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Employee Bargaining Agreements and Benefit Plans - Assumption Rates Used for Benefit Obligations (Detail) | Dec. 31, 2020 | Dec. 31, 2019
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Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rate: | 0.70% | 2.00%
Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Discount rate: | 1.20% | 2.10%

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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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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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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration

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- Details
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- Details
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