The Travelers Companies, Inc. (TRV) 10-K 16 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 10, 2017	Jun. 30, 2016
Document and Entity Information
Registrant name	TRAVELERS COMPANIES, INC.
Central index key	86,312
Document type	10-K
Document period end date	Dec. 31, 2016
Amendment flag	false
Current fiscal year end date	--12-31
Well-known seasoned issuer	Yes
Voluntary filers	No
Current reporting status	Yes
Filer category	Large Accelerated Filer
Entity public float			$ 34,172,576,191
Common stock shares outstanding		279,685,489
Document fiscal year focus	2,016
Document fiscal period focus	FY

Consolidated Statement of Incom

Consolidated Statement of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Premiums										$ 24,534	$ 23,874	$ 23,713
Net investment income										2,302	2,379	2,787
Fee income										458	460	450
Net realized investment gains	[1]									68	3	79
Other revenues										263	99	145
Total revenues		$ 7,193	$ 6,961	$ 6,785	$ 6,686	$ 6,678	$ 6,798	$ 6,710	$ 6,629	27,625	26,815	27,174
Claims and expenses
Claims and claim adjustment expenses										15,070	13,723	13,870
Amortization of deferred acquisition costs										3,985	3,885	3,882
General and administrative expenses										4,154	4,094	3,964
Interest expense										363	373	369
Total claims and expenses		5,891	6,014	5,898	5,769	5,469	5,491	5,634	5,481	23,572	22,075	22,085
Income before income taxes		1,302	947	887	917	1,209	1,307	1,076	1,148	4,053	4,740	5,089
Income tax expense		359	231	223	226	343	379	264	315	1,039	1,301	1,397
Net income		$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Net income per share
Basic		$ 3.32	$ 2.48	$ 2.27	$ 2.33	$ 2.87	$ 3	$ 2.56	$ 2.58	$ 10.39	$ 10.99	$ 10.82
Diluted		$ 3.28	$ 2.45	$ 2.24	$ 2.30	$ 2.83	$ 2.97	$ 2.53	$ 2.55	$ 10.28	$ 10.88	$ 10.70
Weighted average number of common shares outstanding
Basic										288.1	310.6	338.8
Diluted										291	313.9	342.5
Cash dividends declared per common share										$ 2.62	$ 2.38	$ 2.15
[1]	Total other-than-temporary impairment (OTTI) losses were $(40) million, $(54) million and $(22) million for the years ended December 31, 2016, 2015 and 2014, respectively. Of total OTTI, credit losses of $(29) million, $(52) million and $(26) million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $(11) million, $(2) million and $4 million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.

Consolidated Statement of Inco3

Consolidated Statement of Income Parentheticals - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statement of Income
Total other-than-temporary impairment losses	$ (40)	$ (54)	$ (22)
Other-than-temporary impairment, credit losses recognized in net realized investment gains	(29)	(52)	(26)
Unrealized gains (losses) from other changes in total other-than-temporary impairments recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	$ (11)	$ (2)	$ 4

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statement of Comprehensive Income
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Other comprehensive income (loss):
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(883)	(1,020)	976
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									21	(14)	2
Net changes in benefit plan assets and obligations									16	66	(494)
Net changes in unrealized foreign currency translation									(41)	(461)	(289)
Other comprehensive income (loss) before income taxes									(887)	(1,429)	195
Income tax expense (benefit)									(289)	(392)	125
Other comprehensive income (loss), net of taxes									(598)	(1,037)	70
Comprehensive income									$ 2,416	$ 2,402	$ 3,762

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Fixed maturities, available for sale, at fair value (amortized cost $59,650 and $58,878)	$ 60,515	$ 60,658
Equity securities, available for sale, at fair value (cost $504 and $528)	732	705
Real estate investments	928	989
Short-term securities	4,865	4,671
Other investments	3,448	3,447
Total investments	70,488	70,470
Cash	307	380	$ 374	$ 294
Investment income accrued	630	642
Premiums receivable	6,722	6,437
Reinsurance recoverables	8,287	8,910
Ceded unearned premiums	589	656
Deferred acquisition costs	1,923	1,849	1,835
Deferred taxes	465	296
Contractholder receivables	4,609	4,374
Goodwill	3,580	3,573
Other intangible assets	268	279
Other assets	2,377	2,318
Total assets	100,245	100,184
Liabilities
Claims and claim adjustment expense reserves	47,949	48,295	49,850
Unearned premium reserves	12,329	11,971	11,839
Contractholder payables	4,609	4,374
Payables for reinsurance premiums	273	296
Debt	6,437	6,344
Other liabilities	5,427	5,306
Total liabilities	77,024	76,586
Shareholders' equity
Common stock (1,750.0 shares authorized; 279.6 and 295.9 shares issued and outstanding)	22,614	22,172
Retained earnings	32,196	29,945
Accumulated other comprehensive loss	(755)	(157)
Treasury stock, at cost (489.5 and 467.6 shares)	(30,834)	(28,362)
Total shareholders' equity	23,221	23,598	$ 24,836
Total liabilities and shareholders' equity	$ 100,245	$ 100,184

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parentheticals - USD ($) shares in Millions, $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Consolidated Balance Sheet
Fixed maturities, available for sale, amortized cost	$ 59,650	$ 58,878
Equity securities, available for sale, cost	$ 504	$ 528
Common stock, shares authorized	1,750	1,750
Common stock, shares issued	279.6	295.9
Common stock, shares outstanding	279.6	295.9
Treasury stock, at cost, shares	489.5	467.6

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common stock [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss), net of tax [Member]	Treasury stock, at cost [Member]	Common shares outstanding [Member]
Shareholders' equity, beginning of year at Dec. 31, 2013		$ 21,500	$ 24,291	$ 810	$ (21,805)
Shareholders' Equity [Rollforward]
Employee share-based compensation		149
Compensation amortization under share-based plans and other changes		194
Net income	$ 3,692		3,692
Dividends			(735)
Other			3
Other comprehensive income (loss)	70			70
Treasury stock acquired - share repurchase authorization					(3,275)
Net shares acquired related to employee share-based compensation plans					(58)
Shareholders' equity, end of year at Dec. 31, 2014	24,836	21,843	27,251	880	(25,138)
Balance, beginning of year at Dec. 31, 2013						353.5
Common shares outstanding
Treasury stock acquired - share repurchase authorization						(35.1)
Net shares issued under employee share-based compensation plans						3.8
Balance, end of year at Dec. 31, 2014						322.2
Shareholders' Equity [Rollforward]
Employee share-based compensation		133
Compensation amortization under share-based plans and other changes		196
Net income	3,439		3,439
Dividends			(744)
Other			(1)
Other comprehensive income (loss)	(1,037)			(1,037)
Treasury stock acquired - share repurchase authorization					(3,150)
Net shares acquired related to employee share-based compensation plans	(74)				(74)
Shareholders' equity, end of year at Dec. 31, 2015	$ 23,598	22,172	29,945	(157)	(28,362)
Common shares outstanding
Treasury stock acquired - share repurchase authorization						(29.6)
Net shares issued under employee share-based compensation plans						3.3
Balance, end of year at Dec. 31, 2015	295.9					295.9
Shareholders' Equity [Rollforward]
Employee share-based compensation		287
Compensation amortization under share-based plans and other changes		155
Net income	$ 3,014		3,014
Dividends			(762)
Other			(1)
Other comprehensive income (loss)	(598)			(598)
Treasury stock acquired - share repurchase authorization	(2,400)				(2,400)
Net shares acquired related to employee share-based compensation plans	(72)				(72)
Shareholders' equity, end of year at Dec. 31, 2016	$ 23,221	$ 22,614	$ 32,196	$ (755)	$ (30,834)
Common shares outstanding
Treasury stock acquired - share repurchase authorization	(21.3)					(21.3)
Net shares issued under employee share-based compensation plans						5
Balance, end of year at Dec. 31, 2016	279.6					279.6

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net income		$ 3,014	$ 3,439	$ 3,692
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	[1]	(68)	(3)	(79)
Depreciation and amortization		826	818	864
Deferred federal income tax expense		110	117	121
Amortization of deferred acquisition costs		3,985	3,885	3,882
Equity in income from other investments		(232)	(218)	(486)
Premiums receivable		(286)	(185)	(207)
Reinsurance recoverables		610	272	400
Deferred acquisition costs		(4,061)	(3,920)	(3,926)
Claims and claim adjustment expense reserves		(257)	(1,075)	(704)
Unearned premium reserves		372	248	73
Other operating activities		189	56	63
Net cash provided by operating activities		4,202	3,434	3,693
Cash flows from investing activities
Proceeds from maturities of fixed maturities		8,975	11,116	10,894
Proceeds from sales of investments:
Fixed maturities		1,417	1,950	1,049
Equity securities		92	59	158
Real estate investments		69	31	15
Other investments		839	713	855
Purchases of investments:
Fixed maturities		(11,609)	(12,090)	(11,325)
Equity securities		(51)	(49)	(52)
Real estate investments		(48)	(123)	(48)
Other investments		(580)	(534)	(554)
Net purchases of short-term securities		(199)	(326)	(498)
Securities transactions in course of settlement		(21)	(113)	82
Acquisition, net of cash acquired			(13)	(12)
Other investing activities		(344)	(304)	(358)
Net cash provided by (used in) investing activities		(1,460)	317	206
Cash flows from financing activities
Treasury stock acquired - share repurchase authorization		(2,400)	(3,150)	(3,275)
Treasury stock acquired - net employee share-based compensation		(72)	(74)	(57)
Dividends paid to shareholders		(757)	(739)	(729)
Payment of debt		(400)	(400)
Issuance of debt		491	392
Issuance of common stock - employee share options		332	183	195
Excess tax benefits from share-based payment arrangements			55	57
Net cash used in financing activities		(2,806)	(3,733)	(3,809)
Effect of exchange rate changes on cash		(9)	(12)	(10)
Net increase (decrease) in cash		(73)	6	80
Cash at beginning of year		380	374	294
Cash at end of year		307	380	374
Supplemental disclosure of cash flow information
Income taxes paid		892	1,207	1,147
Interest paid		$ 358	$ 365	$ 365
[1]	Total other-than-temporary impairment (OTTI) losses were $(40) million, $(54) million and $(22) million for the years ended December 31, 2016, 2015 and 2014, respectively. Of total OTTI, credit losses of $(29) million, $(52) million and $(26) million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $(11) million, $(2) million and $4 million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies disclosure
Summary of Significant Accounting Policies disclosure [Text Block]	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles (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 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 and 2014 financial statements to conform to the 2016 presentation. All material intercompany transactions and balances have been eliminated. 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. In August 2014, the FASB issued guidance to address the diversity in practice in determining when there is substantial doubt about an entity's ability to continue as a going concern and when an entity must disclose certain relevant conditions and events. The new guidance requires an entity to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued (or available to be issued). The new guidance allows the entity to consider the mitigating effects of management's plans that will alleviate the substantial doubt and requires certain disclosures when substantial doubt is alleviated as a result of consideration of management's plans. If conditions or events raise substantial doubt that is not alleviated, an entity should disclose that there is substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued (or available to be issued), along with the principal conditions or events that raise substantial doubt, management's evaluation of the significance of those conditions or events in relation to the entity's ability to meet its obligations and management's plans that are intended to mitigate those conditions. The updated guidance was effective for annual periods ending after December 15, 2016, and interim and annual periods thereafter. The adoption of this guidance did not have any effect on the Company's results of operations, financial position or liquidity. 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. 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. 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. 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. 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. In May 2014, the FASB issued updated guidance to clarify the principles for recognizing revenue. While insurance contracts are not within the scope of this updated guidance, the Company's fee income related to providing claims and policy management services as well as claim and loss prevention services will be subject to this updated guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The following steps are applied in the updated guidance: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. The updated guidance is effective for the quarter ending March 31, 2018. The adoption of this guidance is not expected to have a material effect on the Company's results of operations, financial position or liquidity. In January 2016, the 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 changes in fair value recognized in net income. Equity investments that do not have readily determinable fair values may be remeasured at fair value either upon the occurrence of an observable price change or upon identification of an impairment. 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 is effective for the quarter ending March 31, 2018 and will require recognition of a cumulative effect adjustment at adoption. Based on the equity investments currently held by the Company, there would not be a material effect on the Company's results of operations, financial position or liquidity if the new guidance were able to be adopted in the current accounting period. The impact on the Company's results of operations, financial position or liquidity at the date of adoption of the updated guidance will be determined by the equity investments held by the Company and the economic conditions at that time. In February 2016, the FASB issued updated guidance to require lessees to recognize a right-to-use asset and a lease liability for leases with terms of more than 12 months. The updated guidance retains the two classifications of a lease as either an operating or finance lease (previously referred to as a capital lease). Both lease classifications require the lessee to record the right-to-use asset and the lease liability based upon the present value of cash flows. Finance leases will reflect the financial arrangement by recognizing interest expense on the lease liability separately from the amortization expense of the right-to-use asset. Operating leases will recognize lease expense (with no separate recognition of interest expense) on a straight-line basis over the term of the lease. The accounting by lessors is not significantly changed by the updated guidance. The updated guidance requires expanded qualitative and quantitative disclosures, including additional information about the amounts recorded in the financial statements. The updated guidance is effective for reporting periods beginning after December 15, 2018, and will require that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. Early adoption is permitted. The adoption of this guidance is not expected to have a material effect on the Company's results of operations, financial position or liquidity. In March 2016, the FASB issued updated guidance that eliminates the requirement to retroactively apply the equity method of accounting when an investment that was previously accounted for using another method of accounting becomes qualified to apply the equity method due to an increase in the level of ownership interest or degree of influence. If the investment was previously accounted for as an available-for-sale security, any related unrealized gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for the equity method is recognized through earnings. The updated guidance is effective for reporting periods beginning after December 15, 2016, and is to be applied prospectively. Early adoption is permitted. The adoption of this guidance is not expected to have a material effect on the Company's results of operations, financial position or liquidity. In March 2016, the FASB issued updated guidance clarifying that when a call (put) option in a debt instrument is contingently exercisable, the event that triggers the ability to exercise the option is considered to be clearly and closely related to the debt instrument (i.e., the economic characteristics and risks of the option are related to interest rates or credit risks) and the entity does not have to assess whether the option should be accounted for separately. The updated guidance is effective for reporting periods beginning after December 15, 2016. Early adoption is permitted. The adoption of this guidance is not expected to have a material effect on the Company's results of operations, financial position or liquidity. In June 2016, the FASB issued updated guidance for the accounting for credit losses for financial instruments. The updated guidance applies a new credit loss model (current expected credit losses or CECL) for determining credit-related impairments for financial instruments measured at amortized cost (e.g. reinsurance recoverables) and requires an entity to estimate the credit losses expected over the life of an exposure or pool of exposures. The estimate of expected credit losses should consider historical information, current information, as well as reasonable and supportable forecasts, including estimates of prepayments. The expected credit losses, and subsequent adjustments to such losses, will be recorded through an allowance account that is deducted from the amortized cost basis of the financial asset, with the net carrying value of the financial asset presented on the consolidated balance sheet at the amount expected to be collected. The updated guidance also amends the current other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security's amortized cost basis and its fair value. In addition, the length of time a security has been in an unrealized loss position will no longer impact the determination of whether a credit loss exists. The updated guidance is effective for reporting periods beginning after December 15, 2019. Early adoption is permitted for reporting periods beginning after December 15, 2018. Based on the financial instruments currently held by the Company, there would not be a material effect on the Company's results of operations, financial position or liquidity if the new guidance were able to be adopted in the current accounting period. The impact on the Company's results of operations, financial position or liquidity at the date of adoption of the updated guidance will be determined by the financial instruments held by the Company and the economic conditions at that time. In January 2017, the FASB issued updated guidance that eliminates the requirement to calculate the implied fair value of goodwill (i.e., Step 2 of the current goodwill impairment test) to measure a goodwill impairment charge. Instead, entities will record an impairment charge by comparing a reporting unit's fair value with its carrying amount and recognizing an impairment charge for the excess of the carrying amount over estimated fair value (i.e., Step 1 of current guidance). The implied fair value of goodwill is currently determined in Step 2 by deducting the fair value of all assets and liabilities of the reporting unit (determined in the same manner as a business combination) from the reporting unit's fair value as determined in Step 1 (including any corporate-level assets or liabilities that were included in the determination of the carrying amount and fair value of the reporting unit in Step 1). The updated guidance requires an entity to perform its annual, or interim, impairment test by either: (1) an initial qualitative assessment of factors (such as changes in management, key personnel, strategy, key technology or customers) that may impact a reporting unit's fair value and lead to the determination that it is more likely than not that the reporting unit's fair value is less than its carrying value, including goodwill (consistent with current guidance), or (2) applying Step 1. The updated guidance is effective for reporting periods beginning after December 15, 2019 and is to be applied prospectively. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a material effect on the Company's results of operations, financial position or liquidity. Fixed maturities include bonds, notes and redeemable preferred stocks. Fixed maturities, including instruments subject to securities lending agreements, are classified as available for sale and are reported at fair value, with unrealized investment gains and losses, net of income taxes, charged or credited directly to other comprehensive income. Equity securities, which include public common and non-redeemable preferred stocks, are classified as available for sale and are reported at fair value with unrealized gains and losses, net of income taxes, charged or credited directly to other comprehensive income. The Company's real estate investments include warehouses, office buildings and other commercial land and properties that are directly owned. Real estate is recorded on the purchase date at the purchase price, which generally represents fair value, and is supported by internal analysis or external appraisals that use discounted cash flow analyses and other acceptable valuation techniques. Real estate held for investment purposes is subsequently carried at cost less accumulated depreciation. Buildings are depreciated on a straight-line basis over the shorter of the expected useful life of the building or 39 years. Real estate held for sale is carried at lower of cost or fair value, less estimated costs to sell. Short-term securities have an original maturity of less than one year and are carried at amortized cost, which approximates fair value. Investments in Private Equity Limited Partnerships, Hedge Funds and Real Estate Partnerships The Company uses the equity method of accounting for investments in private equity limited partnerships, hedge funds and real estate partnerships. The partnerships and the hedge funds generally report investments on their balance sheet at fair value. The financial statements prepared by the investee are received by the Company on a lag basis, with the lag period generally dependent upon the type of underlying investments. The private equity and real estate partnerships provide financial information quarterly which is generally available to investors, including the Company, within three to six months following the date of the reporting period. The hedge funds provide financial information monthly, which is generally available to investors within one month following the date of the reporting period. The Company regularly requests financial information from the partnerships prior to the receipt of the partnerships' financial statements and records any material information obtained from these requests in its consolidated financial statements. Other Also included in other investments are non-public common equities, preferred equities and derivatives. Non-public common equities and preferred equities are reported at fair value with changes in fair value, net of income taxes, charged or credited directly to other comprehensive income. The Company's derivative financial instruments are carried at fair value, with the changes in fair value reflected in the consolidated statement of income in net realized investment gains (losses). For a further discussion of the derivatives used by the Company, see note 3. Investment income from fixed maturities is recognized based on the constant effective yield method which includes an adjustment for estimated principal pre-payments, if any. The effective yield used to determine amortization for fixed maturities subject to prepayment risk (e.g., asset-backed, loan-backed and structured securities) is recalculated and adjusted periodically based upon actual historical and/or projected future cash flows, which are obtained from a widely-accepted securities data provider. The adjustments to the yield for highly rated prepayable fixed maturities are accounted for using the retrospective method. The adjustments to the yield for non-highly rated prepayable fixed maturities are accounted for using the prospective method. Dividends on equity securities (including those with transfer restrictions) are recognized in income when declared. Rental income on real estate is recognized on a straight-line basis over the lease term. See the section titled: Real Estate in note 3 for further discussion. Investments in private equity limited partnerships, hedge funds, real estate partnerships and joint ventures are accounted for using the equity method of accounting, whereby the Company's share of the investee's earnings or losses in the fund is reported in net investment income. Accrual of income is suspended on non-securitized fixed maturities that are in default, or on which it is likely that future payments will not be made as scheduled. Interest income on investments in default is recognized only when payments are received. Investments included in the consolidated balance sheet that were not income-producing for the preceding 12 months were not material. For fixed maturities where the Company records an other-than-temporary impairment, a determination is made as to the cause of the impairment and whether the Company expects a recovery in the value. For fixed maturities where the Company expects a recovery in value, not necessarily to par, the constant effective yield method is utilized, and the investment is amortized to the expected recovery amount. Net realized investment gains and losses are included as a component of pre-tax revenues based upon specific identification of the investments sold on the trade date. Included in net realized investment gains (losses) are other-than-temporary impairment losses on invested assets other than those investments accounted for using the equity method of accounting as described in the "Investment Impairments" section that follows. The Company conducts a periodic review to identify and evaluate invested assets having other-than-temporary impairments. Some of the factors considered in identifying other-than-temporary impairments include: (1) for fixed maturity investments, whether the Company intends to sell the investment or whether it is more likely than not that the Company will be required to sell the investment prior to an anticipated recovery in value; (2) for non-fixed maturity investments, the Company's ability and intent to retain the investment for a reasonable period of time sufficient to allow for an anticipated recovery in value; (3) the likelihood of the recoverability of principal and interest for fixed maturity securities (i.e., whether there is a credit loss) or cost for equity securities; (4) the length of time and extent to which the fair value has been less than amortized cost for fixed maturity securities or cost for equity securities; and (5) the financial condition, near-term and long-term prospects for the issuer, including the relevant industry conditions and trends, and implications of rating agency actions and offering prices. For fixed maturity investments that the Company does not intend to sell or for which it is more likely than not that the Company would not be required to sell before an anticipated recovery in value, the Company separates the credit loss component of the impairment from the amount related to all other factors and reports the credit loss component in net realized investment gains (losses). The impairment related to all other factors is reported in other comprehensive income. For equity securities (including public common and non-redeemable preferred stock) and for fixed maturity investments the Company intends to sell or for which it is more likely than not that the Company will be required to sell before an anticipated recovery in value, the full amount of the impairment is included in net realized investment gains (losses). Upon recognizing an other-than-temporary impairment, the new cost basis of the investment is the previous amortized cost basis less the other-than-temporary impairment recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value; however, for fixed maturity investments the difference between the new cost basis and the expected cash flows is accreted on a quarterly basis to net investment income over the remaining expected life of the investment. The Company determines the credit loss component of fixed maturity investments by utilizing discounted cash flow modeling to determine the present value of the security and comparing the present value with the amortized cost of the security. If the amortized cost is greater than the present value of the expected cash flows, the difference is considered a credit loss and recognized in net realized investment gains (losses). For non-structured fixed maturities (U.S. Treasury securities, obligations of U.S. government and government agencies and authorities, obligations of states, municipalities and political subdivisions, debt securities issued by foreign governments and certain corporate debt), the estimate of expected cash flows is determined by projecting a recovery value and a recovery time frame and assessing whether further principal and interest will be received. The determination of recovery value incorporates an issuer valuation assumption utilizing one or a combination of valuation methods as deemed appropriate by the Company. The Company determines the undiscounted recovery value by allocating the estimated value of the issuer to the Company's assessment of the priority of claims. The present value of the cash flows is determined by applying the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment) and an estimated recovery time frame. Generally, that time frame for securities for which the issuer is in bankruptcy is 12 months. For securities for which the issuer is financially troubled but not in bankruptcy, that time frame is generally 24 months. Included in the present value calculation are expected principal and interest payments; however, for securities for which the issuer is classified as bankrupt or in default, the present value calculation assumes no interest payments and a single recovery amount. In estimating the recovery value, significant judgment is involved in the development of assumptions relating to a myriad of factors related to the issuer including, but not limited to, revenue, margin and earnings projections, the likely market or liquidation values of assets, potential additional debt to be incurred pre- or post-bankruptcy/restructuring, the ability to shift existing or new debt to different priority layers, the amount of restructuring/bankruptcy expenses, the size and priority of unfunded pension obligations, litigation or other contingent claims, the treatment of intercompany claims and the likely outcome with respect to inter-creditor conflicts. For structured fixed maturity securities (primarily residential and commercial mortgage-backed securities and asset-backed securities), the Company estimates the present value of the security by projecting future cash flows of the assets underlying the securitization, allocating the flows to the various tranches based on the structure of the securitization and determining the present value of the cash flows using the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment or changes in expected cash flows). The Company incorporates levels of delinquencies, defaults and severities as well as credit attributes of the remaining assets in the securitization, along with other economic data, to arrive at its best estimate of the parameters applied to the assets underlying the securitization. In order to project cash flows, the following assumptions are applied to the assets underlying the securitization: (1) voluntary prepayment rates, (2) default rates and (3) loss severity. The key assumptions made for the Prime, Alt-A and first-lien Sub-Prime mortgage-backed securities at December 31, 2016 were as follows: (at December 31, 2016) Prime Alt-A Sub-Prime Voluntary prepayment rates 0% - 35% 4% - 15% 3% - 12% Percentage of remaining pool liquidated due to defaults 0% - 46% 20% - 73% 22% - 52% Loss severity 30% - 65% 42% - 90% 75% - 110% On at least an annual basis, the Company obtains independent appraisals for substantially all of its real estate investments. In addition, the carrying value of all real estate investments is reviewed for impairment on a quarterly basis or when events or changes in circumstances indicate tha

