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Benefit Plans (Employees Participate In Defined Contribution Retirement Plans) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
401(k) costs | $ 25.1 | $ 24.8 | $ 23.6
IPL [Member] |  |  |
401(k) costs | 13.0 | 12.8 | 12.0
WPL [Member] |  |  |
401(k) costs | $ 11.2 | $ 11.1 | $ 10.7

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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Details
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Data Type: | na
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- Details
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