Condensed Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Utility:
Electric	$ 675.8	$ 633.2
Gas	240.7	197.3
Other	22.8	17.2
Non-regulated	13.5	11.9
Total operating revenues	952.8	859.6
Utility:
Electric production fuel and energy purchases	213.9	179.1
Purchased electric capacity	24.8	57.0
Electric transmission service	114.1	103.7
Cost of gas sold	161.9	128.0
Other operation and maintenance	161.0	150.2
Non-regulated operation and maintenance	1.3	2.2
Depreciation and amortization	95.5	92.6
Taxes other than income taxes	26.1	26.1
Total operating expenses	798.6	738.9
Operating income	154.2	120.7
Interest expense and other:
Interest expense	45.2	42.6
Equity income from unconsolidated investments, net	(11.4)	(10.7)
Allowance for funds used during construction	(9.1)	(5.6)
Interest income and other	(1.7)	(0.8)
Total interest expense and other	23.0	25.5
Income from continuing operations before income taxes	131.2	95.2
Income tax expense (benefit)	20.6	12.1
Income from continuing operations, net of tax	110.6	83.1
Income (loss) from discontinued operations, net of tax	0	(3.0)
Net income (loss)	110.6	80.1
Preferred dividend requirements of subsidiaries	2.6	10.2
Net income (loss) attributable to common shareowners	108.0	69.9
Weighted average number of common shares outstanding (basic and diluted) (in shares)	110.8	110.8
Earnings per weighted average common share attributable to Alliant Energy common shareowners (basic and diluted):
Income from continuing operations, net of tax (in dollars per share)	$ 0.97	$ 0.66
Income (loss) from discontinued operations, net of tax (in dollars per share)	$ 0.00	$ (0.03)
Net income (in dollars per share)	$ 0.97	$ 0.63
Amounts attributable to common shareowners:
Income from continuing operations, net of tax	108.0	72.9
Income (loss) from discontinued operations, net of tax	0	(3.0)
Net income (loss) attributable to common shareowners	108.0	69.9
Dividends declared per common share (in dollars per share)	$ 0.51	$ 0.47
IPL [Member]
Utility:
Electric	374.2	350.2
Gas	135.7	114.3
Other	19.0	13.4
Total operating revenues	528.9	477.9
Utility:
Electric production fuel and energy purchases	115.2	96.7
Purchased electric capacity	24.8	41.4
Electric transmission service	83.6	74.6
Cost of gas sold	88.1	72.1
Other operation and maintenance	97.2	90.5
Depreciation and amortization	48.7	47.6
Taxes other than income taxes	13.8	13.9
Total operating expenses	471.4	436.8
Operating income	57.5	41.1
Interest expense and other:
Interest expense	22.5	19.6
Allowance for funds used during construction	(6.0)	(3.8)
Interest income and other	0	(0.1)
Total interest expense and other	16.5	15.7
Income from continuing operations before income taxes	41.0	25.4
Income tax expense (benefit)	(5.0)	(6.1)
Net income (loss)	46.0	31.5
Preferred dividend requirements of subsidiaries	2.6	8.6
Net income (loss) attributable to common shareowners	43.4	22.9
Amounts attributable to common shareowners:
Net income (loss) attributable to common shareowners	43.4	22.9
WPL [Member]
Utility:
Electric	301.6	283.0
Gas	105.0	83.0
Other	3.8	3.8
Total operating revenues	410.4	369.8
Utility:
Electric production fuel and energy purchases	98.7	82.4
Purchased electric capacity	0	15.6
Electric transmission service	30.5	29.1
Cost of gas sold	73.8	55.9
Other operation and maintenance	63.8	59.7
Depreciation and amortization	44.7	43.1
Taxes other than income taxes	11.2	11.3
Total operating expenses	322.7	297.1
Operating income	87.7	72.7
Interest expense and other:
Interest expense	21.1	21.3
Equity income from unconsolidated investments, net	(11.4)	(10.8)
Allowance for funds used during construction	(3.1)	(1.8)
Interest income and other	0	(0.1)
Total interest expense and other	6.6	8.6
Income from continuing operations before income taxes	81.1	64.1
Income tax expense (benefit)	26.3	20.5
Net income (loss)	54.8	43.6
Preferred dividend requirements of subsidiaries	0	1.6
Net income (loss) attributable to common shareowners	54.8	42.0
Amounts attributable to common shareowners:
Net income (loss) attributable to common shareowners	$ 54.8	$ 42.0