Investments In Securities and Fair Value (Schedule of Variable Interest Entities) (Details) - Other investments $ in Thousands	Jun. 30, 2020 USD ($)
Variable Interest Entity, Not Primary Beneficiary [Line Items]
Carrying Value	$ 12,321
Estimated Fair Value	13,880
Maximum Potential Loss (a)	21,398
Tax Credit LPs
Variable Interest Entity, Not Primary Beneficiary [Line Items]
Carrying Value	267
Estimated Fair Value	267
Maximum Potential Loss (a)	1,768
Real Estate LLCs or LPs
Variable Interest Entity, Not Primary Beneficiary [Line Items]
Carrying Value	5,406
Estimated Fair Value	7,356
Maximum Potential Loss (a)	6,675
Small Business Investment LPs
Variable Interest Entity, Not Primary Beneficiary [Line Items]
Carrying Value	6,648
Estimated Fair Value	6,257
Maximum Potential Loss (a)	$ 12,955

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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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=121559654&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=121559654&loc=d3e5728-111685

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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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- Details

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