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Benefit Plans - Weighted-Average Asset Allocation of Pension Plan Assets (Detail) - Pension | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Equities | 100.00% | 100.00%
Domestic equities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Equities | 39.00% | 37.00%
Foreign equities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Equities | 12.00% | 11.00%
Fixed income |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Equities | 47.00% | 50.00%
Real estate |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Equities | 2.00% | 2.00%
Cash |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Equities | 0.00% | 0.00%

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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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