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Investments Low Income Housing Tax Credits (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Investments, All Other Investments [Abstract] |  |
Low Income Housing Tax Credits | $ 10.4 | $ 10.4
Amortization of Low Income Housing Investments | (7.0) | (5.8)
Tax Benefits from Low Income Housing Investments | $ 3.4 | $ 4.6

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- Definition The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; includes deferred investment tax credits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
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