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Regulatory Matters (Tables) | 9 Months Ended
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Sep. 30, 2017
Regulated Operations [Abstract] |
Regulatory Assets and Liabilities [Table Text Block] |
Regulatory Assets and Liabilities | September 30, 2017 |  |  | December 31, 2016 |
Millions |  |  |
Current Regulatory Assets |  |  |
Deferred Fuel Adjustment Clause |  | $20.2 |  |  |  | $18.6 |
Total Current Regulatory Assets | 20.2 |  |  | 18.6 |
Non-Current Regulatory Assets |  |  |
Defined Benefit Pension and Other Postretirement Benefit Plans | 221.4 |  |  | 226.1 |
Income Taxes (a) | 35.7 |  |  | 33.8 |
Asset Retirement Obligations | 29.8 |  |  | 26.0 |
Cost Recovery Riders | 5.2 |  |  | 30.5 |
PPACA Income Tax Deferral | 5.0 |  |  | 5.0 |
Conservation Improvement Program | 4.9 |  |  | 4.0 |
Other | 8.6 |  |  | 4.7 |
Total Non-Current Regulatory Assets | 310.6 |  |  | 330.1 |
Total Regulatory Assets |  | $330.8 |  |  |  | $348.7 |
Non-Current Regulatory Liabilities |  |  |
Wholesale and Retail Contra AFUDC |  | $57.0 |  |  |  | $56.8 |
Plant Removal Obligations | 19.2 |  |  | 19.1 |
Income Taxes | 18.6 |  |  | 19.1 |
North Dakota Investment Tax Credits | 13.9 |  |  | 28.2 |
Other | 2.8 |  |  | 2.6 |
Total Non-Current Regulatory Liabilities |  | $111.5 |  |  |  | $125.8 |
(a) | See Note 1. Operations and Significant Accounting Policies – Revision of Prior Balance Sheet.

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- Definition The entire disclosure for detailed information about regulatory assets and liabilities, including current and noncurrent assets created when regulatory agencies permit the deferral of costs to the balance sheet that would otherwise be required to appear on the company's income statement and would be charged against current expenses or revenues, as well as current and noncurrent liabilities created when regulatory agencies permit. + References No definition available. + Details
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