Investments (Tables)

6 Months Ended

Jun. 30, 2015

Schedule of Investments [Line Items]

Unconsolidated Equity Investments

Equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and six months ended June 30 was as follows (in millions):

	Alliant Energy												WPL
	Three Months						Six Months						Three Months						Six Months
	2015			2014			2015			2014			2015			2014			2015			2014
ATC		($10.9	)		($11.1	)		($18.7	)		($22.3	)		($10.9	)		($11.1	)		($18.7	)		($22.3	)
Other	(0.4		)	(0.2		)	0.9			(0.4		)	(0.4		)	(0.3		)	(0.4		)	(0.5		)
		($11.3	)		($11.3	)		($17.8	)		($22.7	)		($11.3	)		($11.4	)		($19.1	)		($22.8	)

WPL [Member]

Schedule of Investments [Line Items]

Unconsolidated Equity Investments

Equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and six months ended June 30 was as follows (in millions):

	Alliant Energy												WPL
	Three Months						Six Months						Three Months						Six Months
	2015			2014			2015			2014			2015			2014			2015			2014
ATC		($10.9	)		($11.1	)		($18.7	)		($22.3	)		($10.9	)		($11.1	)		($18.7	)		($22.3	)
Other	(0.4		)	(0.2		)	0.9			(0.4		)	(0.4		)	(0.3		)	(0.4		)	(0.5		)
		($11.3	)		($11.3	)		($17.8	)		($22.7	)		($11.3	)		($11.4	)		($19.1	)		($22.8	)