Basis of Presentation and Accounting Policies (policies)	9 Months Ended
Sep. 30, 2016
Basis of Presentation and Accounting Policies disclosure
Accounting Policies, Basis of Presentation [Policy Text Block]	Basis of Presentation The interim consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). These financial statements are prepared in conformity with U.S. generally accepted accounting principles (GAAP) and are unaudited. In the opinion of the Company’s management, all adjustments necessary for a fair presentation have been reflected. Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but that is not required for interim reporting purposes, has been omitted. All material intercompany transactions and balances have been eliminated. The accompanying interim consolidated financial statements and related notes should be read in conjunction with the Company’s consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 (the Company’s 2015 Annual Report). The preparation of the interim consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the interim consolidated financial statements and the reported amounts of revenues and claims and expenses during the reporting period. Actual results could differ from those estimates. Certain reclassifications have been made to the 2015 financial statements to conform to the 2016 presentation.
Accounting Policies, Adoption of Accounting Standards [Policy Text Block]	Adoption of Accounting Standards Compensation — Stock Compensation: Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period In June 2014, the Financial Accounting Standards Board (FASB) issued updated guidance to resolve diversity in practice concerning employee share-based payments that contain performance targets that could be achieved after the requisite service period. The updated guidance requires that a performance target that affects vesting and that can be achieved after the requisite service period be treated as a performance condition. As such, the performance target that affects vesting should not be reflected in estimating the fair value of the award at the grant date. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the periods for which service has been rendered. If the performance target becomes probable of being achieved before the end of the service period, the remaining unrecognized compensation cost for which requisite service has not yet been rendered is recognized prospectively over the remaining service period. The total amount of compensation cost recognized during and after the service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The updated guidance was effective for reporting periods beginning after December 15, 2015. The adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity. Derivatives and Hedging: Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity In November 2014, the FASB issued updated guidance to clarify when the separation of certain embedded derivative features in a hybrid financial instrument that is issued in the form of a share is required. That is, an entity will continue to evaluate whether the economic characteristics and risks of the embedded derivative feature are clearly and closely related to those of the host contract. Specifically, the updated guidance clarifies that an entity should consider all relevant terms and features, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of the host contract. Furthermore, the amendments clarify that no single term or feature would necessarily determine the economic characteristics and risks of the host contract. Rather, the nature of the host contract depends upon the economic characteristics and risks of the entire hybrid financial instrument. The updated guidance was effective for reporting periods beginning after December 15, 2015. The adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity. Consolidation: Amendments to the Consolidation Analysis In February 2015, the FASB issued updated guidance that makes targeted amendments to the current consolidation accounting guidance. The update is in response to accounting complexity concerns, particularly from the asset management industry. The guidance simplifies consolidation accounting by reducing the number of approaches to consolidation, provides a scope exception to registered money market funds and similar unregistered money market funds and ends the indefinite deferral granted to investment companies from applying the variable interest entity guidance. The updated guidance was effective for reporting periods beginning after December 15, 2015. The adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity. Interest — Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued updated guidance to clarify the required presentation of debt issuance costs. The updated guidance requires that debt issuance costs be presented in the balance sheet as a direct reduction from the carrying amount of the recognized debt liability, consistent with the treatment of debt discounts. Amortization of debt issuance costs is to be reported as interest expense. The recognition and measurement guidance for debt issuance costs are not affected by the updated guidance. The updated guidance was effective for reporting periods beginning after December 15, 2015. The updated guidance is consistent with the Company’s accounting policy and its adoption did not have any effect on the Company’s results of operations, financial position or liquidity. Business Combinations: Simplifying the Accounting for Measurement-Period Adjustments In September 2015, the FASB issued updated guidance regarding business combinations that requires an acquirer to recognize post-close measurement adjustments for provisional amounts in the period the adjustment amounts are determined rather than retrospectively. The acquirer is also required to recognize, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the provisional amount, calculated as if the accounting had been completed at the acquisition date. The updated guidance is to be applied prospectively effective for reporting periods beginning after December 15, 2015. In connection with business combinations which have already been completed, the adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity. Compensation — Stock Compensation: Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued updated guidance to simplify several aspects of accounting for share-based payment transactions as follows: Accounting for Income Taxes Under current accounting guidance, if the deduction for a share-based payment award for tax purposes exceeds, or is less than, the compensation cost recognized for financial reporting purposes, the resulting excess tax benefit, or tax deficiency, is reported as part of additional paid-in capital. Under the updated guidance, these excess tax benefits, or tax deficiencies, are reported as part of income tax expense or benefit in the income statement. The updated guidance also removes the requirement to delay recognition of any excess tax benefit when there are no current taxes payable to which the benefit would be applied. The tax-related cash flows resulting from share-based payments are to be included with other income tax cash flows as an operating activity rather than being reported separately as a financing activity. Forfeitures The updated guidance permits an entity to make an accounting policy election to either account for forfeitures when they occur or continue to apply the current method of accruing the compensation cost based on the number of awards that are expected to vest. Minimum Statutory Tax Withholding Requirements The updated guidance changes the threshold amount an entity can withhold for taxes when settling an equity award and still qualify for equity classification. A company can withhold up to the maximum statutory tax rates in the employees’ applicable jurisdiction rather than withholding up to the employers’ minimum statutory withholding requirement. The update also clarifies that all cash payments made to taxing authorities on behalf of employees for withheld shares are to be presented in financing activities on the statement of cash flows. Transition The updated guidance is effective for reporting periods beginning after December 15, 2016. Early adoption is permitted in any interim period; if early adoption is elected, the entity must adopt all of the amendments in the same reporting period and reflect any adjustments as of the beginning of the fiscal year. The Company adopted the updated guidance effective January 1, 2016. With respect to the forfeiture accounting policy election, the Company elected to retain its policy of accruing the compensation cost based on the number of awards that are expected to vest. The adoption did not result in any cumulative effect adjustments or restatement and did not have a material effect on the Company’s results of operations, financial position or liquidity.

