Fair Value of Financial Instruments - Quantitative Information About Level III Significant Unobservable Inputs (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Non-recurring | Impaired loans
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	$ 13,860	$ 14,368
Non-recurring | Impaired loans | Level I
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	0	0
Non-recurring | Impaired loans | Level II
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	0	0
Non-recurring | Impaired loans | Level III
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	13,860	14,368
Non-recurring | Other real estate owned
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	1,750	1,346
Non-recurring | Other real estate owned | Level I
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	0	0
Non-recurring | Other real estate owned | Level II
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	0	0
Non-recurring | Other real estate owned | Level III
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	1,750	1,346
Recurring | Municipal Bonds | Level III
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	29,324	22,909
Recurring | Interest rate lock commitment | Level III
Quantitative Information about Level III Fair Value Measurements
Assets, fair value	$ 1,672	$ 1,426
Appraisal adjustments | Non-recurring | Impaired loans | Appraisal of collateral | Level III | Minimum
Quantitative Information about Level III Fair Value Measurements
Impaired loans	0.20	0.20
Appraisal adjustments | Non-recurring | Impaired loans | Appraisal of collateral | Level III | Maximum
Quantitative Information about Level III Fair Value Measurements
Impaired loans	0.62	0.62
Appraisal adjustments | Non-recurring | Other real estate owned | Appraisal of collateral | Level III | Minimum
Quantitative Information about Level III Fair Value Measurements
Other real estate owned	0.20	0.20
Appraisal adjustments | Non-recurring | Other real estate owned | Appraisal of collateral | Level III | Maximum
Quantitative Information about Level III Fair Value Measurements
Other real estate owned	0.30	0.30
Appraisal adjustments | Recurring | Municipal Bonds | Appraisal of bond | Level III | Minimum
Quantitative Information about Level III Fair Value Measurements
Debt securities	0.05	0.05
Appraisal adjustments | Recurring | Municipal Bonds | Appraisal of bond | Level III | Maximum
Quantitative Information about Level III Fair Value Measurements
Debt securities	0.15	0.15
Liquidation expense | Non-recurring | Impaired loans | Appraisal of collateral | Level III | Minimum
Quantitative Information about Level III Fair Value Measurements
Impaired loans	0.05	0.05
Liquidation expense | Non-recurring | Impaired loans | Appraisal of collateral | Level III | Maximum
Quantitative Information about Level III Fair Value Measurements
Impaired loans	0.10	0.10
Liquidation expense | Non-recurring | Other real estate owned | Appraisal of collateral | Level III | Minimum
Quantitative Information about Level III Fair Value Measurements
Other real estate owned	0.05	0.05
Liquidation expense | Non-recurring | Other real estate owned | Appraisal of collateral | Level III | Maximum
Quantitative Information about Level III Fair Value Measurements
Other real estate owned	0.10	0.10
Pull through rates | Recurring | Interest rate lock commitment | Pricing model | Level III | Minimum
Quantitative Information about Level III Fair Value Measurements
Debt securities	0.76	0.73
Pull through rates | Recurring | Interest rate lock commitment | Pricing model | Level III | Maximum
Quantitative Information about Level III Fair Value Measurements
Debt securities	0.92	0.85