Loans and the Allowance for Credit Losses (Details 6) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Recorded investment in non-accrual loans and TDR
Non-accrual loans	$ 42,726	$ 39,372
TDRs	37,526	39,282
Commercial real estate land and construction [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	6,123	4,668
TDRs	5,556	5,472
Commercial real estate improved property [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	20,998	18,239
TDRs	14,456	16,650
Commercial real estate [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	27,121	22,907
TDRs	20,012	22,122
Commercial and industrial [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	3,642	3,387
TDRs	1,312	1,360
Residential real estate [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	10,219	11,247
TDRs	13,496	13,099
Home equity [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	1,090	1,184
TDRs	1,461	1,541
Consumer [Member]
Recorded investment in non-accrual loans and TDR
Non-accrual loans	654	647
TDRs	1,245	1,160
Non Accrual TDRs [Member]
Recorded investment in non-accrual loans and TDR
TDRs	17,106	15,001
Non Accrual TDRs [Member] | Commercial real estate land and construction [Member]
Recorded investment in non-accrual loans and TDR
TDRs	3,877	2,935
Non Accrual TDRs [Member] | Commercial real estate improved property [Member]
Recorded investment in non-accrual loans and TDR
TDRs	8,088	6,452
Non Accrual TDRs [Member] | Commercial real estate [Member]
Recorded investment in non-accrual loans and TDR
TDRs	11,965	9,387
Non Accrual TDRs [Member] | Commercial and industrial [Member]
Recorded investment in non-accrual loans and TDR
TDRs	723	728
Non Accrual TDRs [Member] | Residential real estate [Member]
Recorded investment in non-accrual loans and TDR
TDRs	3,470	4,077
Non Accrual TDRs [Member] | Home equity [Member]
Recorded investment in non-accrual loans and TDR
TDRs	511	519
Non Accrual TDRs [Member] | Consumer [Member]
Recorded investment in non-accrual loans and TDR
TDRs	437	290
Accruing TDRs [Member]
Recorded investment in non-accrual loans and TDR
TDRs	20,420	24,281
Accruing TDRs [Member] | Commercial real estate land and construction [Member]
Recorded investment in non-accrual loans and TDR
TDRs	1,679	2,537
Accruing TDRs [Member] | Commercial real estate improved property [Member]
Recorded investment in non-accrual loans and TDR
TDRs	6,368	10,198
Accruing TDRs [Member] | Commercial real estate [Member]
Recorded investment in non-accrual loans and TDR
TDRs	8,047	12,735
Accruing TDRs [Member] | Commercial and industrial [Member]
Recorded investment in non-accrual loans and TDR
TDRs	589	632
Accruing TDRs [Member] | Residential real estate [Member]
Recorded investment in non-accrual loans and TDR
TDRs	10,026	9,022
Accruing TDRs [Member] | Home equity [Member]
Recorded investment in non-accrual loans and TDR
TDRs	950	1,022
Accruing TDRs [Member] | Consumer [Member]
Recorded investment in non-accrual loans and TDR
TDRs	$ 808	$ 870