Industry Segment Information (Tables)

12 Months Ended

Dec. 31, 2011

Segment Reporting [Abstract]

Schedule of segment information

Years ended December 31,(in thousands)	2011			2010			2009
Operating revenues
Oil and gas operations	$	948,526		$	958,762		$	822,546
Natural gas distribution	534,953			619,772			617,874
Total	$	1,483,479		$	1,578,534		$	1,440,420
Operating income (loss)
Oil and gas operations	$	363,131		$	406,729		$	353,645
Natural gas distribution	86,216			88,383			83,984
Eliminations and corporate expenses	(1,078		)	(1,735		)	(2,236		)
Total	$	448,269		$	493,377		$	435,393
Depreciation, depletion and amortization expense
Oil and gas operations	$	244,081		$	203,823		$	184,089
Natural gas distribution	39,916			44,042			50,995
Total	$	283,997		$	247,865		$	235,084
Interest expense
Oil and gas operations	$	30,907		$	25,753		$	25,775
Natural gas distribution	14,740			13,894			13,714
Eliminations and other	(825		)	(425		)	(110		)
Total	$	44,822		$	39,222		$	39,379
Income tax expense (benefit)
Oil and gas operations	$	120,079		$	138,775		$	117,969
Natural gas distribution	26,670			29,875			27,353
Other	(1,048		)	(1,660		)	(1,351		)
Total	$	145,701		$	166,990		$	143,971
Capital expenditures
Oil and gas operations	$	1,115,452		$	717,782		$	427,399
Natural gas distribution	73,984			93,566			77,809
Total	$	1,189,436		$	811,348		$	505,208
Identifiable assets
Oil and gas operations	$	4,046,242		$	3,160,601		$	2,654,068
Natural gas distribution	1,163,959			1,166,899			1,084,666
Eliminations and other	27,215			36,060			64,384
Total	$	5,237,416		$	4,363,560		$	3,803,118
Property, plant and equipment, net
Oil and gas operations	$	3,806,787		$	2,936,284		$	2,422,623
Natural gas distribution	813,471			782,665			721,846
Other	518			278			—
Total	$	4,620,776		$	3,719,227		$	3,144,469