Common Equity (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Common Equity [Line Items]

Common Stock Activity

A summary of Alliant Energy’s common stock activity was as follows:

	2017		2016	2015
Shares outstanding, January 1	227,673,654		226,918,432	221,871,360
At-the-market offering programs	3,074,931		—	4,373,234
Shareowner Direct Plan issuances	640,723		732,814	606,010
Equity-based compensation plans (Note 12(b))	5,185		22,408	112,756
Other	(45,847	)	—	(44,928	)
Shares outstanding, December 31	231,348,646		227,673,654	226,918,432