Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs That Were Restructured (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 loan
Financing Receivable, Modifications [Line Items]
Number of Loans	6
Pre- Modification Recorded Investment	$ 1,571
Funds Disbursed	30
Interest and Escrow Capitalized	6
Charge-offs	0
Post- Modification Recorded Investment	1,607
Commercial And Industrial
Financing Receivable, Modifications [Line Items]
Number of Loans	2
Pre- Modification Recorded Investment	716
Funds Disbursed	0
Interest and Escrow Capitalized	2
Charge-offs	0
Post- Modification Recorded Investment	718
Office Retail And Industrial
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Pre- Modification Recorded Investment	215
Funds Disbursed	30
Interest and Escrow Capitalized	0
Charge-offs	0
Post- Modification Recorded Investment	245
Construction
Financing Receivable, Modifications [Line Items]
Number of Loans	2
Pre- Modification Recorded Investment	508
Funds Disbursed	0
Interest and Escrow Capitalized	0
Charge-offs	0
Post- Modification Recorded Investment	508
1-4 family mortgages
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Pre- Modification Recorded Investment	132
Funds Disbursed	0
Interest and Escrow Capitalized	4
Charge-offs	0
Post- Modification Recorded Investment	$ 136