]	(312)	[1]	13,567	[1]
Net income (loss)	294,338		278,570		(754)
Net loss attributable to noncontrolling interest	(3,895)		(363)		0
Dividends declared on preferred stocks	685		685		685
Earnings (loss) on common stock	$ 297,548		$ 278,248		$ (1,439)
Earnings (loss) per common share - basic:
Earnings (loss) before discontinued operations	$ 1.53		$ 1.47		$ (0.08)
Discontinued operations, net of tax	$ 0.02		$ 0.00		$ 0.07
Earnings (loss) per common share - basic	$ 1.55		$ 1.47		$ (0.01)
Earnings (loss) per common share - diluted:
Earnings (loss) before discontinued operations	$ 1.53		$ 1.47		$ (0.08)
Discontinued operations, net of tax	$ 0.02		$ 0.00		$ 0.07
Earnings (loss) per common share - diluted	$ 1.55		$ 1.47		$ (0.01)
Weighted average common shares outstanding - basic	192,507		188,855		188,826
Weighted average common shares outstanding - diluted	192,587		189,693		188,826

[1] Reflected in the Other category.