Contingencies, Commitments and Guarantees (details) (USD $) In Billions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Contingencies and Commitments disclosure
Unfunded commitments to private equity limited partnerships and real estate partnerships	$ 1.63	$ 1.52

The amount of unfunded commitments to private equity limited partnerships and real estate partnerships in which the Company invests.

No definition available.

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