XML 12 R39.htm IDEA: XBRL DOCUMENT v2.4.0.8

Investment Securities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Held-to-maturity securities
Amortized Cost	$ 2,400,000	$ 2,400,000
Estimated Fair Value	2,400,000	2,400,000
Carrying Value	2,400,000	2,400,000
Available-for-sale securities
Amortized Cost	5,259,440,000	5,372,594,000
Gross Unrealized Gains	66,045,000	65,104,000
Gross Unrealized Losses	(102,928,000)	(133,119,000)
Total investment securities	5,222,557,000	5,304,579,000
Estimated Fair Value
Available-for-sale securities
Total investment securities	5,222,557,000	5,304,579,000
Carrying Value
Available-for-sale securities
Total investment securities	5,222,557,000	5,304,579,000
Other securities
Held-to-maturity securities
Amortized Cost	2,400,000	2,400,000
Estimated Fair Value	2,400,000	2,400,000
Carrying Value	2,400,000	2,400,000
Residential mortgage-backed securities
Available-for-sale securities
Amortized Cost	4,976,280,000	5,096,165,000
Gross Unrealized Gains	52,022,000	56,110,000
Gross Unrealized Losses	(95,797,000)	(124,574,000)
Residential mortgage-backed securities | Estimated Fair Value
Available-for-sale securities
Total investment securities	4,932,505,000	5,027,701,000
Residential mortgage-backed securities | Carrying Value
Available-for-sale securities
Total investment securities	4,932,505,000	5,027,701,000
Mortgage-backed securities by Ginnie Mae
Available-for-sale securities
Total investment securities	1,639,116,000	1,799,807,000
Mortgage-backed securities by Fannie Mae and Freddie Mac
Available-for-sale securities
Total investment securities	3,266,433,000	3,200,042,000
Mortgage-backed securities by non-government entities
Available-for-sale securities
Total investment securities	26,956,000	27,852,000
Obligations of states and political subdivisions
Available-for-sale securities
Amortized Cost	255,085,000	248,354,000
Gross Unrealized Gains	12,780,000	8,063,000
Gross Unrealized Losses	(6,740,000)	(8,007,000)
Obligations of states and political subdivisions | Estimated Fair Value
Available-for-sale securities
Total investment securities	261,125,000	248,410,000
Obligations of states and political subdivisions | Carrying Value
Available-for-sale securities
Total investment securities	261,125,000	248,410,000
Equity Securities
Available-for-sale securities
Amortized Cost	28,075,000	28,075,000
Gross Unrealized Gains	1,243,000	931,000
Gross Unrealized Losses	(391,000)	(538,000)
Equity Securities | Estimated Fair Value
Available-for-sale securities
Total investment securities	28,927,000	28,468,000
Equity Securities | Carrying Value
Available-for-sale securities
Total investment securities	$ 28,927,000	$ 28,468,000

X

- Definition

Amount of accumulated unrealized gain before deducting unrealized loss on investments in available-for-sale securities impacting investments.

+ References

No definition available.

+ Details

Name:	iboc_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
Namespace Prefix:	iboc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of accumulated unrealized loss before deducting unrealized gain on investments in available-for-sale securities impacting investments.

+ References

No definition available.

+ Details

Name:	iboc_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
Namespace Prefix:	iboc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.6)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_HeldToMaturitySecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

+ References

No definition available.

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_HeldToMaturitySecuritiesClassifiedAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Fair value of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant