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Employee Benefit Plans - Assumptions Used to Determine Projected and Accumulated Benefit Obligations of Domestic Defined Benefit Pension and Postretirement Benefit Plans (Detail) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Pre-65 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Health care cost trend rate | 7.00% | 7.00% |
Ultimate cost trend rate | 4.50% | 4.50% |
Year that the rate reaches the ultimate cost trend rate | 2025 | 2024 | 2023
Post-65 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Health care cost trend rate | 6.80% | 7.80% |
Ultimate cost trend rate | 4.50% | 4.50% |
Year that the rate reaches the ultimate cost trend rate | 2025 | 2024 | 2024
Defined benefit pension plans |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 4.10% | 3.40% |
Postretirement benefit plans |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 4.10% | 3.40% |
Annual increase in Medicare Part B premium | 6.00% | 6.00% |
Projected and accumulated benefit obligations | Pre-65 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Year that the rate reaches the ultimate cost trend rate | 2025 | 2024 |
Projected and accumulated benefit obligations | Post-65 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Year that the rate reaches the ultimate cost trend rate | 2025 | 2024 |

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- Definition Annual Increase In Medicare Part B Premium Used To Determine Projected And Accumulated Benefit Obligations For Domestic Postretirement Benefit Plans + References No definition available. + Details
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- Definition The ultimate trend rate for health care costs used to determine projected and accumulated benefit obligation. + References No definition available. + Details
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- Definition Health Care Cost Trend Rate used to Determine Projected and Accumulated Benefit Obligation + References No definition available. + Details
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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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=108410482&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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- Definition Year ultimate health care cost trend rate is expected to be reached, in CCYY format. + 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 (l) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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