Loans and Allowance for Loan Losses, Impaired Financing Receivable (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Recorded investment	$ 21,836,000		$ 22,823,000
Unpaid principal balance	24,081,000		35,057,000
Related allowance	1,748,000	[1]	1,764,000	[1]
Average recorded investment	24,167,000		32,623,000
Interest income recognized	0		0
Interest income from cash payments received	0		0
Collateral Dependent Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	15,588,000		15,474,000
Unpaid principal balance	16,259,000		21,404,000
Related allowance	0	[1]	0	[1]
Average recorded investment	16,607,000		18,695,000
Interest income recognized	0		0
Collateral Dependent Impaired Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	8,352,000		8,740,000
Unpaid principal balance	8,772,000		11,187,000
Related allowance	0	[1]	0	[1]
Average recorded investment	9,220,000		9,612,000
Interest income recognized	0		0
Collateral Dependent Impaired Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	5,030,000		3,641,000
Unpaid principal balance	5,158,000		6,394,000
Related allowance	0	[1]	0	[1]
Average recorded investment	5,162,000		5,266,000
Interest income recognized	0		0
Collateral Dependent Impaired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	1,516,000		1,546,000
Unpaid principal balance	1,605,000		2,062,000
Related allowance	0	[1]	0	[1]
Average recorded investment	1,526,000		1,753,000
Interest income recognized	0		0
Collateral Dependent Impaired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	690,000		1,547,000
Unpaid principal balance	724,000		1,761,000
Related allowance	0	[1]	0	[1]
Average recorded investment	699,000		2,064,000
Interest income recognized	0		0
Collateral Dependent Impaired Loans [Member] | Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	0		0
Unpaid principal balance	0		0
Related allowance	0	[1]	0	[1]
Average recorded investment	0		0
Interest income recognized	0		0
Cash Flow Dependent Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	6,248,000		7,349,000
Unpaid principal balance	7,822,000		13,653,000
Related allowance	1,748,000	[1]	1,764,000	[1]
Average recorded investment	7,560,000		13,928,000
Interest income recognized	0		0
Cash Flow Dependent Impaired Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	2,713,000		551,000
Unpaid principal balance	2,773,000		1,841,000
Related allowance	571,000	[1]	154,000	[1]
Average recorded investment	2,901,000		2,893,000
Interest income recognized	0		0
Cash Flow Dependent Impaired Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	2,464,000		2,265,000
Unpaid principal balance	2,582,000		4,473,000
Related allowance	852,000	[1]	573,000	[1]
Average recorded investment	2,488,000		4,656,000
Interest income recognized	0		0
Cash Flow Dependent Impaired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	283,000		2,963,000
Unpaid principal balance	350,000		4,701,000
Related allowance	111,000	[1]	201,000	[1]
Average recorded investment	297,000		4,147,000
Interest income recognized	0		0
Cash Flow Dependent Impaired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	685,000		1,491,000
Unpaid principal balance	1,989,000		2,459,000
Related allowance	174,000	[1]	814,000	[1]
Average recorded investment	1,770,000		2,089,000
Interest income recognized	0		0
Cash Flow Dependent Impaired Loans [Member] | Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment	103,000		79,000
Unpaid principal balance	128,000		179,000
Related allowance	40,000	[1]	22,000	[1]
Average recorded investment	104,000		143,000
Interest income recognized	$ 0		$ 0

[1] Collateral dependent loans are typically charged-off to their net realizable value pursuant to requirements of our primary regulators and no specific allowance is carried related to those loans.