Securities - Additional Information (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) security	Jun. 30, 2016 USD ($) security	Jun. 30, 2017 USD ($) security	Jun. 30, 2016 USD ($) security	Dec. 31, 2016 USD ($) security
Schedule Of Available-For-Sale And Held-To-Maturity [Line Items]
Available for sale securities carrying value pledged to secure public deposits	$ 44,500,000		$ 44,500,000		$ 34,300,000
Gross gains on sales of securities available for sale	19,000	$ 97,000	165,000	$ 264,000
Gross losses on sales of securities available for sale (less than in 2016)	49,000	$ 0	88	$ 1,000
Fair value of available-for-sale securities	42,382,000		42,382,000		56,987,000
Unrealized loss of available-for-sale securities	$ 778,000		$ 778,000		1,600,000
Number of held-to-maturity securities sold | security		1		1
Gross realized gain on sale of security		$ 8,000		$ 8,000
Fair value of held-to-maturity securities					789,000
Unrealized loss of held-to-maturity securities					$ 2,000
U.S. Government Agencies [Member]
Schedule Of Available-For-Sale And Held-To-Maturity [Line Items]
Number of securities with unrealized losses, available-for-sale | security	3		3		5
Fair value of available-for-sale securities	$ 5,166,000		$ 5,166,000		$ 7,078,000
Unrealized loss of available-for-sale securities	$ 27,000		$ 27,000		$ 57,000
State And Political Subdivisions [Member]
Schedule Of Available-For-Sale And Held-To-Maturity [Line Items]
Number of securities with unrealized losses, available-for-sale | security	12		12		31
Fair value of available-for-sale securities	$ 11,915,000		$ 11,915,000		$ 23,989,000
Unrealized loss of available-for-sale securities	$ 267,000		$ 267,000		$ 770,000
Number of securities with unrealized losses from state and political subdivisions maturity minimum number of years			10 years
Number of securities with unrealized losses, held-to-maturity | security					2
Fair value of held-to-maturity securities					$ 789,000
Unrealized loss of held-to-maturity securities					$ 2,000
U.S. Government-Sponsored Enterprises [Member]
Schedule Of Available-For-Sale And Held-To-Maturity [Line Items]
Number of securities with unrealized losses, available-for-sale | security	16		16		16
Fair value of available-for-sale securities	$ 25,301,000		$ 25,301,000		$ 23,938,000
Unrealized loss of available-for-sale securities	$ 484,000		$ 484,000		$ 755,000
Corporate Debt [Member]
Schedule Of Available-For-Sale And Held-To-Maturity [Line Items]
Number of securities with unrealized losses, available-for-sale | security					1
Fair value of available-for-sale securities					$ 1,982,000
Unrealized loss of available-for-sale securities					$ 18,000