Summary of Significant Accounting Policies (tables)

6 Months Ended

Jun. 30, 2014

Accounting Policies [Abstract]

Schedule of Regulatory Assets [Table Text Block]

	Regulatory Assets
	June 30,				December 31,
In thousands	2014		2013		2013
Current:
Unrealized loss on derivatives(1)	$	1,466	$	9,392	$	1,891
Gas costs	19,268		—		4,286
Other(2)	17,531		16,560		16,458
Total current	$	38,265	$	25,952	$	22,635
Non-current:
Unrealized loss on derivatives(1)	$	191	$	1,754	$	615
Pension balancing(3)	28,997		20,327		25,713
Deferred income taxes	49,007		53,065		51,814
Pension and other postretirement benefit liabilities(3)	120,942		191,312		125,855
Environmental costs(4)	52,117		120,224		148,389
Gas costs	3,768		5,322		1,105
Other(2)	12,226		1,648		16,112
Total non-current	$	267,248	$	393,652	$	369,603

Schedule of Regulatory Liabilities [Table Text Block]

	Regulatory Liabilities
	June 30,				December 31,
In thousands	2014		2013		2013
Current:
Gas costs	$	6,423	$	6,353	$	7,510
Unrealized gain on derivatives(1)	11,286		547		5,290
Other(2)	9,033		9,744		15,535
Total current	$	26,742	$	16,644	$	28,335
Non-current:
Gas costs	$	1,057	$	481	$	2,172
Unrealized gain on derivatives(1)	1,202		1,054		1,880
Accrued asset removal costs	303,567		289,105		296,294
Other(2)	3,501		3,562		3,139
Total non-current	$	309,327	$	294,202	$	303,485