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Allowance for Probable Loan Losses (Impaired Loans) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Interest Recognized |  |
Total trouble debt restructuring | $ 15,346 | $ 22,418
Period of charge off for past due unsecured commercial loans | 90 days |
Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | $ 1,894 | 4,828
Total impaired loans with no related allowance | 61,310 | 42,577
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 2,336 | 5,981
Total impaired loans with no related allowance recorded | 89,664 | 74,677
Related Allowance | 434 | 961
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 1,985 | 9,579
Total impaired loans with no related allowance recorded | 72,417 | 40,450
Interest Recognized |  |
Total impaired loans with no related allowance recorded | 391 | 547
Commercial |  |
Interest Recognized |  |
Total trouble debt restructuring | 6,910 | 10,710
Commercial | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 1,300 |
Total impaired loans with no related allowance | 16,646 | 21,412
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 1,577 |
Total impaired loans with no related allowance recorded | 44,095 | 50,737
Related Allowance | 300 |
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 1,346 |
Total impaired loans with no related allowance recorded | 19,615 | 19,354
Interest Recognized |  |
Total impaired loans with no related allowance recorded | 3 | 3
Commercial Real Estate: Other Construction and Land Development | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 145 | 1,958
Total impaired loans with no related allowance | 2,310 | 2,818
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 169 | 1,971
Total impaired loans with no related allowance recorded | 2,455 | 4,419
Related Allowance | 116 | 371
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 150 | 2,512
Total impaired loans with no related allowance recorded | 3,493 | 2,336
Interest Recognized |  |
Total impaired loans with no related allowance recorded |  | 67
Commercial Real Estate: Farmland & Commercial |  |
Interest Recognized |  |
Total trouble debt restructuring |  | 3,086
Commercial Real Estate: Farmland & Commercial | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance | 449 | 2,808
Total impaired loans with no related allowance | 32,675 | 8,002
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded | 590 | 3,948
Total impaired loans with no related allowance recorded | 33,275 | 9,054
Related Allowance | 18 | 546
Average recorded investment: |  |
Total impaired loans with an allowance recorded | 489 | 3,247
Total impaired loans with no related allowance recorded | 38,536 | 8,523
Interest Recognized |  |
Total impaired loans with no related allowance recorded |  | 110
Commercial Real Estate: Multifamily | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with related allowance |  | 62
Total impaired loans with no related allowance | 476 | 552
Unpaid principal balance: |  |
Total impaired loans with an allowance recorded |  | 62
Total impaired loans with no related allowance recorded | 505 | 562
Related Allowance |  | 44
Average recorded investment: |  |
Total impaired loans with an allowance recorded |  | 62
Total impaired loans with no related allowance recorded | 511 | 401
Residential First Lien |  |
Interest Recognized |  |
Total trouble debt restructuring | 6,140 | 6,181
Residential First Lien | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 6,852 | 6,774
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 6,968 | 6,847
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 7,249 | 6,860
Interest Recognized |  |
Total impaired loans with no related allowance recorded | 324 | 298
Residential Junior Lien |  |
Interest Recognized |  |
Total trouble debt restructuring | 712 | 812
Residential Junior Lien | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 723 | 978
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 736 | 1,017
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 970 | 1,011
Interest Recognized |  |
Total impaired loans with no related allowance recorded | 45 | 52
Consumer |  |
Interest Recognized |  |
Total trouble debt restructuring | 1,237 | 1,269
Consumer | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 1,281 | 1,295
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 1,283 | 1,295
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 1,293 | 1,214
Interest Recognized |  |
Total impaired loans with no related allowance recorded | 3 | 1
Foreign |  |
Interest Recognized |  |
Total trouble debt restructuring | 347 | 360
Foreign | Class of Financing Receivable |  |
Recorded investment: |  |
Total impaired loans with no related allowance | 347 | 746
Unpaid principal balance: |  |
Total impaired loans with no related allowance recorded | 347 | 746
Average recorded investment: |  |
Total impaired loans with no related allowance recorded | 750 | 751
Interest Recognized |  |
Total impaired loans with no related allowance recorded | $ 16 | $ 16

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- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 + Details
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