Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2013

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, 2013 and December 31, 2012 are as follows (in millions):

Regulatory Assets	2013		2012
Grossed-up deferred taxes on equity funds used during construction	$	80.6	$	83.5
Asset retirement obligations	128.5		125.1
Asset retirement costs - Eminence	68.2		—
Deferred taxes	8.1		9.1
Postretirement benefits other than pension	—		4.6
Fuel cost	0.7		29.3
Other	8.0		—
Total Regulatory Assets	$	294.1	$	251.6

Schedule of Regulatory Liabilities [Table Text Block]

Regulatory Liabilities	2013		2012
Negative salvage	$	241.7	$	203.8
Deferred cash out	1.6		6.2
Sentinel meter station depreciation	5.0		3.9
Postretirement benefits other than pension	25.3		24.7
Electric power cost	13.8		7.7
Other	0.2		1.2
Total Regulatory Liabilities	$	287.6	$	247.5