Basis of Presentation and Accounting Policies	6 Months Ended
Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES 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, 2017 (the Company’s 2017 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 2017 financial statements to conform to the 2018 presentation. Adoption of Accounting Standards Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the Financial Accounting Standards Board (FASB) issued updated guidance to address the recognition, measurement, presentation and disclosure of certain financial instruments. The updated guidance requires equity investments, except those accounted for under the equity method of accounting, that have readily determinable fair value to be measured at fair value with any changes in fair value recognized in net income. Equity securities that do not have readily determinable fair values may be measured at estimated fair value or cost less impairment, if any, adjusted for subsequent observable price changes, with changes in the carrying value recognized in net income. A qualitative assessment for impairment is required for equity investments without readily determinable fair values. The updated guidance also eliminates the requirement to disclose the method and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost on the balance sheet. The updated guidance was effective for the quarter ended March 31, 2018. The adoption of this guidance resulted in the recognition of $22 million of net after-tax unrealized gains on equity investments as a cumulative effect adjustment that increased retained earnings as of January 1, 2018 and decreased accumulated other comprehensive income (AOCI) by the same amount. The Company elected to report changes in the fair value of equity investments in net realized investment gains (losses). At December 31, 2017, equity investments were classified as available-for-sale on the Company's balance sheet. However, upon adoption, the updated guidance eliminated the available-for-sale balance sheet classification for equity investments. Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income On February 14, 2018, the FASB issued updated guidance that allows a reclassification from AOCI to retained earnings of the stranded tax effects that occurred due to the enactment of the Tax Cuts and Jobs Act of 2017 (TCJA). The updated guidance is effective for reporting periods beginning after December 15, 2018 and is to be applied retrospectively to each period in which there are items impacted by the TCJA remaining in AOCI or at the beginning of the period of adoption. Early adoption is permitted. The Company adopted the updated guidance effective January 1, 2018 and elected to reclassify the income tax effects of the TCJA from AOCI to retained earnings as of January 1, 2018. This reclassification resulted in an increase in retained earnings of $24 million as of January 1, 2018 and a decrease in AOCI by the same amount. Revenue from Contracts with Customers In May 2014, the FASB issued updated guidance to clarify the principles for recognizing revenue. The updated guidance was effective for reporting periods beginning after December 15, 2017, and requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. For the six months ended June 30, 2018, approximately $83 million, or less than 1% of the Company's total revenues, were within the scope of this updated guidance and were generated from the services described below. While insurance contracts are not within the scope of this updated guidance, the Company’s revenue related to certain services with no underlying insurance risk is subject to the updated guidance. These services include the following: (i) insurance-related services, such as risk management services, claims administration, loss control and risk management information services on behalf of non-insureds; (ii) servicing carrier fees for various residual market pools and associations; and (iii) administrative fees related to servicing third-party insurers’ obligations to participate in the Workers' Compensation Residual Market Plans in certain states. The revenues earned from these service contracts were not impacted by the adoption of the updated guidance. These revenues are earned on a pro rata basis over the contract service period and reported in fee income in the Company’s consolidated statement of income. Commissions earned from on-line insurance brokerage services are also subject to this updated guidance and were also not impacted by the adoption of the updated guidance. Commissions are earned upon collection of the gross premium in accordance with the contracts and an accrual is made to recognize policy cancellations, either at the policyholder’s direction or for non-payment. Commissions are reported in other revenues in the Company's consolidated statement of income. The Company does not capitalize the costs to obtain or fulfill the contracts for which revenues are reported in fee income and other income, and has not recognized any impairment losses on the receivables related to these contracts during the six months ended June 30, 2018. The Company adopted the updated guidance effective January 1, 2018. The adoption did not have an effect on the Company’s results of operations, financial position or liquidity. Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued updated guidance on the classification of cash flows related to certain activities in the statement of cash flows to reduce diversity in practice. The updated guidance was effective for reporting periods beginning after December 15, 2017 and was applied retrospectively to all periods presented. Under the new guidance, distributions received on equity method investments that are considered to be a return on investment are reported as cash flows from operating activities. These distributions were previously reported as cash flows from investing activities. The adoption of this guidance had no effect on the Company’s results of operations, financial position or liquidity. For information regarding accounting standards that the Company adopted during the years presented, see the “Adoption of Accounting Standards” section of note 1 of notes to the consolidated financial statements in the Company’s 2017 Annual Report. Accounting Standards Not Yet Adopted For information regarding accounting standards that the Company has not yet adopted, see the “Other Accounting Standards Not Yet Adopted” section of note 1 of notes to the consolidated financial statements in the Company’s 2017 Annual Report. Nature of Operations The Company’s results are reported in the following three business segments — Business Insurance, Bond & Specialty Insurance and Personal Insurance. These segments reflect the manner in which the Company’s businesses are currently managed and represent an aggregation of products and services based on the type of customer, how the business is marketed and the manner in which risks are underwritten. For more information regarding the Company’s nature of operations, see the “Nature of Operations” section of note 1 of notes to the consolidated financial statements in the Company’s 2017 Annual Report.

