Short-Term Borrowings (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Average balances and cost of funds of short-term borrowings
Average Balances	$ 223,090	$ 22,233	$ 13,179
Cost of Funds (percent)	0.18%	0.17%	0.17%
Overnight borrowings
Average balances and cost of funds of short-term borrowings
Average Balances	$ 207,575	$ 17,899	$ 8,072
Cost of Funds (percent)	0.18%	0.17%	0.17%
Securities sold under agreements to repurchase
Average balances and cost of funds of short-term borrowings
Average Balances	$ 15,515	$ 4,334	$ 5,107
Cost of Funds (percent)	0.21%	0.15%	0.17%