Borrowed Funds - Short-Term Borrowings and Repurchase Agreements (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Short-term borrowings from FHLB
Short-term borrowings and Repurchase Agreements
Balance at end of period	$ 132,901	$ 179,917
Average balance	169,309	121,425
Maximum month-end balance	$ 210,600	$ 179,917
Weighted-average rate	0.47%	0.34%
Rate at end of period	0.46%	0.44%
Investment Securities
Short-term borrowings and Repurchase Agreements
Investment securities held as collateral	$ 28,000	$ 28,300
Repurchase agreements
Short-term borrowings and Repurchase Agreements
Balance at end of period	27,192	27,437
Average balance	26,238	26,884
Maximum month-end balance	$ 29,561	$ 32,470
Weighted-average rate	0.28%	0.31%
Rate at end of period	0.25%	0.30%