Loans and the Allowance for Credit Losses (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Summary of Impaired Loans
Unpaid principal balance	$ 82,498		$ 82,498		$ 100,946
Recorded investment	68,117		68,117		86,903
Related allowance	3,582		3,582		3,353
Average recorded investment	74,547	97,346	78,665	97,310
Interest income recognized	415	652	830	1,148
Impaired Loans With No Related Allowance Recorded [Member]
Summary of Impaired Loans
Unpaid principal balance	66,816		66,816		89,745
Recorded investment	58,214		58,214		76,002
Related allowance	0		0		0
Average recorded investment	62,411	71,111	66,940	68,010
Interest income recognized	344	337	650	613
Impaired Loans With No Related Allowance Recorded [Member] | Commercial Real Estate Land and Construction [Member]
Summary of Impaired Loans
Unpaid principal balance	10,993		10,993		19,733
Recorded investment	9,266		9,266		14,731
Related allowance	0		0		0
Average recorded investment	9,249	12,307	11,076	10,553
Interest income recognized	80	39	172	117
Impaired Loans With No Related Allowance Recorded [Member] | Commercial Real Estate Improved Property [Member]
Summary of Impaired Loans
Unpaid principal balance	31,544		31,544		38,629
Recorded investment	27,915		27,915		34,352
Related allowance	0		0		0
Average recorded investment	30,151	34,308	31,551	33,396
Interest income recognized	162	179	282	328
Impaired Loans With No Related Allowance Recorded [Member] | Commercial and Industrial [Member]
Summary of Impaired Loans
Unpaid principal balance	7,940		7,940		11,536
Recorded investment	6,143		6,143		9,078
Related allowance	0		0		0
Average recorded investment	6,860	8,942	7,599	8,630
Interest income recognized	41	88	59	97
Impaired Loans With No Related Allowance Recorded [Member] | Residential Real Estate [Member]
Summary of Impaired Loans
Unpaid principal balance	15,128		15,128		18,038
Recorded investment	13,807		13,807		16,221
Related allowance	0		0		0
Average recorded investment	14,946	14,211	15,371	14,184
Interest income recognized	60	29	134	69
Impaired Loans With No Related Allowance Recorded [Member] | Home Equity [Member]
Summary of Impaired Loans
Unpaid principal balance	1,012		1,012		1,465
Recorded investment	908		908		1,331
Related allowance	0		0		0
Average recorded investment	988	1,134	1,102	1,007
Interest income recognized	0	0	2	0
Impaired Loans With No Related Allowance Recorded [Member] | Consumer [Member]
Summary of Impaired Loans
Unpaid principal balance	199		199		344
Recorded investment	175		175		289
Related allowance	0		0		0
Average recorded investment	217	209	241	240
Interest income recognized	1	2	1	2
Impaired Loans With Allowance Recorded [Member]
Summary of Impaired Loans
Unpaid principal balance	15,682		15,682		11,201
Recorded investment	9,903		9,903		10,901
Related allowance	3,582		3,582		3,353
Average recorded investment	12,136	26,235	11,725	29,300
Interest income recognized	71	315	180	535
Impaired Loans With Allowance Recorded [Member] | Commercial Real Estate Land and Construction [Member]
Summary of Impaired Loans
Unpaid principal balance	8,574		8,574		2,813
Recorded investment	2,795		2,795		2,813
Related allowance	1,675		1,675		1,788
Average recorded investment	4,188	2,993	3,730	4,698
Interest income recognized	0	70	0	82
Impaired Loans With Allowance Recorded [Member] | Commercial Real Estate Improved Property [Member]
Summary of Impaired Loans
Unpaid principal balance	7,108		7,108		8,388
Recorded investment	7,108		7,108		8,088
Related allowance	1,907		1,907		1,565
Average recorded investment	7,948	21,402	7,995	23,375
Interest income recognized	71	245	180	453
Impaired Loans With Allowance Recorded [Member] | Commercial and Industrial [Member]
Summary of Impaired Loans
Unpaid principal balance	0		0		0
Recorded investment	0		0		0
Related allowance	0		0		0
Average recorded investment	0	1,840	0	1,227
Interest income recognized	$ 0	$ 0	$ 0	$ 0