Name:	trv_MinimumCollateralProvidedByBorrowersOfSecuritiesAsPercentageOfMarketValueOfLoanedSecuritiesPlusAccruedInterest
Namespace Prefix:	trv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Expected payment period for loss-based assessments and recoveries, minimum (in years) .

No definition available.

Name:	trv_MinimumExpectedPaymentPeriodForLossBasedAssessmentsAndRecoveries
Namespace Prefix:	trv_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Net written premiums for participating dividend policies expressed as a percentage of total net written premiums.

No definition available.

Name:	trv_NetWrittenPremiumsForParticipatingDividendPoliciesAsPercentOfTotalNetWrittenPremiums
Namespace Prefix:	trv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Number of principal businesses underwritten by International through its Lloyd's syndicate.

No definition available.

Name:	trv_NumberOfPrincipalBusinessUnitsThroughWhichLloydsSyndicateWritesBusiness
Namespace Prefix:	trv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Percentage of capital provided by the Company to its Lloyd's syndicate.

No definition available.

Name:	trv_PercentOfCapitalProvidedByInternationalToLloydsSyndicate
Namespace Prefix:	trv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of receivable related to a loss contingency accrual. For example, an insurance recovery receivable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12053-110248

Name:	us-gaap_LossContingencyReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The liability as of the balance sheet date representing required funding mandated by statute or regulatory authority that is related directly or indirectly to underwriting activities, including pools for self-insurance and excluding premium taxes and income taxes. The funds derived from the assessments generally enable a government guarantor to pay insurance claims in the event that the underwriting insurer is insolvent or otherwise unable to meet its payment obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 405
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6392405&loc=d3e24119-109301

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 405
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=99384745&loc=d3e23169-109297

Name:	us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

No definition available.

Name:	us-gaap_NumberOfReportingUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Carrying value as of the balance sheet date of the liability for dividends that are payable to the policyholders based upon the terms of the underlying insurance contracts.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.14(a))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 50
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6483535&loc=d3e16392-158451