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2016
Segment Information disclosure
Segment Information disclosure [Text Block]	2. SEGMENT INFORMATION The accounting policies used to prepare the segment reporting data for the Company's three reportable business segments are the same as those described in the Summary of Significant Accounting Policies in note 1. Except as described below for certain legal entities, the Company allocates its invested assets and the related net investment income to its reportable business segments. Pre-tax net investment income is allocated based upon an investable funds concept, which takes into account liabilities (net of non-invested assets) and appropriate capital considerations for each segment. For investable funds, a benchmark investment yield is developed that reflects the estimated duration of the loss reserves' future cash flows, the interest rate environment at the time the losses were incurred and A+ rated corporate debt instrument yields. For capital, a benchmark investment yield is developed that reflects the average yield on the total investment portfolio. The benchmark investment yields are applied to each segment's investable funds and capital, respectively, to produce a total notional investment income by segment. The Company's actual net investment income is allocated to each segment in proportion to the respective segment's notional investment income to total notional investment income. There are certain legal entities within the Company that are dedicated to specific reportable business segments. The invested assets and related net investment income from these legal entities are reported in the applicable business segment and are not allocated among the other business segments. The cost of the Company's catastrophe treaty program is included in the Company's ceded premiums and is allocated among reportable business segments based on an estimate of actual market reinsurance pricing using expected losses calculated by the Company's catastrophe model, adjusted for any experience adjustments. The following tables summarize the components of the Company's operating revenues, operating income, net written premiums and total assets by reportable business segments. (for the year ended December 31, in millions) Business and Bond & Personal Total 2016 Premiums 14,620 2,088 7,826 24,534 Net investment income 1,763 210 329 2,302 Fee income 442 — 16 458 Other revenues 176 20 56 252 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues(1) 17,001 2,318 8,227 27,546 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization and depreciation 2,956 457 1,391 4,804 Income tax expense 659 307 191 1,157 Operating income(1) 2,048 653 510 3,211 2015 Premiums 14,521 2,085 7,268 23,874 Net investment income 1,824 223 332 2,379 Fee income 445 — 15 460 Other revenues 23 22 48 93 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues(1) 16,813 2,330 7,663 26,806 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization and depreciation 2,907 467 1,322 4,696 Income tax expense 769 272 402 1,443 Operating income(1) 2,170 633 889 3,692 2014 Premiums 14,512 2,076 7,125 23,713 Net investment income 2,156 252 379 2,787 Fee income 438 — 12 450 Other revenues 46 19 80 145 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues(1) 17,152 2,347 7,596 27,095 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization and depreciation 2,909 482 1,347 4,738 Income tax expense 798 348 366 1,512 Operating income(1) 2,347 727 824 3,898 (1) Operating revenues for reportable business segments exclude net realized investment gains. Operating income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains. Net written premiums by market were as follows: (for the year ended December 31, in millions) 2016 2015 2014 Business and International Insurance: Domestic: Select Accounts 2,729 2,716 2,707 Middle Market 6,463 6,302 6,077 National Accounts 1,058 1,048 1,047 First Party 1,601 1,564 1,579 Specialized Distribution 1,094 1,111 1,074 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Domestic 12,945 12,741 12,484 International 1,730 1,842 2,152 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Business and International Insurance 14,675 14,583 14,636 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Bond & Specialty Insurance 2,099 2,081 2,103 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Personal Insurance: Automobile 4,327 3,700 3,390 Homeowners and Other 3,857 3,757 3,775 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Personal Insurance 8,184 7,457 7,165 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated net written premiums 24,958 24,121 23,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (for the year ended December 31, in millions) 2016 2015 2014 Revenue reconciliation Earned premiums Business and International Insurance: Domestic: Workers' compensation 3,969 3,867 3,711 Commercial automobile 2,010 1,922 1,900 Commercial property 1,769 1,766 1,747 General liability 1,977 1,898 1,834 Commercial multi-peril 3,148 3,133 3,071 Other 31 39 42 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Domestic 12,904 12,625 12,305 International 1,716 1,896 2,207 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Business and International Insurance 14,620 14,521 14,512 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Bond & Specialty Insurance: Fidelity and surety 962 954 936 General liability 946 955 963 Other 180 176 177 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Bond & Specialty Insurance 2,088 2,085 2,076 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Personal Insurance: Automobile 4,013 3,512 3,316 Homeowners and Other 3,813 3,756 3,809 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Personal Insurance 7,826 7,268 7,125 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total earned premiums 24,534 23,874 23,713 Net investment income 2,302 2,379 2,787 Fee income 458 460 450 Other revenues 252 93 145 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues for reportable segments 27,546 26,806 27,095 Other revenues 11 6 — Net realized investment gains 68 3 79 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated revenues 27,625 26,815 27,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income reconciliation, net of tax Total operating income for reportable segments 3,211 3,692 3,898 Interest Expense and Other(1) (244 ) (255 ) (257 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating income 2,967 3,437 3,641 Net realized investment gains 47 2 51 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated net income 3,014 3,439 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The primary component of Interest Expense and Other was after-tax interest expense of $236 million, $242 million and $240 million in 2016, 2015 and 2014, respectively. (at December 31, in millions) 2016 2015 Asset reconciliation: Business and International Insurance 79,468 79,692 Bond & Specialty Insurance 7,296 7,360 Personal Insurance 13,118 12,748 ​ ​ ​ ​ ​ ​ ​ Total assets for reportable segments 99,882 99,800 Other assets(1) 363 384 ​ ​ ​ ​ ​ ​ ​ Total consolidated assets 100,245 100,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The primary components of other assets at December 31, 2016 and 2015 were other intangible assets and deferred taxes. The Company does not have revenue from transactions with a single customer amounting to 10 percent or more of its revenues. The following table presents revenues of the Company's operations based on location: (for the year ended December 31, in millions) 2016 2015 2014 U.S. 25,904 25,127 25,103 Non-U.S.: Canada 1,154 1,202 1,474 Other Non-U.S. 567 486 597 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Non-U.S. 1,721 1,688 2,071 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 27,625 26,815 27,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Investments

