Environmental Matters (Tables)

3 Months Ended

Mar. 31, 2016

Environmental Remediation Obligations [Abstract]

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

	Current Liabilities						Non-Current Liabilities
	March 31,				December 31,		March 31,				December 31,
In thousands	2016		2015		2015		2016		2015		2015
Portland Harbor site:
Gasco/Siltronic Sediments	$	2,747	$	1,572	$	2,229	$	42,079	$	38,379	$	42,641
Other Portland Harbor	1,655		1,308		1,972		4,775		5,186		5,073
Gasco Upland site	10,405		8,205		10,599		51,070		36,833		52,117
Siltronic Upland site	221		750		951		333		405		337
Central Service Center site	25		170		25		—		—		—
Front Street site	1,071		755		1,155		7,746		115		7,748
Oregon Steel Mills	—		—		—		179		179		179
Total	$	16,124	$	12,760	$	16,931	$	106,182	$	81,097	$	108,095

Environmental Regulatory Table [Table Text Block]

	March 31,						December 31,
In thousands	2016			2015			2015
Deferred costs and interest(1)	$	57,359		$	76,790		$	79,505
Accrued site liabilities	122,306			93,858			125,026
Insurance proceeds and interest	(102,570		)	(120,473		)	(118,677		)
Total regulatory asset deferral(1)	77,095			50,175			85,854
Current regulatory assets(2)	9,096			—			9,270
Long-term regulatory assets	67,999			50,175			76,584