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Allowance for Probable Loan Losses (By Loan Class) (Details) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2017 USD ($) item | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | $ 66,988 | $ 64,661 | $ 66,988 | $ 64,828
Losses charged to allowance |  |  | (13,098) | (35,901) | (27,125)
Recoveries credited to allowance |  |  | 4,903 | 13,715 | 4,880
Net losses charged to allowance |  |  | (8,195) | (22,186) | (22,245)
Provision (credit) charged to operations |  |  | 11,221 | 19,859 | 24,405
Balance at the end of the period |  |  | $ 67,687 | 64,661 | 66,988
Period of time for determining the historical charge-off experience |  |  | 3 years |  |
Number of large recoveries | item |  |  | 2 |  |
Watch - List Impaired |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Losses charged to allowance |  |  | $ (19,400) |  |
Commercial |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 21,431 | 25,649 | 21,431 | 22,352
Losses charged to allowance |  |  | (12,094) | (32,959) | (24,802)
Recoveries credited to allowance |  | 4,400 | 4,020 | 7,110 | 3,135
Net losses charged to allowance |  |  | (8,074) | (25,849) | (21,667)
Provision (credit) charged to operations |  |  | 10,330 | 30,067 | 20,746
Balance at the end of the period |  |  | 27,905 | 25,649 | 21,431
Commercial | Transportation Equipment |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Losses charged to allowance |  |  |  |  | (13,500)
Commercial Real Estate: Other Construction and Land Development |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 13,920 | 13,889 | 13,920 | 12,955
Losses charged to allowance |  |  | (213) | (16) | (695)
Recoveries credited to allowance | $ 6,000 |  | 21 | 6,099 | 141
Net losses charged to allowance |  |  | (192) | 6,083 | (554)
Provision (credit) charged to operations |  |  | (2,022) | (6,114) | 1,519
Balance at the end of the period |  |  | 11,675 | 13,889 | 13,920
Commercial Real Estate: Farmland & Commercial |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 19,769 | 16,731 | 19,769 | 18,683
Losses charged to allowance |  |  | (40) | (1,890) | (492)
Recoveries credited to allowance |  |  | 527 | 119 | 963
Net losses charged to allowance |  |  | 487 | (1,771) | 471
Provision (credit) charged to operations |  |  | (555) | (1,267) | 615
Balance at the end of the period |  |  | 16,663 | 16,731 | 19,769
Commercial Real Estate: Multifamily |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 1,248 | 806 | 1,248 | 846
Losses charged to allowance |  |  |  | (180) |
Net losses charged to allowance |  |  |  | (180) |
Provision (credit) charged to operations |  |  | 303 | (262) | 402
Balance at the end of the period |  |  | 1,109 | 806 | 1,248
Residential First Lien |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 3,509 | 2,455 | 3,509 | 3,589
Losses charged to allowance |  |  | (101) | (70) | (157)
Recoveries credited to allowance |  |  | 11 | 21 | 30
Net losses charged to allowance |  |  | (90) | (49) | (127)
Provision (credit) charged to operations |  |  | 585 | (1,005) | 47
Balance at the end of the period |  |  | 2,950 | 2,455 | 3,509
Residential Junior Lien |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 5,321 | 3,716 | 5,321 | 4,683
Losses charged to allowance |  |  | (340) | (331) | (275)
Recoveries credited to allowance |  |  | 258 | 278 | 431
Net losses charged to allowance |  |  | (82) | (53) | 156
Provision (credit) charged to operations |  |  | 2,469 | (1,552) | 482
Balance at the end of the period |  |  | 6,103 | 3,716 | 5,321
Consumer |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | 638 | 531 | 638 | 660
Losses charged to allowance |  |  | (309) | (414) | (704)
Recoveries credited to allowance |  |  | 45 | 69 | 170
Net losses charged to allowance |  |  | (264) | (345) | (534)
Provision (credit) charged to operations |  |  | 173 | 238 | 512
Balance at the end of the period |  |  | 440 | 531 | 638
Foreign |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |
Balance at the beginning of the period |  | $ 1,152 | 884 | 1,152 | 1,060
Losses charged to allowance |  |  | (1) | (41) |
Recoveries credited to allowance |  |  | 21 | 19 | 10
Net losses charged to allowance |  |  | 20 | (22) | 10
Provision (credit) charged to operations |  |  | (62) | (246) | 82
Balance at the end of the period |  |  | $ 842 | $ 884 | $ 1,152

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- Definition Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
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- Definition Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.1) -URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b)(1)(ii) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 + Details
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