Investments	12 Months Ended
	Dec. 31, 2016
Investments disclosure
Investments disclsoure [Text Block]	3. INVESTMENTS The amortized cost and fair value of investments in fixed maturities classified as available for sale were as follows: Gross Unrealized Amortized Cost Fair (at December 31, 2016, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,031 9 5 2,035 Obligations of states, municipalities and political subdivisions: Local general obligation 13,955 271 182 14,044 Revenue 10,910 215 147 10,978 State general obligation 1,717 36 22 1,731 Pre-refunded 4,968 190 1 5,157 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total obligations of states, municipalities and political subdivisions 31,550 712 352 31,910 Debt securities issued by foreign governments 1,631 34 3 1,662 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,614 100 6 1,708 All other corporate bonds 22,737 508 138 23,107 Redeemable preferred stock 87 6 — 93 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 59,650 1,369 504 60,515 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Unrealized Amortized Fair (at December 31, 2015, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,202 8 16 2,194 Obligations of states, municipalities and political subdivisions: Local general obligation 12,744 577 3 13,318 Revenue 9,492 472 4 9,960 State general obligation 1,978 97 2 2,073 Pre-refunded 5,813 247 — 6,060 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total obligations of states, municipalities and political subdivisions 30,027 1,393 9 31,411 Debt securities issued by foreign governments 1,829 45 1 1,873 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,863 124 6 1,981 All other corporate bonds 22,854 523 288 23,089 Redeemable preferred stock 103 7 — 110 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 58,878 2,100 320 60,658 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The amortized cost and fair value of fixed maturities by contractual maturity follow. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. (at December 31, 2016, in millions) Amortized Fair Due in one year or less 5,619 5,677 Due after 1 year through 5 years 16,417 16,926 Due after 5 years through 10 years 14,258 14,449 Due after 10 years 21,742 21,755 ​ ​ ​ ​ ​ ​ ​ 58,036 58,807 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,614 1,708 ​ ​ ​ ​ ​ ​ ​ Total 59,650 60,515 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-refunded bonds of $5.16 billion and $6.06 billion at December 31, 2016 and 2015, respectively, were bonds for which states or municipalities have established irrevocable trusts, almost exclusively comprised of U.S. Treasury securities, which were created to satisfy their responsibility for payments of principal and interest. The Company's fixed maturity investment portfolio at December 31, 2016 and 2015 included $1.71 billion and $1.98 billion, respectively, of residential mortgage-backed securities, which include pass-through securities and collateralized mortgage obligations (CMOs). Included in the totals at December 31, 2016 and 2015 were $563 million and $676 million, respectively, of GNMA, FNMA, FHLMC (excluding FHA project loans) and Canadian government guaranteed residential mortgage-backed pass-through securities classified as available for sale. Also included in those totals were residential CMOs classified as available for sale with a fair value of $1.15 billion and $1.30 billion at December 31, 2016 and 2015, respectively. Approximately 51% and 48% of the Company's CMO holdings at December 31, 2016 and 2015, respectively, were guaranteed by or fully collateralized by securities issued by GNMA, FNMA or FHLMC. The average credit rating of the $566 million and $683 million of non-guaranteed CMO holdings at December 31, 2016 and 2015, respectively, was "Baa2" at both dates. The average credit rating of all of the above securities was "Aa2" and "Aa3" at December 31, 2016 and 2015, respectively. At December 31, 2016 and 2015, the Company held commercial mortgage-backed securities (CMBS, including FHA project loans) of $938 million and $865 million, respectively, which are included in "All other corporate bonds" in the tables above. At December 31, 2016 and 2015, approximately $290 million and $303 million of these securities, respectively, or the loans backing such securities, contained guarantees by the U.S. government or a government-sponsored enterprise. The average credit rating of the $648 million and $562 million of non-guaranteed securities at December 31, 2016 and 2015, respectively, was "Aaa" at both dates. The CMBS portfolio is supported by loans that are diversified across economic sectors and geographical areas. The average credit rating of the CMBS portfolio was "Aaa" at both December 31, 2016 and 2015. At December 31, 2016 and 2015, the Company had $286 million and $269 million, respectively, of securities on loan as part of a tri-party lending agreement. Proceeds from sales of fixed maturities classified as available for sale were $1.42 billion, $1.95 billion and $1.05 billion in 2016, 2015 and 2014, respectively. Gross gains of $79 million, $95 million and $44 million and gross losses of $20 million, $14 million and $12 million were realized on those sales in 2016, 2015 and 2014, respectively. At December 31, 2016 and 2015, the Company's insurance subsidiaries had $4.56 billion and $4.68 billion, respectively, of securities on deposit at financial institutions in certain states pursuant to the respective states' insurance regulatory requirements. Funds deposited with third parties to be used as collateral to secure various liabilities on behalf of insureds, cedants and other creditors had a fair value of $35 million and $28 million at December 31, 2016 and 2015, respectively. Other investments pledged as collateral securing outstanding letters of credit had a fair value of $3 million and $21 million at December 31, 2016 and 2015, respectively. In addition, the Company utilized a Lloyd's trust deposit at December 31, 2016 and 2015, whereby owned securities with a fair value of approximately $97 million and $140 million, respectively, held by an insurance subsidiary were pledged into a Lloyd's trust account to support capital requirements for the Company's operations at Lloyd's. The cost and fair value of investments in equity securities were as follows: Gross (at December 31, 2016, in millions) Cost Gains Losses Fair Value Public common stock 390 216 3 603 Non-redeemable preferred stock 114 20 5 129 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 504 236 8 732 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Fair (at December 31, 2015, in millions) Cost Gains Losses Public common stock 386 164 7 543 Non-redeemable preferred stock 142 26 6 162 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 528 190 13 705 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Proceeds from sales of equity securities classified as available for sale were $92 million, $59 million and $158 million in 2016, 2015 and 2014, respectively. Gross gains of $17 million, $16 million and $27 million and gross losses of $3 million, $10 million and $3 million were realized on those sales in 2016, 2015 and 2014, respectively. The Company's real estate investments include warehouses, office buildings and other commercial land and properties that are directly owned. The Company negotiates commercial leases with individual tenants through unrelated, licensed real estate brokers. Negotiated terms and conditions include, among others, rental rates, length of lease period and improvements to the premises to be provided by the landlord. Proceeds from the sale of real estate investments were $69 million, $31 million and $15 million in 2016, 2015 and 2014, respectively. Gross gains of $7 million, $4 million and $6 million were realized on those sales in 2016, 2015 and 2014, respectively, and there were no gross losses. Accumulated depreciation on real estate held for investment purposes was $332 million and $320 million at December 31, 2016 and 2015, respectively. Future minimum rental income on operating leases relating to the Company's real estate properties is expected to be $84 million, $74 million, $62 million, $46 million and $34 million for 2017, 2018, 2019, 2020 and 2021, respectively, and $45 million for 2022 and thereafter. The Company's short-term securities consist of Aaa-rated registered money market funds, U.S. Treasury securities, high-quality commercial paper (primarily A1/P1) and high-quality corporate securities purchased within a year to their maturity with a combined average of 80 days to maturity at December 31, 2016. The amortized cost of these securities, which totaled $4.87 billion and $4.67 billion at December 31, 2016 and 2015, respectively, approximated their fair value. Entities which do not have sufficient equity at risk to allow the entity to finance its activities without additional financial support or in which the equity investors, as a group, do not have the characteristic of a controlling financial interest are referred to as variable interest entities (VIE). A VIE is consolidated by the variable interest holder that is determined to have the controlling financial interest (primary beneficiary) as a result of having both the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE's capital structure, contractual terms, nature of the VIE's operations and purpose and the Company's relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE. The Company reassesses its VIE determination with respect to an entity on an ongoing basis. The Company is a passive investor in limited partner equity interests issued by third party VIEs. These include certain of the Company's investments in private equity limited partnerships, hedge funds and real estate partnerships where the Company is not related to the general partner. These investments are generally accounted for under the equity method and reported in the Company's consolidated balance sheet as other investments unless the Company is deemed the primary beneficiary. These equity interests generally cannot be redeemed. Distributions from these investments are received by the Company as a result of liquidation of the underlying investments of the funds and/or as income distribution. The Company's maximum exposure to loss with respect to these investments is limited to the investment carrying amounts reported in the Company's consolidated balance sheet and any unfunded commitment. Neither the carrying amounts nor the unfunded commitments related to these VIEs are material. The following tables summarize, for all investments in an unrealized loss position at December 31, 2016 and 2015, the aggregate fair value and gross unrealized loss by length of time those securities have been continuously in an unrealized loss position. The fair value amounts reported in the tables are estimates that are prepared using the process described in note 4. The Company also relies upon estimates of several factors in its review and evaluation of individual investments, using the process described in note 1, in determining whether such investments are other-than-temporarily impaired. Less than 12 months 12 months or longer Total (at December 31, 2016, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 1,124 5 — — 1,124 5 Obligations of states, municipalities and political subdivisions 9,781 352 12 — 9,793 352 Debt securities issued by foreign governments 360 3 — — 360 3 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 528 5 43 1 571 6 All other corporate bonds 6,470 115 437 23 6,907 138 Redeemable preferred stock — — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 18,263 480 492 24 18,755 504 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 45 2 10 1 55 3 Non-redeemable preferred stock 2 — 59 5 61 5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 47 2 69 6 116 8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 18,310 482 561 30 18,871 512 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months 12 months or longer Total (at December 31, 2015, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 1,820 15 28 1 1,848 16 Obligations of states, municipalities and political subdivisions 928 7 142 2 1,070 9 Debt securities issued by foreign governments 172 1 — — 172 1 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 473 4 57 2 530 6 All other corporate bonds 7,725 197 710 91 8,435 288 Redeemable preferred stock 8 — — — 8 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 11,126 224 937 96 12,063 320 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 48 6 33 1 81 7 Non-redeemable preferred stock 47 3 38 3 85 6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 95 9 71 4 166 13 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,221 233 1,008 100 12,229 333 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table summarizes, for all fixed maturities and equity securities reported at fair value for which fair value is less than 80% of amortized cost at December 31, 2016, the gross unrealized investment loss by length of time those securities have continuously been in an unrealized loss position of greater than 20% of amortized cost: Period For Which Fair Value Is Less Than 80% of Amortized Cost (in millions) 3 Months Greater Than Greater Than Greater Than Total Fixed maturities Mortgage-backed securities — — — — — Other 1 — — 2 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 1 — — 2 3 Equity securities 1 — — — 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 2 — — 2 4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ These unrealized losses at December 31, 2016 represented less than 1% of the combined fixed maturity and equity security portfolios on a pre-tax basis and less than 1% of shareholders' equity on an after-tax basis. Impairment charges included in net realized investment gains in the consolidated statement of income were as follows: (for the year ended December 31, in millions) 2016 2015 2014 Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities — — — Obligations of states, municipalities and political subdivisions — — — Debt securities issued by foreign governments — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities — — 1 All other corporate bonds 15 13 15 Redeemable preferred stock — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 15 13 16 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 9 37 9 Non-redeemable preferred stock 3 — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 12 37 9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments 2 2 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 29 52 26 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following tables present the cumulative amount of and the changes during the year in credit losses on fixed maturities held at December 31, 2016 and 2015, that were recognized in the consolidated statement of income from other-than-temporary impairments (OTTI) and for which a portion of the OTTI was recognized in other comprehensive income (loss) in the consolidated balance sheet. Year ended December 31, 2016 Cumulative Additions for Additions for Reductions Adjustments to Cumulative OTTI Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 32 — — — (1 ) 31 All other corporate bonds 51 13 — (7 ) (3 ) 54 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 83 13 — (7 ) (4 ) 85 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2015 Cumulative Additions for Additions for Reductions Adjustments to Cumulative OTTI Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 40 — — (6 ) (2 ) 32 All other corporate bonds 59 2 — (4 ) (6 ) 51 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 99 2 — (10 ) (8 ) 83 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Concentrations of credit risk arise from exposure to counterparties that are engaged in similar activities and have similar economic characteristics that could cause their ability to meet contractual obligations to be similarly affected by changes in economic or other conditions. The Company seeks to mitigate credit risk by actively monitoring the creditworthiness of counterparties, obtaining collateral as deemed appropriate and applying controls that include credit approvals, limits of credit exposure and other monitoring procedures. At December 31, 2016, other than U.S. Treasury securities and obligations of U.S. government and government agencies and authorities, the Company was not exposed to any concentration of credit risk of a single issuer greater than 5% of the Company's shareholders' equity. At December 31, 2015, other than U.S. Treasury securities, obligations of U.S. government and government agencies and authorities, and obligations of the Canadian government, the Company was not exposed to any concentration of credit risk of a single issuer greater than 5% of the Company's shareholders' equity. Included in fixed maturities are below investment grade securities totaling $1.76 billion and $1.71 billion at December 31, 2016 and 2015, respectively. The Company defines its below investment grade securities as those securities rated below investment grade by external rating agencies, or the equivalent by the Company when a public rating does not exist. Such securities include below investment grade bonds that are publicly traded and certain other privately issued bonds that are classified as below investment grade loans. (for the year ended December 31, in millions) 2016 2015 2014 Gross investment income Fixed maturities 1,981 2,091 2,244 Equity securities 37 39 40 Short-term securities 29 12 9 Real estate investments 51 48 44 Other investments 242 230 489 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross investment income 2,340 2,420 2,826 Investment expenses 38 41 39 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net investment income 2,302 2,379 2,787 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Changes in net unrealized gains on investment securities that are included as a separate component of other comprehensive income (loss) were as follows: (at and for the year ended December 31, in millions) 2016 2015 2014 Changes in net unrealized investment gains Fixed maturities (915 ) (893 ) 913 Equity securities 51 (143 ) 63 Other investments 2 2 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in net pre-tax unrealized gains on investment securities (862 ) (1,034 ) 978 Related tax expense (benefit) (303 ) (357 ) 334 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in net unrealized gains on investment securities (559 ) (677 ) 644 Balance, beginning of year 1,289 1,966 1,322 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of year 730 1,289 1,966 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ From time to time, the Company enters into U.S. Treasury note futures contracts to modify the effective duration of specific assets within the investment portfolio. U.S. Treasury futures contracts require a daily mark-to-market and settlement with the broker. At both December 31, 2016 and 2015, the Company had $400 million notional value of open U.S. Treasury futures contracts. Net realized investment losses related to U.S. Treasury futures contracts in 2016, 2015 and 2014 were not significant. The Company also sells a small amount of U.S. equity index put option contracts that are settled for cash upon their expiration or when they are rolled over. Net realized investment losses related to these derivatives in 2016, 2015 and 2014 were not significant.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Measurements disclosure
Fair Value Measurements disclosure [Text Block]	4. FAIR VALUE MEASUREMENTS The Company's estimates of fair value for financial assets and financial liabilities are based on the framework established in the fair value accounting guidance. The framework is based on the inputs used in valuation, gives the highest priority to quoted prices in active markets and requires that observable inputs be used in the valuations when available. The disclosure of fair value estimates in the fair value accounting guidance hierarchy is based on whether the significant inputs into the valuation are observable. In determining the level of the hierarchy in which the estimate is disclosed, the highest priority is given to unadjusted quoted prices in active markets and the lowest priority to unobservable inputs that reflect the Company's significant market assumptions. The level in the fair value hierarchy within which the fair value measurement is reported is based on the lowest level input that is significant to the measurement in its entirety. The three levels of the hierarchy are as follows: • Level 1 — Unadjusted quoted market prices for identical assets or liabilities in active markets that the Company has the ability to access. • Level 2 — Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in inactive markets; or valuations based on models where the significant inputs are observable (e.g., interest rates, yield curves, prepayment speeds, default rates, loss severities, etc.) or can be corroborated by observable market data. • Level 3 — Valuations based on models where significant inputs are not observable. The unobservable inputs reflect the Company's own assumptions about the inputs that market participants would use. The fair value of a financial instrument is the estimated amount at which the instrument could be exchanged in an orderly transaction between knowledgeable, unrelated, willing parties, i.e., not in a forced transaction. The estimated fair value of a financial instrument may differ from the amount that could be realized if the security was sold in an immediate sale, e.g., a forced transaction. Additionally, the valuation of investments is more subjective when markets are less liquid due to the lack of market based inputs, which may increase the potential that the estimated fair value of an investment is not reflective of the price at which an actual transaction would occur. For investments that have quoted market prices in active markets, the Company uses the unadjusted quoted market prices as fair value and includes these prices in the amounts disclosed in Level 1 of the hierarchy. The Company receives the quoted market prices from third party, nationally recognized pricing services. When quoted market prices are unavailable, the Company utilizes these pricing services to determine an estimate of fair value. The fair value estimates provided from these pricing services are included in the amount disclosed in Level 2 of the hierarchy. If quoted market prices and an estimate from a pricing service are unavailable, the Company produces an estimate of fair value based on internally developed valuation techniques, which, depending on the level of observable market inputs, will render the fair value estimate as Level 2 or Level 3. The Company bases all of its estimates of fair value for assets on the bid price as it represents what a third-party market participant would be willing to pay in an arm's length transaction. The Company utilized a pricing service to estimate fair value measurements for approximately 98% of its fixed maturities at both December 31, 2016 and 2015. The pricing service utilizes market quotations for fixed maturity securities that have quoted prices in active markets. Since fixed maturities other than U.S. Treasury securities generally do not trade on a daily basis, the pricing service prepares estimates of fair value measurements for these securities using its proprietary pricing applications, which include available relevant market information, benchmark curves, benchmarking of like securities, sector groupings and matrix pricing. Additionally, the pricing service uses an Option Adjusted Spread model to develop prepayment and interest rate scenarios. The pricing service evaluates each asset class based on relevant market information, relevant credit information, perceived market movements and sector news. The market inputs utilized in the pricing evaluation, listed in the approximate order of priority, include: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, and industry and economic events. The extent of the use of each market input depends on the asset class and the market conditions. Depending on the security, the priority of the use of inputs may change or some market inputs may not be relevant. For some securities, additional inputs may be necessary. The pricing service utilized by the Company has indicated that it will only produce an estimate of fair value if there is objectively verifiable information to produce a valuation. If the pricing service discontinues pricing an investment, the Company would be required to produce an estimate of fair value using some of the same methodologies as the pricing service but would have to make assumptions for any market-based inputs that were unavailable due to market conditions. The Company reviews the estimates of fair value provided by the pricing service and compares the estimates to the Company's knowledge of the market to determine if the estimates obtained are representative of the prices in the market. In addition, the Company has periodic discussions with the pricing service to discuss and understand any changes in process and their responsiveness to changes occurring in the markets. The Company also monitors all monthly price changes and further evaluates any securities whose value changed more than 10% from the prior month. The Company has implemented various other processes including randomly selecting purchased or sold securities and comparing execution prices to the estimates from the pricing service as well as reviewing securities whose valuation did not change from their previous valuation (stale price review). The Company also uses a second independent pricing service to further test the primary pricing service's valuation of the Company's fixed maturity portfolio. These processes have not highlighted any significant issues with the fair value estimates received from the primary pricing service. The fair value estimates of most fixed maturity investments are based on observable market information rather than market quotes. Accordingly, the estimates of fair value for such fixed maturities, other than U.S. Treasury securities, provided by the pricing service are included in the amount disclosed in Level 2 of the hierarchy. The estimated fair value of U.S. Treasury securities is included in the amount disclosed in Level 1 as the estimates are based on unadjusted market prices. The Company also holds certain fixed maturity investments which are not priced by the pricing service and, accordingly, estimates the fair value of such fixed maturities using an internal matrix that is based on market information regarding interest rates, credit spreads and liquidity. The underlying source data for calculating the matrix of credit spreads relative to the U.S. Treasury curve are the BofA Merrill Lynch U.S. Corporate Index and the BofA Merrill Lynch High Yield BB Rated Index. The Company includes the fair value estimates of these corporate bonds in Level 2, since all significant inputs are market observable. While the vast majority of the Company's fixed maturities are included in Level 2, the Company holds a number of municipal bonds and corporate bonds which are not valued by the pricing service and estimates the fair value of these bonds using an internal pricing matrix with some unobservable inputs that are significant to the valuation. Due to the limited amount of observable market information, the Company includes the fair value estimates for these particular bonds in Level 3. The fair value of the fixed maturities for which the Company used an internal pricing matrix was $99 million and $101 million at December 31, 2016 and 2015, respectively. Additionally, the Company holds a small amount of other fixed maturity investments that have characteristics that make them unsuitable for matrix pricing. For these fixed maturities, the Company obtains a quote from a broker (primarily the market maker). The fair value of the fixed maturities for which the Company received a broker quote was $85 million and $117 million at December 31, 2016 and 2015, respectively. Due to the disclaimers on the quotes that indicate that the price is indicative only, the Company includes these fair value estimates in Level 3. For public common stock and non-redeemable preferred stocks, the Company receives prices from pricing services that are based on observable market transactions and includes these estimates in the amount disclosed in Level 1. When current market quotes in active markets are unavailable for certain non-redeemable preferred stocks held by the Company, the Company receives an estimate of fair value from the pricing services. The services utilize similar methodologies to price the non-redeemable preferred stocks as they do for the fixed maturities. The Company includes the fair value estimate for these non-redeemable preferred stocks in the amount disclosed in Level 2. The Company holds investments in various publicly-traded securities which are reported in other investments. These investments include mutual funds and other small holdings. The $17 million and $18 million fair value of these investments at December 31, 2016 and 2015, respectively, was disclosed in Level 1. At December 31, 2016 and 2015, the Company held investments in non-public common and preferred equity securities, with fair value estimates of $36 million and $38 million, respectively, reported in other investments, where the fair value estimate is determined either internally or by an external fund manager based on recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the Company includes the total fair value estimate for all of these investments at December 31, 2016 and 2015 in the amount disclosed in Level 3. At December 31, 2015, the Company held $2 million of convertible bonds containing embedded conversion options that are valued separately from the host bond contract in the amount disclosed in Level 2—fixed maturities. At December 31, 2016, the Company held no such convertible bonds. The following tables present the level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured on a recurring basis. An investment transferred between levels during a period is transferred at its fair value as of the beginning of that period. (at December 31, 2016, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,035 2,035 — — Obligations of states, municipalities and political subdivisions 31,910 — 31,898 12 Debt securities issued by foreign governments 1,662 — 1,662 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,708 — 1,704 4 All other corporate bonds 23,107 — 22,939 168 Redeemable preferred stock 93 3 90 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 60,515 2,038 58,293 184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 603 603 — — Non-redeemable preferred stock 129 51 78 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 732 654 78 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments 53 17 — 36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 61,300 2,709 58,371 220 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (at December 31, 2015, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,194 2,194 — — Obligations of states, municipalities and political subdivisions 31,411 — 31,398 13 Debt securities issued by foreign governments 1,873 — 1,873 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,981 — 1,957 24 All other corporate bonds 23,089 — 22,915 174 Redeemable preferred stock 110 3 100 7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 60,658 2,197 58,243 218 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 543 543 — — Non-redeemable preferred stock 162 55 107 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 705 598 107 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments 56 18 — 38 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 61,419 2,813 58,350 256 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ During the years ended December 31, 2016 and 2015, the Company's transfers between Level 1 and Level 2 were not significant. The following tables present the changes in the Level 3 fair value category for the years ended December 31, 2016 and 2015. (in millions) Fixed Other Total Balance at December 31, 2015 218 38 256 Total realized and unrealized investment gains (losses): Reported in net realized investment gains(1) 3 5 8 Reported in increases in other comprehensive income 2 3 5 Purchases, sales and settlements/maturities: Purchases 123 — 123 Sales (19 ) (10 ) (29 ) Settlements/maturities (66 ) — (66 ) Gross transfers into Level 3 19 — 19 Gross transfers out of Level 3 (96 ) — (96 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, 2016 184 36 220 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date — (2 ) (2 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities. (in millions) Fixed Other Total Balance at December 31, 2014 232 36 268 Total realized and unrealized investment gains (losses): Reported in net realized investment gains(1) 1 2 3 Reported in increases (decreases) in other comprehensive income (4 ) 1 (3 ) Purchases, sales and settlements/maturities: Purchases 202 1 203 Sales (7 ) (2 ) (9 ) Settlements/maturities (41 ) — (41 ) Gross transfers into Level 3 21 — 21 Gross transfers out of Level 3 (186 ) — (186 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, 2015 218 38 256 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date — (1 ) (1 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities. The following tables present the carrying value and fair value of the Company's financial assets and financial liabilities disclosed, but not carried, at fair value, and the level within the fair value hierarchy at which such assets and liabilities are categorized. (at December 31, 2016, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets: Short-term securities 4,865 4,865 1,223 3,607 35 Financial liabilities: Debt 6,337 7,262 — 7,262 — Commercial paper 100 100 — 100 — (at December 31, 2015, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets: Short-term securities 4,671 4,671 1,685 2,958 28 Financial liabilities: Debt 6,244 7,180 — 7,180 — Commercial paper 100 100 — 100 — The Company utilized a pricing service to estimate fair value for approximately 98% and 99% of short-term securities at December 31, 2016 and 2015, respectively. A description of the process and inputs used by the pricing service to estimate fair value is discussed in the " Fixed Maturities " section above. Estimates of fair value for U.S. Treasury securities and money market funds are based on market quotations received from the pricing service and are disclosed in Level 1 of the hierarchy. The fair value of other short-term fixed maturity securities is estimated by the pricing service using observable market inputs and is disclosed in Level 2 of the hierarchy. For short-term securities where an estimate is not obtained from the pricing service, the carrying value approximates fair value and is included in Level 3 of the hierarchy. The Company utilized a pricing service to estimate fair value for 100% of its debt, including commercial paper, at December 31, 2016 and 2015. The pricing service utilizes market quotations for debt that have quoted prices in active markets. Since fixed maturities other than U.S. Treasury securities generally do not trade on a daily basis, the fair value estimates are based on market observable inputs and disclosed in Level 2 of the hierarchy. The Company had no material assets or liabilities that were measured at fair value on a non-recurring basis during the years ended December 31, 2016 and 2015.

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2016
Reinsurance disclosure
Reinsurance disclosure [Text Block]	5. REINSURANCE The Company's consolidated financial statements reflect the effects of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance involves transferring certain insurance risks (along with the related written and earned premiums) the Company has underwritten to other insurance companies who agree to share these risks. The primary purpose of ceded reinsurance is to protect the Company, at a cost, from losses in excess of the amount it is prepared to accept and to protect the Company's capital. Reinsurance is placed on both a quota-share and excess-of-loss basis. Ceded reinsurance arrangements do not discharge the Company as the primary insurer, except for instances where the primary policy or policies have been novated, such as in certain structured settlement agreements. The Company utilizes a corporate catastrophe excess-of-loss reinsurance treaty with unaffiliated reinsurers to manage its exposure to losses resulting from catastrophes and to protect its capital. In addition to the coverage provided under this treaty, the Company also utilizes catastrophe bonds to protect against certain weather-related and earthquake losses in the Northeastern United States, and a Northeast catastrophe reinsurance treaty to protect against losses resulting from weather-related and earthquake catastrophes in the Northeastern United States. The Company also utilizes excess-of-loss treaties to protect against earthquake losses up to a certain threshold in Business and International Insurance (for certain markets) and for Personal Insurance, and several reinsurance treaties specific to its international operations. The Company monitors the financial condition of its reinsurers under voluntary reinsurance arrangements to evaluate the collectability of amounts due from reinsurers and as a basis for determining the reinsurers with which the Company conducts ongoing business. In addition, in the ordinary course of business, the Company may become involved in coverage disputes with its reinsurers. Some of these disputes could result in lawsuits and arbitrations brought by or against the reinsurers to determine the Company's rights and obligations under the various reinsurance agreements. The Company employs dedicated specialists and strategies to manage reinsurance collections and disputes. Included in reinsurance recoverables are amounts related to involuntary reinsurance arrangements. The Company is required to participate in various involuntary reinsurance arrangements through assumed reinsurance, principally with regard to residual market mechanisms in workers' compensation and automobile insurance, as well as homeowners' insurance in certain coastal areas. In addition, the Company provides services for several of these involuntary arrangements (mandatory pools and associations) under which it writes such residual market business directly, then cedes 100% of this business to the mandatory pool. Such participations and servicing arrangements are arranged to mitigate credit risk to the Company, as any ceded balances are jointly backed by all the pool members. Also included in reinsurance recoverables are amounts related to certain structured settlements. Structured settlements are annuities purchased from various life insurance companies to settle certain personal physical injury claims, of which workers' compensation claims comprise a significant portion. In cases where the Company did not receive a release from the claimant, the structured settlement is included in reinsurance recoverables and the related claim cost is included in the liability for claims and claim adjustment expense reserves, as the Company retains the contingent liability to the claimant. If it is expected that the life insurance company is not able to pay, the Company would recognize an impairment of the related reinsurance recoverable if, and to the extent, the purchased annuities are not covered by state guaranty associations. In the event that the life insurance company fails to make the required annuity payments, the Company would be required to make such payments. The following is a summary of reinsurance financial data reflected in the consolidated statement of income: (for the year ended December 31, in millions) 2016 2015 2014 Written premiums Direct 25,567 24,939 24,844 Assumed 928 843 788 Ceded (1,537 ) (1,661 ) (1,728 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net written premiums 24,958 24,121 23,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earned premiums Direct 25,262 24,740 24,810 Assumed 875 814 743 Ceded (1,603 ) (1,680 ) (1,840 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net earned premiums 24,534 23,874 23,713 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of assumed earned premiums to net earned premiums 3.6 % 3.4 % 3.1 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ceded claims and claim adjustment expenses incurred 762 1,034 953 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ceded premiums include the premiums paid for coverage provided by the Company's catastrophe bonds. Reinsurance recoverables include amounts recoverable on both paid and unpaid claims and claim adjustment expenses and were as follows: (at December 31, in millions) 2016 2015 Gross reinsurance recoverables on paid and unpaid claims and claim adjustment expenses 3,181 3,848 Allowance for uncollectible reinsurance (116 ) (157 ) ​ ​ ​ ​ ​ ​ ​ Net reinsurance recoverables 3,065 3,691 Mandatory pools and associations 2,054 2,015 Structured settlements 3,168 3,204 ​ ​ ​ ​ ​ ​ ​ Total reinsurance recoverables 8,287 8,910 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Terrorism Risk Insurance Program is a Federal program administered by the Department of the Treasury authorized through December 31, 2020 that provides for a system of shared public and private compensation for certain insured losses resulting from certified acts of terrorism. In order for a loss to be covered under the program (subject losses), the loss must meet certain aggregate industry loss minimums and must be the result of an event that is certified as an act of terrorism by the U.S. Secretary of the Treasury, in consultation with the Secretary of Homeland Security and the Attorney General of the United States. The annual aggregate industry loss minimum under the program is $140 million for 2017, but will increase over the life of the program to $200 million by December 31, 2020. The program excludes from participation the following types of insurance: Federal crop insurance, private mortgage insurance, financial guaranty insurance, medical malpractice insurance, health or life insurance, flood insurance, reinsurance, commercial automobile, professional liability (other than directors and officers'), surety, burglary and theft, and farm-owners multi-peril. In the case of a war declared by Congress, only workers' compensation losses are covered by the program. All commercial property and casualty insurers licensed in the United States are generally required to participate in the program. Under the program, a participating insurer, in exchange for making terrorism insurance available, is entitled to be reimbursed by the Federal Government for 83% of subject losses in 2017, after an insurer deductible, subject to an annual cap. This reimbursement percentage will decrease over the remaining four-year life of the program to 80% of subject losses by December 31, 2020. The deductible for any calendar year is equal to 20% of the insurer's direct earned premiums for covered lines for the preceding calendar year. The Company's estimated deductible under the program is $2.45 billion for 2017. The annual cap limits the amount of aggregate subject losses for all participating insurers to $100 billion. Once subject losses have reached the $100 billion aggregate during a program year, participating insurers will not be liable under the program for additional covered terrorism losses for that program year. There have been no terrorism-related losses that have triggered program coverage since the program was established. Since the law is untested, there is substantial uncertainty as to how it will be applied if an act of terrorism is certified under the program. It is also possible that future legislative action could change or eliminate the program. Further, given the unpredictable frequency and severity of terrorism losses, as well as the limited terrorism coverage in the Company's own reinsurance program, future losses from acts of terrorism, particularly involving nuclear, biological, chemical or radiological events, could be material to the Company's operating results, financial position and/or liquidity in future periods. In addition, the Company may not have sufficient resources to respond to claims arising from a high frequency of high severity natural catastrophes and/or of man-made catastrophic events involving conventional means. While the Company seeks to manage its exposure to man-made catastrophic events involving conventional means, the Company may not have sufficient resources to respond to claims arising out of one or more man-made catastrophic events involving nuclear, biological, chemical or radiological means.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill and Other Intangible Assets disclosure
Goodwill and Other Intangible Assets disclosure [Text Block]	6. GOODWILL AND OTHER INTANGIBLE ASSETS The following table presents the carrying amount of the Company's goodwill by segment: (at December 31, in millions) 2016 2015 Business and International Insurance(1) 2,446 2,439 Bond & Specialty Insurance 496 496 Personal Insurance 612 612 Other 26 26 ​ ​ ​ ​ ​ ​ ​ Total 3,580 3,573 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes goodwill associated with the Company's international business which is subject to the impact of changes in foreign currency exchange rates. The following tables present a summary of the Company's other intangible assets by major asset class: (at December 31, 2016, in millions) Gross Accumulated Net Subject to amortization(1) 210 159 51 Not subject to amortization 217 — 217 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 427 159 268 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (at December 31, 2015, in millions) Gross Accumulated Net Subject to amortization(1) 210 148 62 Not subject to amortization 217 — 217 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 427 148 279 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Intangible assets subject to amortization are comprised of fair value adjustments on claims and claim adjustment expense reserves, reinsurance recoverables and other contract and customer-related intangibles. Fair value adjustments recorded in connection with insurance acquisitions were based on management's estimate of nominal claims and claim adjustment expense reserves and reinsurance recoverables. The method used calculated a risk adjustment to a risk-free discounted reserve that would, if reserves ran off as expected, produce results that yielded the assumed cost-of-capital on the capital supporting the loss reserves. The fair value adjustments are reported as other intangible assets on the consolidated balance sheet, and the amounts measured in accordance with the acquirer's accounting policies for insurance contracts have been reported as part of the claims and claim adjustment expense reserves and reinsurance recoverables. The intangible assets are being recognized into income over the expected payment pattern. Because the time value of money and the risk adjustment (cost of capital) components of the intangible assets run off at different rates, the amount recognized in income may be a net benefit in some periods and a net expense in other periods. Amortization expense of intangible assets was $11 million, $26 million and $46 million for the years ended December 31, 2016, 2015 and 2014, respectively. Intangible asset amortization expense is estimated to be $9 million in 2017, $8 million in 2018, $6 million in 2019, $5 million in 2020 and $5 million in 2021.

