Loans and reserve for credit losses (Loans, Covered Loans, Loss Share Payable (Receivable)) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Loans and Leases Receivable, Covered [Roll Forward]
Balance at beginning of period	$ (449)
Paid to FDIC	1,408
Increase due to impairment	73
FDIC reimbursement	(1,450)
Shared loss expenses	232
Adjustments from prior periods	(141)
OREO loss carryforward	38
Balance at end of period	$ (289)