Short-term Borrowings (Details)	Sep. 30, 2017 USD ($) bank	Dec. 31, 2016 USD ($)
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	43,240,000	$ 39,166,000	[1]
Other short-term borrowings	0	20,000,000	[1]
Short-term borrowings	$ 43,240,000	$ 59,166,000

[1] Derived from audited consolidated financial statements.