Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-term Borrowings
Federal Funds Available from Correspondent Banks	$ 5,000
Short-term borrowings	209,491	$ 305,607
FHLB Advances
Short-term Borrowings
Long-term borrowings reclassified to short-term based on maturity date	50,600
Short-term borrowings	92,592	$ 231,000	$ 76,000
FHLB Advances | Matured Debt [Member]
Short-term Borrowings
Long-term borrowings reclassified to short-term based on maturity date	20,000
National Market Repurchase Agreements
Short-term Borrowings
Long-term borrowings reclassified to short-term based on maturity date	40,000
Short-term borrowings	$ 40,000