Derivative Financial Instruments (Back-to-back loan swaps) (Balance sheet category and fair values) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Feb. 05, 2016
Other liabilities
Derivative [Line Items]
Notional Amount			$ 2,000,000
Back-to-Back Loan Swaps | Other assets
Derivative [Line Items]
Notional Amount	$ 162,882,000	$ 126,766,000
Fair Value, Receive fixed-pay floating interest rate swap	3,763,000	2,377,000
Back-to-Back Loan Swaps | Other liabilities
Derivative [Line Items]
Notional Amount	162,882,000	126,766,000
Fair Value, Pay fixed-receive floating interest rate swap	$ (3,763,000)	$ (2,377,000)
Long | Back-to-Back Loan Swaps | Other assets
Derivative [Line Items]
Derivative, Average Variable Interest Rate	4.82%	4.70%
Long | Back-to-Back Loan Swaps | Other liabilities
Derivative [Line Items]
Derivative, Average Variable Interest Rate	4.73%	4.03%
Short | Back-to-Back Loan Swaps | Other assets
Derivative [Line Items]
Derivative, Average Variable Interest Rate	4.73%	4.03%
Short | Back-to-Back Loan Swaps | Other liabilities
Derivative [Line Items]
Derivative, Average Variable Interest Rate	4.82%	4.70%