Fair Value of Assets and Liabilities (Details 6) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2018
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Investment securities available-for-sale, fair value	$ 159,841	$ 137,845
Minimum
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	9.10%
Maximum
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	14.74%
Trust preferred securities
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Investment securities available-for-sale, fair value	$ 895
Trust preferred securities | Minimum
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	9.10%
Trust preferred securities | Maximum
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	14.74%
Trust preferred securities | Discounted Cash Flow
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Investment securities available-for-sale, fair value	$ 895
Impaired Loans | Minimum
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	4.50%
Impaired Loans | Maximum
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	5.38%
Impaired Loans | Weighted average
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Fair value input discount rate	4.88%
Impaired Loans | Appraisal Of Collateral
Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis
Investment securities available-for-sale, fair value	$ 4,891