Insurance Claim Reserves

Insurance Claim Reserves	12 Months Ended
	Dec. 31, 2016
Insurance Claim Reserves disclosure
Insurance Claim Reserves disclosure [Text Block]	7. INSURANCE CLAIM RESERVES Claims and claim adjustment expense reserves were as follows: (at December 31, in millions) 2016 2015 Property-casualty 47,929 48,272 Accident and health 20 23 ​ ​ ​ ​ ​ ​ ​ Total 47,949 48,295 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table presents a reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses: (at and for the year ended December 31, in millions) 2016 2015 2014 Claims and claim adjustment expense reserves at beginning of year 48,272 49,824 50,865 Less reinsurance recoverables on unpaid losses 8,449 8,788 9,280 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net reserves at beginning of year 39,823 41,036 41,585 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Estimated claims and claim adjustment expenses for claims arising in the current year 15,675 14,471 14,688 Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (680 ) (817 ) (885 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total increases 14,995 13,654 13,803 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and claim adjustment expense payments for claims arising in: Current year 6,220 5,725 5,895 Prior years 8,576 8,749 8,171 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total payments 14,796 14,474 14,066 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Acquisition(1) — 2 — Unrealized foreign exchange gain (74 ) (395 ) (286 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net reserves at end of year 39,948 39,823 41,036 Plus reinsurance recoverables on unpaid losses 7,981 8,449 8,788 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and claim adjustment expense reserves at end of year 47,929 48,272 49,824 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Amount represents acquired net claims and claim adjustment expense reserves of Travelers Participações em Seguros Brasil S.A. at October 1, 2015. Gross claims and claim adjustment expense reserves at December 31, 2016 decreased by $343 million from December 31, 2015. This decrease primarily reflected the impacts of (i) payments related to operations in runoff, including the Company's $524 million payment related to the settlement of the PPG Industries, Inc. litigation and (ii) net favorable prior year reserve development, partially offset by the impacts of (iii) higher volumes of insured exposures and (iv) loss cost trends for the current accident year. Gross claims and claim adjustment expense reserves at December 31, 2015 decreased by $1.55 billion from December 31, 2014. This decrease primarily reflected the impacts of (i) payments related to operations in runoff, including a $579 million payment related to the settlement of the Asbestos Direct Action Litigation as described in more detail in note 16, (ii) net favorable prior year reserve development and (iii) changes in foreign currency exchange rates, partially offset by (iv) the impact of loss cost trends for the current accident year. Reinsurance recoverables on unpaid losses at December 31, 2016 decreased by $468 million from December 31, 2015, primarily reflecting the impact of cash collections in 2016, including the settlement of a reinsurance dispute which is discussed in more detail in note 16. Reinsurance recoverables on unpaid losses at December 31, 2015 decreased by $339 million from December 31, 2014, primarily reflecting the impact of cash collections in 2015. Included in the claims and claim adjustment expense reserves are reserves for long-term disability and annuity claim payments, primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, that are discounted to the present value of the estimated future payments. The discount rate used was 5% at both December 31, 2016 and 2015. Total reserves net of the discount were $2.17 billion and $2.13 billion, and the related amount of discount was $1.08 billion and $1.07 billion, at December 31, 2016 and 2015, respectively. Accretion of the discount is reported as part of "claims and claim adjustment expenses" in the Consolidated Statement of Income. The following disclosures regarding reserve development are on a "net of reinsurance" basis. In 2016, estimated claims and claim adjustment expenses incurred included $680 million of net favorable development for claims arising in prior years, including $771 million of net favorable prior year reserve development impacting the Company's results of operations and $50 million of accretion of discount. Business and International Insurance. Net favorable prior year reserve development in 2016 totaled $484 million, primarily driven by better than expected loss experience in the Company's domestic operations in (i) the workers' compensation product line for accident years 2006 and prior as well as accident years 2009, 2013 and 2015 and (ii) the general liability product line (excluding an increase to asbestos and environmental reserves discussed below), related to both primary and excess coverages for accident years 2007 and prior, accident year 2009 and accident years 2011 through 2015, as well as in the Company's international operations in Europe and Canada. These factors contributing to net favorable prior year reserve development in 2016 were partially offset by $225 million and $82 million increases to asbestos and environmental reserves, respectively, which are discussed in further detail in the "Asbestos and Environmental Reserves" section below. Bond & Specialty Insurance. Net favorable prior year reserve development in 2016 totaled $326 million, primarily driven by better than expected loss experience in (i) the fidelity and surety product line for accident years 2009 through 2015 and (ii) the general liability product line for accident years 2006 through 2011. Personal Insurance. Net unfavorable prior year reserve development in 2016 totaled $39 million, primarily driven by worse than expected loss experience in the automobile product line for bodily injury coverages for the 2015 accident year. In 2015, estimated claims and claim adjustment expenses incurred included $817 million of net favorable development for claims arising in prior years, including $941 million of net favorable prior year reserve development impacting the Company's results of operations and $51 million of accretion of discount. Business and International Insurance. Net favorable prior year reserve development in 2015 totaled $405 million, primarily driven by better than expected loss experience in the Company's domestic operations in (i) the general liability product line (excluding increases to asbestos and environmental reserves discussed below), for both primary and excess coverages for accident years 2005 through 2013, (ii) the workers' compensation line of business for accident years 2006 and prior, (iii) the property product line related to catastrophe losses for accident years 2011, 2012 and 2014 and non-catastrophe losses for accident years 2013 and 2014, as well as in the Company's operations in Canada and at Lloyd's. These factors contributing to net favorable prior year reserve development in 2015 were partially offset by $224 million and $72 million increases to asbestos and environmental reserves, respectively, which are discussed in further detail in the "Asbestos and Environmental Reserves" section below. Bond & Specialty Insurance. Net favorable prior year reserve development in 2015 totaled $258 million, primarily driven by better than expected loss experience in the fidelity and surety product line for accident years 2008 through 2014, which was partially driven by a reduction in outstanding exposures related to the financial crisis that commenced in 2007. Personal Insurance. Net favorable prior year reserve development in 2015 totaled $278 million, primarily driven by better than expected loss experience in (i) the Homeowners and Other product line for liability coverages for accident years 2011 through 2014, for non-catastrophe weather-related losses and non-weather-related losses for accident year 2014 and (ii) the Automobile product line for liability coverages for accident years 2012 through 2014. In 2014, estimated claims and claim adjustment expenses incurred included $885 million of net favorable development for claims arising in prior years, including $941 million of net favorable prior year reserve development impacting the Company's results of operations and $50 million of accretion of discount. Business and International Insurance. Net favorable prior year reserve development in 2014 totaled $322 million, primarily driven by (i) better than expected loss experience in the Company's domestic operations in the general liability product line (excluding increases to asbestos and environmental reserves discussed below), primarily related to excess coverages for accident years 2008 through 2012, (ii) a $162 million benefit resulting from better than expected loss experience related to, and the commutation of reinsurance treaties associated with, a workers' compensation reinsurance pool for accident years 1996 and prior, and better than expected loss experience in the Company's domestic operations in (iii) the property product line for accident years 2010 through 2013, including catastrophe losses from Storm Sandy for accident year 2012 and (iv) the commercial auto product line for accident years 2011 and 2012. These factors contributing to net favorable prior year reserve development in 2014 were partially offset by (i) $250 million and $87 million increases to asbestos and environmental reserves, respectively, which are discussed in further detail in the "Asbestos and Environmental Reserves" section below, (ii) an increase in unallocated loss adjustment expense reserves of $77 million for interest awarded as part of damages pursuant to a court decision in the third quarter of 2014 related to a legal matter, which is discussed in more detail in the "Settlement of Asbestos Direct Action Litigation" section of note 16 and (iii) higher than expected loss experience for liability coverages in the commercial multi-peril product line for accident years 2010 through 2013. Bond & Specialty Insurance. Net favorable prior year reserve development in 2014 totaled $450 million, primarily driven by better than expected loss experience in the contract surety product line for accident years 2012 and prior. Personal Insurance. Net favorable prior year reserve development in 2014 totaled $169 million, primarily driven by better than expected loss experience in the Homeowners and Other product line for (i) non-catastrophe weather-related losses for accident year 2013 and (ii) catastrophe losses for accident years 2011 through 2013. The following is a summary of claims and claim adjustment expense reserves, including certain components, for the Company's major product lines by reporting segment at December 31, 2016. At December 31, 2016 (in millions) Net Undiscounted Discount Subtotal: Reinsurance Claims and Business and International Insurance General liability 7,034 (168 ) 6,866 712 7,578 Commercial property 866 — 866 194 1,060 Commercial multi-peril 3,414 — 3,414 81 3,495 Commercial automobile 2,270 — 2,270 256 2,526 Workers' compensation(1) 15,439 (832 ) 14,607 729 15,336 International—Canada 1,482 — 1,482 157 1,639 Bond & Specialty Insurance General liability 2,042 — 2,042 82 2,124 Fidelity and surety 450 — 450 17 467 Personal Insurance Automobile 2,277 — 2,277 465 2,742 Homeowners (excluding Other) 742 — 742 2 744 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal—claims and allocated claim adjustment expenses for the products presented in the development tables below 36,016 (1,000 ) 35,016 2,695 37,711 Other insurance contracts(2) 2,955 (3 ) 2,952 2,058 5,010 Unallocated loss adjustment expense reserves 1,936 — 1,936 40 1,976 Structured settlements(3) — — — 3,168 3,168 Other 44 — 44 20 64 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total property-casualty 40,951 (1,003 ) 39,948 7,981 47,929 Accident and health — — — 20 20 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 40,951 (1,003 ) 39,948 8,001 47,949 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Net discount amount includes discount of $80 million on reinsurance recoverables for long-term disability and annuity claim payments. (2) Primarily includes residual market, non-Canadian international and runoff assumed reinsurance business. (3) Includes structured settlements in cases where the Company did not receive a release from the claimant. The claim development tables that follow present, by accident year, incurred and cumulative paid claims and allocated claim adjustment expense on a historical basis. This claim development information is presented on an undiscounted, net of reinsurance basis for ten years, or the number of years for which claims incurred typically remain outstanding if less than ten years. The claim development tables also provide the historical average annual percentage payout of incurred claims by age, net of reinsurance, as supplementary information (identified as unaudited in the tables below). The claim development information reflects the acquisition of The Dominion of Canada General Insurance Company (Dominion) in November 2013 on a retrospective basis (includes Dominion data for years prior to the Company's acquisition of Dominion). General Liability (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,136 1,162 1,087 1,089 968 919 888 883 865 824 78 23,840 2008 1,143 1,209 1,222 1,079 1,041 994 946 931 935 88 25,385 1,060 1,071 1,028 960 869 837 809 796 95 25,457 2010 1,028 1,031 1,021 959 927 912 918 108 27,678 1,004 1,074 1,065 998 972 935 146 27,210 2012 989 985 935 913 892 184 24,384 965 975 958 940 256 21,836 2014 976 989 983 438 20,926 998 956 592 18,771 2016 1,075 908 13,810 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 9,254 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 32 134 316 467 549 632 682 697 713 726 2008 35 154 359 497 615 694 734 759 799 35 167 314 446 543 613 643 667 2010 35 139 324 487 629 702 756 Liability for Claims 2011 47 187 355 539 660 725 And Allocated Claim 2012 32 150 295 489 589 Adjustment Expenses, 2013 35 175 363 498 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 37 163 321 36 137 2007 - Before 2016 35 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,253 4,001 3,033 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 3.9 % 13.3 % 19.1 % 17.6 % 12.4 % 8.4 % 5.0 % 2.5 % 3.1 % 1.6 % Commercial Property (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,054 988 924 889 895 13 28,183 2013 789 755 737 731 10 22,141 936 860 836 15 21,490 2015 786 750 28 19,859 896 131 19,327 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 4,108 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 453 770 845 865 872 Adjustment Expenses, 2013 389 610 683 703 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 464 710 775 2015 376 615 2012 - Before 2016 441 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,406 702 164 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 51.7 % 31.8 % 8.7 % 2.5 % 0.8 % Commercial Multi-Peril (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,490 1,430 1,364 1,402 1,398 1,375 1,373 1,369 1,376 1,369 51 96,767 2008 1,725 1,674 1,683 1,688 1,674 1,684 1,674 1,688 1,681 47 108,382 1,484 1,506 1,501 1,498 1,511 1,514 1,514 1,509 42 103,198 2010 1,711 1,826 1,832 1,861 1,895 1,892 1,898 51 111,586 2,235 2,244 2,269 2,286 2,296 2,287 66 125,358 2012 1,885 1,883 1,903 1,888 1,888 88 104,419 1,615 1,623 1,620 1,609 122 82,936 2014 1,663 1,627 1,625 193 76,833 1,568 1,625 354 68,278 2016 1,662 658 56,471 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 17,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 498 824 982 1,110 1,208 1,256 1,278 1,296 1,307 1,312 2008 712 1,103 1,264 1,396 1,490 1,551 1,581 1,602 1,617 603 958 1,121 1,264 1,360 1,408 1,436 1,449 2010 709 1,180 1,395 1,579 1,698 1,763 1,798 Liability for Claims 2011 1,060 1,573 1,803 1,979 2,088 2,156 And Allocated Claim 2012 795 1,246 1,424 1,590 1,699 Adjustment Expenses, 2013 644 987 1,167 1,304 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 628 956 1,154 595 970 2007 - Before 2016 585 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 14,044 3,109 305 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 39.5 % 22.9 % 10.8 % 8.8 % 6.0 % 3.3 % 1.8 % 1.1 % 0.9 % 0.4 % Commercial Automobile (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,294 1,350 1,327 1,325 1,337 35 214,780 2013 1,235 1,236 1,240 1,245 67 197,041 1,165 1,166 1,168 131 184,067 2015 1,198 1,215 246 179,963 1,290 516 173,790 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 6,255 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 467 753 960 1,134 1,235 Adjustment Expenses, 2013 435 675 884 1,039 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 397 618 821 2015 409 658 2012 - Before 2016 416 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 4,169 2,086 184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 34.0 % 20.0 % 16.6 % 12.7 % 7.6 % Workers' Compensation (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,554 1,519 1,484 1,448 1,390 1,373 1,358 1,340 1,328 1,341 217 103,064 2008 1,714 1,745 1,734 1,683 1,639 1,634 1,621 1,617 1,617 237 107,565 1,799 1,778 1,746 1,753 1,753 1,766 1,775 1,750 272 104,229 2010 1,886 2,042 2,035 2,056 2,049 2,052 2,055 354 116,837 2,284 2,303 2,347 2,350 2,379 2,385 430 135,061 2012 2,447 2,456 2,457 2,456 2,445 519 133,417 2,553 2,545 2,540 2,506 651 128,111 2014 2,554 2,553 2,547 839 123,110 2,644 2,585 1,142 120,681 2016 2,768 1,651 108,357 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 21,999 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 216 450 589 683 747 802 845 880 910 936 2008 274 571 752 875 961 1,036 1,088 1,130 1,162 288 623 828 961 1,065 1,137 1,193 1,235 2010 341 750 978 1,133 1,246 1,321 1,385 Liability for Claims 2011 420 911 1,185 1,365 1,487 1,583 And Allocated Claim 2012 443 940 1,217 1,394 1,536 Adjustment Expenses, 2013 458 954 1,237 1,413 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 455 944 1,224 430 893 2007 - Before 2016 421 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,788 10,211 5,228 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 17.0 % 19.2 % 11.2 % 7.4 % 5.4 % 4.1 % 3.2 % 2.5 % 2.1 % 1.9 % International—Canada (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 632 626 616 608 607 609 611 608 601 597 4 66,327 2008 681 685 670 665 658 655 651 646 642 5 71,803 724 718 707 714 714 702 696 690 13 71,671 2010 715 722 721 735 724 715 706 20 71,437 723 696 686 682 678 669 30 72,063 2012 664 642 631 611 616 50 67,320 723 717 701 685 56 71,183 2014 665 678 682 83 67,935 597 610 112 58,238 2016 612 102 54,948 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 6,509 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 228 355 410 450 488 524 547 561 570 578 2008 256 406 460 501 543 579 603 616 622 274 419 479 525 573 608 630 648 2010 258 403 465 522 573 615 641 Liability for Claims 2011 253 380 432 481 538 571 And Allocated Claim 2012 225 336 389 435 482 Adjustment Expenses, 2013 260 388 439 494 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 252 382 445 228 346 2007 - Before 2016 295 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,122 1,387 95 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 38.9 % 20.0 % 8.5 % 7.2 % 7.2 % 5.5 % 3.6 % 2.3 % 1.2 % 1.4 % The incurred and paid amounts have been translated from the local currency to U.S. dollars using the December 31, 2016 spot rate for all years presented in the table above in order to isolate changes in foreign exchange rates from loss development. General Liability (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 584 571 638 582 551 511 479 467 462 454 4 11,018 2008 579 769 743 697 716 712 672 643 631 24 6,463 592 624 665 686 680 660 655 641 24 6,287 2010 571 612 679 679 661 668 653 18 5,655 565 596 639 632 601 545 34 5,191 2012 538 591 614 605 601 137 4,824 510 565 606 630 204 4,371 2014 549 571 563 232 4,182 528 524 272 3,814 2016 512 405 2,676 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,754 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 35 134 229 303 357 373 393 400 410 415 2008 47 157 281 387 471 529 562 579 590 36 167 310 390 460 497 563 592 2010 33 152 291 396 482 565 597 Liability for Claims 2011 33 143 249 324 414 447 And Allocated Claim 2012 38 160 255 342 383 Adjustment Expenses, 2013 34 154 252 352 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 38 150 239 38 141 2007 - Before 2016 30 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,786 1,968 74 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 6.3 % 19.7 % 18.8 % 15.1 % 12.1 % 7.5 % 6.2 % 3.0 % 1.9 % 1.1 % Fidelity and Surety (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 255 262 249 175 140 9 1,148 2013 240 246 199 146 6 1,006 223 212 165 32 992 2015 217 191 79 768 226 128 595 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 868 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 42 108 124 110 111 Adjustment Expenses, 2013 37 113 128 131 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 58 96 111 2015 32 75 2012 - Before 2016 54 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 482 386 64 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 26.1 % 36.2 % 10.1 % (3.6)%(1 ) 0.8 % (1) Includes recovery activity. Automobile (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,417 2,454 2,448 2,432 2,428 15 793,669 2013 2,108 2,095 2,049 2,044 36 694,650 2,014 1,994 1,981 75 669,990 2015 2,186 2,244 224 755,762 2,779 646 839,962 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,476 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 1,503 1,983 2,189 2,311 2,376 Adjustment Expenses, 2013 1,251 1,628 1,814 1,935 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 1,193 1,564 1,763 2015 1,319 1,768 2012 - Before 2016 1,610 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 9,452 2,024 253 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 60.0 % 19.2 % 9.2 % 5.5 % 2.7 % Homeowners (excluding Other) (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,136 2,056 2,029 2,018 2,019 1 259,006 2013 1,488 1,397 1,365 1,375 4 149,373 1,515 1,450 1,453 9 151,517 2015 1,438 1,454 28 144,367 1,556 307 129,630 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 7,857 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Debt

