Employee Benefits (Detail Textuals) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule Of Employee Benefits [Line Items]
Percentage of internal revenue contribution			25.00%
Percentage of internal revenue service limitations			6.00%
Estimated net actuarial loss			$ 374
Employer contribution	$ 570	$ 0	570	$ 0
Cash surrender value of life insurance	17,918		17,918		$ 17,577
Increase in cash surrender value of insurance	101	116	300	345
Accrued expenses and other liabilities	8,679		8,679		9,682
Noninterest expense	6,473	$ 6,010	19,240	18,850	460
Employer contribution in defined contribution plan			$ 577	508	686
Maximum
Schedule Of Employee Benefits [Line Items]
Post retirement benefit period			20 years
Minimum
Schedule Of Employee Benefits [Line Items]
Post retirement benefit period			15 years
Trustees' Plan
Schedule Of Employee Benefits [Line Items]
Accrued expenses and other liabilities	1,760		$ 1,760		1,648
Noninterest expense			61	44	62
Executive Long-Term Incentive and Retention Plan
Schedule Of Employee Benefits [Line Items]
Accrued expenses and other liabilities	840		840		813
Noninterest expense			$ 27	23	76
Executive Long-Term Incentive and Retention Plan | Maximum
Schedule Of Employee Benefits [Line Items]
Terms of services			5 years
Executive Long-Term Incentive and Retention Plan | Minimum
Schedule Of Employee Benefits [Line Items]
Terms of services			1 year
Group Term Replacement Plan
Schedule Of Employee Benefits [Line Items]
Liability related to these postretirement benefits	$ 1,300		$ 1,300		1,260
Postemployment benefit expense			40	41	71
Other Director and Officer Postretirement Benefits
Schedule Of Employee Benefits [Line Items]
Noninterest expense			75	$ 178	292
Postemployment benefit expense			$ 2,105		$ 2,078