Pension and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2016

Pension and Other Postretirement Benefit Expense [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	Postretirement Benefit Plans
	Pension Benefits						Other Benefits
In thousands	2016			2015			2016			2015
Reconciliation of change in benefit obligation:
Obligation at January 1	$	445,628		$	487,278		$	31,049		$	32,072
Service cost	7,083			8,267			391			527
Interest cost	18,399			18,360			1,175			1,179
Plan amendments(1)	—			—			—			(3,435		)
Net actuarial (gain) loss	7,688			(32,354		)	(1,488		)	2,724
Benefits paid	(20,959		)	(35,923		)	(1,732		)	(2,018		)
Obligation at December 31	$	457,839		$	445,628		$	29,395		$	31,049
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	$	249,338		$	279,164		$	—		$	—
Actual return on plan assets	12,593			(9,599		)	—			—
Employer contributions	16,742			15,696			1,732			2,018
Benefits paid	(20,959		)	(35,923		)	(1,732		)	(2,018		)
Fair value of plan assets at December 31	$	257,714		$	249,338		$	—		$	—
Funded status at December 31	$	(200,125	)	$	(196,290	)	$	(29,395	)	$	(31,049	)

Schedule Of Amounts Recognized In Regulatory Assets Or Other Comprehensive Income Loss [Table Text Block]

	Regulatory Assets																		Other Comprehensive Loss (Income)
	Pension Benefits									Other Postretirement Benefits									Pension Benefits
In thousands	2016			2015			2014			2016			2015			2014			2016			2015			2014
Net actuarial loss (gain)	$	14,005		$	419		$	83,027		$	(1,488	)	$	2,724		$	3,454		$	(1,196	)	$	(2,549	)	$	7,221
Settlement Loss	—			—			—			—			—			—			193			—			—
Amortization of:
Prior service cost	(230		)	(230		)	(230		)	468			(197		)	(197		)	—			—			7
Actuarial loss	(13,238		)	(16,372		)	(9,823		)	(705		)	(554		)	(221		)	1,386			(2,236		)	(1,091		)
Total	$	537		$	(16,183	)	$	72,974		$	(1,725	)	$	1,973		$	3,036		$	383		$	(4,785	)	$	6,137

Schedule Of Defined Benefit Plan Amounts In AOCL And Regulatory Assets [Table Text Block]

	Regulatory Assets										AOCL
	Pension Benefits				Other Postretirement Benefits						Pension Benefits
In thousands	2016		2015		2016			2015			2016		2015
Prior service cost (credit)	$	176	$	406	$	(2,675	)	$	(3,143	)	$	1	$	1
Net actuarial loss	177,660		176,894		7,874			10,067			11,434		11,870
Total	$	177,836	$	177,300	$	5,199		$	6,924		$	11,435	$	11,871

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

	Year Ended December 31,
In thousands	2016			2015
Beginning balance	$	(7,162	)	$	(10,076	)
Amounts reclassified to AOCL	(1,196		)	2,549
Amounts reclassified from AOCL:
Amortization of actuarial losses	1,386			—
Loss from plan settlement	193			2,236
Total reclassifications before tax	383			4,785
Tax (benefit) expense	(172		)	(1,871		)
Total reclassifications for the period	211			2,914
Ending balance	$	(6,951	)	$	(7,162	)

Schedule of Allocation of Plan Assets [Table Text Block]

Asset Category	Target Allocation
U.S. large cap equity	18.0	%
U.S. small/mid cap equity	10.0
Non-U.S. equity	18.0
Emerging markets equity	5.0
Long government/credit	20.0
High yield bonds	5.0
Emerging market debt	5.0
Real estate funds	7.0
Absolute return strategy	12.0