Debt	12 Months Ended
	Dec. 31, 2016
Debt disclosure
Debt disclosure [Text Block]	8. DEBT Debt outstanding was as follows: (at December 31, in millions) 2016 2015 Short-term: Commercial paper 100 100 5.75% Senior notes due December 15, 2017 450 — 6.25% Senior notes due June 20, 2016 — 400 ​ ​ ​ ​ ​ ​ ​ Total short-term debt 550 500 ​ ​ ​ ​ ​ ​ ​ Long-term: 5.75% Senior notes due December 15, 2017 — 450 5.80% Senior notes due May 15, 2018 500 500 5.90% Senior notes due June 2, 2019 500 500 3.90% Senior notes due November 1, 2020 500 500 7.75% Senior notes due April 15, 2026 200 200 7.625% Junior subordinated debentures due December 15, 2027 125 125 6.375% Senior notes due March 15, 2033 500 500 6.75% Senior notes due June 20, 2036 400 400 6.25% Senior notes due June 15, 2037 800 800 5.35% Senior notes due November 1, 2040 750 750 4.60% Senior notes due August 1, 2043 500 500 4.30% Senior notes due August 25, 2045 400 400 8.50% Junior subordinated debentures due December 15, 2045 56 56 3.75% Senior notes dues May 15, 2046 500 — 8.312% Junior subordinated debentures due July 1, 2046 73 73 6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 107 107 ​ ​ ​ ​ ​ ​ ​ Total long-term debt 5,911 5,861 ​ ​ ​ ​ ​ ​ ​ Total debt principal 6,461 6,361 Unamortized fair value adjustment 47 49 Unamortized debt issuance costs (71 ) (66 ) ​ ​ ​ ​ ​ ​ ​ Total debt 6,437 6,344 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2016 Debt Issuance. On May 11, 2016, the Company issued $500 million aggregate principal amount of 3.75% senior notes that will mature on May 15, 2046. The net proceeds of the issuance, after the deduction of underwriting and other expenses, totaled approximately $491 million. Interest on the senior notes is payable semi-annually in arrears on May 15 and November 15. Prior to November 15, 2045, the senior notes may be redeemed, in whole or in part, at the Company's option, at any time or from time to time, at a redemption price equal to the greater of (a) 100% of the principal amount of any senior notes to be redeemed or (b) the sum of the present values of the remaining scheduled payments of principal and interest on any senior notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the date of redemption on a semi-annual basis (assuming a 360-day year consisting of twelve 30- day months) at the then current Treasury Rate (as defined in the senior notes), plus 20 basis points. On or after November 15, 2045, the senior notes may be redeemed, in whole or in part, at the Company's option, at any time or from time to time, at a redemption price equal to 100% of the principal amount of any senior notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. 2016 Debt Repayment. On June 20, 2016, the Company's $400 million, 6.25% senior notes matured and were fully paid. 2015 Debt Issuance. On August 25, 2015, the Company issued $400 million aggregate principal amount of 4.30% senior notes that will mature on August 25, 2045. The net proceeds of the issuance, after original issuance discount and the deduction of underwriting expenses and commissions and other expenses, totaled approximately $392 million. Interest on the senior notes is payable semi-annually in arrears on February 25 and August 25. Prior to February 25, 2045, the senior notes may be redeemed, in whole or in part, at the Company's option, at any time or from time to time, at a redemption price equal to the greater of (a) 100% of the principal amount of any senior notes to be redeemed or (b) the sum of the present values of the remaining scheduled payments of principal and interest on any senior notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the date of redemption on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the then current Treasury Rate (as defined in the senior notes), plus 25 basis points. On or after February 25, 2045, the senior notes may be redeemed, in whole or in part, at the Company's option, at any time or from time to time, at a redemption price equal to 100% of the principal amount of any senior notes to be redeemed. 2015 Debt Repayment. On December 1, 2015, the Company's $400 million, 5.50% senior notes matured and were fully paid. Commercial Paper —The Company maintains an $800 million commercial paper program, supported by a $1.0 billion bank credit agreement that expires on June 7, 2018. (See "Credit Agreement" discussion that follows.) Interest rates on commercial paper issued in 2016 ranged from 0.35% to 0.55%, and in 2015 ranged from 0.09% to 0.30%. Senior Notes —The Company's various senior debt issues are unsecured obligations that rank equally with one another. Interest payments are made semi-annually. The Company generally may redeem some or all of the notes prior to maturity in accordance with terms unique to each debt instrument. Junior Subordinated Debentures —The Company's $107 million remaining aggregate principal amount of 6.25% fixed-to-floating rate debentures bear interest at an annual rate of 6.25% from the date of issuance to, but excluding, March 15, 2017, payable semi-annually in arrears on March 15 and September 15. From and including March 15, 2017, the debentures will bear interest at an annual rate equal to three-month LIBOR plus 2.215%, payable quarterly on March 15, June 15, September 15 and December 15 of each year. The Company can redeem the debentures at its option, in whole or in part, at any time on or after March 15, 2017 at a redemption price of 100% of the principal amount being redeemed plus accrued but unpaid interest. The Company can redeem the debentures at its option prior to March 15, 2017 (a) in whole at any time or in part from time to time or (b) in whole, but not in part, in the event of certain tax or rating agency events relating to the debentures, at a redemption price equal to the greater of 100% of the principal amount being redeemed and the applicable make-whole amount, in each case plus any accrued and unpaid interest. The Company has the right, on one or more occasions, to defer the payment of interest on the debentures. The Company will not be required to settle deferred interest until it has deferred interest for five consecutive years or, if earlier, made a payment of current interest during a deferral period. The Company may defer interest for up to ten consecutive years without giving rise to an event of default. Deferred interest will accumulate additional interest at an annual rate equal to the annual interest rate then applicable to the debentures. The debentures have a final maturity date of March 15, 2067 and a scheduled maturity date of March 15, 2037. The Company can redeem the debentures at its option any time (as described above) using any source of funds, including cash. If the Company chooses not to redeem the debentures, then during the 180-day period ending not more than 15 and not less than ten business days prior to the scheduled maturity date, the Company will be required to use commercially reasonable efforts to sell enough qualifying capital securities to permit repayment of the debentures at the scheduled maturity date. If any debentures remain outstanding after the scheduled maturity date, unless and until the Company redeems the debentures (as described above) using any source of funds, including cash, the Company shall be required to use its commercially reasonable efforts on a quarterly basis to raise sufficient proceeds from the sale of qualifying capital securities to permit the repayment in full of the debentures. If there are remaining debentures at the final maturity date, the Company is required to redeem the debentures using any source of funds. Qualifying capital securities are securities (other than common stock, qualifying warrants, mandatorily convertible preferred stock, debt exchangeable for common equity, and debt exchangeable for preferred equity) which generally are treated by the ratings agencies as having similar equity content to the debentures. The Company's three other junior subordinated debenture instruments are all similar in nature to each other. Three separate business trusts issued preferred securities to investors and used the proceeds to purchase the Company's subordinated debentures. Interest on each of the instruments is paid semi-annually. The Company's consolidated balance sheet includes the debt instruments acquired in a business acquisition, which were recorded at fair value as of the acquisition date. The resulting fair value adjustment is being amortized over the remaining life of the respective debt instruments using the effective-interest method. The amortization of the fair value adjustment reduced interest expense by $2 million and $1 million for the years ended December 31, 2016 and 2015, respectively. The following table presents merger-related unamortized fair value adjustments and the related effective interest rate: Unamortized Effective (in millions) Issue Rate Maturity Date 2016 2015 Subordinated debentures 7.625 % Dec. 2027 14 15 6.147 % 8.500 % Dec. 2045 15 15 6.362 % 8.312 % Jul. 2046 18 19 6.362 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 47 49 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Travelers Companies, Inc. fully and unconditionally guarantees the payment of all principal, premiums, if any, and interest on certain debt obligations of its subsidiaries TPC and Travelers Insurance Group Holdings Inc. The guarantees pertain to the $200 million 7.75% notes due 2026 and the $500 million 6.375% notes due 2033. Maturities —The amount of debt obligations, other than commercial paper, that become due in each of the next five years is as follows: 2017, $450 million; 2018, $500 million; 2019, $500 million; 2020, $500 million; and 2021, $0. The Company is party to a five-year, $1.0 billion revolving credit agreement with a syndicate of financial institutions that expires on June 7, 2018. Pursuant to the credit agreement covenants, the Company must maintain a minimum consolidated net worth, defined as shareholders' equity determined in accordance with GAAP plus (a) trust preferred securities (not to exceed 15% of total capital) and (b) mandatorily convertible securities (combined with trust preferred securities, not to exceed 25% of total capital) less goodwill and other intangible assets, of $13.73 billion. In addition, the credit agreement contains other customary restrictive covenants as well as certain customary events of default, including with respect to a change in control, which is defined to include the acquisition of 35% or more of the Company's voting stock and certain changes in the composition of the Company's board of directors. At December 31, 2016, the Company was in compliance with these covenants. Generally, the cost of borrowing under this agreement will range from LIBOR plus 87.5 basis points to LIBOR plus 150 basis points, depending on the Company's credit ratings. At December 31, 2016, that cost would have been LIBOR plus 112.5 basis points, had there been any amounts outstanding under the credit agreement. This credit agreement also supports the Company's commercial paper program. In June 2016, the Company filed with the Securities and Exchange Commission a universal shelf registration statement that expires on June 17, 2019 for the potential offering and sale of securities to replace the Company's previous universal registration statement that had expired three years after its effective date. The Company may offer these securities from time to time at prices and on other terms to be determined at the time of offering.

Shareholders' Equity and Divide

Shareholders' Equity and Dividend Availability	12 Months Ended
	Dec. 31, 2016
Shareholders' Equity and Dividend Availability disclosure
Shareholders' Equity and Dividend Availability disclosure [Text Block]	9. SHAREHOLDERS' EQUITY AND DIVIDEND AVAILABILITY The number of authorized shares of the Company is 1.755 billion, consisting of five million of preferred stock, 1.745 billion shares of voting common stock and five million undesignated shares. The Company's Articles of Incorporation authorize the Board of Directors to establish, from the undesignated shares, one or more classes and series of shares, and to further designate the type of shares and terms thereof. The Company's Articles of Incorporation provide authority to issue up to five million shares of preferred stock. The Company is governed by the Minnesota Business Corporation Act. All authorized shares of voting common stock have no par value. Shares of common stock reacquired are considered authorized and unissued shares. The Company's Board of Directors has approved common share repurchase authorizations under which repurchases may be made from time to time in the open market, pursuant to pre-set trading plans meeting the requirements of Rule 10b5-1 under the Securities Exchange Act of 1934, in private transactions or otherwise. The authorizations do not have a stated expiration date. The timing and actual number of shares to be repurchased in the future will depend on a variety of factors, including the Company's financial position, earnings, share price, catastrophe losses, maintaining capital levels commensurate with the Company's desired ratings from independent rating agencies, funding of the Company's qualified pension plan, capital requirements of the Company's operating subsidiaries, legal requirements, regulatory constraints, other investment opportunities (including mergers and acquisitions and related financings), market conditions and other factors. The following table summarizes repurchase activity in 2016 and remaining repurchase capacity at December 31, 2016. (in millions, except per share amounts) Number of Cost of Average price Remaining capacity March 31, 2016 5.1 550 108.46 2,784 June 30, 2016 4.9 550 112.12 2,234 September 30, 2016 4.7 550 117.25 1,684 December 31, 2016 6.6 750 113.54 934 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 21.3 2,400 112.82 934 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company's Amended and Restated 2004 Stock Incentive Plan and the Amended and Restated 2014 Stock Incentive Plan provide settlement alternatives to employees in which the Company retains shares to cover payroll withholding taxes in connection with the vesting of restricted stock unit awards and performance share awards, and to cover the price of certain stock options that were exercised. During the years ended December 31, 2016 and 2015, the Company acquired $72 million and $74 million, respectively, of its common stock under these plans. Common shares acquired are reported as treasury stock in the consolidated balance sheet. The Company's U.S. insurance subsidiaries, domiciled principally in the State of Connecticut, are subject to various regulatory restrictions that limit the maximum amount of dividends available to be paid by each insurance subsidiary to its respective parent company without prior approval of insurance regulatory authorities. A maximum of $3.69 billion is available by the end of 2017 for such dividends to the holding company, TRV, without prior approval of the Connecticut Insurance Department. The Company may choose to accelerate the timing within 2017 and/or increase the amount of dividends from its insurance subsidiaries in 2017, which could result in certain dividends being subject to approval by the Connecticut Insurance Department. In addition to the regulatory restrictions on the availability of dividends that can be paid by the Company's U.S. insurance subsidiaries, the maximum amount of dividends that may be paid to the Company's shareholders is limited, to a lesser degree, by certain covenants contained in its line of credit agreement with a syndicate of financial institutions that require the Company to maintain a minimum consolidated net worth as described in note 8. TRV is not dependent on dividends or other forms of repatriation from its foreign operations to support its liquidity needs. The undistributed earnings of the Company's foreign operations are not material and are intended to be permanently reinvested in those operations. TRV and its two non-insurance holding company subsidiaries received dividends of $3.05 billion, $3.75 billion and $4.10 billion from their U.S. insurance subsidiaries in 2016, 2015 and 2014, respectively. For the years ended December 31, 2016, 2015 and 2014, TRV declared cash dividends per common share of $2.62, $2.38 and $2.15, respectively, and paid cash dividends of $757 million, $739 million and $729 million, respectively. Statutory net income of the Company's domestic and international insurance subsidiaries was $3.20 billion, $3.80 billion and $3.97 billion for the years ended December 31, 2016, 2015 and 2014, respectively. Statutory capital and surplus of the Company's domestic and international insurance subsidiaries was $20.76 billion and $20.57 billion at December 31, 2016 and 2015, respectively.

