Pension and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2016

Pension and Other Postretirement Benefit Expense [Abstract]

Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]

	Three Months Ended March 31,
In thousands	2016			2015
Beginning balance	$	(7,162	)	$	(10,076	)
Amounts reclassified from AOCL:
Amortization of actuarial losses	321			548
Total reclassifications before tax	321			548
Tax (benefit) expense	(127		)	(216		)
Total reclassifications for the period	194			332
Ending balance	$	(6,968	)	$	(9,744	)

Schedule of Net Benefit Costs [Table Text Block]

	Three Months Ended March 31,
	Pension Benefits						Other Postretirement Benefits
In thousands	2016			2015			2016			2015
Service cost	$	1,944		$	2,308		$	121		$	145
Interest cost	4,574			4,596			300			291
Expected return on plan assets	(5,017		)	(5,174		)	—			—
Amortization of net actuarial loss	3,502			4,561			192			126
Amortization of prior service costs	58			58			(117		)	49
Net periodic benefit cost	5,061			6,349			496			611
Amount allocated to construction	(1,548		)	(1,825		)	(164		)	(191		)
Amount deferred to regulatory balancing account(1)	(1,627		)	(2,175		)	—			—
Net amount charged to expense	$	1,886		$	2,349		$	332		$	420