XML 78 R63.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Allowance for Probable Loan Losses (Changes by Loan Class) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | $ 64,828 |  |  |  | $ 70,161 | $ 64,828 | $ 70,161 | $ 58,193
Losses charged to allowance |  |  |  |  |  |  |  |  | (27,125) | (23,465) | (14,455)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 4,880 | 3,709 | 3,455
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | (22,245) | (19,756) | (11,000)
Provision (credit) charged to operations | $ 5,429 | $ 8,832 | $ 7,767 | 2,377 | $ 5,884 | $ 2,816 | $ 3,645 | 2,078 | 24,405 | 14,423 | 22,968
Balance at the end of the period | 66,988 |  |  |  | 64,828 |  |  |  | 66,988 | 64,828 | 70,161
Commercial |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 22,352 |  |  |  | 22,433 | 22,352 | 22,433 | 11,632
Losses charged to allowance |  |  |  |  |  |  |  |  | (24,802) | (19,110) | (11,737)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 3,135 | 2,979 | 2,690
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | (21,667) | (16,131) | (9,047)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 20,746 | 16,050 | 19,848
Balance at the end of the period | 21,431 |  |  |  | 22,352 |  |  |  | 21,431 | 22,352 | 22,433
Commercial Real Estate: Other Construction and Land Development |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 12,955 |  |  |  | 12,541 | 12,955 | 12,541 | 12,720
Losses charged to allowance |  |  |  |  |  |  |  |  | (695) | (680) | (278)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 141 | 72 | 87
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | (554) | (608) | (191)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 1,519 | 1,022 | 12
Balance at the end of the period | 13,920 |  |  |  | 12,955 |  |  |  | 13,920 | 12,955 | 12,541
Commercial real estate: farmland and commercial |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 18,683 |  |  |  | 24,467 | 18,683 | 24,467 | 21,880
Losses charged to allowance |  |  |  |  |  |  |  |  | (492) | (1,893) | (600)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 963 | 107 | 152
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | 471 | (1,786) | (448)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 615 | (3,998) | 3,035
Balance at the end of the period | 19,769 |  |  |  | 18,683 |  |  |  | 19,769 | 18,683 | 24,467
Commercial real estate: multifamily |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 846 |  |  |  | 776 | 846 | 776 | 694
Losses charged to allowance |  |  |  |  |  |  |  |  |  |  | (5)
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  |  |  | (5)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 402 | 70 | 87
Balance at the end of the period | 1,248 |  |  |  | 846 |  |  |  | 1,248 | 846 | 776
Residential: first lien |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 3,589 |  |  |  | 3,812 | 3,589 | 3,812 | 4,390
Losses charged to allowance |  |  |  |  |  |  |  |  | (157) | (351) | (632)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 30 | 49 | 61
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | (127) | (302) | (571)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 47 | 79 | (7)
Balance at the end of the period | 3,509 |  |  |  | 3,589 |  |  |  | 3,509 | 3,589 | 3,812
Residential: junior lien |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 4,683 |  |  |  | 4,249 | 4,683 | 4,249 | 4,448
Losses charged to allowance |  |  |  |  |  |  |  |  | (275) | (661) | (620)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 431 | 242 | 298
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | 156 | (419) | (322)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 482 | 853 | 123
Balance at the end of the period | 5,321 |  |  |  | 4,683 |  |  |  | 5,321 | 4,683 | 4,249
Consumer |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | 660 |  |  |  | 750 | 660 | 750 | 1,289
Losses charged to allowance |  |  |  |  |  |  |  |  | (704) | (719) | (561)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 170 | 210 | 162
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | (534) | (509) | (399)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 512 | 419 | (140)
Balance at the end of the period | 638 |  |  |  | 660 |  |  |  | 638 | 660 | 750
Foreign |  |  |  |  |  |  |  |  |  |  |
Allowance for probable loan losses |  |  |  |  |  |  |  |  |  |  |
Balance at the beginning of the period |  |  |  | $ 1,060 |  |  |  | $ 1,133 | 1,060 | 1,133 | 1,140
Losses charged to allowance |  |  |  |  |  |  |  |  |  | (51) | (22)
Recoveries credited to allowance |  |  |  |  |  |  |  |  | 10 | 50 | 5
Net (losses) recoveries charged to allowance |  |  |  |  |  |  |  |  | 10 | (1) | (17)
Provision (credit) charged to operations |  |  |  |  |  |  |  |  | 82 | (72) | 10
Balance at the end of the period | $ 1,152 |  |  |  | $ 1,060 |  |  |  | $ 1,152 | $ 1,060 | $ 1,133

X
- 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=35738203&loc=SL6953423-111524 + Details
Name: | us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_AllowanceForLoanAndLeaseLossesRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss. + 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)(3) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9 + Details
Name: | us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after recoveries, of loans and leases that have been written-off. + References No definition available. + Details
Name: | us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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=35738203&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=35738203&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 30 -Section 50 -Paragraph 2 -Subparagraph (b)(1)(ii) -URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section L -Subsection 1 + Details
Name: | us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of expense related to estimated loss from loan and lease transactions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 11 -Article 9 + Details
Name: | us-gaap_ProvisionForLoanAndLeaseLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateMultifamilyReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ResidentialFirstMortgageFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ResidentialSecondMortgageFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ForeignReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |