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Note 4 - Regulatory Assets and Liabilities - Amount of Regulatory Assets and Liabilities Recorded on Consolidated Balance Sheets (Details) - USD ($) $ in Thousands | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2020 | Dec. 31, 2019
Regulatory Assets - Current |  | $ 19,958 | $ 21,650
Regulatory Assets - Long -Term |  | 141,063 | 144,138
Regulatory Assets - Total |  | 161,021 | 165,788
Regulatory Liabilities - Current |  | 13,023 | 7,480
Regulatory Liabilities - Long -Term |  | 238,160 | 239,906
Regulatory Liabilities - Total |  | 251,183 | 247,386
Net Regulatory Asset Position - Current |  | 6,935 | 14,170
Net Regulatory Asset Position - Long-Term |  | (97,097) | (95,768)
Net Regulatory Asset/(Liability) Position |  | (90,162) | (81,598)
Deferred Income Taxes [Member] |  |  |
Regulatory Liabilities - Current |  | 0 | 0
Regulatory Liabilities - Long -Term |  | 138,517 | 141,707
Regulatory Liabilities - Total |  | 138,517 | 141,707
Accumulated Reserve for Estimated Removal Costs - Net of Salvage [Member] |  |  |
Regulatory Liabilities - Current |  | 0 | 0
Regulatory Liabilities - Long -Term |  | 99,055 | 97,726
Regulatory Liabilities - Total |  | 99,055 | 97,726
Refundable Fuel Clause Adjustment Revenues [Member] |  |  |
Regulatory Liabilities - Current |  | 10,241 | 3,982
Regulatory Liabilities - Long -Term |  | 0 | 0
Regulatory Liabilities - Total |  | $ 10,241 | $ 3,982
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 12 months | 12 months
North Dakota Transmission Cost Recovery Rider Accrued Refund [Member] |  |  |
Regulatory Liabilities - Current |  | $ 1,010 | $ 700
Regulatory Liabilities - Long -Term |  | 0 | 0
Regulatory Liabilities - Total |  | $ 1,010 | $ 700
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 6 months | 12 months
South Dakota Phase-in Rate Plan Rider Accrued Refund [Member] |  |  |
Regulatory Liabilities - Current |  | $ 783 | $ 355
Regulatory Liabilities - Long -Term |  | 0 | 0
Regulatory Liabilities - Total |  | $ 783 | $ 355
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 2 months | 9 months
Revenue for Rate Case Expenses Subject to Refund - Minnesota [Member] |  |  |
Regulatory Liabilities - Current |  | $ 0 | $ 0
Regulatory Liabilities - Long -Term |  | 518 | 401
Regulatory Liabilities - Total |  | 518 | 401
Prior Service Costs and Actuarial Losses on Pensions and Other Postretirement Benefits [Member] |  |  |
Regulatory Liabilities - Current |  | 471 | 471
Regulatory Liabilities - Long -Term |  | 0 | 0
Regulatory Liabilities - Total |  | $ 471 | $ 471
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 12 months | 12 months
Minnesota Energy Intensive Trade Exposed Rider Accrued Refund [Member] |  |  |
Regulatory Liabilities - Current |  | $ 198 | $ 164
Regulatory Liabilities - Long -Term |  | 0 | 0
Regulatory Liabilities - Total |  | $ 198 | $ 164
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 3 months | 12 months
South Dakota Transmission Cost Recovery Rider Accrued Refund [Member] |  |  |
Regulatory Liabilities - Current |  | $ 159 |
Regulatory Liabilities - Long -Term |  | 0 |
Regulatory Liabilities - Total |  | $ 159 |
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 8 months |
North Dakota Renewable Resource Recovery Rider Accrued Refund [Member] |  |  |
Regulatory Liabilities - Current |  | $ 156 | $ 1,515
Regulatory Liabilities - Long -Term |  | 0 | 0
Regulatory Liabilities - Total |  | $ 156 | $ 1,515
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 9 months | 12 months
North Dakota Generation Cost Recovery Rider Accrued Refund [Member] |  |  |
Regulatory Liabilities - Current |  |  | $ 287
Regulatory Liabilities - Long -Term |  |  | 0
Regulatory Liabilities - Total |  |  | $ 287
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  |  | 6 months
Other [Member] |  |  |
Regulatory Liabilities - Current |  | $ 5 | $ 6
Regulatory Liabilities - Long -Term |  | 70 | 72
Regulatory Liabilities - Total |  | $ 75 | $ 78
Regulatory Liabilities - Remaining Recovery/Refund Period (Month) |  | 162 months | 168 months
Prior Service Costs and Actuarial Losses on Pensions and Other Postretirement Benefits [Member] |  |  |
Regulatory Assets - Current | [1] | $ 9,018 | $ 9,090
Regulatory Assets - Long -Term | [1] | 124,901 | 129,102
Regulatory Assets - Total | [1] | 133,919 | 138,192
Accumulated Asset Retirement Obligation (ARO) Accretion/Depreciation Adjustment [Member] |  |  |
Regulatory Assets - Current | [1] | 0 | 0
Regulatory Assets - Long -Term | [1] | 8,243 | 7,772
Regulatory Assets - Total | [2] | 8,243 | 7,772
Minnesota Transmission Cost Recovery Rider Accrued Revenues [Member] |  |  |
Regulatory Assets - Current | [2] | 6,563 | 4,208
