Summary of Significant Accounting Policies (tables)

12 Months Ended

Dec. 31, 2012

Accounting Policies [Abstract]

Schedule of Regulatory Assets [Table Text Block]

	Regulatory Assets
In thousands	2012		2011
Current:
Unrealized loss on derivatives(1)	$	10,796	$	57,317
Pension and other postretirement benefit liabilities(2)	17,247		15,491
Other(3)	24,405		21,865
Total current	$	52,448	$	94,673
Non-current:
Unrealized loss on derivatives(1)	$	578	$	6,536
Pension balancing(2)	15,022		6,008
Income tax asset	55,879		65,264
Pension and other postretirement benefit liabilities(2)	182,688		170,512
Environmental costs(4)	126,482		105,670
Other(3)	7,239		17,402
Total non-current	$	387,888	$	371,392

Schedule of Regulatory Liabilities [Table Text Block]

	Regulatory Liabilities
In thousands	2012		2011
Current:
Gas costs	$	9,100	$	17,994
Unrealized gain on derivatives(1)	1,950		2,853
Other(3)	9,742		10,199
Total current	$	20,792	$	31,046
Non-current:
Gas costs	$	—	$	8,420
Unrealized gain on derivatives(1)	3,639		—
Accrued asset removal costs	281,213		267,355
Other(3)	3,261		2,607
Total non-current	$	288,113	$	278,382