Consolidating Financial Statements (Unaudited) (details) $ in Millions	Jun. 30, 2017 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.

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