Pension and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2016

Pension and Other Postretirement Benefit Expense [Abstract]

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

	Three Months Ended June 30,						Six Months Ended June 30,
In thousands	2016			2015			2016			2015
Beginning balance	$	(6,968	)	$	(9,744	)	$	(7,162	)	$	(10,076	)
Amounts reclassified from AOCL:
Amortization of actuarial losses	269			548			590			1,096
Total reclassifications before tax	269			548			590			1,096
Tax (benefit) expense	(126		)	(217		)	(253		)	(433		)
Total reclassifications for the period	143			331			337			663
Ending balance	$	(6,825	)	$	(9,413	)	$	(6,825	)	$	(9,413	)

Schedule of Net Benefit Costs [Table Text Block]

	Three Months Ended June 30,												Six Months Ended June 30,
	Pension Benefits						Other Postretirement Benefits						Pension Benefits						Other Postretirement Benefits
In thousands	2016			2015			2016			2015			2016			2015			2016			2015
Service cost	$	1,944		$	2,309		$	121		$	145		$	3,888		$	4,618		$	242		$	290
Interest cost	4,574			4,595			300			292			9,148			9,190			600			583
Expected return on plan assets	(5,017		)	(5,174		)	—			—			(10,034		)	(10,348		)	—			—
Amortization of net actuarial loss	3,502			4,561			192			125			7,004			9,122			384			251
Amortization of prior service costs	58			58			(117		)	49			116			116			(234		)	98
Net periodic benefit cost	5,061			6,349			496			611			10,122			12,698			992			1,222
Amount allocated to construction	(1,574		)	(1,879		)	(164		)	(198		)	(3,122		)	(3,704		)	(328		)	(389		)
Amount deferred to regulatory balancing account(1)	(1,593		)	(2,165		)	—			—			(3,220		)	(4,340		)	—			—
Net amount charged to expense	$	1,894		$	2,305		$	332		$	413		$	3,780		$	4,654		$	664		$	833