Note 4 - Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Regulatory Assets and Liabilities [Table Text Block]

	December 31 , 2017								Remaining Recovery/
(in thousands)	Current		Long-Term			Total			Refund Period (months)
Regulatory Assets:
Prior Service Costs and Actuarial Losses on Pensions and Other Postretirement Benefits 1	$	9,090	$	112,487		$	121,577		see below
Conservation Improvement Program Costs and Incentives 2		7,385		2,774			10,159			21
Accumulated ARO Accretion/Depreciation Adjustment 1		--		6,651			6,651		asset lives
Deferred Marked-to-Market Losses 1		4,063		2,405			6,468			36
Big Stone II Unrecovered Project Costs – Minnesota 1		650		1,636			2,286			40
MISO Schedule 26/26A Transmission Cost Recovery Rider True-up 2		--		1,985			1,985			24
Debt Reacquisition Premiums 1		254		960			1,214			177
Big Stone II Unrecovered Project Costs – South Dakota 2		100		442			542			65
North Dakota Renewable Resource Rider Accrued Revenues 2		206		236			442			15
North Dakota Deferred Rate Case Expenses Subject to Recovery 1		309		--			309			12
Minnesota Deferred Rate Case Expenses Subject to Recovery 1		267		--			267			4
North Dakota Environmental Cost Recovery Rider Accrued Revenues 2		152		--			152			12
Minnesota E nergy Intensive Trade Exposed Rider Accrued Revenues 2		75		--			75			12
Total Regulatory Assets	$	22,551	$	129,576		$	152,127
Regulatory Liabilities:
Deferred Income Taxes	$	--	$	149,052		$	149,052		asset lives
Accumulated Reserve for Estimated Removal Costs – Net of Salvage		--		83,100			83,100		asset lives
Re fundable Fuel Clause Adjustment Revenues		5,778		--			5,778			12
Minnesota Environmental Cost Recovery Rider Accrued Refund		1,667		--			1,667			11
Minnesota Transmission Cost Recovery Rider Accrued Refund		802		609			1,411			22
Minnesota Renewable Resource Recovery Rider Accrued Refund		409		--			409			12
North Dakota Transmission Cost Recovery Rider Accrued Refund		349		--			349			12
Revenue for Rate Case Expenses Subject to Refund – Minnesota		208		--			208			4
South Dakota Environmental Cost Recovery Rider Accrued Refund		187		--			187			12
MISO Schedule 26/26A Transmission Cost Recovery Rider True-up		132		48			180			24
South Dakota Transmission Cost Recovery Rider Accrued Refund		151		--			151			12
Other		5		84			89			192
Total Regulatory Liabilities	$	9,688	$	232,893		$	242,581
Net Regulatory Asset /(Liability) Position	$	12,863	$	(103,317	)	$	(90,454	)

	December 31, 2016						Remaining Recovery/
(in thousands)	Current		Long-Term		Total		Refund Period (months)
Regulatory Assets:
Prior Service Costs and Actuarial Losses on Pensions and Other Postretirement Benefits 1	$	6,443	$	108,267	$	114,710	see below
Conservation Improvement Program Costs and Incentives 2		4,836		5,158		9,994		21
Accumulated ARO Accretion/Depreciation Adjustment 1		--		6,153		6,153	asset lives
Deferred Marked-to-Market Losses 1		4,063		6,467		10,530		48
Big Stone II Unrecovered Project Costs – Minnesota 1		778		2,087		2,865		52
MISO Schedule 26/26A Transmission Cost Recovery Rider True-up 2		333		--		333		12
Debt Reacquisition Premiums 1		325		1,214		1,539		189
Big Stone II Unrecovered Project Costs – South Dakota 2		100		543		643		77
North Dakota Renewable Resource Rider Accrued Revenues 2		1,319		482		1,801		15
Minnesota Deferred Rate Case Expenses Subject to Recovery 1		1,082		--		1,082		12
North Dakota Environmental Cost Recovery Rider Accrued Revenues 2		113		--		113		12
Deferred Income Taxes 1		--		1,014		1,014	asset lives
Recoverable Fuel and Purchased Power Costs 1		1,798		--		1,798		12
Minnesota Renewable Resource Rider Accrued Revenues 2		34		--		34		9
North Dakota Transmission Cost Recovery Rider Accrued Revenues 2		--		568		568		24
South Dakota Transmission Cost Recovery Rider Accrued Revenues 2		73		141		214		14
Total Regulatory Assets	$	21,297	$	132,094	$	153,391
Regulatory Liabilities:
Deferred Income Taxes	$	--	$	818	$	818	asset lives
Accumulated Reserve for Estimated Removal Costs – Net of Salvage		--		80,404		80,404	asset lives
Minnesota Environmental Cost Recovery Rider Accrued Refund		139		--		139		12
Minnesota Transmission Cost Recovery Rider Accrued Refund		757		--		757		12
North Dakota Transmission Cost Recovery Rider Accrued Refund		1,381		782		2,163		24
Revenue for Rate Case Expenses Subject to Refund – Minnesota		711		208		919		16
South Dakota Environmental Cost Recovery Rider Accrued Refund		285		--		285		12
MISO Schedule 26/26A Transmission Cost Recovery Rider True-up		--		132		132		24
Other		21		89		110		204
Total Regulatory Liabilities	$	3,294	$	82,433	$	85,727
Net Regulatory Asset Position	$	18,003	$	49,661	$	67,664