Investments in Securities and Fair Value Investments in Securities (Schedule of Variable Interest Entities) (Details) - Other Investments $ in Thousands	Dec. 31, 2021 USD ($)
Variable Interest Entity [Line Items]
VariableInterestEntityNonconsolidatedCarryingAmount	$ 13,179
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	13,816
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	22,813
Tax credit LPs
Variable Interest Entity [Line Items]
VariableInterestEntityNonconsolidatedCarryingAmount	276
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	276
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	1,768
Real estate LLCs or LPs
Variable Interest Entity [Line Items]
VariableInterestEntityNonconsolidatedCarryingAmount	4,567
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	5,286
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	7,750
Small business investment LLCs or LPs
Variable Interest Entity [Line Items]
VariableInterestEntityNonconsolidatedCarryingAmount	8,336
Variable Interest Entity, Nonconsolidated, Estimated Fair Value	8,254
Variable Interest Entity, Reporting Entity Involvement, Maximum Potential Loss	$ 13,295

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary

No definition available.

+ Details

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Namespace Prefix:	itic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Estimated fair value amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

No definition available.

+ Details

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Namespace Prefix:	itic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123419778&loc=d3e5747-111685

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=123419778&loc=d3e5728-111685

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Details

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- Details

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- Details

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- Details

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