Earnings Per Common Share and Share Awards Schedule of Weighted Average Grant Date Fair Value of Stock Awards Plans (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Weighted average market price	$ 188.71	$ 192.71	$ 93.87
Weighted average grant-date fair value	$ 78.61	$ 55.40	$ 28.75

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Weighted Average Grant Date Fair Value

No definition available.

Name:	itic_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValue
Namespace Prefix:	itic_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant