Contingent liabilities and commitments (Details) $ in Millions	Sep. 30, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Guarantee of indebtedness, relating to unused letters of credit	$ 5.6

Contingent liabilities for guarantees of consolidated subsidiaries, unused letters of credit.

No definition available.

Name:	stc_ContingentLiabilitiesForGuaranteesOfConsolidatedSubsidiariesUnusedLettersofCredit
Namespace Prefix:	stc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant