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Allowance for Probable Loan Losses (Details 4) (USD $) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2013 | Dec. 31, 2012
Interest income recognized: |  |
Loans accounted for as troubled debt restructuring | $ 19,232,000 | $ 24,300,000
Period of charge off for past due unsecured commercial loans | 90 days |
Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 30,622,000 | 11,982,000
Total impaired loans with no related allowance | 48,851,000 | 71,023,000
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 34,024,000 | 15,273,000
Total impaired loans with no related allowance recorded | 49,828,000 | 73,728,000
Related Allowance | 15,011,000 | 4,746,000
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 30,618,000 | 35,076,000
Total impaired loans with no related allowance recorded | 48,651,000 | 65,536,000
Interest income recognized: |  |
Total impaired loans with an allowance recorded | 32,000 | 131,000
Total impaired loans with no related allowance recorded | 81,000 | 323,000
Commercial | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 18,668,000 | 1,633,000
Total impaired loans with no related allowance | 14,440,000 | 31,135,000
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 18,702,000 | 1,679,000
Total impaired loans with no related allowance recorded | 14,487,000 | 31,170,000
Related Allowance | 11,544,000 | 1,477,000
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 18,688,000 | 21,126,000
Total impaired loans with no related allowance recorded | 15,147,000 | 2,996,000
Interest income recognized: |  |
Total impaired loans with an allowance recorded | 9,000 | 39,000
Total impaired loans with no related allowance recorded | 1,000 | 4,000
Commercial real estate: other construction and land development | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 5,516,000 | 3,671,000
Total impaired loans with no related allowance | 20,656,000 | 24,989,000
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 5,605,000 | 3,671,000
Total impaired loans with no related allowance recorded | 20,743,000 | 25,160,000
Related Allowance | 823,000 | 539,000
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 5,478,000 | 6,608,000
Total impaired loans with no related allowance recorded | 20,878,000 | 39,449,000
Interest income recognized: |  |
Total impaired loans with no related allowance recorded | 18,000 | 141,000
Commercial real estate: farmland and commercial | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 6,438,000 | 6,678,000
Total impaired loans with no related allowance | 5,462,000 | 7,267,000
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 9,717,000 | 9,923,000
Total impaired loans with no related allowance recorded | 6,232,000 | 9,340,000
Related Allowance | 2,644,000 | 2,730,000
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 6,452,000 | 7,342,000
Total impaired loans with no related allowance recorded | 5,006,000 | 16,536,000
Interest income recognized: |  |
Total impaired loans with an allowance recorded | 23,000 | 92,000
Total impaired loans with no related allowance recorded |  | 8,000
Commercial real estate: multifamily | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 338,000 | 353,000
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 338,000 | 353,000
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 345,000 | 381,000
Residential: first lien | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 4,546,000 | 3,656,000
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 4,595,000 | 3,984,000
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 3,840,000 | 2,876,000
Interest income recognized: |  |
Total impaired loans with no related allowance recorded | 33,000 | 60,000
Residential: junior lien | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 1,702,000 | 1,850,000
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 1,720,000 | 1,944,000
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 1,732,000 | 1,939,000
Interest income recognized: |  |
Total impaired loans with no related allowance recorded | 24,000 | 104,000
Consumer | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 1,245,000 | 1,326,000
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 1,250,000 | 1,330,000
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 1,246,000 | 1,193,000
Foreign | Class of financing receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 462,000 | 447,000
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 463,000 | 447,000
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 457,000 | 166,000
Interest income recognized: |  |
Total impaired loans with no related allowance recorded | $ 5,000 | $ 6,000

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