Short-term Borrowings (Details)	Dec. 31, 2017 USD ($) bank	Dec. 31, 2016 USD ($)
Short-term Debt [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	10,726,000	$ 39,166,000
Other short-term borrowings	24,000,000	20,000,000
Short-term borrowings	$ 34,726,000	$ 59,166,000
Customer repurchase agreements, weighted average rate	0.01%	0.01%
Short-term borrowings, weighted average rate	1.59%	0.80%