Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2016

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, 2016 and December 31, 2015 are as follows (in millions):

Regulatory Assets	2016		2015
Grossed-up deferred taxes on equity funds used during construction	$	73.2	$	75.8
Asset retirement obligations	117.2		113.5
Asset retirement costs - Eminence	53.9		58.8
Deferred taxes	4.8		5.9
Deferred cash out	48.2		43.9
Fuel cost	51.3		43.8
Other	2.5		1.6
Total Regulatory Assets	$	351.1	$	343.3

Schedule of Regulatory Liabilities [Table Text Block]

Regulatory Liabilities	2016		2015
Negative salvage	$	357.1	$	318.3
Sentinel meter station depreciation	6.2		6.0
Postretirement benefits other than pension	63.0		51.0
Electric power cost	6.3		0.8
Pension - deferred collections	21.3		8.0
Deferred gas costs	4.5		1.6
Other	0.1		0.2
Total Regulatory Liabilities	$	458.5	$	385.9