Other Comprehensive Income and

Other Comprehensive Income and Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2016
Other Comprehensive Income and Accumulated Other Comprehensive Income disclosure
Other Comprehensive Income and Accumulated Other Comprehensive Income disclosure [Text Block]	10. OTHER COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME The following table presents the changes in the Company's accumulated other comprehensive income (AOCI) for the years ended December 31, 2016, 2015 and 2014. Changes in Net Unrealized Gains on Net Benefit Plan Net Total (in millions) Having No Credit Having Credit Losses Balance, December 31, 2013 1,125 197 (431 ) (81 ) 810 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) (OCI) before reclassifications 667 (2 ) (363 ) (250 ) 52 Amounts reclassified from AOCI (24 ) 3 39 — 18 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net OCI, current period 643 1 (324 ) (250 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2014 1,768 198 (755 ) (331 ) 880 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ OCI before reclassifications (641 ) (11 ) (18 ) (419 ) (1,089 ) Amounts reclassified from AOCI (27 ) 2 60 17 52 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net OCI, current period (668 ) (9 ) 42 (402 ) (1,037 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2015 1,100 189 (713 ) (733 ) (157 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ OCI before reclassifications (530 ) 4 (30 ) (49 ) (605 ) Amounts reclassified from AOCI (42 ) 9 40 — 7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net OCI, current period (572 ) 13 10 (49 ) (598 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2016 528 202 (703 ) (782 ) (755 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table presents the pre-tax components of the Company's other comprehensive income (loss) and the related income tax expense (benefit). (for the year ended December 31, in millions) 2016 2015 2014 Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (883 ) (1,020 ) 976 Income tax expense (benefit) (311 ) (352 ) 333 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes (572 ) (668 ) 643 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Having credit losses recognized in the consolidated statement of income 21 (14 ) 2 Income tax expense (benefit) 8 (5 ) 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 13 (9 ) 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net changes in benefit plan assets and obligations 16 66 (494 ) Income tax expense (benefit) 6 24 (170 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 10 42 (324 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net changes in unrealized foreign currency translation (41 ) (461 ) (289 ) Income tax expense (benefit) 8 (59 ) (39 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes (49 ) (402 ) (250 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income (loss) (887 ) (1,429 ) 195 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense (benefit) (289 ) (392 ) 125 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income (loss), net of taxes (598 ) (1,037 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table presents the pre-tax and related income tax (expense) benefit components of the amounts reclassified from the Company's AOCI to the Company's consolidated statement of income. (for the year ended December 31, in millions) 2016 2015 2014 Reclassification adjustments related to unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income(1) (64 ) (42 ) (36 ) Income tax expense(2) (22 ) (15 ) (12 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes (42 ) (27 ) (24 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Having credit losses recognized in the consolidated statement of income(1) 13 2 4 Income tax benefit(2) 4 — 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 9 2 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment related to benefit plan assets and obligations(3) 62 93 60 Income tax benefit(2) 22 33 21 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 40 60 39 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment related to foreign currency translation(1) — 26 — Income tax benefit(2) — 9 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes — 17 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total reclassifications 11 79 28 Total income tax benefit 4 27 10 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total reclassifications, net of taxes 7 52 18 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) (Increases) decreases net realized investment gains on the consolidated statement of income. (2) (Increases) decreases income tax expense on the consolidated statement of income. (3) Increases (decreases) general and administrative expenses on the consolidated statement of income.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2016
Earnings per Share disclosure
Earnings per Share disclosure [Text Block]	11. EARNINGS PER SHARE Basic earnings per share was computed by dividing income available to common shareholders by the weighted average number of common shares outstanding during the period. The computation of diluted earnings per share reflected the effect of potentially dilutive securities. The following is a reconciliation of the income and share data used in the basic and diluted earnings per share computations: (for the year ended December 31, in millions, except per share amounts) 2016 2015 2014 Basic and Diluted Net income, as reported 3,014 3,439 3,692 Participating share-based awards—allocated income (22 ) (25 ) (27 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common shareholders—basic and diluted 2,992 3,414 3,665 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common Shares Basic Weighted average shares outstanding 288.1 310.6 338.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted Weighted average shares outstanding 288.1 310.6 338.8 Weighted average effects of dilutive securities: Stock options and performance shares 2.9 3.3 3.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 291.0 313.9 342.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income Per Common Share Basic 10.39 10.99 10.82 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted 10.28 10.88 10.70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Taxes disclosure
Income Taxes disclosure [Text Block]	12. INCOME TAXES The following table presents the components of income tax expense included in the amounts reported in the Company's consolidated financial statements: (for the year ended December 31, in millions) 2016 2015 2014 Composition of income tax expense included in the consolidated statement of income Current expense: Federal 899 1,144 1,216 Foreign 21 29 28 State 8 9 10 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total current tax expense 928 1,182 1,254 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred expense: Federal 110 117 121 Foreign 1 2 22 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax expense 111 119 143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense included in the consolidated statement of income 1,039 1,301 1,397 Composition of income tax expense (benefit) included in shareholders' equity Expense (benefit) relating to share-based compensation, the changes in unrealized gain on investments, unrealized loss on foreign exchange and other items in other comprehensive income (289 ) (448 ) 68 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense included in the consolidated financial statements 750 853 1,465 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following is a reconciliation of income tax expense at the U.S. federal statutory income tax rate to the income tax expense reported in the Company's consolidated statement of income: (for the year ended December 31, in millions) 2016 2015 2014 Income before income taxes U.S. 3,946 4,621 4,899 Foreign 107 119 190 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income before income taxes 4,053 4,740 5,089 Effective tax rate Statutory tax rate 35 % 35 % 35 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Expected federal income tax expense 1,419 1,659 1,781 Tax effect of: Nontaxable investment income (323 ) (345 ) (379 ) Other, net (57 ) (13 ) (5 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense 1,039 1,301 1,397 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective tax rate 26 % 27 % 27 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company paid income taxes of $892 million, $1.21 billion and $1.15 billion during the years ended December 31, 2016, 2015 and 2014, respectively. The current income tax payable was $72 million and $50 million at December 31, 2016 and 2015, respectively, and was included in other liabilities in the consolidated balance sheet. The net deferred tax asset comprises the tax effects of temporary differences related to the following assets and liabilities: (at December 31, in millions) 2016 2015 Deferred tax assets Claims and claim adjustment expense reserves 664 691 Unearned premium reserves 760 731 Compensation-related liabilities 268 326 Other 272 320 ​ ​ ​ ​ ​ ​ ​ Total gross deferred tax assets 1,964 2,068 Less: valuation allowance 3 — ​ ​ ​ ​ ​ ​ ​ Adjusted gross deferred tax assets 1,961 2,068 ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities Deferred acquisition costs 604 580 Investments 592 867 Internally developed software 157 134 Other 143 191 ​ ​ ​ ​ ​ ​ ​ Total gross deferred tax liabilities 1,496 1,772 ​ ​ ​ ​ ​ ​ ​ Net deferred tax asset 465 296 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ If the Company determines that any of its deferred tax assets will not result in future tax benefits, a valuation allowance must be established for the portion of these assets that are not expected to be realized. The valuation allowance increased by $3 million in 2016 relating to the Company's consolidated Brazilian subsidiary. Based upon a review of the Company's anticipated future taxable income, and also including all other available evidence, both positive and negative, the Company's management concluded that it is more likely than not that the net deferred tax assets will be realized. For tax return purposes, as of December 31, 2016, the Company had net operating loss (NOL) carryforwards in Brazil and the United Kingdom. The amount and timing of realizing the benefits of NOL carryforwards depend on future taxable income and limitations imposed by tax laws. Only the benefits of the United Kingdom NOL carryforwards have been recognized in the consolidated financial statements and are included in net deferred tax assets. The NOL amounts by jurisdiction and year of expiration are as follows: (in millions) Amount Year of Brazil 8 None United Kingdom 106 None U.S. income taxes have not been recognized on $358 million of the Company's foreign operations' undistributed earnings as of December 31, 2016, as such earnings are intended to be permanently reinvested in those operations. Furthermore, any taxes paid to foreign governments on these earnings may be used as credits against the U.S. tax on any dividend distributions from such earnings. The following is a reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2016 and 2015: (in millions) 2016 2015 Balance at January 1 16 23 Additions for tax positions of prior years 3 2 Reductions for tax positions of prior years (6 ) (9 ) Additions based on tax positions related to current year — — ​ ​ ​ ​ ​ ​ ​ Balance at December 31 13 16 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Included in the balances at December 31, 2016 and 2015 were $7 million and $4 million, respectively, of unrecognized tax benefits that, if recognized, would affect the annual effective tax rate. Also included in the balances at those dates were $6 million and $12 million, respectively, of tax positions for which the ultimate deductibility is certain, but for which there is uncertainty about the timing of deductibility. The timing of such deductibility would not affect the annual effective tax rate. The Company recognizes accrued interest and penalties, if any, related to unrecognized tax benefits in income taxes. During the years ended December 31, 2016, 2015 and 2014, the Company recognized approximately $31 million, $(32) million and $31 million in interest, respectively. The Company had approximately $57 million and $26 million accrued for the payment of interest at December 31, 2016 and 2015, respectively. The IRS is conducting an examination of the Company's U.S. income tax returns for 2013 and 2014. The Company does not expect any significant changes to its liability for unrecognized tax benefits during the next twelve months.

Share-Based Incentive Compensat

Share-Based Incentive Compensation	12 Months Ended
	Dec. 31, 2016
Share-Based Incentive Compensation disclosure
Share-Based Incentive Compensation disclosure [Text Block]	13. SHARE-BASED INCENTIVE COMPENSATION The Company has a share-based incentive compensation plan, The Travelers Companies, Inc. Amended and Restated 2014 Stock Incentive Plan (the 2014 Incentive Plan), the purposes of which are to align the interests of the Company's non-employee directors, executive officers and other employees with those of the Company's shareholders and to attract and retain personnel by providing incentives in the form of share-based awards. The 2014 Incentive Plan permits grants of nonqualified stock options, incentive stock options, stock appreciation rights, restricted stock, restricted stock units, deferred stock, deferred stock units, performance awards and other share-based or share-denominated awards with respect to the Company's common stock. The Company has a policy of issuing new shares to settle the exercise of stock option awards and the vesting of other equity awards. In connection with the adoption of the 2014 Incentive Plan, The Travelers Companies, Inc. Amended and Restated 2004 Stock Incentive Plan, as amended (the 2004 Incentive Plan) was terminated, joining several other legacy share-based incentive compensation plans that had been terminated in prior years (together, the legacy plans). Outstanding grants were not affected by the termination of the legacy plans. The 2014 Incentive Plan is currently the only plan pursuant to which future stock-based awards may be granted. The number of shares of the Company's common stock initially authorized for grant under the 2014 Incentive Plan was 10 million shares. In May 2016, the Company's shareholders authorized an additional 4.4 million shares of the Company's common stock for grant under the 2014 Incentive Plan. The following are not counted towards the combined 14.4 million shares available and will be available for future grants under the 2014 Incentive Plan: (i) shares of common stock subject to awards that expire unexercised, that are forfeited, terminated or canceled, that are settled in cash or other forms of property, or otherwise do not result in the issuance of shares of common stock, in whole or in part; (ii) shares that are used to pay the exercise price of stock options and shares used to pay withholding taxes on awards generally; and (iii) shares purchased by the Company on the open market using cash option exercise proceeds; provided, however, that the increase in the number of shares of common stock available for grant pursuant to such market purchases shall not be greater than the number that could be repurchased at fair market value on the date of exercise of the stock option giving rise to such option proceeds. In addition, the 14.4 million shares authorized by shareholders for issuance under the 2014 Incentive Plan will be increased by any shares subject to awards under the 2004 Incentive Plan that were outstanding as of May 27, 2014 and subsequently expire, are forfeited, cancelled, settled in cash or otherwise terminate without the issuance of shares. The Company also has a compensation program for non-employee directors (the Director Compensation Program). Under the Director Compensation Program, non-employee directors' compensation consists of an annual retainer, a deferred stock award, committee chair fees and a lead director fee. Each non-employee director may choose to receive all or a portion of his or her annual retainer in the form of cash or deferred stock units which vest upon grant. The annual deferred stock awards vest in full one day prior to the date of the Company's annual meeting of shareholders occurring in the year following the year of the grant date, subject to continued service. The deferred stock awards, including dividend equivalents, accumulate until distribution either in a lump sum six months after termination of service as a director or, if the director so elects, in annual installments beginning at least six months following termination of service as a director. The deferred stock units issued under the Director Compensation Program are awarded under the 2014 Incentive Plan. Stock option awards granted to eligible officers and key employees have a ten-year term. Prior to January 1, 2007, stock options were granted with an exercise price equal to the fair market value of the Company's common stock on the day preceding the date of grant. Beginning January 1, 2007, all stock options are granted with an exercise price equal to the closing price of the Company's common stock on the date of grant. The stock options granted generally vest upon meeting certain years of service criteria. Except as the Compensation Committee of the board of directors may allow in the future, stock options cannot be sold or transferred by the participant. Stock options outstanding under the 2014 Incentive Plan and the 2004 Incentive Plan generally vest three years after grant date (cliff vest). The fair value of each option award is estimated on the date of grant by application of a variation of the Black-Scholes option pricing model using the assumptions noted in the following table. The expected term of newly granted stock options is the time to vest plus half the remaining time to expiration. This considers the vesting restriction and represents an even pattern of exercise behavior over the remaining term. The expected volatility assumption is based on the historical volatility of the Company's common stock for the same period as the estimated option term based on the mid-month of the option grant. The expected dividend is based upon the Company's current quarter dividend annualized and assumed to be constant over the expected option term. The risk-free interest rate for each option is the interpolated market yield for the mid-month of the option grant on a U.S. Treasury bill with a term comparable to the expected option term of the granted stock option. The following table provides information about options granted: (for the year ended December 31,) 2016 2015 2014 Assumptions used in estimating fair value of options on grant date Expected term of stock options 5 - 6 years 6 years 6 years Expected volatility of Company's stock 15.14% - 16.80% 19.29% 27.2% - 27.5% Weighted average volatility 16.79% 19.29% 27.5% Expected annual dividend per share $2.44 - $2.68 $2.20 $2.00 - $2.20 Risk-free rate 1.36% - 2.23% 1.31% 1.81% - 1.82% Additional information Weighted average grant-date fair value of options granted (per share) $13.29 $15.78 $17.22 Total intrinsic value of options exercised during the year (in millions) $167 $120 $117 ​ ​ ​ ​ ​ ​ A summary of stock option activity under the 2014 Incentive Plan and the legacy plans as of and for the year ended December 31, 2016 is as follows: Stock Options Number Weighted Weighted Aggregate Outstanding, beginning of year 9,864,255 74.48 Original grants 2,847,398 106.21 Exercised (4,069,532 ) 69.13 Forfeited or expired (82,085 ) 97.44 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding, end of year 8,560,036 87.36 6.8 years 300 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vested at end of year(1) 5,588,061 80.74 6.0 years 233 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercisable at end of year 3,007,663 65.18 4.2 years 172 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Represents awards for which the requisite service has been rendered, including those that are retirement eligible. On February 9, 2017, the Company, under the 2014 Incentive Plan, granted 2,106,022 stock option awards with an exercise price of $118.78 per share. The fair value attributable to the stock option awards on the date of grant was $16.15 per share. The Company issues restricted stock unit awards to eligible officers and key employees under the Equity Awards program established pursuant to the 2014 Incentive Plan. A restricted stock unit represents the right to receive a share of common stock. These restricted stock unit awards are granted at market price, generally vest three years from the date of grant, do not have voting rights and the underlying shares of common stock are not issued until the vesting criteria is satisfied. In addition, the Company's board of directors can be issued deferred stock units from (i) an annual award; (ii) deferred compensation (in lieu of cash retainer); and (iii) dividend equivalents earned on outstanding deferred compensation. The Company also has a Performance Share Awards Program established pursuant to the 2004 Incentive Plan and which continues pursuant to the 2014 Incentive Plan. Under the program, the Company may issue performance share awards to certain employees of the Company who hold positions of Vice President (or its equivalent) or above. The performance share awards provide the recipient the right to earn shares of the Company's common stock based upon the Company's attainment of certain performance goals and the recipient meeting certain years of service criteria. The performance goals for performance share awards are based on the Company's adjusted return on equity over a three-year performance period. Vesting of performance shares is contingent upon the Company attaining the relevant performance period minimum threshold return on equity and the recipient meeting certain years of service criteria, generally three years for full vesting, subject to proration for certain termination conditions. If the performance period return on equity is below the minimum threshold, none of the performance shares will vest. If performance meets or exceeds the minimum performance threshold, a range of performance shares will vest (50% to 150% for awards granted in 2015, 2016 and 2017), depending on the actual return on equity attained. The fair value of restricted stock units, deferred stock units and performance shares is measured at the market price of the Company stock at date of grant. Under terms of the 2014 Incentive Plan, holders of deferred stock units and performance shares may receive dividend equivalents. The total fair value of shares that vested during the years ended December 31, 2016, 2015 and 2014 was $175 million, $179 million and $147 million, respectively. A summary of restricted stock units, deferred stock units and performance share activity under the 2014 Incentive Plan and the legacy plans as of and for the year ended December 31, 2016 is as follows: Restricted and Deferred Stock Performance Shares Other Equity Instruments Number Weighted Average Number Weighted Average Nonvested, beginning of year 1,435,958 88.35 1,101,989 91.27 Granted 676,736 106.93 476,411 106.03 Vested (667,650 ) (1) 86.85 (818,360 ) (2) 84.43 Forfeited (68,552 ) 97.82 (63,495 ) 100.02 Performance-based adjustment — — 100,073 (3) 88.22 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nonvested, end of year 1,376,492 97.75 796,618 106.03 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Represents awards for which the requisite service has been rendered. (2) Reflects the number of performance shares attributable to the performance goals attained over the completed performance period (three years) and for which service conditions have been met. (3) Represents the current year change in estimated performance shares to reflect the attainment of performance goals for the awards that were granted in each of the years 2014 through 2016. In addition to the nonvested shares presented in the above table, there are related nonvested dividend equivalent shares. The number of nonvested dividend equivalent shares related to deferred stock units was 396 at the beginning of the year and 408 at the end of the year and the number of nonvested dividend equivalent shares related to performance shares was 40,663 at the beginning of the year and 28,480 at the end of the year. The dividend equivalent shares are subject to the same vesting terms as the deferred stock units and performance shares. On February 9, 2017, the Company, under the 2014 Incentive Plan, granted 960,515 common stock awards in the form of restricted stock units, deferred stock units and performance share awards to participating officers, non-employee directors and other key employees. The restricted stock units and deferred stock units totaled 567,006 shares while the performance share awards totaled 393,509 shares. The fair value per share attributable to the common stock awards on the date of grant was $118.78. The amount of compensation cost for awards subject to a service condition is based on the number of shares expected to be issued and is recognized over the time period for which service is to be provided (requisite service period). Awards granted to retiree-eligible employees or to employees who become retiree-eligible before an award's vesting date are considered to have met the requisite service condition. The compensation cost for awards subject to a performance condition is based upon the probable outcome of the performance condition, which on the grant date reflects an estimate of attaining 100% of the performance shares granted. The compensation cost reflects an estimated annual forfeiture rate from 3.0% to 4.0% over the requisite service period of the awards. That estimate is revised if subsequent information indicates that the actual number of instruments expected to vest is likely to differ from previous estimates. Compensation costs for awards are recognized on a straight-line basis over the requisite service period. For awards that have graded vesting terms, the compensation cost is recognized on a straight-line basis over the requisite service period for each separate vesting portion of the award as if the award was, in substance, multiple awards. The total compensation cost for all share-based incentive compensation awards recognized in earnings for the years ended December 31, 2016, 2015 and 2014 was $155 million, $141 million and $138 million, respectively. Included in these amounts are compensation cost adjustments of $11 million, $8 million and $14 million, for the years ended December 31, 2016, 2015 and 2014, respectively, that reflected the cost associated with the updated estimate of performance shares due to attaining certain performance levels from the date of the initial grant of the performance awards. The related tax benefits recognized in earnings were $52 million, $47 million and $47 million for the years ended December 31, 2016, 2015 and 2014, respectively. At December 31, 2016, there was $124 million of total unrecognized compensation cost related to all nonvested share-based incentive compensation awards. This includes stock options, restricted and deferred stock units and performance shares granted under the 2014 Incentive Plan and the 2004 Incentive Plan. The unrecognized compensation cost is expected to be recognized over a weighted-average period of 1.7 years. Cash received from the exercise of employee stock options under share-based compensation plans totaled $332 million and $183 million in 2016 and 2015, respectively. The tax benefit for tax deductions from employee stock options exercised during 2016 and 2015 totaled $58 million and $41 million, respectively.

