Pension and Other Postretirement Benefits (tables)

3 Months Ended

Mar. 31, 2015

General Discussion of Pension and Other Postretirement Benefits [Abstract]

Net Periodic Benefit Cost Components

	Three Months Ended March 31,
							Other Postretirement
	Pension Benefits						Benefits
In thousands	2015			2014			2015			2014
Service cost	$	2,308		$	1,918		$	145		$	136
Interest cost	4,596			4,512			291			309
Expected return on plan assets	(5,174		)	(4,886		)	—			—
Amortization of net actuarial loss	4,561			2,580			126			46
Amortization of prior service costs	58			56			49			49
Net periodic benefit cost	6,349			4,180			611			540
Amount allocated to construction	(1,825		)	(1,201		)	(191		)	(171		)
Amount deferred to regulatory balancing account(1)	(2,175		)	(1,101		)	—			—
Net amount charged to expense	$	2,349		$	1,878		$	420		$	369

Schedule Of Accumulated Other Comprehensive Income Loss Rollforward [Table Text Block]

	Three Months Ended March 31,
In thousands	2015			2014
Beginning balance	$	(10,076	)	$	(6,358	)
Amounts reclassified from AOCL:
Amortization of prior service costs	—			(2		)
Amortization of actuarial losses	548			276
Total reclassifications before tax	548			274
Tax expense	(216		)	(109		)
Total reclassifications for the period	332			165
Ending balance	$	(9,744	)	$	(6,193	)