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Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Revenues: |  |  |
Electric utility | $ 3,063.6 | $ 3,000.3 | $ 2,894.7
Gas utility | 455.2 | 446.6 | 400.9
Other utility | 46.5 | 48.0 | 47.5
Non-utility | 82.4 | 39.6 | 39.1
Total revenues | 3,647.7 | 3,534.5 | 3,382.2
Operating expenses: |  |  |
Electric production fuel and purchased power | 776.7 | 855.0 | 818.1
Electric transmission service | 481.4 | 495.7 | 480.9
Cost of gas sold | 221.7 | 232.3 | 211.4
Other operation and maintenance | 712.2 | 645.8 | 633.2
Depreciation and amortization | 567.2 | 506.9 | 461.8
Taxes other than income taxes | 110.8 | 104.4 | 105.6
Total operating expenses | 2,870.0 | 2,840.1 | 2,711.0
Operating income (loss) | 777.7 | 694.4 | 671.2
Other (income) and deductions: |  |  |
Interest expense | 272.9 | 247.0 | 215.6
Equity income from unconsolidated investments, net | (53.0) | (54.6) | (44.8)
Allowance for funds used during construction | (92.7) | (75.6) | (49.7)
Other | 14.4 | 7.6 | 17.3
Total other (income) and deductions | 141.6 | 124.4 | 138.4
Income from continuing operations before income taxes | 636.1 | 570.0 | 532.8
Income tax expense (benefit) | 68.7 | 47.7 | 66.7
Income from continuing operations, net of tax | 567.4 | 522.3 | 466.1
Income from discontinued operations, net of tax | 0.0 | 0.0 | 1.4
Net income | 567.4 | 522.3 | 467.5
Preferred dividend requirements of Interstate Power and Light Company | 10.2 | 10.2 | 10.2
Net income attributable to common shareowners | $ 557.2 | $ 512.1 | $ 457.3
Weighted average number of common shares outstanding: |  |  |
Basic (in shares) | 238.5 | 233.6 | 229.7
Diluted (in shares) | 239.0 | 233.6 | 229.7
Earnings per weighted average common share attributable to Alliant Energy common shareowners: |  |  |
Basic (in dollars per share) | $ 2.34 | $ 2.19 | $ 1.99
Diluted (in dollars per share) | $ 2.33 | $ 2.19 | $ 1.99
Amounts attributable to common shareowners: |  |  |
Income from continuing operations, net of tax | $ 557.2 | $ 512.1 | $ 455.9
Income from discontinued operations, net of tax | 0.0 | 0.0 | 1.4
Net income | 557.2 | 512.1 | 457.3
IPL [Member] |  |  |
Revenues: |  |  |
Electric utility | 1,781.2 | 1,731.1 | 1,598.9
Gas utility | 264.2 | 266.2 | 226.0
Other utility | 44.2 | 45.0 | 45.4
Total revenues | 2,089.6 | 2,042.3 | 1,870.3
Operating expenses: |  |  |
Electric production fuel and purchased power | 434.5 | 469.0 | 443.6
Electric transmission service | 340.2 | 352.9 | 310.4
Cost of gas sold | 119.9 | 129.6 | 115.6
Other operation and maintenance | 404.6 | 402.6 | 396.6
Depreciation and amortization | 326.7 | 283.5 | 245.0
Taxes other than income taxes | 60.9 | 53.9 | 55.0
Total operating expenses | 1,686.8 | 1,691.5 | 1,566.2
Operating income (loss) | 402.8 | 350.8 | 304.1
Other (income) and deductions: |  |  |
Interest expense | 126.9 | 119.4 | 112.4
Allowance for funds used during construction | (49.4) | (42.2) | (31.4)
Other | 6.9 | 2.6 | 7.0
Total other (income) and deductions | 84.4 | 79.8 | 88.0
Income from continuing operations before income taxes | 318.4 | 271.0 | 216.1
Income tax expense (benefit) | 24.1 | (3.2) | (10.9)
Net income | 294.3 | 274.2 | 227.0
Preferred dividend requirements of Interstate Power and Light Company | 10.2 | 10.2 | 10.2
Net income attributable to common shareowners | 284.1 | 264.0 | 216.8
Amounts attributable to common shareowners: |  |  |
Net income | 284.1 | 264.0 | 216.8
WPL [Member] |  |  |
Revenues: |  |  |
Electric utility | 1,282.4 | 1,269.2 | 1,295.8
Gas utility | 191.0 | 180.4 | 174.9
Other utility | 2.3 | 3.0 | 2.1
Total revenues | 1,475.7 | 1,452.6 | 1,472.8
Operating expenses: |  |  |
Electric production fuel and purchased power | 342.2 | 386.0 | 374.5
Electric transmission service | 141.2 | 142.8 | 170.5
Cost of gas sold | 101.8 | 102.7 | 95.8
Other operation and maintenance | 260.9 | 241.6 | 238.5
Depreciation and amortization | 235.6 | 219.4 | 212.9
Taxes other than income taxes | 46.8 | 47.2 | 46.9
Total operating expenses | 1,128.5 | 1,139.7 | 1,139.1
Operating income (loss) | 347.2 | 312.9 | 333.7
Other (income) and deductions: |  |  |
Interest expense | 102.2 | 97.8 | 93.8
Allowance for funds used during construction | (43.3) | (33.4) | (18.3)
Other | 6.0 | 4.2 | 9.7
Total other (income) and deductions | 64.9 | 68.6 | 85.2
Income from continuing operations before income taxes | 282.3 | 244.3 | 248.5
Income tax expense (benefit) | 49.3 | 36.2 | 61.9
Net income | $ 233.0 | $ 208.1 | $ 186.6

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