BASIS OF PRESENTATION AND ACCOUNTING POLICIES

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, 2017 (the Company’s 2017 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 2017 financial statements to conform to the 2018 presentation.

Adoption of Accounting Standards

Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities

In January 2016, the Financial Accounting Standards Board (FASB) issued updated guidance to address the recognition, measurement, presentation and disclosure of certain financial instruments. The updated guidance requires equity investments, except those accounted for under the equity method of accounting, that have readily determinable fair value to be measured at fair value with any changes in fair value recognized in net income. Equity securities that do not have readily determinable fair values may be measured at estimated fair value or cost less impairment, if any, adjusted for subsequent observable price changes, with changes in the carrying value recognized in net income. A qualitative assessment for impairment is required for equity investments without readily determinable fair values. The updated guidance also eliminates the requirement to disclose the method and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost on the balance sheet. The updated guidance was effective for the quarter ended March 31, 2018. The adoption of this guidance resulted in the recognition of $22 million of net after-tax unrealized gains on equity investments as a cumulative effect adjustment that increased retained earnings as of January 1, 2018 and decreased accumulated other comprehensive income (AOCI) by the same amount. The Company elected to report changes in the fair value of equity investments in net realized investment gains (losses). At December 31, 2017, equity investments were classified as available-for-sale on the Company's balance sheet. However, upon adoption, the updated guidance eliminated the available-for-sale balance sheet classification for equity investments.

Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

On February 14, 2018, the FASB issued updated guidance that allows a reclassification from AOCI to retained earnings of the stranded tax effects that occurred due to the enactment of the Tax Cuts and Jobs Act of 2017 (TCJA). The updated guidance is effective for reporting periods beginning after December 15, 2018 and is to be applied retrospectively to each period in which there are items impacted by the TCJA remaining in AOCI or at the beginning of the period of adoption. Early adoption is permitted. The Company adopted the updated guidance effective January 1, 2018 and elected to reclassify the income tax effects of the TCJA from AOCI to retained earnings as of January 1, 2018. This reclassification resulted in an increase in retained earnings of $24 million as of January 1, 2018 and a decrease in AOCI by the same amount.

Revenue from Contracts with Customers

In May 2014, the FASB issued updated guidance to clarify the principles for recognizing revenue. The updated guidance was effective for reporting periods beginning after December 15, 2017, and requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. For the six months ended June 30, 2018, approximately $83 million, or less than 1% of the Company's total revenues, were within the scope of this updated guidance and were generated from the services described below.

While insurance contracts are not within the scope of this updated guidance, the Company’s revenue related to certain services with no underlying insurance risk is subject to the updated guidance. These services include the following: (i) insurance-related services, such as risk management services, claims administration, loss control and risk management information services on behalf of non-insureds; (ii) servicing carrier fees for various residual market pools and associations; and (iii) administrative fees related to servicing third-party insurers’ obligations to participate in the Workers' Compensation Residual Market Plans in certain states. The revenues earned from these service contracts were not impacted by the adoption of the updated guidance. These revenues are earned on a pro rata basis over the contract service period and reported in fee income in the Company’s consolidated statement of income.

Commissions earned from on-line insurance brokerage services are also subject to this updated guidance and were also not impacted by the adoption of the updated guidance. Commissions are earned upon collection of the gross premium in accordance with the contracts and an accrual is made to recognize policy cancellations, either at the policyholder’s direction or for non-payment. Commissions are reported in other revenues in the Company's consolidated statement of income.

The Company does not capitalize the costs to obtain or fulfill the contracts for which revenues are reported in fee income and other income, and has not recognized any impairment losses on the receivables related to these contracts during the six months ended June 30, 2018.

The Company adopted the updated guidance effective January 1, 2018. The adoption did not have an effect on the Company’s results of operations, financial position or liquidity.

Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments

In August 2016, the FASB issued updated guidance on the classification of cash flows related to certain activities in the statement of cash flows to reduce diversity in practice. The updated guidance was effective for reporting periods beginning after December 15, 2017 and was applied retrospectively to all periods presented. Under the new guidance, distributions received on equity method investments that are considered to be a return on investment are reported as cash flows from operating activities. These distributions were previously reported as cash flows from investing activities. The adoption of this guidance had no effect on the Company’s results of operations, financial position or liquidity.

For information regarding accounting standards that the Company adopted during the years presented, see the “Adoption of Accounting Standards” section of note 1 of notes to the consolidated financial statements in the Company’s 2017 Annual Report.

Accounting Standards Not Yet Adopted

For information regarding accounting standards that the Company has not yet adopted, see the “Other Accounting Standards Not Yet Adopted” section of note 1 of notes to the consolidated financial statements in the Company’s 2017 Annual Report.

Nature of Operations

The Company’s results are reported in the following three business segments — Business Insurance, Bond & Specialty Insurance and Personal Insurance. These segments reflect the manner in which the Company’s businesses are currently managed and represent an aggregation of products and services based on the type of customer, how the business is marketed and the manner in which risks are underwritten. For more information regarding the Company’s nature of operations, see the “Nature of Operations” section of note 1 of notes to the consolidated financial statements in the Company’s 2017 Annual Report.