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Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Income Statement [Abstract] |  |  |
Reclassification adjustments to cash flow hedges included in net income, tax | $ (0.0) | $ 7.9 | $ 1.3
Changes in unrealized gains on marketable debt securities, tax | 0.1 | 0.0 | 0.0
Amortization of pension and postretirement plans actuarial loss and prior service cost, tax | 3.6 | 3.2 | 4.0
Changes in unfunded employee benefit obligations, tax | $ (1.3) | $ 13.6 | $ (0.8)

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- Definition Tax effect of the adjustment out of other comprehensive income for prior service costs and net loss recognized as a component of net periodic benefit cost during the period. + References No definition available. + Details
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- Definition Tax effect of the accumulated change in the value of either the projected benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption that has not been recognized in net periodic benefit cost. Also includes the tax effect of the cost (credit) resulting from a plan amendment that occurred during the period that has not been recognized in net periodic benefit cost. + References No definition available. + Details
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- Definition Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580 + Details
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- Definition Amount, before adjustment, of tax expense (benefit) for unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580 + Details
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