Short-term Borrowings (Details)	Sep. 30, 2018 USD ($) bank	Dec. 31, 2017 USD ($)
Debt Disclosure [Abstract]
Federal funds line of credit, number of banks | bank	2
Federal funds line of credit, amount per agreement	$ 15,000,000
Customer repurchase agreements	29,104,000	$ 10,726,000	[1]
Other short-term borrowings	0	24,000,000	[1]
Short-term borrowings	$ 29,104,000	$ 34,726,000

[1] Derived from audited consolidated financial statements.