Regulatory Assets - Long -Term | [2] | 0 | 0
Regulatory Assets - Total | [2] | $ 6,563 | $ 4,208
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [2] | 12 months | 12 months
Conservation Improvement Program Costs and Incentives [Member] |  |  |
Regulatory Assets - Current | [2] | $ 276 | $ 4,024
Regulatory Assets - Long -Term | [2] | 3,553 | 2,844
Regulatory Assets - Total | [2] | $ 3,829 | $ 6,868
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [2] | 27 months | 21 months
MISO Schedule 26/26A Transmission Cost Recovery Rider True-up [Member] |  |  |
Regulatory Assets - Current | [1] | $ 1,500 | $ 2,033
Regulatory Assets - Long -Term | [1] | 963 | 968
Regulatory Assets - Total | [1] | $ 2,463 | $ 3,001
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 30 months | 24 months
Nonservice Costs Components of Postretirement Benefits Capitalized for Ratemaking Purposes and Subject to Deferred Recovery [Member] |  |  |
Regulatory Assets - Current | [1] | $ 0 | $ 0
Regulatory Assets - Long -Term | [1] | 1,974 | 1,681
Regulatory Assets - Total | [1] | 1,974 | 1,681
Minnesota Renewable Resource Rider Accrued Revenues [Member] |  |  |
Regulatory Assets - Current | [2] | 722 | 131
Regulatory Assets - Long -Term | [2] | 0 | 0
Regulatory Assets - Total | [2] | $ 722 | $ 131
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 12 months | 12 months
Debt Reacquisition Premiums [Member] |  |  |
Regulatory Assets - Current | [1] | $ 204 | $ 201
Regulatory Assets - Long -Term | [1] | 430 | 548
Regulatory Assets - Total | [1] | $ 634 | $ 749
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 147 months | 153 months
Big Stone II Unrecovered Project Costs - Minnesota [Member] |  |  |
Regulatory Assets - Current | [1] | $ 583 | $ 715
Regulatory Assets - Long -Term | [1] | 0 | 225
Regulatory Assets - Total | [1] | $ 583 | $ 940
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 10 months | 16 months
Minnesota SPP Transmission Cost Recovery Tracker [Member] |  |  |
Regulatory Assets - Current | [1] | $ 0 | $ 0
Regulatory Assets - Long -Term | [1] | 401 | 202
Regulatory Assets - Total | [1] | 401 | 202
Deferred Marked-to-Market Losses [Member] |  |  |
Regulatory Assets - Current | [1] | 372 | 743
Regulatory Assets - Total | [1] | $ 372 | $ 743
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 6 months | 12 months
Big Stone II Unrecovered Project Costs - South Dakota [Member] |  |  |
Regulatory Assets - Current | [1] | $ 144 | $ 144
Regulatory Assets - Long -Term | [1] | 180 | 253
Regulatory Assets - Total | [1] | $ 324 | $ 397
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 27 months | 33 months
South Dakota Deferred Rate Case Expenses Subject to Recovery [Member] |  |  |
Regulatory Assets - Current | [1] | $ 138 | $ 138
Regulatory Assets - Long -Term | [1] | 177 | 245
Regulatory Assets - Total | [1] | $ 315 | $ 383
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 28 months | 34 months
North Dakota Generation Cost Recovery Rider Accrued Revenues [Member] |  |  |
Regulatory Assets - Current | [2] | $ 312 |
Regulatory Assets - Long -Term | [2] | 0 |
Regulatory Assets - Total | [2] | $ 312 |
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [2] | 12 months |
North Dakota Deferred Rate Case Expenses Subject to Recovery [Member] |  |  |
Regulatory Assets - Current | [1] | $ 122 | $ 122
Regulatory Assets - Long -Term | [1] | 183 | 244
Regulatory Assets - Total | [1] | $ 305 | $ 366
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 30 months | 36 months
Deferred Lease Expenses [Member] |  |  |
Regulatory Assets - Current | [1] | $ 0 | $ 0
Regulatory Assets - Long -Term | [1] | 58 | 54
Regulatory Assets - Total | [1] | $ 58 | $ 54
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [1] | 33 months | 39 months
Minnesota Environmental Cost Recovery Rider Accrued Revenues [Member] |  |  |
Regulatory Assets - Current | [2] | $ 4 | $ 4
Regulatory Assets - Long -Term | [2] | 0 | 0
Regulatory Assets - Total | [2] | $ 4 | $ 4
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [2] | 12 months | 12 months
South Dakota Transmission Cost Recovery Rider Accrued Revenues [Member] |  |  |
Regulatory Assets - Current | [2] |  | $ 97
Regulatory Assets - Long -Term | [2] |  | 0
Regulatory Assets - Total | [2] |  | $ 97
Regulatory Assets - Remaining Recovery/Refund Period (Month) | [2] |  | 2 months
[1] | Costs subject to recovery without a rate of return.
[2] | Amount eligible for recovery under an alternative revenue program which includes an incentive or rate of return.

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- Definition Amortization period for the recovery of regulatory asset, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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