Adoption of Accounting Standards

Compensation — Stock Compensation: Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period

In June 2014, the Financial Accounting Standards Board (FASB) issued updated guidance to resolve diversity in practice concerning employee share-based payments that contain performance targets that could be achieved after the requisite service period. The updated guidance requires that a performance target that affects vesting and that can be achieved after the requisite service period be treated as a performance condition. As such, the performance target that affects vesting should not be reflected in estimating the fair value of the award at the grant date. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the periods for which service has been rendered. If the performance target becomes probable of being achieved before the end of the service period, the remaining unrecognized compensation cost for which requisite service has not yet been rendered is recognized prospectively over the remaining service period. The total amount of compensation cost recognized during and after the service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The updated guidance was effective for reporting periods beginning after December 15, 2015. The adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity.

Derivatives and Hedging: Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity

In November 2014, the FASB issued updated guidance to clarify when the separation of certain embedded derivative features in a hybrid financial instrument that is issued in the form of a share is required. That is, an entity will continue to evaluate whether the economic characteristics and risks of the embedded derivative feature are clearly and closely related to those of the host contract. Specifically, the updated guidance clarifies that an entity should consider all relevant terms and features, including the embedded derivative feature being evaluated for bifurcation, in evaluating the nature of the host contract. Furthermore, the amendments clarify that no single term or feature would necessarily determine the economic characteristics and risks of the host contract. Rather, the nature of the host contract depends upon the economic characteristics and risks of the entire hybrid financial instrument. The updated guidance was effective for reporting periods beginning after December 15, 2015. The adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity.

Consolidation: Amendments to the Consolidation Analysis

In February 2015, the FASB issued updated guidance that makes targeted amendments to the current consolidation accounting guidance. The update is in response to accounting complexity concerns, particularly from the asset management industry. The guidance simplifies consolidation accounting by reducing the number of approaches to consolidation, provides a scope exception to registered money market funds and similar unregistered money market funds and ends the indefinite deferral granted to investment companies from applying the variable interest entity guidance. The updated guidance was effective for reporting periods beginning after December 15, 2015. The adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity.

Interest — Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs

In April 2015, the FASB issued updated guidance to clarify the required presentation of debt issuance costs. The updated guidance requires that debt issuance costs be presented in the balance sheet as a direct reduction from the carrying amount of the recognized debt liability, consistent with the treatment of debt discounts. Amortization of debt issuance costs is to be reported as interest expense. The recognition and measurement guidance for debt issuance costs are not affected by the updated guidance. The updated guidance was effective for reporting periods beginning after December 15, 2015. The updated guidance is consistent with the Company’s accounting policy and its adoption did not have any effect on the Company’s results of operations, financial position or liquidity.

Business Combinations: Simplifying the Accounting for Measurement-Period Adjustments

In September 2015, the FASB issued updated guidance regarding business combinations that requires an acquirer to recognize post-close measurement adjustments for provisional amounts in the period the adjustment amounts are determined rather than retrospectively. The acquirer is also required to recognize, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the provisional amount, calculated as if the accounting had been completed at the acquisition date. The updated guidance is to be applied prospectively effective for reporting periods beginning after December 15, 2015. In connection with business combinations which have already been completed, the adoption of this guidance did not have a material effect on the Company’s results of operations, financial position or liquidity.

Compensation — Stock Compensation: Improvements to Employee Share-Based Payment Accounting

In March 2016, the FASB issued updated guidance to simplify several aspects of accounting for share-based payment transactions as follows:

Accounting for Income Taxes

Under current accounting guidance, if the deduction for a share-based payment award for tax purposes exceeds, or is less than, the compensation cost recognized for financial reporting purposes, the resulting excess tax benefit, or tax deficiency, is reported as part of additional paid-in capital. Under the updated guidance, these excess tax benefits, or tax deficiencies, are reported as part of income tax expense or benefit in the income statement. The updated guidance also removes the requirement to delay recognition of any excess tax benefit when there are no current taxes payable to which the benefit would be applied. The tax-related cash flows resulting from share-based payments are to be included with other income tax cash flows as an operating activity rather than being reported separately as a financing activity.

Forfeitures

The updated guidance permits an entity to make an accounting policy election to either account for forfeitures when they occur or continue to apply the current method of accruing the compensation cost based on the number of awards that are expected to vest.

Minimum Statutory Tax Withholding Requirements

The updated guidance changes the threshold amount an entity can withhold for taxes when settling an equity award and still qualify for equity classification. A company can withhold up to the maximum statutory tax rates in the employees’ applicable jurisdiction rather than withholding up to the employers’ minimum statutory withholding requirement. The update also clarifies that all cash payments made to taxing authorities on behalf of employees for withheld shares are to be presented in financing activities on the statement of cash flows.

Transition

The updated guidance is effective for reporting periods beginning after December 15, 2016. Early adoption is permitted in any interim period; if early adoption is elected, the entity must adopt all of the amendments in the same reporting period and reflect any adjustments as of the beginning of the fiscal year.

The Company adopted the updated guidance effective January 1, 2016. With respect to the forfeiture accounting policy election, the Company elected to retain its policy of accruing the compensation cost based on the number of awards that are expected to vest. The adoption did not result in any cumulative effect adjustments or restatement and did not have a material effect on the Company’s results of operations, financial position or liquidity.