Loans and reserve for credit losses (Schedule of Financing Receivables, Non Accrual Status) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	$ 11,335	$ 5,053
Total accruing loans which are contractually past due 90 days or more	29	68
Owner occupied
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	1,961	2,742
Non-owner occupied
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	320	434
Commercial real estate
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	2,281	3,176
Construction
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	0	0
Residential real estate
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	1,512	1,427
Commercial and industrial
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	7,542	447
Total accruing loans which are contractually past due 90 days or more	18	56
Consumer
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	0	3
Total accruing loans which are contractually past due 90 days or more	$ 11	$ 12