Loans and Allowance for Credit Losses Troubled Debt Restructuring Modification (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 loans	Mar. 31, 2012 loans
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	58	27
Recorded investment of loans modified as TDRs during the reporting periods	$ 8,898	$ 19,924
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	74	24
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	16,921	13,706
Real-estate commercial mortage [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	5	4
Recorded investment of loans modified as TDRs during the reporting periods	2,652	5,669
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	12	9
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	6,893	4,088
Real-estate - residential mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	28	13
Recorded investment of loans modified as TDRs during the reporting periods	3,966	4,679
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	31	8
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	5,849	1,714
Construction - commercial residential [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	2	3
Recorded investment of loans modified as TDRs during the reporting periods	628	6,365
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	4	3
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	1,308	7,550
Real-estate - home equity [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	17	2
Recorded investment of loans modified as TDRs during the reporting periods	1,180	171
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	20	2
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	1,233	239
Commercial - Secured [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	5	5
Recorded investment of loans modified as TDRs during the reporting periods	457	3,040
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	6	2
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	708	115
Commercial - unsecured [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs during the reporting periods	1	0
Recorded investment of loans modified as TDRs during the reporting periods	15	0
Construction - Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	1	0
Recorded investment of loans modified as TDRs within the previous 12 months which had a payment default during the reporting period	$ 930	$ 0