Commitments And Contingencies (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Like-kind exchange deposits and reverse exchange property	$ 149.5	$ 185.0

Like-kind exchange deposits and reverse exchange property

No definition available.

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