Securities - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) security	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Investments, Debt and Equity Securities [Abstract]
Equity securities, at fair value | $	$ 2,069,000	$ 2,320,000	$ 1,830,000	[1]
Unrealized holding gains on equity securities | $	319,000	113,000
Equity securities sold during period | $	$ 80,000
Unrealized gain on equity securities | $		$ 113,000
FHLB stock requirement, percentage of outstanding capital	3.00%
FHLB stock requirement, percentage subject to call	3.00%
FHLB stock requirement, percentage of outstanding borrowings	4.25%
Debt Securities, Available-for-sale [Line Items]
Other-than-temporary impairment losses recognized | $	$ 0		$ 0
Federal agencies and GSEs
Debt Securities, Available-for-sale [Line Items]
Number of securities with unrealized losses	20
Number of securities in unrealized loss position for 12 months or more	20
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of securities with unrealized losses	65
Number of securities in unrealized loss position for 12 months or more	59
Collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Number of securities with unrealized losses	1
Number of securities in unrealized loss position for 12 months or more	1
State and municipal securities
Debt Securities, Available-for-sale [Line Items]
Number of securities with unrealized losses	43
Number of securities in unrealized loss position for 12 months or more	39
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Number of securities with unrealized losses	1
Number of securities in unrealized loss position for 12 months or more	1

[1] Derived from audited consolidated financial statements.