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Retirement Plans and Other Post-Retirement Benefits - Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Pension Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial (gain) loss | $ 32.9 | $ (6.8)
Plan amendments | 0.1 | 4.1
Recognized actuarial losses | (7.1) | (7.1)
Total recognized in other comprehensive (income) loss | 25.9 | (9.8)
Total recognized in net periodic benefit cost and other comprehensive (income) loss | 27.5 | (9.2)
Other Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial (gain) loss | (3.1) | (0.6)
Recognized actuarial losses | 0.3 |
Total recognized in other comprehensive (income) loss | (2.8) | (0.6)
Total recognized in net periodic benefit cost and other comprehensive (income) loss | $ (2.5) | $ (0.1)

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- Definition Defined benefit plan amounts recognized in other comprehensive income. + References No definition available. + Details
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- Definition Amount recognized in net periodic benefit cost (credit) and other comprehensive (income) loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=112275985&loc=d3e4179-114921 + Details
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- Definition Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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- Definition Amount, before tax, of gain (loss) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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