Pension Plans, Retirement Benef

Pension Plans, Retirement Benefits and Savings Plans	12 Months Ended
	Dec. 31, 2016
Pension Plans, Retirement Benefits and Savings Plans disclosure
Pension Plans, Retirement Benefits and Savings Plans disclosure [Text Block]	14. PENSION PLANS, RETIREMENT BENEFITS AND SAVINGS PLANS The Company sponsors a qualified non-contributory defined benefit pension plan (the qualified domestic pension plan), which covers substantially all U.S. domestic employees and provides benefits under a cash balance formula, except that employees satisfying certain age and service requirements remain covered by a prior final average pay formula. In addition, the Company sponsors a nonqualified defined benefit pension plan which covers certain highly-compensated employees, pension plans for employees of its foreign subsidiaries, and a postretirement health and life insurance benefit plan for employees satisfying certain age and service requirements and for certain retirees. The following tables summarize the funded status, obligations and amounts recognized in the consolidated balance sheet for the Company's benefit plans. The Company uses a December 31 measurement date for its pension and postretirement benefit plans. Qualified Nonqualified Total (at and for the year ended December 31, in millions) 2016 2015 2016 2015 2016 2015 Change in projected benefit obligation: Benefit obligation at beginning of year 3,250 3,385 228 227 3,478 3,612 Benefits earned 111 124 7 7 118 131 Interest cost on benefit obligation 114 135 8 9 122 144 Actuarial loss (gain) 54 (203 ) 15 2 69 (201 ) Benefits paid (162 ) (191 ) (15 ) (8 ) (177 ) (199 ) Settlement — — (3 ) — (3 ) — Foreign currency exchange rate change — — (15 ) (9 ) (15 ) (9 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at end of year 3,367 3,250 225 228 3,592 3,478 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in plan assets: Fair value of plan assets at beginning of year 3,127 3,235 115 122 3,242 3,357 Actual return on plan assets 222 (17 ) 11 3 233 (14 ) Company contributions 200 100 14 7 214 107 Benefits paid (162 ) (191 ) (15 ) (8 ) (177 ) (199 ) Settlement — — (3 ) — (3 ) — Foreign currency exchange rate change — — (16 ) (9 ) (16 ) (9 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year 3,387 3,127 106 115 3,493 3,242 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Funded status of plan at end of year 20 (123 ) (119 ) (113 ) (99 ) (236 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in the consolidated balance sheet consist of: Accrued over-funded benefit plan assets 20 — 5 4 25 4 Accrued under-funded benefit plan liabilities — (123 ) (124 ) (117 ) (124 ) (240 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 20 (123 ) (119 ) (113 ) (99 ) (236 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive income consist of: Net actuarial loss 1,072 1,079 55 52 1,127 1,131 Prior service benefit (6 ) (8 ) — — (6 ) (8 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 1,066 1,071 55 52 1,121 1,123 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Postretirement (at and for the year ended December 31, in millions) 2016 2015 Change in projected benefit obligation: Benefit obligation at beginning of year 233 255 Benefits earned — — Interest cost on benefit obligation 8 10 Actuarial gain (17 ) (3 ) Benefits paid (11 ) (13 ) Plan amendments — (11 ) Foreign currency exchange rate change 1 (5 ) ​ ​ ​ ​ ​ ​ ​ Benefit obligation at end of year 214 233 ​ ​ ​ ​ ​ ​ ​ Change in plan assets: Fair value of plan assets at beginning of year 15 16 Actual return on plan assets — — Company contributions 10 12 Benefits paid (11 ) (13 ) ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year 14 15 ​ ​ ​ ​ ​ ​ ​ Funded status of plan at end of year (200 ) (218 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in the consolidated balance sheet consist of: Accrued under-funded benefit plan liability (200 ) (218 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive income consist of: Net actuarial (gain) loss (13 ) 4 Prior service benefit (31 ) (35 ) ​ ​ ​ ​ ​ ​ ​ Total (44 ) (31 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The total accumulated benefit obligation for the Company's defined benefit pension plans was $3.48 billion and $3.37 billion at December 31, 2016 and 2015, respectively. The qualified domestic pension plan accounted for $3.26 billion and $3.15 billion of the total accumulated benefit obligation at December 31, 2016 and 2015, respectively, whereas the nonqualified and foreign plans accounted for $0.22 billion of the total accumulated benefit obligation at both December 31, 2016 and 2015. For pension plans with an accumulated benefit obligation in excess of plan assets, the aggregate projected benefit obligation was $0.2 billion and $3.47 billion at December 31, 2016 and 2015, respectively, and the aggregate accumulated benefit obligation was $0.2 billion and $3.36 billion at December 31, 2016 and 2015, respectively. The fair value of plan assets for the above plans was $0.1 billion and $3.23 billion at December 31, 2016 and 2015, respectively. The Company has discretion regarding whether to provide additional funding and when to provide such funding to its qualified domestic pension plan. In 2016, 2015 and 2014, there were no required contributions to the qualified domestic pension plan. In 2016, 2015 and 2014, the Company voluntarily made contributions totaling $200 million, $100 million and $200 million, respectively, to the qualified domestic pension plan. There is no required contribution to the qualified domestic pension plan during 2017, and the Company has not determined whether or not additional funding will be made during 2017. With respect to the Company's foreign pension plans, there are no significant required contributions in 2017. The following table summarizes the components of net periodic benefit cost and other amounts recognized in other comprehensive income related to the benefit plans. Pension Plans Postretirement (for the year ended December 31, in millions) 2016 2015 2014 2016 2015 2014 Net Periodic Benefit Cost: Service cost 118 131 110 — — — Interest cost on benefit obligation 122 144 150 8 10 10 Expected return on plan assets (230 ) (230 ) (218 ) — — — Curtailment — — (1 ) — — — Settlement 1 — 2 — — — Amortization of unrecognized: Prior service benefit (1 ) (1 ) — (3 ) (3 ) (2 ) Net actuarial loss (gain) 66 96 65 — 1 (3 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net periodic benefit cost 76 140 108 5 8 5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Changes in Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Prior service benefit — — (8 ) — (11 ) — Net actuarial loss (gain) 66 43 516 (17 ) (3 ) 50 Foreign currency exchange rate change (2 ) — — 1 — — Curtailment — — (2 ) — — — Settlement (1 ) — (2 ) — — — Amortization of prior service benefit 1 1 — 3 3 2 Amortization of net actuarial gain (loss) (66 ) (96 ) (65 ) — (1 ) 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other changes recognized in other comprehensive income (2 ) (52 ) 439 (13 ) (12 ) 55 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other changes recognized in net periodic benefit cost and other comprehensive income 74 88 547 (8 ) (4 ) 60 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In 2016, the Company began using a full yield-curve approach in the estimation of the service and interest cost components of net periodic benefit costs for its qualified and nonqualified domestic pension plans and its domestic postretirement benefit plans. The full yield curve approach applies the specific spot rates along the yield curve that the Company used to determine its projected benefit obligation at the beginning of the year to the projected cash flows related to service and interest costs. Previously, the Company estimated these service and interest cost components by applying a single weighted-average discount rate derived from this yield curve. This change was made to provide a better estimate of the service and interest cost components of net periodic benefit costs, consistent with the methodology used to estimate the projected benefit obligation for each of the benefit plans. This change did not affect the measurement of the Company's total benefit obligations as the change in the service cost and interest cost is completely offset in the actuarial (gain) loss reported for the period. The change reduced the service and interest cost components of net periodic benefit costs for 2016 by $6 million and $30 million, respectively, and resulted in an $0.08 increase in diluted net income per share for 2016. The weighted average discount rates that were used to measure service and interest costs during 2016 were 4.77% and 3.64%, respectively, for the domestic qualified pension plan, 4.53% and 3.47%, respectively, for the domestic nonqualified pension plan and 0.00% and 3.53%, respectively, for the domestic postretirement benefit plan. The discount rate associated with the service cost component of the domestic postretirement benefit plan is zero as it is a closed plan and all participants are fully vested. Under the Company's prior estimation approach, the weighted average discount rate for both the service and interest cost components would have been 4.50% for the domestic qualified pension plan, 4.37% for the domestic nonqualified pension plan and 4.35% for the domestic postretirement benefit plan. The Company accounted for this change as a change in estimate, and accordingly, recognized the effect prospectively beginning in 2016. For the defined benefit pension plans, the estimated net actuarial loss that will be reclassified (amortized) from accumulated other comprehensive income into net income as part of net periodic benefit cost over the next fiscal year is $75 million and the estimated prior service benefit to be amortized over the next fiscal year is $1 million. For the postretirement benefit plans, the estimated net actuarial gain that will be reclassified (amortized) from accumulated other comprehensive income into net income as part of net periodic benefit cost over the next fiscal year is less than $1 million, and the estimated prior service benefit to be amortized over the next fiscal year is $3 million. The following table summarizes assumptions used with regard to the Company's qualified and nonqualified domestic pension plans and the domestic postretirement benefit plans. (at and for the year ended December 31,) 2016 2015 Assumptions used to determine benefit obligations Discount rate: Qualified domestic pension plan 4.23 % 4.50 % Nonqualified domestic pension plan 4.15 % 4.37 % Domestic postretirement benefit plan 4.10 % 4.35 % Future compensation increase rate 4.00 % 4.00 % Assumptions used to determine net periodic benefit cost Discount rate: Qualified domestic pension plan: Service cost 4.77 % 4.10 % Interest cost 3.64 % 4.10 % Nonqualified domestic pension plan: Service cost 4.53 % 4.10 % Interest cost 3.47 % 4.10 % Domestic postretirement benefit plan: Interest cost 3.53 % 4.10 % Expected long-term rate of return on assets: Pension plan 7.00 % 7.25 % Postretirement benefit plan 4.00 % 4.00 % Assumed health care cost trend rates Following year: Medical (before age 65) 6.50 % 6.75 % Medical (age 65 and older) 7.25 % 7.50 % Rate to which the cost trend rate is assumed to decline (ultimate trend rate) Year that the rate reaches the ultimate trend rate: Medical (before age 65) 2022 2022 Medical (age 65 and older) 2025 2025 The discount rate assumption used to determine the benefit obligation is based on a yield-curve approach. Under this approach, individual spot rates from the yield curve of a hypothetical portfolio of high quality fixed maturity corporate bonds (rated Aa) available at the year-end valuation date, for which the timing and amount of cash outflows correspond with the timing and amount of the estimated benefit payouts of the Company's benefit plan, are applied to expected future benefits payments in measuring the projected benefit obligation . The discount rate assumption used to determine benefit obligations disclosed above represents the weighted average of the individual spot rates. The discount rate assumption used to determine the net periodic benefit cost is the single weighted average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the year. In choosing the expected long-term rate of return on plan assets, the Company selected the rate that was set as the return objective by the Company's Benefit Plans Investment Committee, which had considered the historical returns of equity and fixed maturity markets in conjunction with prevailing economic and financial market conditions. As an indicator of sensitivity, increasing the assumed health care cost trend rate by 1% would have increased the accumulated postretirement benefit obligation by $20 million at December 31, 2016, and the aggregate of the service and interest cost components of net postretirement benefit expense by $1 million for the year ended December 31, 2016. Decreasing the assumed health care cost trend rate by 1% would have decreased the accumulated postretirement benefit obligation at December 31, 2016 by $17 million and the aggregate of the service and interest cost components of net postretirement benefit expense by $1 million for the year ended December 31, 2016. The assumptions made for the Company's foreign pension and foreign postretirement benefit plans are not materially different from those of the Company's qualified domestic pension plan and the domestic postretirement benefit plan. The qualified domestic pension plan assets are invested for the exclusive benefit of the plan participants and beneficiaries and are intended, over time, to satisfy the benefit obligations under the plan. Risk tolerance is established through consideration of plan liabilities, plan funded status and corporate financial position. The asset mix guidelines have been established and are reviewed quarterly. These guidelines are intended to serve as tools to facilitate the investment of plan assets to maximize long-term total return and the ongoing oversight of the plan's investment performance. Investment risk is measured and monitored on an ongoing basis through daily and monthly investment portfolio reviews, annual liability measurements and periodic asset/liability studies. The Company's overall investment strategy for the qualified domestic pension plan is to achieve a mix of approximately 85% to 90% of investments for long-term growth and 10% to 15% for near-term benefit payments with a diversification of asset types, fund strategies and fund managers. The current target allocations for plan assets are 55% to 65% equity securities and 20% to 40% fixed income securities, with the remainder allocated to short-term securities. Equity securities primarily include investments in large, medium and small-cap companies primarily located in the United States. Fixed income securities include corporate bonds of companies from diversified industries, mortgage-backed securities, U.S. Treasury securities and debt securities issued by foreign governments. Other investments include two private equity funds held by the Company's qualified defined benefit pension plan. One private equity fund is focused on financial companies, and the other is focused on real estate-related investments. Assets of the Company's foreign pension plans are not significant. For a discussion of the methods employed by the Company to measure the fair value of invested assets, see note 4. The following discussion of fair value measurements applies exclusively to the Company's pension plans and other postretirement benefit assets. Fair value estimates for equity and bond mutual funds held by the pension plans reflect prices received from an external pricing service that are based on observable market transactions. These estimates are included in Level 1. Short-term securities are carried at fair value which approximates cost plus accrued interest or amortized discount. The fair value or market value of these is periodically compared to this amortized cost and is based on significant observable inputs as determined by an external pricing service. Accordingly, the estimates of fair value for such short-term securities, other than U.S. Treasury securities and money market mutual funds, provided by an external pricing service are included in the amount disclosed in Level 2 of the hierarchy. The estimated fair value of U.S. Treasury securities and money market mutual funds is included in the amount disclosed in Level 1 as the estimates are based on unadjusted market prices. The following tables present the level within the fair value hierarchy at which the financial assets of the Company's pension plans are measured on a recurring basis. (at December 31, 2016, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions 9 — 9 — Debt securities issued by foreign governments 14 — 14 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 12 — 12 — All other corporate bonds 511 — 511 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 546 — 546 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mutual funds Equity mutual funds 1,285 1,278 7 — Bond mutual funds 641 638 3 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total mutual funds 1,926 1,916 10 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities 747 747 — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments(1) 1 — — 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and short-term securities U.S. Treasury securities 45 45 — — Money market mutual funds 20 19 1 — Other 208 28 180 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and short-term securities 273 92 181 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,493 2,755 737 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value estimates of the two private equity funds comprising these investments are determined by an external fund manager based on recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the total fair value estimates are disclosed in Level 3. The balance of Level 3 fair value investments was $1 million at December 31, 2016 and the change in balance from the prior year was insignificant. (at December 31, 2015, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions 17 — 17 — Debt securities issued by foreign governments 16 — 16 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 16 — 16 — All other corporate bonds 491 — 491 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 540 — 540 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mutual funds Equity mutual funds 1,237 1,231 6 — Bond mutual funds 649 646 3 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total mutual funds 1,886 1,877 9 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities 625 624 1 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments(1) 2 — — 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and short-term securities U.S. Treasury securities 25 25 — — Money market mutual funds 23 19 4 — Other 141 20 121 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and short-term securities 189 64 125 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,242 2,565 675 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value estimates of the two private equity funds comprising these investments are determined by an external fund manager based on recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the total fair value estimates are disclosed in Level 3. The balance of Level 3 fair value investments was $2 million at December 31, 2015 and the change in balance from the prior year was insignificant. The Company's overall investment strategy is to achieve a mix of approximately 35% to 65% of investments for long-term growth and 35% to 60% for near-term insurance payments with a wide diversification of asset types, fund strategies and fund managers. The current target allocations for plan assets are 25% to 75% fixed income securities, with the remainder allocated to short-term securities. Fixed income securities include corporate bonds of companies from diversified industries, mortgage-backed securities and U.S. Treasuries. The Company's other postretirement benefit plans had financial assets of $14 million and $15 million at December 31, 2016 and 2015, respectively, which are measured at fair value on a recurring basis. The assets are primarily corporate bonds and short-term securities and categorized as level 2 in the fair value hierarchy. The following table presents the estimated benefits expected to be paid by the Company's pension and postretirement benefit plans for the next ten years (reflecting estimated future employee service). Benefits Expected to be Paid (in millions) Pension Plans Postretirement 2017 230 13 2018 240 14 2019 247 14 2020 253 14 2021 258 14 2022 through 2026 1,327 71 The Company has a savings plan, The Travelers 401(k) Savings Plan (the Savings Plan), in which substantially all U.S. domestic Company employees are eligible to participate. Under the Savings Plan, the Company matches employee contributions up to 5% of eligible pay, with a maximum annual match of $6,000 which becomes 100% vested after three years of service. The Company's matching contribution is made in cash and invested according to the employee's current investment elections and can be reinvested into other investment options in accordance with the terms of the plan. The Company's non-U.S. employees participate in separate savings plans. The total expense related to all of the savings plans was $114 million, $109 million and $103 million for the years ended December 31, 2016, 2015 and 2014, respectively. All common shares held by the Savings Plan are considered outstanding for basic and diluted EPS computations and dividends paid on all shares are charged to retained earnings.

Leases

Leases	12 Months Ended
	Dec. 31, 2016
Leases disclosure
Leases disclosure [Text Block]	15. LEASES Rent expense was $197 million, $202 million and $215 million in 2016, 2015 and 2014, respectively. Future minimum annual rental payments under noncancellable operating leases for 2017, 2018, 2019, 2020 and 2021 are $147 million, $118 million, $100 million, $80 million and $60 million, respectively, and $100 million for 2022 and thereafter. Future sublease rental income aggregating approximately $4 million will partially offset these commitments.

Contingencies, Commitments and

Contingencies, Commitments and Guarantees	12 Months Ended
	Dec. 31, 2016
Contingencies, Commitments and Guarantees disclosure
Contingencies, Commitments and Guarantees disclosure [Text Block]	16. CONTINGENCIES, COMMITMENTS AND GUARANTEES The major pending legal proceedings, other than ordinary routine litigation incidental to the business, to which the Company or any of its subsidiaries is a party or to which any of the Company's properties is subject are described below. In the ordinary course of its insurance business, the Company has received and continues to receive claims for insurance arising under policies issued by the Company asserting alleged injuries and damages from asbestos- and environmental-related exposures that are the subject of related coverage litigation. The Company is defending asbestos- and environmental-related litigation vigorously and believes that it has meritorious defenses; however, the outcomes of these disputes are uncertain. In this regard, the Company employs dedicated specialists and aggressive resolution strategies to manage asbestos and environmental loss exposure, including settling litigation under appropriate circumstances. Currently, it is not possible to predict legal outcomes and their impact on the future development of claims and litigation relating to asbestos and environmental claims. Any such development will be affected by future court decisions and interpretations, as well as changes in applicable legislation. Because of these uncertainties, additional liabilities may arise for amounts in excess of the Company's current insurance reserves. In addition, the Company's estimate of ultimate claims and claim adjustment expenses may change. These additional liabilities or increases in estimates, or a range of either, cannot now be reasonably estimated and could result in income statement charges that could be material to the Company's results of operations in future periods. In 2001 and 2002, a number of lawsuits, including two purported class action suits, were filed against certain subsidiaries of the Company (collectively or individually, Travelers) and other insurers in state courts in West Virginia, Massachusetts and Hawaii. The plaintiffs alleged that the insurer defendants had inappropriately handled and settled asbestos claims in violation of those states' statutes regulating insurance claims handling and/or those states' common law. In all these suits, the plaintiffs sought to reopen large numbers of settled asbestos claims and to impose liability for damages, including punitive damages, directly on insurers. These suits are collectively referred to as the Statutory Actions. Plaintiffs also filed complaints during 2001 and 2002 in State Courts in West Virginia, Texas and Ohio, and occasionally in other jurisdictions, against Travelers and other insurers, alleging that the insurers breached alleged duties to individuals allegedly exposed to asbestos products. The plaintiffs sought damages for personal injuries and wrongful death, including punitive damages. These suits are collectively referred to as the Common Law Actions. In response to these claims, Travelers moved to enjoin the Statutory Actions and the Common Law Actions in the federal bankruptcy court that had presided over the bankruptcy of its former policyholder Johns-Manville Corporation on the ground that the suits violated injunctions entered in connection with confirmation of the Johns-Manville bankruptcy (the 1986 Orders). The bankruptcy court issued a temporary restraining order and referred the parties to mediation, which resulted in settlements of the Statutory Actions and the Common Law Actions (the Settlements). The Settlements were contingent upon, among other contingencies, a final order confirming that the 1986 Orders enjoined the Statutory Actions and the Common Law Actions as well as related contribution claims against Travelers (the Clarifying Order). Numerous proceedings took place in the bankruptcy, district and appellate courts concerning the entry of the Clarifying Order and approval of the Settlements and their effect on other parties. In 2009, the United States Supreme Court affirmed the bankruptcy court's entry of the Clarifying Order enjoining the Statutory Actions and the Common Law Actions. The Supreme Court remanded the case to the lower courts to consider any properly preserved objections. Following resolution, after remand, of one remaining objection (regarding potential contribution claims against the Company), and entry of a final judgment by the bankruptcy court approving the Settlements, Travelers made payment of $579 million to the plaintiffs in January 2015, comprising $502 million provided under the terms of the Settlements, plus pre-judgment and post-judgment interest totaling $77 million. The payment was fully accrued in the Company's financial statements at December 31, 2014. The Company is involved in other lawsuits, including lawsuits alleging extra-contractual damages relating to insurance contracts or reinsurance agreements, that do not arise under insurance contracts or reinsurance agreements. The legal costs associated with such lawsuits are expensed in the period in which the costs are incurred. Based upon currently available information, the Company does not believe it is reasonably possible that any such lawsuit or related lawsuits would be material to the Company's results of operations or would have a material adverse effect on the Company's financial position or liquidity. On August 17, 2010, in a reinsurance dispute in New York state court captioned United States Fidelity & Guaranty Company v. American Re-Insurance Company, et al. , the trial court granted summary judgment for United States Fidelity and Guaranty Company (USF&G), a subsidiary of the Company, and denied summary judgment for the reinsurers. The Court of Appeals largely affirmed the entry of summary judgment, but remanded two discrete issues for trial. Thereafter, the reinsurers filed a motion with the trial court to change venue, and the trial court denied the motion. On November 7, 2016, the Company agreed to a settlement with one of the three defendants then remaining in this dispute. The Company received payment under the settlement in the fourth quarter of 2016 and, as a result, recognized a $126 million pre-tax ($82 million after-tax) gain in the fourth quarter, which is included in "other revenues" in the consolidated statement of income. The reinsurance recoverable balance related to this case was reduced from approximately $238 million to approximately $31 million in the Company's consolidated balance sheet. On December 22, 2016, the Appellate Court, First Department affirmed the denial of the reinsurers' motion to change venue and a trial is set to proceed on May 1, 2017 with regard to the remaining two defendants—both of which are subsidiaries of the same company. At December 31, 2016, the claim related to the remaining defendants totaled $69 million, comprising $31 million of a reinsurance recoverable plus interest amounting to $38 million as of that date. Interest will continue to accrue at an annual rate of 9% until the amounts owed by the remaining defendants are paid, though the reinsurers still party to the case contested that interest is owed in a brief filed on June 6, 2016. The interest that would be owed as part of any judgment ultimately entered in favor of the Company related to the remaining defendants is treated for accounting purposes as a gain contingency in accordance with FASB Topic 450, Contingencies, and accordingly has not been recognized in the Company's consolidated financial statements. Investment Commitments —The Company has unfunded commitments to private equity limited partnerships and real estate partnerships in which it invests. These commitments totaled $1.60 billion and $1.71 billion at December 31, 2016 and 2015, respectively. In the ordinary course of selling businesses to third parties, the Company has agreed to indemnify purchasers for losses arising out of breaches of representations and warranties with respect to the businesses being sold, covenants and obligations of the Company and/or its subsidiaries and, in certain cases, obligations arising from certain liabilities. Such indemnification provisions generally are applicable from the closing date to the expiration of the relevant statutes of limitations, although, in some cases, there may be agreed upon term limitations or no term limitations. Certain of these contingent obligations are subject to deductibles which have to be incurred by the obligee before the Company is obligated to make payments. The maximum amount of the Company's contingent obligation for indemnifications related to the sale of businesses that are quantifiable was $358 million at December 31, 2016, of which $2 million was recognized on the balance sheet at that date. The Company also has contingent obligations for guarantees related to certain investments, third-party loans related to certain investments, certain insurance policy obligations of former insurance subsidiaries and various other indemnifications. The Company also provides standard indemnifications to service providers in the normal course of business. The indemnification clauses are often standard contractual terms. The maximum amount of the Company's obligation for guarantees of certain investments and third-party loans related to certain investments that are quantifiable was $150 million at December 31, 2016, approximately $75 million of which is indemnified by a third party. The maximum amount of the Company's obligation related to the guarantee of certain insurance policy obligations of a former insurance subsidiary was $480 million at December 31, 2016, all of which is indemnified by a third party. Certain of the guarantees and indemnifications described above have no stated or notional amounts or limitation to the maximum potential future payments, and, accordingly, the Company is unable to provide an estimate of the maximum potential payments for such arrangements.

