Benefit Plans - Defined Benefit Plans - Change in Projected Benefit Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Split-Dollar Life Insurance Benefit Plan
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$ 6,711	$ 6,301
Interest cost	227	243
Actuarial loss (gain)	(35)	167
Projected benefit obligation at end of period	6,903	6,711
Supplemental Retirement Plan
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	28,510	27,376
Interest cost	947	1,034
Actuarial loss (gain)	1,885	(790)
Benefits paid	(1,040)	(1,015)
Projected benefit obligation at end of period	$ 26,781	$ 28,510

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

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- Definition

Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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