Segment Reporting (tables)

12 Months Ended

Dec. 31, 2014

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

In thousands	Utility		Gas Storage			Other		Total
2014
Operating revenues	$	731,578	$	22,235		$	224	$	754,037
Depreciation and amortization	72,660		6,533			—		79,193
Income from operations	138,711		3,987			267		142,965
Net income	58,587		(364		)	469		58,692
Capital expenditures	117,322		2,770			—		120,092
Total assets at December 31, 2014	2,775,011		273,813			16,121		3,064,945
2013
Operating revenues	$	727,182	$	31,112		$	224	$	758,518
Depreciation and amortization	69,420		6,485			—		75,905
Income from operations	128,066		14,669			11		142,746
Net income	54,920		5,569			49		60,538
Capital expenditures	137,466		1,458			—		138,924
Total assets at December 31, 2013	2,644,367		310,097			16,447		2,970,911
2012
Operating revenues	$	699,862	$	30,520		$	225	$	730,607
Depreciation and amortization	66,545		6,472			—		73,017
Income from operations	128,854		13,226			100		142,180
Net income	54,049		4,521			209		58,779
Capital expenditures	130,151		1,541			337		132,029
Total assets at December 31, 2012	2,505,655		291,568			15,897		2,813,120

Utility Margin [Table Text Block]

In thousands	2014		2013		2012
Utility margin calculation:
Utility operating revenues	$	731,578	$	727,182	$	699,862
Less: Utility cost of gas	365,490		373,298		355,335
Utility margin	$	366,088	$	353,884	$	344,527