Consolidating Financial Statements (Unaudited) (details) $ in Millions	Sep. 30, 2015 USD ($)
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 700

Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.

No definition available.

Name:	trv_AmountOfDebtObligationsUnconditionallyGuaranteedByParent
Namespace Prefix:	trv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant