DISPOSITIONS - DISCONTINUED OPERATIONS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended			1 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 IES Combined Locks Energy Center	Sep. 30, 2013 IES Combined Locks Energy Center	Sep. 30, 2014 IES Combined Locks Energy Center	Sep. 30, 2013 IES Combined Locks Energy Center	Dec. 31, 2013 IES Combined Locks Energy Center	Sep. 30, 2014 IES WPS Empire State, Inc WPS Beaver Falls Generation, LLC and WPS Syracuse Generation, LLC	Mar. 31, 2013 IES WPS Empire State, Inc WPS Beaver Falls Generation, LLC and WPS Syracuse Generation, LLC	Sep. 30, 2014 IES WPS Empire State, Inc WPS Beaver Falls Generation, LLC and WPS Syracuse Generation, LLC	Sep. 30, 2014 IES WPS Empire State, Inc WPS Beaver Falls Generation, LLC and WPS Syracuse Generation, LLC	Sep. 30, 2013 IES WPS Empire State, Inc WPS Beaver Falls Generation, LLC and WPS Syracuse Generation, LLC	Sep. 30, 2013 Holding Company and Other
Disclosures related to discontinued operations
Earn-out mechanism period												4 years
Earn-out settlement payment											$ 2.0
Assets classified as held for sale on balance sheets
Total assets	10.4		10.4		277.9	0.7		0.7		0.7
Discontinued operations recorded in income statements
Discontinued operations, net of tax	$ 1.1	$ (0.6)	$ 0.9	$ 4.7		$ (0.1)	$ (0.6)	$ (0.3)	$ (1.4)				$ 1.2	$ 1.2	$ 0.2	$ 5.9