Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018 and December 31, 2017 are as follows (in millions):

Regulatory Assets	2018		2017
Grossed-up deferred taxes on equity funds used during construction	$	39.0	$	37.9
Asset retirement obligations	171.9		168.7
Asset retirement costs - Eminence	45.5		49.5
Deferred taxes - asset	2.7		3.8
Deferred cash out	54.9		42.5
Deferred gas costs	4.0		6.0
Fuel cost	61.2		61.4
Other	6.0		3.7
Total Regulatory Assets	$	385.2	$	373.5

Schedule of Regulatory Liabilities [Table Text Block]

Regulatory Liabilities	2018		2017
Negative salvage	$	444.5	$	409.7
Deferred taxes - liability	450.2		471.1
Sentinel meter station depreciation	6.4		6.3
Postretirement benefits other than pension	79.8		73.9
Electric power cost	0.1		13.3
Pension - deferred collections	48.5		32.5
Other	2.5		0.3
Total Regulatory Liabilities	$	1,032.0	$	1,007.1