Summary of Significant Accounting Policies (tables)

9 Months Ended

Sep. 30, 2014

Accounting Policies [Abstract]

Schedule of Regulatory Assets [Table Text Block]

	Regulatory Assets
	September 30,				December 31,
In thousands	2014		2013		2013
Current:
Unrealized loss on derivatives(1)	$	5,520	$	8,275	$	1,891
Gas costs	23,795		—		4,286
Other(2)	22,935		18,018		16,458
Total current	$	52,250	$	26,293	$	22,635
Non-current:
Unrealized loss on derivatives(1)	$	551	$	1,404	$	615
Pension balancing(3)	30,682		22,976		25,713
Deferred income taxes	49,007		53,065		51,814
Pension and other postretirement benefit liabilities(3)	118,485		187,000		125,855
Environmental costs(4)	51,861		118,029		148,389
Gas costs	1,936		—		1,840
Other(2)	10,799		5,202		15,377
Total non-current	$	263,321	$	387,676	$	369,603

Schedule of Regulatory Liabilities [Table Text Block]

	Regulatory Liabilities
	September 30,				December 31,
In thousands	2014		2013		2013
Current:
Gas costs	$	6,704	$	3,096	$	7,510
Unrealized gain on derivatives(1)	5,320		1,386		5,290
Other(2)	11,328		12,024		15,535
Total current	$	23,352	$	16,506	$	28,335
Non-current:
Gas costs	$	410	$	11	$	2,172
Unrealized gain on derivatives(1)	602		1,682		1,880
Accrued asset removal costs	307,815		293,005		296,294
Other(2)	3,673		3,522		3,139
Total non-current	$	312,500	$	298,220	$	303,485