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v3.19.3.a.u2

Consolidated Statements of Capitalization (Parentheticals) | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
The 3.55% Guaranteed Senior Notes, due December 15, 2026 [Member] | Parent Company [Member] |  |
Long-term Debt, Interest Rate | 3.55% | 3.55%
Long-term Debt, Due Date | Dec. 15, 2026 | Dec. 15, 2026
Partnership in Assisting Community Expansion Note, 2.54%, due March 18, 2021 [Member] | Parent Company [Member] |  |
Long-term Debt, Interest Rate | 2.54% | 2.54%
Long-term Debt, Due Date | Mar. 18, 2021 | Mar. 18, 2021
Senior Unsecured Notes 4.63%, Due December 1, 2021 [Member] |  |
Long-term Debt, Interest Rate | 4.63% | 4.63%
Long-term Debt, Due Date | Dec. 01, 2021 | Dec. 01, 2021
Senior Unsecured Notes 4.63%, Due December 1, 2021 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 4.63% | 4.63%
Long-term Debt, Due Date | Dec. 01, 2021 | Dec. 01, 2021
Senior Unsecured Notes 6.15%, Series B, Due August 20, 2022 [Member] |  |
Long-term Debt, Interest Rate | 6.15% | 6.15%
Long-term Debt, Due Date | Aug. 20, 2022 | Aug. 20, 2022
Senior Unsecured Notes 6.15%, Series B, Due August 20, 2022 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 6.15% | 6.15%
Long-term Debt, Due Date | Aug. 20, 2022 | Aug. 20, 2022
Senior Unsecured Notes 6.37%, Series C, Due August 20, 2027 [Member] |  |
Long-term Debt, Interest Rate | 6.37% | 6.37%
Long-term Debt, Due Date | Aug. 20, 2027 | Aug. 20, 2027
Senior Unsecured Notes 6.37%, Series C, Due August 20, 2027 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 6.37% | 6.37%
Long-term Debt, Due Date | Aug. 20, 2027 | Aug. 20, 2027
Senior Unsecured Notes 4.68%, Series A, Due February 27, 2029 [Member] |  |
Long-term Debt, Interest Rate | 4.68% | 4.68%
Long-term Debt, Due Date | Feb. 27, 2029 | Feb. 27, 2029
Senior Unsecured Notes 4.68%, Series A, Due February 27, 2029 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 4.68% | 4.68%
Long-term Debt, Due Date | Feb. 27, 2029 | Feb. 27, 2029
Senior Unsecured notes 3.07%, Series 2019A, Due October 10, 2029 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 3.07% |
Long-term Debt, Due Date | Oct. 10, 2029 |
Senior Unsecured Notes 6.47%, Series D, Due August 20, 2037 [Member] |  |
Long-term Debt, Interest Rate | 6.47% | 6.47%
Long-term Debt, Due Date | Aug. 20, 2037 | Aug. 20, 2037
Senior Unsecured Notes 6.47%, Series D, Due August 20, 2037 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 6.47% | 6.47%
Long-term Debt, Due Date | Aug. 20, 2037 | Aug. 20, 2037
Senior Unsecured Notes 3.52%, Series 2019B, Due October 10, 2039 [Member] |  |
Long-term Debt, Interest Rate | 3.52% |
Long-term Debt, Due Date | Oct. 10, 2039 |
Senior Unsecured Notes 3.52%, Series 2019B, Due October 10, 2039 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 3.52% |
Long-term Debt, Due Date | Oct. 10, 2039 |
Senior Unsecured Notes 5.47%, Series B, Due February 27, 2044 [Member] |  |
Long-term Debt, Interest Rate | 5.47% | 5.47%
Long-term Debt, Due Date | Feb. 27, 2044 | Feb. 27, 2044
Senior Unsecured Notes 5.47%, Series B, Due February 27, 2044 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 5.47% | 5.47%
Long-term Debt, Due Date | Feb. 27, 2044 | Feb. 27, 2044
Senior Unsecured Notes 4.07%, Series 2018A, Due February 7, 2048 [Member] |  |
Long-term Debt, Interest Rate | 4.07% | 4.07%
Long-term Debt, Due Date | Feb. 07, 2048 | Feb. 07, 2048
Senior Unsecured Notes 4.07%, Series 2018A, Due February 7, 2048 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 4.07% | 4.07%
Long-term Debt, Due Date | Feb. 07, 2048 | Feb. 07, 2048
Senior Unsecured Notes 3.82%, Sericies C, Due October 10, 2049 [Member] |  |
Long-term Debt, Interest Rate | 3.82% |
Long-term Debt, Due Date | Oct. 10, 2049 |
Senior Unsecured Notes 3.82%, Sericies C, Due October 10, 2049 [Member] | Otter Tail Power Company [Member] |  |
Long-term Debt, Interest Rate | 3.82% |
Long-term Debt, Due Date | Oct. 10, 2049 |

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