Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets [Table Text Block]

The regulatory assets and regulatory liabilities resulting from our application of the provisions of ASC Topic 980, Regulated Operations, included in the accompanying Consolidated Balance Sheet at December 31, 2020 and December 31, 2019 are as follows (in millions):

Regulatory Assets	2020		2019
Grossed-up deferred taxes on equity funds used during construction	$	36.1	$	37.5
Asset retirement obligations	139.5		147.6
Asset retirement costs - Eminence	36.6		42.2
Deferred cash out	70.0		64.4
Fuel cost	34.1		40.2
Electric power cost	7.8		8.4
Slug catcher	6.4		6.6
Other	14.2		13.5
Total Regulatory Assets	$	344.7	$	360.4

Schedule of Regulatory Liabilities [Table Text Block]

Regulatory Liabilities	2020		2019
Negative salvage	$	504.5	$	482.6
Deferred taxes - liability	392.8		423.5
Sentinel meter station depreciation	6.8		6.6
Postretirement benefits other than pension	60.9		68.0
Pension	38.9		43.3
Other	—		0.3
Total Regulatory Liabilities	$	1,003.9	$	1,024.3