Investments In Securities Investments In Securities (Schedule of Variable Interest Entities) (Details) - Other investments $ in Thousands	Sep. 30, 2019 USD ($)
Variable Interest Entity [Line Items]
Carrying Value	$ 10,572
Estimated Fair Value	11,084
Maximum Potential Loss	17,355
Tax credit LPs
Variable Interest Entity [Line Items]
Carrying Value	228
Estimated Fair Value	228
Maximum Potential Loss	1,325
Real estate LLCs or LPs
Variable Interest Entity [Line Items]
Carrying Value	5,048
Estimated Fair Value	5,766
Maximum Potential Loss	7,075
Small business investment LPs
Variable Interest Entity [Line Items]
Carrying Value	5,296
Estimated Fair Value	5,090
Maximum Potential Loss	$ 8,955

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.

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=118582676&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=118582676&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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph a
-URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685

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Period Type:	instant

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- Details

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- Details

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- Details

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