Environmental Matters (Tables)

6 Months Ended

Jun. 30, 2016

Environmental Remediation Obligations [Abstract]

Schedule of Environmental Loss Contingencies by Site [Table Text Block]

	Current Liabilities						Non-Current Liabilities
	June 30,				December 31,		June 30,				December 31,
In thousands	2016		2015		2015		2016		2015		2015
Portland Harbor site:
Gasco/Siltronic Sediments	$	1,777	$	1,512	$	2,229	$	42,991	$	38,342	$	42,641
Other Portland Harbor	1,580		1,208		1,972		4,541		4,941		5,073
Gasco Upland site	9,033		5,938		10,599		51,081		37,031		52,117
Siltronic Upland site	—		710		951		352		390		337
Central Service Center site	112		153		25		—		—		—
Front Street site	984		665		1,155		7,739		107		7,748
Oregon Steel Mills	—		—		—		179		179		179
Total	$	13,486	$	10,186	$	16,931	$	106,883	$	80,990	$	108,095

Environmental Regulatory Table [Table Text Block]

	June 30,						December 31,
In thousands	2016			2015			2015
Deferred costs and interest(1)	$	53,065		$	79,135		$	79,505
Accrued site liabilities(2)	120,075			91,176			125,026
Insurance proceeds and interest	(97,547		)	(120,394		)	(118,677		)
Total regulatory asset deferral(1)	75,593			49,917			85,854
Current regulatory assets(3)	9,610			—			9,270
Long-term regulatory assets	65,983			49,917			76,584