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v3.20.4

Related Parties (Details) - Pension Plans, Defined Benefit - Investment Management Services for Defined Benefit Plan - Fayez Sarofim & Co. - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Related Party Transaction [Line Items] |  |  |
Assets managed by related party | $ 64.7 | $ 149.3 | $ 124.5
Investment expenses from agreement with related party | $ 0.7 | $ 0.9 | $ 0.9

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