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v3.19.3.a.u2

Note 3 - Rate and Regulatory Matters (Details Textual) - USD ($) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 2 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 21, 2019 | Jul. 16, 2019 | Jul. 09, 2019 | Jun. 11, 2019 | May 30, 2019 | Sep. 26, 2018 | Apr. 20, 2018 | Mar. 23, 2018 | Mar. 22, 2018 | Nov. 17, 2017 | Nov. 16, 2016 | Sep. 28, 2016 | May 25, 2016 | Feb. 12, 2015 | Jan. 05, 2015 | Nov. 06, 2014 | Nov. 12, 2013 | Apr. 30, 2019 | Jun. 30, 2016 | Dec. 22, 2015 | Sep. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Mar. 01, 2018 | Jan. 01, 2018 | Nov. 02, 2017 | Oct. 31, 2017 | Dec. 31, 2016 | Apr. 16, 2016
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 21.00% | 21.00% | 35.00% |  |  |  |  |  |
Regulatory Liabilities, Total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 247,386,000 | $ 227,207,000 |  |  |  |  |  |  |
Minnesota1 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Effect of Tax Cuts and Jobs Act, Refund to Customers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 11,500,000 |  |  |  |  |  |  |  |  |  |
Federal Energy Regulatory Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional Refund from Reducing ROE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 200,000 |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Environmental Cost Recovery Rider Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.00% |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Litigation Case with Minnesota Customers [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingency, Estimate of Possible Loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,600,000 |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Federal Energy Regulatory Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current Return on Equity Used in Transmission Rates |  |  |  |  |  |  |  |  |  |  |  | 10.32% |  |  |  |  | 12.38% |  |  | 10.32% |  |  | 12.38% |  |  |  |  |  |  |  |
Proposed Reduced Return on Equity Used in Transmission Rates |  |  |  |  |  |  |  |  |  |  |  | 9.88% |  | 8.67% |  |  | 9.15% |  | 9.70% |  |  |  | 9.88% |  |  |  |  |  |  |  |
Additional Incentive Basis Point |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected Percentage of Return on Equity |  |  |  |  |  |  |  |  |  |  |  | 10.82% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Liabilities, Total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,600,000 |  |  |  |  |  |  |  |  | $ 2,700,000 |
Contract with Customer, Refund Liability, Total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,000,000.0 | $ 1,600,000 |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Federal Energy Regulatory Commission [Member] | First Complaint Period [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current Return on Equity Used in Transmission Rates |  |  |  |  |  |  |  |  |  |  |  | 10.82% |  |  |  |  |  |  |  |  |  |  | 10.38% |  |  |  |  |  |  |  |
Additional Incentive Basis Point |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contract with Customer, Refund Liability, Total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,300,000 |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Federal Energy Regulatory Commission [Member] | Second Complaint Period [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current Return on Equity Used in Transmission Rates | 9.88% |  |  |  |  |  |  |  |  |  |  | 12.38% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional Incentive Basis Point |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contract with Customer, Refund Liability, Total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,500,000 |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Minnesota Public Utilities Commission [Member] | The 2016 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Allowed Rate of Return on Rate Base |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.5056%
Percentage of Allowed Rate of Return on Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9.41%
Estimated Interim Rate Refund |  |  |  |  |  |  |  |  |  | $ 9,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Minnesota Public Utilities Commission [Member] | Environmental Cost Recovery Rider [Member] | The 2016 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues Collected Under Riders, Subject to Customer Refund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 900,000 |  |
Otter Tail Power Company [Member] | Minnesota Public Utilities Commission [Member] | Transmission Cost Recovery Rider [Member] | The 2016 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues Collected Under Riders, Subject to Customer Refund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,400,000 |  |
Otter Tail Power Company [Member] | Minnesota Public Utilities Commission [Member] | ECR and TCR Riders [Member] | The 2016 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues Collected Under Riders, Subject to Refund, Period of Refund |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 months |  |  |  |  |  |
Otter Tail Power Company [Member] | Minnesota Public Utilities Commission [Member] | Conservation Improvement Program [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Utility Incentive Percentage in Next Rolling Twelve Months |  |  |  |  |  |  |  |  |  |  |  |  | 13.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Utility Incentive Percentage in Next Rolling Year Two |  |  |  |  |  |  |  |  |  |  |  |  | 12.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Utility Incentive Percentage in Next Rolling Year Three |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assumed Savings of Utility |  |  |  |  |  |  |  |  |  |  |  |  | 1.70% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Incentive, Maximum Percentage of Spending, Year One |  |  |  |  |  |  |  |  |  |  |  |  | 40.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Incentive, Maximum Percentage of Spending, Year Two |  |  |  |  |  |  |  |  |  |  |  |  | 35.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Incentive, Maximum Percentage of Spending, Year Three |  |  |  |  |  |  |  |  |  |  |  |  | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected Rate of Financial Incentive Reduction |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Incentives Recognized During Period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,700,000 | $ 3,000,000.0 | $ 2,900,000 |  |  |  |  |  |
Financial Incentives Reserve Increase (Decrease) During Period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (300,000) |  | 300,000 |  |  |  |  |  |
Otter Tail Power Company [Member] | Minnesota Public Utilities Commission [Member] | Conservation Improvement Program [Member] | Recognized in 2017 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Incentives Recognized During Period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,600,000 |  |  |  |  |  |
Otter Tail Power Company [Member] | North Dakota Public Service Commission [Member] | The 2010 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Allowed Rate of Return on Rate Base |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.97% |  |  |
Percentage of Allowed Rate of Return on Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.30% |  |  |
