Allowance for Credit Losses - Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012 Loans	Sep. 30, 2011	Sep. 30, 2012 Loans	Sep. 30, 2011	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	$ 9,440		$ 9,440		$ 5,704
Upaid Principal Balance, With no related allowance recorded	11,060		11,060		6,110
Recorded Investment, With an allowance recorded	8,344		8,344		17,940
Unpaid Principal Balance, With an allowance recorded	8,488		8,488		18,822
Related Allowance	965		965		4,368
Total Recorded Investment	17,784		17,784		23,644
Total Unpaid Principal Balance	19,548		19,548		24,932
Average Recorded Investment, With no related allowance recorded	7,985	9,787	9,299	8,217
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	9,640	9,371	9,457	10,869
Interest Income Recognized, With an allowance recorded	142	0	463	0
Average Recorded Investment, Total	17,625	19,158	18,756	19,086
Interest Income Recognized, Total	142	0	463	0
Forgone interest on nonaccrual loans	181	281	525	749
Number of troubled debt restructurings included in impaired and nonaccrual loans	11		11
Troubled debt restructurings included in impaired and nonaccrual loans	17,036		17,036
Commercial
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	744		744		2,140
Upaid Principal Balance, With no related allowance recorded	744		744		2,160
Recorded Investment, With an allowance recorded	1,720		1,720		1,717
Unpaid Principal Balance, With an allowance recorded	1,720		1,720		1,718
Related Allowance	42		42		231
Average Recorded Investment, With no related allowance recorded	600	1,291	1,235	1,404
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	1,849	1,170	1,624	721
Interest Income Recognized, With an allowance recorded	50	0	178	0
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	744		744		2,140
Upaid Principal Balance, With no related allowance recorded	744		744		2,160
Recorded Investment, With an allowance recorded	1,720		1,720		1,717
Unpaid Principal Balance, With an allowance recorded	1,720		1,720		1,718
Related Allowance	42		42		231
Average Recorded Investment, With no related allowance recorded	600	1,291	1,235	1,404
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	1,849	1,170	1,624	721
Interest Income Recognized, With an allowance recorded	50	0	178	0
Agricultural land and production
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	0		0		0
Upaid Principal Balance, With no related allowance recorded	0		0		0
Recorded Investment, With an allowance recorded	0		0		0
Unpaid Principal Balance, With an allowance recorded	0		0		0
Related Allowance	0		0		0
Average Recorded Investment, With no related allowance recorded	0	0	0	0
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	0	0	0	0
Interest Income Recognized, With an allowance recorded	0	0	0	0
Real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	7,142		7,142		3,564
Upaid Principal Balance, With no related allowance recorded	8,481		8,481		3,950
Recorded Investment, With an allowance recorded	6,312		6,312		13,795
Unpaid Principal Balance, With an allowance recorded	6,444		6,444		14,449
Related Allowance	909		909		3,764
Average Recorded Investment, With no related allowance recorded	5,770	6,509	6,498	6,466
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	7,479	7,810	7,242	9,902
Interest Income Recognized, With an allowance recorded	92	0	285	0
Owner occupied
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	714		714		231
Upaid Principal Balance, With no related allowance recorded	719		719		243
Recorded Investment, With an allowance recorded	1,182		1,182		1,141
Unpaid Principal Balance, With an allowance recorded	1,314		1,314		1,216
Related Allowance	11		11		268
Average Recorded Investment, With no related allowance recorded	992	709	747	840
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	646	1,282	662	1,182
Interest Income Recognized, With an allowance recorded	0	0	0	0
Real estate construction and other land loans
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	6,428		6,428		1,532
Upaid Principal Balance, With no related allowance recorded	7,762		7,762		1,906
Recorded Investment, With an allowance recorded	5,130		5,130		10,911
Unpaid Principal Balance, With an allowance recorded	5,130		5,130		11,490
Related Allowance	898		898		2,130
Average Recorded Investment, With no related allowance recorded	4,778	3,563	5,551	3,491
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	6,833	5,596	6,387	5,751
Interest Income Recognized, With an allowance recorded	92	0	285	0
Commercial real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	0		0		1,801
Upaid Principal Balance, With no related allowance recorded	0		0		1,801
Recorded Investment, With an allowance recorded	0		0		1,743
Unpaid Principal Balance, With an allowance recorded	0		0		1,743
Related Allowance	0		0		1,366
Average Recorded Investment, With no related allowance recorded	0	2,237	200	1,914
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	0	0	193	932
Interest Income Recognized, With an allowance recorded	0	0	0	0
Agricultural real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	0		0		0
Upaid Principal Balance, With no related allowance recorded	0		0		0
Recorded Investment, With an allowance recorded	0		0		0
Unpaid Principal Balance, With an allowance recorded	0		0		0
Related Allowance	0		0		0
Average Recorded Investment, With no related allowance recorded	0	0	0	0
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	0	932	0	0
Interest Income Recognized, With an allowance recorded	0	0	0	0
Other real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	0		0
Upaid Principal Balance, With no related allowance recorded	0		0
Recorded Investment, With an allowance recorded	0		0		0
Unpaid Principal Balance, With an allowance recorded	0		0		0
Related Allowance	0		0		0
Average Recorded Investment, With no related allowance recorded	0	0	0	221
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	0	0	0	2,037
Interest Income Recognized, With an allowance recorded	0	0	0	0
Consumer
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	1,554		1,554		0
Upaid Principal Balance, With no related allowance recorded	1,835		1,835		0
Recorded Investment, With an allowance recorded	312		312		2,428
Unpaid Principal Balance, With an allowance recorded	324		324		2,655
Related Allowance	14		14		373
Average Recorded Investment, With no related allowance recorded	1,615	1,987	1,566	347
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	312	391	591	246
Interest Income Recognized, With an allowance recorded	0	0	0	0
Equity loans and lines of credit
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	1,554		1,554		0
Upaid Principal Balance, With no related allowance recorded	1,835		1,835		0
Recorded Investment, With an allowance recorded	312		312		2,354
Unpaid Principal Balance, With an allowance recorded	324		324		2,581
Related Allowance	14		14		350
Average Recorded Investment, With no related allowance recorded	1,615	1,987	1,566	347
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	289	391	543	219
Interest Income Recognized, With an allowance recorded	0	0	0	0
Consumer and installment
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	0		0		0
Upaid Principal Balance, With no related allowance recorded	0		0		0
Recorded Investment, With an allowance recorded	0		0		74
Unpaid Principal Balance, With an allowance recorded	0		0		74
Related Allowance	0		0		23
Average Recorded Investment, With no related allowance recorded	0	0	0	0
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	23	0	48	27
Interest Income Recognized, With an allowance recorded	$ 0	$ 0	$ 0	$ 0

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Number of financing receivables that have been modified by troubled debt restructurings.

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-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 33

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The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of allowance for credit losses related to recorded investment.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

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Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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