Short-Term Borrowings (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Average balances and cost of funds of short-term borrowings
Average Balances	$ 217,547	$ 356,929	$ 223,090
Cost of Funds	1.22%	0.45%	0.18%
Federal Home Loan Bank short-term advances
Average balances and cost of funds of short-term borrowings
Average Balances	$ 208,332	$ 344,724	$ 207,575
Cost of Funds	1.27%	0.46%	0.18%
Securities sold under agreements to repurchase
Average balances and cost of funds of short-term borrowings
Average Balances	$ 9,215	$ 12,205	$ 15,515
Cost of Funds	0.17%	0.20%	0.21%