Allowance for Credit Losses - Troubled Debt Restructurings (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2012 Loans	Sep. 30, 2011 Loans		Sep. 30, 2012 Loans		Sep. 30, 2011 Loans
Financing Receivable, Modifications [Line Items]
Reserves specific to modified loans	$ 943,000			$ 943,000
Commitments for additional lending to customers with modified loans	700,000			700,000
Number of Loans	0	6				8
Pre-Modification Outstanding Recorded Investment		15,394,000	[1]			18,739,000	[1]
Principal Modification		0	[2]			0
Post Modification Outstanding Recorded Investment		15,394,000	[3]			18,739,000	[3]
Outstanding Recorded Investment		14,843,000				17,558,000
Defaults on troubled debt restructurings	0			1
Number of TDR's with subsequent defaults		1				1
Recorded investment of TDR's with subsequent defaults	0			0
Increase in allowance related to TDR's with subsequent defaults	6,000	427,000		6,000		427,000
Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans		2				2
Pre-Modification Outstanding Recorded Investment		3,089,000	[1]			3,089,000	[1]
Principal Modification		0	[2]			0	[2]
Post Modification Outstanding Recorded Investment		3,089,000	[3]			3,089,000	[3]
Outstanding Recorded Investment		2,643,000				2,643,000
Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans		2				2
Pre-Modification Outstanding Recorded Investment		3,089,000	[1]			3,089,000	[1]
Principal Modification		0	[2]
Post Modification Outstanding Recorded Investment		3,089,000	[3]			3,089,000	[3]
Outstanding Recorded Investment		2,643,000				2,643,000
Real Estate Portfolio Segment
Financing Receivable, Modifications [Line Items]
Number of Loans		4				6
Pre-Modification Outstanding Recorded Investment		12,305,000	[1]			15,650,000	[1]
Principal Modification		0	[2]			0
Post Modification Outstanding Recorded Investment		12,305,000	[3]			15,650,000	[3]
Outstanding Recorded Investment		12,200,000				14,915,000
Real Estate Portfolio Segment | Owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans				2		1
Pre-Modification Outstanding Recorded Investment				500,000	[1]	1,074,000	[1]
Principal Modification				0	[2]
Post Modification Outstanding Recorded Investment				500,000	[3]	1,074,000	[3]
Outstanding Recorded Investment				493,000		1,034,000
Real Estate Portfolio Segment | Real estate construction and other land loans
Financing Receivable, Modifications [Line Items]
Number of Loans		3				3
Pre-Modification Outstanding Recorded Investment		11,094,000	[1]			11,094,000	[1]
Principal Modification		0	[2]
Post Modification Outstanding Recorded Investment		11,094,000	[3]			11,094,000	[3]
Outstanding Recorded Investment		10,989,000				10,989,000
Real Estate Portfolio Segment | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans		1				1
Pre-Modification Outstanding Recorded Investment		1,211,000	[1]			1,211,000	[1]
Principal Modification		0	[2]
Post Modification Outstanding Recorded Investment		1,211,000	[3]			1,211,000	[3]
Outstanding Recorded Investment		1,211,000				1,211,000
Real Estate Portfolio Segment | Other real estate
Financing Receivable, Modifications [Line Items]
Number of Loans						1
Pre-Modification Outstanding Recorded Investment						2,271,000	[1]
Post Modification Outstanding Recorded Investment						2,271,000	[3]
Outstanding Recorded Investment						$ 1,681,000

[1] Amounts represent the recorded investment in loans before recognizing effects of the TDR, if any.

[2] Principal Modification includes principal forgiveness at the time of modification, contingent principal forgiveness granted over the life of the loan based on borrower performance, and principal that has been legally separated and deferred to the end of the loan, with zero percent contractual interest rate.

[3] Balance outstanding after principal modification, if any borrower reduction to recorded investment.