Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The net result for the period of deducting operating expenses from operating revenues.

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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The number of service areas within southeastern, east central, and northern Wisconsin serviced by Wisconsin Electric Power Company's natural gas utility segment.

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Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
Segment Information (Details) $ in Millions	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) area segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment information
Number of reportable segments \| segment									2
Number of areas serviced by our natural gas utility segment \| area									3
Operating revenues	$ 916.3	$ 1,023.8	$ 877.2	$ 975.5	$ 905.4	$ 981.1	$ 883.0	$ 1,084.6	$ 3,792.8	$ 3,854.1	$ 4,059.4
Other operation and maintenance									1,430.2	1,384.9	1,356.4
Depreciation and amortization									325.4	304.0	278.3
Operating income	104.7	$ 196.4	$ 146.9	$ 181.5	145.7	$ 169.8	$ 128.7	$ 204.7	629.5	648.9	650.4
Equity in earnings of transmission affiliate									55.5	47.8	57.9
Interest expense									117.6	119.0	116.5
Capital expenditures									469.5	519.2	561.8
Assets	13,371.5				13,139.6				13,371.5	13,139.6	12,597.2
Utility
Segment information
Operating revenues									3,792.8	3,854.1	4,059.4
Other operation and maintenance									1,430.2	1,384.9	1,356.4
Depreciation and amortization									325.4	304.0	278.3
Operating income									629.5	648.9	650.4
Equity in earnings of transmission affiliate									0.0	0.0	0.0
Interest expense									116.6	117.7	114.9
Capital expenditures									468.9	518.8	561.8
Assets	12,945.1				12,727.6				12,945.1	12,727.6	12,195.9
Other
Segment information
Operating revenues									0.0	0.0	0.0
Other operation and maintenance									0.0	0.0	0.0
Depreciation and amortization									0.0	0.0	0.0
Operating income									0.0	0.0	0.0
Equity in earnings of transmission affiliate									55.5	47.8	57.9
Interest expense									1.0	1.3	1.6
Capital expenditures									0.6	0.4	0.0
Assets	$ 426.4				$ 412.0				426.4	412.0	401.3
ATC
Segment information
Equity in earnings of transmission affiliate									$ 55.5	$ 47.8	$ 57.9
Equity Method Investment, Ownership Percentage	23.00%								23.00%