Loans and Allowance for Losses and Concentrations of Credit Risk Narrative (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Impaired, Loans Past Due Period, Minimum	90 days
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 6,659	$ 7,296
Alternate minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Impaired, Loans Past Due Period, Minimum	120 days