Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2021

Regulated Operations [Abstract]

Regulatory Assets and Liabilities [Table Text Block]

Regulatory Assets and Liabilities	September 30, 2021	December 31, 2020
Millions
Non-Current Regulatory Assets
Defined Benefit Pension and Other Postretirement Benefit Plans	$247.6	$259.7
Income Taxes	107.2	113.7
Cost Recovery Riders	61.8	54.0
Asset Retirement Obligations	31.4	31.6
Fuel Adjustment Clause	30.1	—
Manufactured Gas Plant	11.9	8.8
PPACA Income Tax Deferral	4.4	4.5
Boswell Units 1 and 2 Net Plant and Equipment	3.2	5.0
Other	5.3	3.6
Total Non-Current Regulatory Assets	$502.9	$480.9
Current Regulatory Liabilities (a)
Fuel Adjustment Clause	$2.6	$3.7
Transmission Formula Rates Refund	3.1	2.9
Other	3.3	1.0
Total Current Regulatory Liabilities	9.0	7.6
Non-Current Regulatory Liabilities
Income Taxes	359.3	375.3
Wholesale and Retail Contra AFUDC	84.4	86.6
Plant Removal Obligations	47.4	41.2
North Dakota Investment Tax Credits	12.3	12.0
Defined Benefit Pension and Other Postretirement Benefit Plans	1.4	4.4
Conservation Improvement Program	—	1.5
Other	4.7	3.8
Total Non-Current Regulatory Liabilities	509.5	524.8
Total Regulatory Liabilities	$518.5	$532.4

(a)Current regulatory liabilities are presented within Other Current Liabilities on the Consolidated Balance Sheet.