Fair Value Measurements - Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018		Sep. 30, 2018
Assets:
Securities available for sale	$ 308,490,000	$ 332,653,000	[1]
Equity securities, at fair value	0	1,830,000	[1]	$ 2,087,000
Level 1
Assets:
Securities available for sale	0	0
Derivative - cash flow hedges	0	0
Level 2
Assets:
Securities available for sale	308,490,000	332,653,000
Equity securities, at fair value		1,830,000
Derivative - cash flow hedges	3,477,000	804,000
Level 3
Assets:
Securities available for sale	0	0
Derivative - cash flow hedges	0	0
Federal agencies and GSEs
Assets:
Securities available for sale	121,256,000	134,039,000
Mortgage-backed and CMOs
Assets:
Securities available for sale	135,201,000	111,867,000
State and municipal
Assets:
Securities available for sale	43,855,000	79,902,000
Corporate
Assets:
Securities available for sale	8,178,000	6,845,000
Fair Value, Measurements, Recurring
Assets:
Securities available for sale	308,490,000	332,653,000
Equity securities, at fair value		1,830,000
Derivative - cash flow hedges	3,477,000	804,000
Fair Value, Measurements, Recurring | Level 1
Assets:
Securities available for sale	0	0
Equity securities, at fair value		0
Derivative - cash flow hedges	0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Securities available for sale	308,490,000	332,653,000
Equity securities, at fair value		1,830,000
Derivative - cash flow hedges	3,477,000	804,000
Fair Value, Measurements, Recurring | Level 3
Assets:
Securities available for sale	0	0
Equity securities, at fair value	0	0
Derivative - cash flow hedges	0	0
Fair Value, Measurements, Recurring | Federal agencies and GSEs
Assets:
Securities available for sale	121,256,000	134,039,000
Fair Value, Measurements, Recurring | Federal agencies and GSEs | Level 1
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | Federal agencies and GSEs | Level 2
Assets:
Securities available for sale	121,256,000	134,039,000
Fair Value, Measurements, Recurring | Federal agencies and GSEs | Level 3
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | Mortgage-backed and CMOs
Assets:
Securities available for sale	135,201,000	111,867,000
Fair Value, Measurements, Recurring | Mortgage-backed and CMOs | Level 1
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | Mortgage-backed and CMOs | Level 2
Assets:
Securities available for sale	135,201,000	111,867,000
Fair Value, Measurements, Recurring | Mortgage-backed and CMOs | Level 3
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | State and municipal
Assets:
Securities available for sale	43,855,000	79,902,000
Fair Value, Measurements, Recurring | State and municipal | Level 1
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | State and municipal | Level 2
Assets:
Securities available for sale	43,855,000	79,902,000
Fair Value, Measurements, Recurring | State and municipal | Level 3
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | Corporate
Assets:
Securities available for sale	8,178,000	6,845,000
Fair Value, Measurements, Recurring | Corporate | Level 1
Assets:
Securities available for sale	0	0
Fair Value, Measurements, Recurring | Corporate | Level 2
Assets:
Securities available for sale	8,178,000	6,845,000
Fair Value, Measurements, Recurring | Corporate | Level 3
Assets:
Securities available for sale	$ 0	$ 0

[1] Derived from audited consolidated financial statements.