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Employee Benefit Plans - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan in excess of minimum required contribution	$ 0	$ 0	$ 0
Accumulated benefit obligation	$ 63,300	65,200
Investment strategy, percentage in long-term growth	97.00%
Investment strategy, percentage in near-term benefit payments	3.00%
Maximum percentage of securities purchasing allowed of the portfolio at any time	5.00%
Maximum market value purchase percentage allowed of any one issuer	8.00%
Postretirement benefit plan, accrued liabilities	$ 109	151
Estimated future net loss for the plan that will be amortized from accumulated other comprehensive income	$ 1,500	$ 66
Portfolio Concentration Commingled Trust Fund1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan assets	15.00%	15.00%
Portfolio Concentration Commingled Trust Fund2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan assets	6.00%	6.00%
Portfolio Concentration Short Term Investment Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan assets	6.00%	6.00%
Commercial Mortgage Back Securities And Assets Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage of securities purchasing allowed of the portfolio at any time	10.00%
Securities Less Than Aquality [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage of securities purchasing allowed of the portfolio at any time	13.00%
Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percent of participant's contribution match	4.50%
Portfolio management, controlled percentage	2.00%	4.00%
First 3% Of Participant's Contribution [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage employer matches of the employee's percentage contribution matched	100.00%
Percentage for which the employer contributes a matching contribution	3.00%
Next 3% Of Participant's Contribution [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage employer matches of the employee's percentage contribution matched	50.00%
Percentage for which the employer contributes a matching contribution	3.00%
Investment Firm One [Member]
Defined Benefit Plan Disclosure [Line Items]
Portfolio management, controlled percentage	62.00%	59.00%
Investment Firm Two [Member]
Defined Benefit Plan Disclosure [Line Items]
Portfolio management, controlled percentage	36.00%	37.00%
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Unfunded pension liability	$ 1,700	$ 1,900
Pension expense	$ 215	$ 194	$ 88

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