Investments In Securities Investments In Securities (Schedule of Variable Interest Entities) (Details) - Other investments $ in Thousands	Mar. 31, 2019 USD ($)
Variable Interest Entity [Line Items]
Carrying Value	$ 9,633
Estimated Fair Value	13,948
Maximum Potential Loss	18,485
Tax credit LPs
Variable Interest Entity [Line Items]
Carrying Value	1,162
Estimated Fair Value	1,129
Maximum Potential Loss	2,010
Real estate LLCs or LPs
Variable Interest Entity [Line Items]
Carrying Value	4,739
Estimated Fair Value	6,319
Maximum Potential Loss	9,250
Small business investment LPs
Variable Interest Entity [Line Items]
Carrying Value	3,732
Estimated Fair Value	6,500
Maximum Potential Loss	$ 7,225

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=108788376&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=108788376&loc=d3e5728-111685

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Namespace Prefix:	us-gaap_
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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=108788376&loc=d3e5728-111685

+ Details

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Balance Type:	debit
Period Type:	instant

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- Details

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- Details

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- Details

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