Short-term borrowings (Details) - Repurchase agreement - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Sale of repurchase agreement [Line items]
Total repurchase agreements	$ 82,826	$ 75,482
U.S. Treasury and U.S. government sponsored entities
Sale of repurchase agreement [Line items]
Total repurchase agreements	7,637	5,276
State and political subdivisions
Sale of repurchase agreement [Line items]
Total repurchase agreements	6,048	2,640
Mortgage-backed securities - residential
Sale of repurchase agreement [Line items]
Total repurchase agreements	61,499	60,391
Collateralized mortgage obligations - residential
Sale of repurchase agreement [Line items]
Total repurchase agreements	$ 7,642	$ 7,175