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	Mar. 31, 2013		Dec. 31, 2012
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	$ 1,335,463		$ 1,312,254
Residential real estate and consumer loan portfolio based on performing and nonperforming status	1,227,851		1,238,319
Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	102,303		119,447
Commercial Secured by Real Estate [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	847,807		807,213
Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	375,409		376,348
Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	9,944		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	51,978		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	696,321		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	79,899		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	119,191		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	280,462		281,477
Pass [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	1,116,073		1,095,796
Pass [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	74,898		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	704,073		665,764
Pass [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	327,158		328,646
Pass [Member] | Equipment Lease [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	9,944		9,246
Watch [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	129,411		121,192
Watch [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	14,142		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	85,439		79,517
Watch [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	29,830		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	14,799		20,402
OAEM [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	56		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	13,769		16,532
OAEM [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	974		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	62,734		62,282
Substandard [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	7,011		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	39,387		40,021
Substandard [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	16,336		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	12,446		12,582
Doubtful [Member] | Commercial Construction [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	6,196		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	5,139		5,379
Doubtful [Member] | Commercial Other [Member]
Credit risk profile, segregated by class [Line Items]
Commercial loan portfolio based on credit risk profile	1,111		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	1,218,611		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	51,111		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	688,923		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	79,382		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	119,112		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	280,083		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	9,240	[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	867	[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	7,398	[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	517	[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	79	[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	$ 379	[1]	$ 381	[1]

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