General Rate Revenue Increase Requested |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12,800,000 | $ 13,100,000 |  |  |
Percentage of Increase in Base Rate Revenue Requested |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8.72% |  |  |
Public Utilities, Interim Rate Requirement, Decrease in Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,500,000 |  |  |  |  |
Public Utilities, Interim Rate Requirement, Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,300,000 |  |  |  |  |
Otter Tail Power Company [Member] | North Dakota Public Service Commission [Member] | The 2017 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  | $ 4,600,000 |  | $ 7,100,000 | $ 13,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Percentage |  |  |  |  |  | 3.10% |  | 4.80% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Rate Revenue Increase Requested, Decrease |  |  |  |  |  |  |  | $ 6,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Rate Revenue Increase Requested, Decrease, Amount Related to Tax Reform |  |  |  |  |  |  |  | 4,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Rate Revenue Increase Requested, Decrease, Amount Related to Updates Other Than Tax Reform |  |  |  |  |  |  |  | $ 1,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Requested Allowed Rate of Return on Equity |  |  |  |  |  | 9.77% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity to Total Capitalization Ratio Basis for Return on Equity |  |  |  |  |  | 52.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Refunds of Excess Revenues Collected, Amounts Collected Under Higher Interim Tax Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 800,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | South Dakota Public Utilities Commission [Member] | The 2018 General Rate Case [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Allowed Rate of Return on Equity |  |  |  |  | 8.75% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  | $ 3,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in Annual Non-fuel Rates Requested, Step One, Percentage |  |  |  |  |  |  | 10.10% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in Annual Non-fuel Rates Requested, Step Two, Percentage |  |  |  |  |  |  | 1.70% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contract with Customer, Liability, Revenue Recognized |  |  |  |  | $ 2,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000,000.0 |  |  |  |  |  |  |  |  |
Understated Amount of OTP's Electric Transmission Plant in Service |  |  | $ 4,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual Revenue Requirement Shortfall Resulted from Understatement |  |  | 341,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in Non-fuel Annual Revenue Resulted from Increased in General Rate Case |  |  | $ 2,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in Non-fuel Annual Revenue Resulted from Increased in General Rate Case, Percentage |  |  | 7.70% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-fuel Annual Revenue Increased, Perecenage of Adjusted Requsted Annual Revenue |  |  | 69.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Adjusted Requested Annual Revenue Increased, Amount |  |  | $ 3,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Adjusted Requested Annual Revenue Increased, Percentage |  |  | 11.10% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Authorized Return of Equity |  |  | 8.75% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Excess Weather-normalized Revenue, Refund to Customer |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum ROE, Input for Refund to Customer |  |  | 9.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Any Earnings Above Maximum ROE |  |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Big Stone South - Ellendale MVP [Member] | Federal Energy Regulatory Commission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current Project Cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 106,000,000 |  |  |  |  |  |  |  |
Expanded Capacity of Projects |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 345 |  |  |  |  |  |  |  |
Percentage of Assets of Project |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | Astoria Station Project [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expanded Capacity of Projects (MW) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 245 |  |  |  |  |  |  |  |
Current Project Capitalized Cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 58,700,000 |  |  |  |  |  |  |  |
Otter Tail Power Company [Member] | EDF [Member] | Merricourt Project [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset Purchase Agreement, Purchase Price |  | $ 37,700,000 |  | $ 37,700,000 |  |  |  |  |  |  | $ 34,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Turnkey Engineering, Procurement and Construction Services Agreement, Costs |  |  |  |  |  |  |  |  |  |  | $ 200,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current Project Cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 81,700,000 |  |  |  |  |  |  |  |

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- Definition The percentage of adjusted requested annual revenue increased. + References No definition available. + Details
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- Definition Represents the amount of purchase price under the asset purchase agreement. + References No definition available. + Details
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- Definition Percentage of assumed savings compared to retail sales. + References No definition available. + Details
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- Definition The percentage of authorized return of equity. + References No definition available. + Details
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- Definition Represents the current return on equity used in MISO's transmission rates. + References No definition available. + Details
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- Definition This element represents amount of estimated interim rate refund. + References No definition available. + Details
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- Definition Represents the expanded capacity of projects, expressed as a number of kV. + References No definition available. + Details
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- Definition Represents percentage of expected return on equity. + References No definition available. + Details
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- Definition Expected rate of financial incentive compared to previous incentive mechanism. + References No definition available. + Details
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- Definition This element represents percentage of allowed rate of return on equity. + References No definition available. + Details
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- Definition Amount of public utility's interim rate requirement allowed while waiting final decision of regulatory agency. + References No definition available. + Details
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- Definition Percentage of incentive net benefit of utility from next rolling two years. + References No definition available. + Details
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