Employee Benefit Plans - Cost Components of Supplemental Executive Retirement Plan (Detail) - Supplemental Employee Retirement Plans, Defined Benefit [Member] - USD ($) $ in Thousands |
12 Months Ended | |
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Dec. 31, 2017 |
Dec. 31, 2016 |
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| Defined Benefit Plan Disclosure [Line Items] | ||
| Service cost | $ 1,711 | $ 1,590 |
| Interest cost | 448 | 383 |
| Net pension expense (benefit) | $ 2,159 | $ 1,973 |
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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. No definition available.
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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