Loans, Impaired Loans, Average Investments in Impaired Loans, and Interest Income Recognized on Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Total impaired loans [Abstract]
Recorded balance	$ 60,891		$ 56,021		$ 60,891	$ 56,021	$ 47,424
Unpaid Contractual Principal Balance	66,227		61,515		66,227	61,515	53,692
Specific Allowance	3,574		6,305		3,574	6,305	4,669
Average investment in impaired loans	61,455		56,031		62,151	63,404	61,647
Interest Income Recognized	441	[1]	786	[1]	1,251	1,600	2,010
Commercial Construction [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance	3,032		5,748		3,032	5,748	4,778
Unpaid Contractual Principal Balance	3,032		5,748		3,032	5,748	4,778
Average Investment in Impaired Loans	3,034		5,733		4,072	9,239	8,992
Interest Income Recognized	32	[1]	76	[1]	90	193	252
Loans with a specific valuation allowance [Abstract]
Recorded Balance	7,070		9,247		7,070	9,247	5,794
Unpaid Contractual Principal Balance	8,298		10,756		8,298	10,756	6,643
Specific Allowance	2,321		3,714		2,321	3,714	2,203
Average Investment in Impaired Loans	7,355		9,440		6,881	8,614	7,681
Interest income recognized	0	[1]	0	[1]	0	0	0
Commercial Secured By Real Estate [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance	34,099		31,308		34,099	31,308	27,811
Unpaid Contractual Principal Balance	34,586		32,483		34,586	32,483	29,765
Average Investment in Impaired Loans	34,229		30,910		35,566	31,901	31,480
Interest Income Recognized	291	[1]	666	[1]	976	1,239	1,543
Loans with a specific valuation allowance [Abstract]
Recorded Balance	3,406		4,619		3,406	4,619	3,525
Unpaid Contractual Principal Balance	3,530		4,754		3,530	4,754	3,669
Specific Allowance	938		1,826		938	1,826	1,156
Average Investment in Impaired Loans	3,436		4,632		3,293	5,025	4,747
Interest income recognized	0	[1]	0	[1]	0	23	23
Commercial Other [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance	11,643		2,996		11,643	2,996	1,770
Unpaid Contractual Principal Balance	13,819		3,091		13,819	3,091	2,501
Average Investment in Impaired Loans	11,756		3,129		10,348	3,677	3,392
Interest Income Recognized	108	[1]	38	[1]	167	126	143
Loans with a specific valuation allowance [Abstract]
Recorded Balance	975		1,793		975	1,793	3,432
Unpaid Contractual Principal Balance	2,295		4,373		2,295	4,373	6,022
Specific Allowance	315		765		315	765	1,310
Average Investment in Impaired Loans	977		1,873		1,582	4,666	5,071
Interest income recognized	0	[1]	0	[1]	0	0	22
Residential [Member]
Total impaired loans [Abstract]
Recorded balance	666		111		666	111	109
Unpaid Contractual Principal Balance	667		111		667	111	109
Specific Allowance	0		0		0	0	0
Average investment in impaired loans	668		111		409	103	103
Interest Income Recognized	10	[1]	1	[1]	18	5	6
Consumer [Member]
Total impaired loans [Abstract]
Recorded balance			199			199	205
Unpaid Contractual Principal Balance			199			199	205
Specific Allowance			0			0	0
Average investment in impaired loans			203			179	181
Interest Income Recognized			5	[1]		14	21
Real Estate Construction [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance			28			28	27
Unpaid Contractual Principal Balance			28			28	27
Average Investment in Impaired Loans			28			19	19
Interest Income Recognized			0	[1]		1	1
Real Estate Mortgage [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance	666		83		666	83	82
Unpaid Contractual Principal Balance	667		83		667	83	82
Average Investment in Impaired Loans	668		83		409	84	84
Interest Income Recognized	10	[1]	1	[1]	18	4	5
Consumer Direct [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance			78			78	93
Unpaid Contractual Principal Balance			78			78	93
Average Investment in Impaired Loans			79			78	82
Interest Income Recognized			2	[1]		6	9
Consumer Indirect [Member]
Loans without a specific valuation allowance [Abstract]
Recorded Balance			121			121	112
Unpaid Contractual Principal Balance			121			121	112
Average Investment in Impaired Loans			124			101	99
Interest Income Recognized			3	[1]		8	12
Commerical [Member]
Total impaired loans [Abstract]
Recorded balance	60,225		55,711		60,225	55,711	47,110
Unpaid Contractual Principal Balance	65,560		61,205		65,560	61,205	53,378
Specific Allowance	3,574		6,305		3,574	6,305	4,669
Average investment in impaired loans	60,787		55,717		61,742	63,122	61,363
Interest Income Recognized	$ 431	[1]	$ 780	[1]	$ 1,233	$ 1,581	$ 1,983

[1] Cash basis interest is substantially the same as interest income recognized.