In thousands	December 31, 2016
Investments	Level 1		Level 2		Level 3		Non-Published NAV(1)		Total
U.S. large cap equity	$	49,841	$	—	$	—	$	5,655	$	55,496
U.S. small/mid cap equity	18,629		—		—		10,232		28,861
Non-U.S. equity	22,404		—		—		25,346		47,750
Emerging markets equity	—		—		—		13,457		13,457
Fixed income	—		—		—		6,719		6,719
Long government/credit	—		34,955		—		17,960		52,915
High yield bonds	—		—		—		14,072		14,072
Emerging market debt	—		—		—		8,504		8,504
Real estate	17,857		—		—		882		18,739
Absolute return strategy	—		—		—		3,111		3,111
Cash and cash equivalents	9		—		—		2,482		2,491
Total investments	$	108,740	$	34,955	$	—	$	108,420	$	252,115
	December 31, 2015
Investments	Level 1		Level 2		Level 3		Non-Published NAV(1)		Total
U.S. large cap equity	$	44,528	$	—	$	—	$	—	$	44,528
U.S. small/mid cap equity	23,495		—		—		—		23,495
Non-U.S. equity	20,725		—		—		22,823		43,548
Emerging markets equity	—		—		—		11,120		11,120
Fixed income	—		—		—		—		—
Long government/credit	—		35,656		—		12,800		48,456
High yield bonds	—		—		—		12,298		12,298
Emerging market debt	7,746		—		—		—		7,746
Real estate	17,261		—		—		—		17,261
Absolute return strategy	—		—		—		36,758		36,758
Cash and cash equivalents	49		—		—		4,067		4,116
Total investments	$	113,804	$	35,656	$	—	$	99,866	$	249,326
					December 31,
					2016				2015
Receivables:
Accrued interest and dividend income					$	451			$	486
Due from broker for securities sold					5,170				88
Total receivables					$	5,621			$	574
Liabilities:
Due to broker for securities purchased					$	22			$	562
Total investment in retirement trust					$	257,714			$	249,338

Schedule of Net Benefit Costs [Table Text Block]

	Pension Benefits									Other Postretirement Benefits
In thousands	2016			2015			2014			2016			2015			2014
Service cost	$	7,083		$	8,267		$	7,213		$	391		$	527		$	483
Interest cost	18,399			18,360			18,198			1,175			1,179			1,252
Expected return on plan assets	(20,054		)	(20,676		)	(19,496		)	—			—			—
Amortization of prior service costs	231			231			223			(468		)	197			197
Amortization of net actuarial loss	14,624			18,609			10,914			705			554			221
Settlement expense	193			—			—			—			—			—
Net periodic benefit cost	20,476			24,791			17,052			1,803			2,457			2,153
Amount allocated to construction	(5,746		)	(6,834		)	(4,625		)	(600		)	(808		)	(702		)
Amount deferred to regulatory balancing account(1)	(6,252		)	(8,241		)	(4,578		)	—			—			—
Net amount charged to expense	$	8,478		$	9,716		$	7,849		$	1,203		$	1,649		$	1,451

Sensitivity Analysis Of Retirement Benefit Costs and Benefit Obligations [Table Text Block]

	Pension Benefits						Other Postretirement Benefits
	2016		2015		2014		2016		2015		2014
Assumptions for net periodic benefit cost:
Weighted-average discount rate	4.17	%	3.82	%	4.71	%	4.00	%	3.74	%	4.45	%
Rate of increase in compensation	3.25-4.5%		3.25-5.0%		3.25-5.0%		n/a		n/a		n/a
Expected long-term rate of return	7.50	%	7.50	%	7.50	%	n/a		n/a		n/a
Assumptions for year-end funded status:
Weighted-average discount rate	4.00	%	4.21	%	3.85	%	3.85	%	4.00	%	3.74	%
Rate of increase in compensation	3.25-4.5%		3.25-4.5%		3.25-5.0%		n/a		n/a		n/a
Expected long-term rate of return	7.50	%	7.50	%	7.50	%	n/a		n/a		n/a

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

In thousands	1% Increase		1% Decrease
Effect on net periodic postretirement health care benefit cost	$	51	$	(45	)
Effect on the accumulated postretirement benefit obligation	644		(577		)

Defined Benefit Plan Estimated Future Employer Contributions Benefit Payments and Estimated Future Payments [Table Text Block]

In thousands	Pension Benefits		Other Benefits
Employer Contributions:
2015	$	15,696	$	2,018
2016	16,742		1,732
2017 (estimated)	21,380		1,876
Benefit Payments:
2014	19,932		1,871
2015	35,923		2,018
2016	20,959		1,732
Estimated Future Benefit Payments:
2017	22,171		1,876
2018	23,088		1,893
2019	23,953		1,977
2020	24,782		2,020
2021	25,690		2,054
2022-2026	136,699		10,189