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Employee Benefit Plans - Summary of Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Pension Plan [Member] |  |
Weighted-average assumptions used to determine Net Periodic Benefit Cost |  |
Discount rate | 1.80% | 3.59%
Expected return on plan assets | 0.00% | 7.00%
Corridor | 10.00% | 10.00%
Supplemental Employee Retirement Plan [Member] |  |
Weighted-average assumptions used to determine Net Periodic Benefit Cost |  |
Discount rate | 3.35% | 3.80%
Corridor | 10.00% | 10.00%
Postretirement Benefits [Member] |  |
Weighted-average assumptions used to determine Net Periodic Benefit Cost |  |
Discount rate |  | 4.00%
Corridor |  | 10.00%

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- Definition Defined benefit plan assumptions used calculating net periodic benefit cost corridor. + 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 net periodic benefit cost 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 Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost 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)(3) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920 + Details
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- Details
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- Details
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- Details
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