Loans and reserve for credit losses (Schedule of Financing Receivables, Non Accrual Status) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	$ 11,680	$ 7,226
Total accruing loans which are contractually past due 90 days or more	790	1,083
Commercial Real Estate Owner Occupied
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	4,222	4,443
Total accruing loans which are contractually past due 90 days or more	0	0
Commercial Real Estate Non Owner Occupied
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	1,431	280
Total accruing loans which are contractually past due 90 days or more	0	0
Commercial Real Estate
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	5,653	4,723
Total accruing loans which are contractually past due 90 days or more	0	0
Construction
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	495	236
Total accruing loans which are contractually past due 90 days or more	746	0
Residential real estate
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	4,222	399
Total accruing loans which are contractually past due 90 days or more	0	0
Commercial and Industrial
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	1,229	1,868
Total accruing loans which are contractually past due 90 days or more	25	1,077
Consumer
Schedule of Financing Receivables Nonaccrual [Line Items]
Total non-accrual loans	81	0
Total accruing loans which are contractually past due 90 days or more	$ 19	$ 6