Loans (Nonaccrual and Past Due Loans) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 8,537,000	$ 13,638,000
Accruing Loans 90 or More Days Past Due	2,597,000	1,235,000
Commercial Real Estate, Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	76,000	0
Accruing Loans 90 or More Days Past Due	0	0
Commercial Real Estate, Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	4,786,000	9,831,000
Accruing Loans 90 or More Days Past Due	0	0
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	4,862,000	9,831,000
Accruing Loans 90 or More Days Past Due	0	0
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	323,000	627,000
Accruing Loans 90 or More Days Past Due	950,000	181,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	3,207,000	3,136,000
Accruing Loans 90 or More Days Past Due	0	0
Home Equity Lines of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Receivables Reclassified as Past Due Since Maturity	2,200,000	1,200,000	800,000
Nonaccrual Loans	85,000	24,000
Accruing Loans 90 or More Days Past Due	1,615,000	1,050,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	60,000	20,000
Accruing Loans 90 or More Days Past Due	$ 32,000	$ 4,000