Allowance for Loan Losses, Nonperforming Assets and Impaired Loans, Non-impaired Loans by Credit Quality Indicator (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Threshold period for considering loans as special mention or classified	75 days
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	$ 541,463	$ 564,331
Pass [Member] | Real Estate Construction [Member] | Construction, 1-4 Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	15,993	14,344
Pass [Member] | Real Estate Construction [Member] | Construction, Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	28,154	29,011
Pass [Member] | Consumer Real Estate [Member] | Equity Lines [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	17,462	17,742
Pass [Member] | Consumer Real Estate [Member] | Closed-end First Liens [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	75,434	113,893
Pass [Member] | Consumer Real Estate [Member] | Closed-end Junior Liens [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	5,410	6,713
Pass [Member] | Consumer Real Estate [Member] | Investor-owned residential real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	37,027
Pass [Member] | Commercial Real Estate [Member] | Commercial Real Estate, Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	93,264	92,628
Pass [Member] | Commercial Real Estate [Member] | Commercial Real Estate, Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	144,248	160,188
Pass [Member] | Commercial Real Estate [Member] | Multifamily Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	35,328	36,421
Pass [Member] | Commercial Non Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	34,725	36,372
Pass [Member] | Public Sector and IDA [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	26,686	26,170
Pass [Member] | Consumer Non Real Estate [Member] | Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	12,171	12,344
Pass [Member] | Consumer Non Real Estate [Member] | Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	9,269	11,815
Pass [Member] | Consumer Non Real Estate [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	6,292	6,690
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Increase in percentage of allocation for internal and external factors used for estimating credit risk for non-impaired loans (in hundredths)	50.00%
Non-impaired loans	10,295	4,639
Special Mention [Member] | Real Estate Construction [Member] | Construction, 1-4 Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	158	158
Special Mention [Member] | Real Estate Construction [Member] | Construction, Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	6,086	0
Special Mention [Member] | Consumer Real Estate [Member] | Equity Lines [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	100
Special Mention [Member] | Consumer Real Estate [Member] | Closed-end First Liens [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	283	652
Special Mention [Member] | Consumer Real Estate [Member] | Closed-end Junior Liens [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	116	119
Special Mention [Member] | Consumer Real Estate [Member] | Investor-owned residential real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	48
Special Mention [Member] | Commercial Real Estate [Member] | Commercial Real Estate, Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	3,092	3,112
Special Mention [Member] | Commercial Real Estate [Member] | Commercial Real Estate, Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	215	253
Special Mention [Member] | Commercial Real Estate [Member] | Multifamily Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	0
Special Mention [Member] | Commercial Non Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	151	99
Special Mention [Member] | Public Sector and IDA [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	0
Special Mention [Member] | Consumer Non Real Estate [Member] | Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	122	101
Special Mention [Member] | Consumer Non Real Estate [Member] | Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	24	45
Special Mention [Member] | Consumer Non Real Estate [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	0
Classified (Excluding Impaired) [Member]
Financing Receivable, Recorded Investment [Line Items]
Increase in percentage of allocation for internal and external factors used for estimating credit risk for non-impaired loans (in hundredths)	100.00%
Non-impaired loans	5,942	4,735
Classified (Excluding Impaired) [Member] | Real Estate Construction [Member] | Construction, 1-4 Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	0
Classified (Excluding Impaired) [Member] | Real Estate Construction [Member] | Construction, Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	30	120
Classified (Excluding Impaired) [Member] | Consumer Real Estate [Member] | Equity Lines [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	84	182
Classified (Excluding Impaired) [Member] | Consumer Real Estate [Member] | Closed-end First Liens [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	2,739	2,413
Classified (Excluding Impaired) [Member] | Consumer Real Estate [Member] | Closed-end Junior Liens [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	143	138
Classified (Excluding Impaired) [Member] | Consumer Real Estate [Member] | Investor-owned residential real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	48
Classified (Excluding Impaired) [Member] | Commercial Real Estate [Member] | Commercial Real Estate, Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	0
Classified (Excluding Impaired) [Member] | Commercial Real Estate [Member] | Commercial Real Estate, Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	1,239	1,079
Classified (Excluding Impaired) [Member] | Commercial Real Estate [Member] | Multifamily Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	1,178	324
Classified (Excluding Impaired) [Member] | Commercial Non Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	298	318
Classified (Excluding Impaired) [Member] | Public Sector and IDA [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	0	0
Classified (Excluding Impaired) [Member] | Consumer Non Real Estate [Member] | Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	115	56
Classified (Excluding Impaired) [Member] | Consumer Non Real Estate [Member] | Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	68	105
Classified (Excluding Impaired) [Member] | Consumer Non Real Estate [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Non-impaired loans	$ 0	$ 0