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Pension Plans - Weighted-Average Target Allocations of Plan Assets (Detail) | Dec. 31, 2020
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Equity Securities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 50.00%
Equity Securities [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 40.00%
Equity Securities [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 60.00%
Fixed Income [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 50.00%
Fixed Income [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 40.00%
Fixed Income [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 60.00%
Cash and Equivalents [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 0.00%
Cash and Equivalents [Member] | Minimum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 0.00%
Cash and Equivalents [Member] | Maximum [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target plan asset allocations | 10.00%

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- Definition Percentage of target 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/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -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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