Allowance for Credit Losses - Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012 Loans	Jun. 30, 2011	Jun. 30, 2012 Loans	Jun. 30, 2011	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	$ 5,777		$ 5,777		$ 5,704
Upaid Principal Balance, With no related allowance recorded	6,598		6,598		6,110
Recorded Investment, With an allowance recorded	12,042		12,042		17,940
Unpaid Principal Balance, With an allowance recorded	12,808		12,808		18,822
Related Allowance	2,195		2,195		4,368
Total Recorded Investment	17,819		17,819		23,644
Total Unpaid Principal Balance	19,406		19,406		24,932
Average Recorded Investment, With no related allowance recorded	8,935	7,615	9,308	6,435
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	8,741	8,909	8,029	9,257
Interest Income Recognized, With an allowance recorded	150	0	320	0
Average Recorded Investment, Total	17,676	16,524	17,337	15,692
Interest Income Recognized, Total	150	0	320	0
Forgone interest on nonaccrual loans	171	263	345	547
Number of troubled debt restructurings included in impaired and nonaccrual loans	11		11
Troubled debt restructurings included in impaired and nonaccrual loans	17,210		17,210
Commercial
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	963		963		2,140
Upaid Principal Balance, With no related allowance recorded	963		963		2,160
Recorded Investment, With an allowance recorded	1,460		1,460		1,717
Unpaid Principal Balance, With an allowance recorded	1,460		1,460		1,718
Related Allowance	536		536		231
Average Recorded Investment, With no related allowance recorded	1,144	1,046	1,412	1,466
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	1,473	9	1,511	165
Interest Income Recognized, With an allowance recorded	56	0	127	0
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	963		963		2,140
Upaid Principal Balance, With no related allowance recorded	963		963		2,160
Recorded Investment, With an allowance recorded	1,460		1,460		1,717
Unpaid Principal Balance, With an allowance recorded	1,460		1,460		1,718
Related Allowance	536		536		231
Average Recorded Investment, With no related allowance recorded	1,144	1,046	1,412	1,466
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	1,473	9	1,511	165
Interest Income Recognized, With an allowance recorded	56	0	127	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	3,077		3,077		3,564
Upaid Principal Balance, With no related allowance recorded	3,641		3,641		3,950
Recorded Investment, With an allowance recorded	10,270		10,270		13,795
Unpaid Principal Balance, With an allowance recorded	11,024		11,024		14,449
Related Allowance	1,600		1,600		3,764
Average Recorded Investment, With no related allowance recorded	6,033	5,756	6,436	4,448
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	6,868	6,718	6,164	9,051
Interest Income Recognized, With an allowance recorded	94	0	193	0
Owner occupied
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	1,630		1,630		231
Upaid Principal Balance, With no related allowance recorded	1,743		1,743		243
Recorded Investment, With an allowance recorded	0		0		1,141
Unpaid Principal Balance, With an allowance recorded	0		0		1,216
Related Allowance	0		0		268
Average Recorded Investment, With no related allowance recorded	1,022	909	625	908
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	0	1,054	0	1,056
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	1,447		1,447		1,532
Upaid Principal Balance, With no related allowance recorded	1,898		1,898		1,906
Recorded Investment, With an allowance recorded	10,270		10,270		10,911
Unpaid Principal Balance, With an allowance recorded	11,024		11,024		11,490
Related Allowance	1,600		1,600		2,130
Average Recorded Investment, With no related allowance recorded	5,011	3,335	5,811	1,808
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	6,868	5,664	6,164	5,780
Interest Income Recognized, With an allowance recorded	94	0	193	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	1,512	0	1,732
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
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	0	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	0
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	0	0	0	2,215
Interest Income Recognized, With an allowance recorded	0	0	0	0
Consumer
Financing Receivable, Impaired [Line Items]
Recorded Investment, With no related allowance recorded	1,737		1,737		0
Upaid Principal Balance, With no related allowance recorded	1,994		1,994		0
Recorded Investment, With an allowance recorded	312		312		2,428
Unpaid Principal Balance, With an allowance recorded	324		324		2,655
Related Allowance	59		59		373
Average Recorded Investment, With no related allowance recorded	1,758	813	1,460	521
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	400	2,182	354	41
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	1,737		1,737		0
Upaid Principal Balance, With no related allowance recorded	1,994		1,994		0
Recorded Investment, With an allowance recorded	241		241		2,354
Unpaid Principal Balance, With an allowance recorded	250		250		2,581
Related Allowance	35		35		350
Average Recorded Investment, With no related allowance recorded	1,758	813	1,460	521
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Average Recorded Investment, With an allowance recorded	352	2,182	294	0
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	71		71		74
Unpaid Principal Balance, With an allowance recorded	74		74		74
Related Allowance	24		24		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	48	0	60	41
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

-Topic 310

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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)

-Number 114

-Paragraph 20

-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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