Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
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-Section 50
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COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) T in Millions, $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 31, 2014	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) T	Dec. 31, 2015	Sep. 30, 2016
Climate Change \| Electric
Air quality
Number of legal cases heard by a court					1
Percentage of nationwide greenhouse gas emissions reduction				32.00%
Interim goal for greenhouse gas emissions reduction (fraction)				0.667
Percentage carbon dioxide emission reduction company goal		40.00%
Carbon dioxide emissions \| T			29.6
Climate Change \| Electric \| Wisconsin
Air quality
Percentage of greenhouse gas emissions reduction by state				41.00%
Climate Change \| Electric \| Michigan
Air quality
Percentage of greenhouse gas emissions reduction by state				39.00%
Climate Change \| Natural gas
Air quality
Carbon dioxide emissions \| T			26.7
Clean Water Act Cooling Water Intake Structure Rule \| Electric
Water quality
Number of compliance options available to meet standard	7
Steam Electric Effluent Guidelines \| Electric
Water quality
Renewal period for facility permits		5 years
Steam Electric Effluent Guidelines \| Minimum \| Electric
Water quality
Expected cost to achieve required emissions reductions		$ 80.0
Steam Electric Effluent Guidelines \| Maximum \| Electric
Water quality
Expected cost to achieve required emissions reductions		110.0
Manufactured Gas Plant Remediation \| Natural gas
Manufactured gas plant remediation
Regulatory assets recorded for remediation of manufactured gas plant sites		685.4	$ 702.7
Reserves recorded for remediation of manufactured gas plant sites		$ 630.5	$ 633.4