Summary of Significant Accounting Policies (tables)

3 Months Ended

Mar. 31, 2014

Accounting Policies [Abstract]

Schedule of Regulatory Assets [Table Text Block]

	Regulatory Assets
	March 31,				December 31,
In thousands	2014		2013		2013
Current:
Unrealized loss on derivatives(1)	$	1,191	$	3,450	$	1,891
Other(2)	26,643		35,551		20,744
Total current	$	27,834	$	39,001	$	22,635
Non-current:
Unrealized loss on derivatives(1)	$	96	$	642	$	615
Pension balancing(3)	27,328		17,322		25,713
Deferred income taxes	49,007		53,065		51,814
Pension and other postretirement benefit liabilities(3)	123,399		178,377		125,855
Environmental costs(4)	63,517		125,671		148,389
Other(2)	21,699		9,376		17,217
Total non-current	$	285,046	$	384,453	$	369,603

Schedule of Regulatory Liabilities [Table Text Block]

	Regulatory Liabilities
	March 31,				December 31,
In thousands	2014		2013		2013
Current:
Gas costs	$	9,137	$	8,694	$	7,510
Unrealized gain on derivatives(1)	15,788		8,054		5,290
Other(2)	12,761		11,491		15,535
Total current	$	37,686	$	28,239	$	28,335
Non-current:
Gas costs	$	2,602	$	1,407	$	2,172
Unrealized gain on derivatives(1)	1,078		2,836		1,880
Accrued asset removal costs	299,026		285,437		296,294
Other(2)	6,152		3,455		3,139
Total non-current	$	308,858	$	293,135	$	303,485