Loans, Credit Risk Profile Based on Rating Category and Payment Activity and on Performing and Nonperforming Status, Segregated by Class (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	$ 1,349,111		$ 1,312,254
Residential real estate and consumer loan portfolio based on performing and nonperforming status	1,235,690		1,238,319
Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	103,800		119,447
Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	859,022		807,213
Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	376,906		376,348
Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	9,383		9,246
Real Estate Construction [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	51,462		55,041
Real Estate Mortgage [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	692,934		696,928
Home Equity [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	80,631		82,292
Consumer Direct [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	123,565		122,581
Consumer Indirect [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	287,098		281,477
Pass [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	1,128,140		1,095,796
Pass [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	77,966		92,140
Pass [Member] | Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	725,401		665,764
Pass [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	315,390		328,646
Pass [Member] | Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	9,383		9,246
Watch [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	132,863		121,192
Watch [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	13,938		12,915
Watch [Member] | Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	79,507		79,517
Watch [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	39,418		28,760
Watch [Member] | Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	0		0
OAEM [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	18,157		20,402
OAEM [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	28		1,054
OAEM [Member] | Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	12,764		16,532
OAEM [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	5,365		2,816
OAEM [Member] | Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	0		0
Substandard [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	56,794		62,282
Substandard [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	7,213		7,383
Substandard [Member] | Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	35,179		40,021
Substandard [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	14,402		14,878
Substandard [Member] | Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	0		0
Doubtful [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	13,157		12,582
Doubtful [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	4,655		5,955
Doubtful [Member] | Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	6,171		5,379
Doubtful [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	2,331		1,248
Doubtful [Member] | Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	0		0
Performing [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	1,226,173		1,229,083
Performing [Member] | Real Estate Construction [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	50,661		54,530
Performing [Member] | Real Estate Mortgage [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	685,226		689,264
Performing [Member] | Home Equity [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	80,008		81,710
Performing [Member] | Consumer Direct [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	123,492		122,483
Performing [Member] | Consumer Indirect [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	286,786		281,096
Nonperforming [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	9,517	[1]	9,236	[1]
Nonperforming [Member] | Real Estate Construction [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	801	[1]	511	[1]
Nonperforming [Member] | Real Estate Mortgage [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	7,708	[1]	7,664	[1]
Nonperforming [Member] | Home Equity [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	623	[1]	582	[1]
Nonperforming [Member] | Consumer Direct [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	73	[1]	98	[1]
Nonperforming [Member] | Consumer Indirect [Member]
Credit risk profile, segregated by class [Line Items]
Residential real estate and consumer loan portfolio based on performing and nonperforming status	$ 312	[1]	$ 381	[1]

[1] A loan is considered nonperforming if it is 90 days or more past due and/or on nonaccrual.