Loans and reserve for credit losses (Receivable) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Covered Loans, Loss Share Payable (Receivable) [Roll Forward]
Balance at beginning of period	$ 76
Paid to FDIC	(76)
FDIC reimbursement	31
Balance at end of period	$ 31