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Pensions and Other Post-retirement Benefits - Schedule of Expected Return on Assets for Net Periodic Pension Cost (Detail) | Dec. 31, 2020 | Dec. 31, 2019
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Defined Benefit Plan Disclosure [Line Items] |  |
Pension Plan Assets at December 31, | 100.00% | 100.00%
Equity securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension Plan Assets at December 31, | 49.00% | 46.00%
Fixed income securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension Plan Assets at December 31, | 25.00% | 30.00%
Pooled investment funds |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension Plan Assets at December 31, | 21.00% | 19.00%
Insurance contracts |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension Plan Assets at December 31, | 4.00% | 4.00%
Cash and cash equivalents |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Pension Plan Assets at December 31, | 1.00% | 1.00%

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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