Short-Term Borrowings (Short Term Borrowing) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Short-term Borrowings
Short-term borrowings	$ 305,607	$ 160,386
Interest on short-term borrowings	508	182	$ 146
Retail Repurchase Agreements
Short-term Borrowings
Short-term borrowings	74,607	84,386	73,277
Average balance	72,886	83,574	59,324
Highest month-end balance	81,353	92,711	76,459
Interest on short-term borrowings	$ 123	$ 140	$ 99
Weighted Average Interest Rate, End of Year	0.17%	0.17%	0.17%
Weighted Average Interest Rate, During the Year	0.17%	0.17%	0.17%
FHLB Advances
Short-term Borrowings
Short-term borrowings	$ 231,000	$ 76,000	$ 15,000
Average balance	86,260	16,863	36,678
Highest month-end balance	231,000	76,000	108,000
Interest on short-term borrowings	$ 384	$ 42	$ 47
Weighted Average Interest Rate, End of Year	0.64%	0.35%	0.14%
Weighted Average Interest Rate, During the Year	0.44%	0.25%	0.13%
Other Short-Term Borrowings
Short-term Borrowings
Short-term borrowings	$ 0	$ 0	$ 0
Average balance	23	0	38
Highest month-end balance	0	0	0
Interest on short-term borrowings	$ 0	$ 0	$ 0
Weighted Average Interest Rate, End of Year	0.00%	0.00%	0.00%
Weighted Average Interest Rate, During the Year	1.11%	0.00%	0.75%