Loans and reserve for credit losses Loans and reserve for credit losses (Schedule of Financing Receivables, Post Modification) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rate reduction	$ 0
Term extension	22
Rate reduction and term extension	0
Total	22
Commercial real estate | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rate reduction	0
Term extension	0
Rate reduction and term extension	0
Total	0
Construction | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rate reduction	0
Term extension	0
Rate reduction and term extension	0
Total	0
Residential real estate | Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rate reduction	0
Term extension	0
Rate reduction and term extension	0
Total	0
Commercial and industrial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rate reduction	0
Term extension	22
Rate reduction and term extension	0
Total	22
Consumer | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rate reduction	0
Term extension	0
Rate reduction and term extension	0
Total	$ 0