Segment Reporting (tables)

3 Months Ended

Mar. 31, 2014

Segment Reporting [Abstract]

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

	Three Months Ended March 31,
In thousands	Utility		Gas Storage		Other			Total
2014
Operating revenues	$	285,495	$	7,835	$	56		$	293,386
Depreciation and amortization	17,967		1,622		—			19,589
Income from operations	71,457		3,553		18			75,028
Net income	36,019		1,627		238			37,884
Capital expenditures	25,350		238		—			25,588
Total assets at March 31, 2014	2,506,930		307,055		16,399			2,830,384
2013
Operating revenues	$	269,659	$	8,146	$	56		$	277,861
Depreciation and amortization	17,188		1,619		—			18,807
Income from operations	70,228		3,957		21			74,206
Net income	36,031		1,636		(28		)	37,639
Capital expenditures	22,388		286		—			22,674
Total assets at March 31, 2013	2,501,724		288,795		15,980			2,806,499
Total assets at December 31, 2013	$	2,644,367	$	310,097	$	16,447		$	2,970,911

Utility Margin [Table Text Block]

	Three Months Ended March 31,
In thousands	2014		2013
Utility margin calculation:
Utility operating revenues	$	285,495	$	269,659
Less: Utility cost of gas	155,201		142,359
Utility margin	$	130,294	$	127,300