Noncash Investing and Financing

Noncash Investing and Financing Activities	12 Months Ended
	Dec. 31, 2016
Noncash Investing and Financing Activities disclosure
Noncash Investing and Financing Activities disclosure [Text Block]	17. NONCASH INVESTING AND FINANCING ACTIVITIES There were no material noncash financing or investing activities during the years ended December 31, 2016, 2015 and 2014.

Consolidating Financial Stateme

Consolidating Financial Statements (Unaudited)	12 Months Ended
	Dec. 31, 2016
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure [Text Block]	18. CONSOLIDATING FINANCIAL STATEMENTS OF THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES The following consolidating financial statements of the Company have been prepared pursuant to Rule 3-10 of Regulation S-X. These consolidating financial statements have been prepared from the Company's financial information on the same basis of accounting as the consolidated financial statements. The Travelers Companies, Inc. (excluding its subsidiaries, TRV) has fully and unconditionally guaranteed certain debt obligations of Travelers Property Casualty Corp. (TPC), which totaled $700 million at December 31, 2016. Prior to the merger of TPC and The St. Paul Companies, Inc. in 2004, TPC fully and unconditionally guaranteed the payment of all principal, premiums, if any, and interest on certain debt obligations of its wholly-owned subsidiary, Travelers Insurance Group Holdings, Inc. (TIGHI). Concurrent with the merger, TRV fully and unconditionally assumed such guarantee obligations of TPC. TPC is deemed to have no assets or operations independent of TIGHI. Consolidating financial information for TIGHI has not been presented herein because such financial information would be substantially the same as the financial information provided for TPC. CONSOLIDATING STATEMENT OF INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Revenues Premiums 16,788 7,746 — — 24,534 Net investment income 1,569 720 13 — 2,302 Fee income 458 — — — 458 Net realized investment gains (losses)(1) 30 39 (1 ) — 68 Other revenues 248 36 — (21 ) 263 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 19,093 8,541 12 (21 ) 27,625 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and expenses Claims and claim adjustment expenses 10,232 4,838 — — 15,070 Amortization of deferred acquisition costs 2,702 1,283 — — 3,985 General and administrative expenses 2,928 1,242 5 (21 ) 4,154 Interest expense 48 — 315 — 363 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total claims and expenses 15,910 7,363 320 (21 ) 23,572 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes 3,183 1,178 (308 ) — 4,053 Income tax expense (benefit) 999 208 (168 ) — 1,039 Net income of subsidiaries — — 3,154 (3,154 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 2,184 970 3,014 (3,154 ) 3,014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2016, and the amounts comprising total OTTI that were recognized in net realized investment gains (losses) and in other comprehensive income (OCI), were as follows: (in millions) TPC Other TRV Eliminations Consolidated Total OTTI losses (19 ) (20 ) (1 ) — (40 ) OTTI losses recognized in net realized investment gains (losses) (13 ) (15 ) (1 ) — (29 ) OTTI losses recognized in OCI (6 ) (5 ) — — (11 ) CONSOLIDATING STATEMENT OF INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Revenues Premiums 16,254 7,620 — — 23,874 Net investment income 1,612 760 7 — 2,379 Fee income 460 — — — 460 Net realized investment gains (losses)(1) 13 (11 ) 1 — 3 Other revenues 78 21 — — 99 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 18,417 8,390 8 — 26,815 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and expenses Claims and claim adjustment expenses 9,208 4,515 — — 13,723 Amortization of deferred acquisition costs 2,627 1,258 — — 3,885 General and administrative expenses 2,853 1,225 16 — 4,094 Interest expense 48 — 325 — 373 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total claims and expenses 14,736 6,998 341 — 22,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes 3,681 1,392 (333 ) — 4,740 Income tax expense (benefit) 1,015 394 (108 ) — 1,301 Net income of subsidiaries — — 3,664 (3,664 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 2,666 998 3,439 (3,664 ) 3,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2015, and the amounts comprising total OTTI that were recognized in net realized investment gains (losses) and in other comprehensive income (OCI), were as follows: (in millions) TPC Other TRV Eliminations Consolidated Total OTTI losses (19 ) (35 ) — — (54 ) OTTI losses recognized in net realized investment gains (losses) (18 ) (34 ) — — (52 ) OTTI losses recognized in OCI (1 ) (1 ) — — (2 ) CONSOLIDATING STATEMENT OF INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Revenues Premiums 16,097 7,616 — — 23,713 Net investment income 1,874 907 6 — 2,787 Fee income 448 2 — — 450 Net realized investment gains(1) 12 64 3 — 79 Other revenues 125 20 — — 145 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 18,556 8,609 9 — 27,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and expenses Claims and claim adjustment expenses 9,274 4,596 — — 13,870 Amortization of deferred acquisition costs 2,604 1,278 — — 3,882 General and administrative expenses 2,755 1,194 15 — 3,964 Interest expense 48 — 321 — 369 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total claims and expenses 14,681 7,068 336 — 22,085 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes 3,875 1,541 (327 ) — 5,089 Income tax expense (benefit) 1,095 417 (115 ) — 1,397 Net income of subsidiaries — — 3,904 (3,904 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 2,780 1,124 3,692 (3,904 ) 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2014, and the amounts comprising total OTTI that were recognized in net realized investment gains and in other comprehensive income (OCI), were as follows: (in millions) TPC Other TRV Eliminations Consolidated Total OTTI losses (16 ) (6 ) — — (22 ) OTTI losses recognized in net realized investment gains (19 ) (7 ) — — (26 ) OTTI gains recognized in OCI 3 1 — — 4 CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Net income 2,184 970 3,014 (3,154 ) 3,014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (696 ) (198 ) 11 — (883 ) Having credit losses recognized in the consolidated statement of income 11 10 — — 21 Net changes in benefit plan assets and obligations 25 11 (20 ) — 16 Net changes in unrealized foreign currency translation 73 (114 ) — — (41 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss before income taxes and other comprehensive loss of subsidiaries (587 ) (291 ) (9 ) — (887 ) Income tax benefit (222 ) (66 ) (1 ) — (289 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss, net of taxes, before other comprehensive loss of subsidiaries (365 ) (225 ) (8 ) — (598 ) Other comprehensive loss of subsidiaries — — (590 ) 590 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss (365 ) (225 ) (598 ) 590 (598 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income 1,819 745 2,416 (2,564 ) 2,416 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Net income 2,666 998 3,439 (3,664 ) 3,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (610 ) (407 ) (3 ) — (1,020 ) Having credit losses recognized in the consolidated statement of income (12 ) (2 ) — — (14 ) Net changes in benefit plan assets and obligations 2 — 64 — 66 Net changes in unrealized foreign currency translation (306 ) (155 ) — — (461 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) before income taxes and other comprehensive loss of subsidiaries (926 ) (564 ) 61 — (1,429 ) Income tax expense (benefit) (257 ) (156 ) 21 — (392 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss), net of taxes, before other comprehensive loss of subsidiaries (669 ) (408 ) 40 — (1,037 ) Other comprehensive loss of subsidiaries — — (1,077 ) 1,077 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss (669 ) (408 ) (1,037 ) 1,077 (1,037 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income 1,997 590 2,402 (2,587 ) 2,402 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Net income 2,780 1,124 3,692 (3,904 ) 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income 681 289 6 — 976 Having credit losses recognized in the consolidated statement of income 9 (7 ) — — 2 Net changes in benefit plan assets and obligations (15 ) (8 ) (471 ) — (494 ) Net changes in unrealized foreign currency translation (173 ) (116 ) — — (289 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) before income taxes and other comprehensive income of subsidiaries 502 158 (465 ) — 195 Income tax expense (benefit) 207 81 (163 ) — 125 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries 295 77 (302 ) — 70 Other comprehensive income of subsidiaries — — 372 (372 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income 295 77 70 (372 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income 3,075 1,201 3,762 (4,276 ) 3,762 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING BALANCE SHEET (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $59,650) 42,014 18,452 49 — 60,515 Equity securities, available for sale, at fair value (cost $504) 169 408 155 — 732 Real estate investments 56 872 — — 928 Short-term securities 2,447 791 1,627 — 4,865 Other investments 2,569 878 1 — 3,448 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments 47,255 21,401 1,832 — 70,488 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash 141 164 2 — 307 Investment income accrued 441 183 6 — 630 Premiums receivable 4,545 2,177 — — 6,722 Reinsurance recoverables 5,664 2,623 — — 8,287 Ceded unearned premiums 536 53 — — 589 Deferred acquisition costs 1,741 182 — — 1,923 Deferred taxes 216 224 25 — 465 Contractholder receivables 3,656 953 — — 4,609 Goodwill 2,578 1,002 — — 3,580 Other intangible assets 202 66 — — 268 Investment in subsidiaries — — 27,137 (27,137 ) — Other assets 1,973 370 34 — 2,377 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets 68,948 29,398 29,036 (27,137 ) 100,245 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Claims and claim adjustment expense reserves 32,168 15,781 — — 47,949 Unearned premium reserves 8,575 3,754 — — 12,329 Contractholder payables 3,656 953 — — 4,609 Payables for reinsurance premiums 156 117 — — 273 Debt 693 — 5,744 — 6,437 Other liabilities 4,106 1,239 82 — 5,427 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities 49,354 21,844 5,826 — 77,024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shareholders' equity Common stock (1,750.0 shares authorized; 279.6 shares issued and outstanding) — 390 22,614 (390 ) 22,614 Additional paid-in capital 11,634 6,499 — (18,133 ) — Retained earnings 7,933 797 32,185 (8,719 ) 32,196 Accumulated other comprehensive income (loss) 27 (132 ) (755 ) 105 (755 ) Treasury stock, at cost (489.5 shares) — — (30,834 ) — (30,834 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total shareholders' equity 19,594 7,554 23,210 (27,137 ) 23,221 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and shareholders' equity 68,948 29,398 29,036 (27,137 ) 100,245 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING BALANCE SHEET (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $58,878) 42,289 18,323 46 — 60,658 Equity securities, available for sale, at fair value (cost $528) 189 375 141 — 705 Real estate investments 56 933 — — 989 Short-term securities 1,947 1,178 1,546 — 4,671 Other investments 2,516 930 1 — 3,447 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments 46,997 21,739 1,734 — 70,470 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash 225 153 2 — 380 Investment income accrued 453 185 4 — 642 Premiums receivable 4,336 2,101 — — 6,437 Reinsurance recoverables 5,849 3,061 — — 8,910 Ceded unearned premiums 610 46 — — 656 Deferred acquisition costs 1,660 189 — — 1,849 Deferred taxes 178 83 35 — 296 Contractholder receivables 3,387 987 — — 4,374 Goodwill 2,573 1,000 — — 3,573 Other intangible assets 203 76 — — 279 Investment in subsidiaries — — 27,573 (27,573 ) — Other assets 1,958 344 16 — 2,318 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets 68,429 29,964 29,364 (27,573 ) 100,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Claims and claim adjustment expense reserves 31,965 16,330 — — 48,295 Unearned premium reserves 8,335 3,636 — — 11,971 Contractholder payables 3,387 987 — — 4,374 Payables for reinsurance premiums 175 121 — — 296 Debt 693 — 5,651 — 6,344 Other liabilities 3,958 1,221 127 — 5,306 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities 48,513 22,295 5,778 — 76,586 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shareholders' equity Common stock (1,750.0 shares authorized; 295.9 shares issued and outstanding) — 390 22,172 (390 ) 22,172 Additional paid-in capital 11,634 6,499 — (18,133 ) — Retained earnings 7,888 688 29,933 (8,564 ) 29,945 Accumulated other comprehensive income (loss) 394 92 (157 ) (486 ) (157 ) Treasury stock, at cost (467.6 shares) — — (28,362 ) — (28,362 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total shareholders' equity 19,916 7,669 23,586 (27,573 ) 23,598 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and shareholders' equity 68,429 29,964 29,364 (27,573 ) 100,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Cash flows from operating activities Net income 2,184 970 3,014 (3,154 ) 3,014 Net adjustments to reconcile net income to net cash provided by operating activities 1,085 66 (119 ) 156 1,188 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 3,269 1,036 2,895 (2,998 ) 4,202 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Proceeds from maturities of fixed maturities 6,589 2,380 6 — 8,975 Proceeds from sales of investments: Fixed maturities 768 647 2 — 1,417 Equity securities 47 45 — — 92 Real estate investments — 69 — — 69 Other investments 586 253 — — 839 Purchases of investments: Fixed maturities (7,921 ) (3,676 ) (12 ) — (11,609 ) Equity securities (6 ) (42 ) (3 ) — (51 ) Real estate investments (1 ) (47 ) — — (48 ) Other investments (453 ) (127 ) — — (580 ) Net sales (purchases) of short-term securities (501 ) 383 (81 ) — (199 ) Securities transactions in course of settlement 12 (32 ) (1 ) — (21 ) Other (334 ) (10 ) — — (344 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in investing activities (1,214 ) (157 ) (89 ) — (1,460 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization — — (2,400 ) — (2,400 ) Treasury stock acquired—net employee share-based compensation — — (72 ) — (72 ) Dividends paid to shareholders — — (757 ) — (757 ) Payment of debt — — (400 ) — (400 ) Issuance of debt — — 491 — 491 Issuance of common stock—employee share options — — 332 — 332 Dividends paid to parent company (2,140 ) (858 ) — 2,998 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,140 ) (858 ) (2,806 ) 2,998 (2,806 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash 1 (10 ) — — (9 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash (84 ) 11 — — (73 ) Cash at beginning of year 225 153 2 — 380 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 141 164 2 — 307 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Income taxes paid (received) 737 287 (132 ) — 892 Interest paid 47 — 311 — 358 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Cash flows from operating activities Net income 2,666 998 3,439 (3,664 ) 3,439 Net adjustments to reconcile net income to net cash provided by operating activities (577 ) 414 330 (172 ) (5 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 2,089 1,412 3,769 (3,836 ) 3,434 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Proceeds from maturities of fixed maturities 7,543 3,563 10 — 11,116 Proceeds from sales of investments: Fixed maturities 1,227 723 — — 1,950 Equity securities 25 34 — — 59 Real estate investments — 31 — — 31 Other investments 503 210 — — 713 Purchases of investments: Fixed maturities (8,276 ) (3,787 ) (27 ) — (12,090 ) Equity securities (3 ) (43 ) (3 ) — (49 ) Real estate investments (1 ) (122 ) — — (123 ) Other investments (423 ) (111 ) — — (534 ) Net sales (purchases) of short-term securities 179 (489 ) (16 ) — (326 ) Securities transactions in course of settlement (52 ) (61 ) — — (113 ) Acquisition, net of cash acquired (13 ) — — — (13 ) Other (343 ) 39 — — (304 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities 366 (13 ) (36 ) — 317 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization — — (3,150 ) — (3,150 ) Treasury stock acquired—net employee share-based compensation — — (74 ) — (74 ) Dividends paid to shareholders — — (739 ) — (739 ) Payment of debt — — (400 ) — (400 ) Issuance of debt — — 392 — 392 Issuance of common stock—employee share options — — 183 — 183 Excess tax benefits from share-based payment arrangements — — 55 — 55 Dividends paid to parent company (2,450 ) (1,383 ) — 3,833 — Capital contributions, loans and other transactions between subsidiaries — (3 ) — 3 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,450 ) (1,386 ) (3,733 ) 3,836 (3,733 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash (1 ) (11 ) — — (12 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase in cash 4 2 — — 6 Cash at beginning of year 221 151 2 — 374 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 225 153 2 — 380 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Income taxes paid (received) 1,032 384 (209 ) — 1,207 Interest paid 47 — 318 — 365 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Cash flows from operating activities Net income 2,780 1,124 3,692 (3,904 ) 3,692 Net adjustments to reconcile net income to net cash provided by operating activities 343 (293 ) 118 (167 ) 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 3,123 831 3,810 (4,071 ) 3,693 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Proceeds from maturities of fixed maturities 6,625 4,258 11 — 10,894 Proceeds from sales of investments: Fixed maturities 595 453 1 — 1,049 Equity securities 111 43 4 — 158 Real estate investments 1 14 — — 15 Other investments 477 378 — — 855 Purchases of investments: Fixed maturities (6,856 ) (4,465 ) (4 ) — (11,325 ) Equity securities (3 ) (42 ) (7 ) — (52 ) Real estate investments (22 ) (26 ) — — (48 ) Other investments (405 ) (149 ) — — (554 ) Net purchases of short-term securities (268 ) (223 ) (7 ) — (498 ) Securities transactions in course of settlement 44 38 — — 82 Acquisition, net of cash acquired (9 ) (3 ) — (12 ) Other (350 ) (8 ) — — (358 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities (60 ) 268 (2 ) — 206 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization — — (3,275 ) — (3,275 ) Treasury stock acquired—net employee share-based compensation — — (57 ) — (57 ) Dividends paid to shareholders — — (729 ) — (729 ) Issuance of common stock—employee share options — — 195 — 195 Excess tax benefits from share-based payment arrangements — — 57 — 57 Dividends paid to parent company (2,978 ) (1,093 ) — 4,071 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,978 ) (1,093 ) (3,809 ) 4,071 (3,809 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash (1 ) (9 ) — — (10 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash 84 (3 ) (1 ) — 80 Cash at beginning of year 137 154 3 — 294 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 221 151 2 — 374 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Income taxes paid (received) 947 336 (136 ) — 1,147 Interest paid 47 — 318 — 365

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2016
Selected Quarterly Financial Data (Unaudited) disclosure
Selected Quarterly Financial Data (Unaudited) disclosure [Text Block]	19. SELECTED QUARTERLY FINANCIAL DATA (Unaudited) 2016 (in millions, except per share amounts) First Second Third Fourth Total Total revenues 6,686 6,785 6,961 7,193 27,625 Total expenses 5,769 5,898 6,014 5,891 23,572 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes 917 887 947 1,302 4,053 Income tax expense 226 223 231 359 1,039 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 691 664 716 943 3,014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per share(1): Basic 2.33 2.27 2.48 3.32 10.39 Diluted 2.30 2.24 2.45 3.28 10.28 2015 (in millions, except per share amounts) First Second Third Fourth Total Total revenues 6,629 6,710 6,798 6,678 26,815 Total expenses 5,481 5,634 5,491 5,469 22,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes 1,148 1,076 1,307 1,209 4,740 Income tax expense 315 264 379 343 1,301 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 833 812 928 866 3,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per share(1): Basic 2.58 2.56 3.00 2.87 10.99 Diluted 2.55 2.53 2.97 2.83 10.88 (1) Due to the averaging of shares, quarterly earnings per share may not add to the total for the full year.

Schedule II

Schedule II	12 Months Ended
	Dec. 31, 2016
Schedule II
Schedule II [Text Block]	SCHEDULE II THE TRAVELERS COMPANIES, INC. CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED STATEMENT OF INCOME For the year ended December 31, 2016 2015 2014 Revenues Net investment income 13 7 6 Net realized investment gains (losses)(1) (1 ) 1 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 12 8 9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Expenses Interest 315 325 321 Other 5 16 15 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses 320 341 336 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss before income taxes and net income of subsidiaries (308 ) (333 ) (327 ) Income tax benefit (168 ) (108 ) (115 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss before net income of subsidiaries (140 ) (225 ) (212 ) Net income of subsidiaries 3,154 3,664 3,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 3,014 3,439 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The parent company had $(1) million, $0 and $0 of other-than-temporary impairment losses recognized in net realized investment gains (losses) during the years ended December 31, 2016, 2015 and 2014, respectively. The parent company had no other-than-temporary impairment gains or losses recognized in other comprehensive income (loss) during the years ended December 31, 2016, 2015 and 2014. The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. SCHEDULE II THE TRAVELERS COMPANIES, INC. CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED STATEMENT OF COMPREHENSIVE INCOME For the year ended December 31, 2016 2015 2014 Consolidated net income 3,014 3,439 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss)—parent company: Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income 11 (3 ) 6 Net changes in benefit plan assets and obligations (20 ) 64 (471 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) before income taxes and other comprehensive income (loss) of subsidiaries (9 ) 61 (465 ) Income tax expense (benefit) (1 ) 21 (163 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries (8 ) 40 (302 ) Other comprehensive income (loss) of subsidiaries (590 ) (1,077 ) 372 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated other comprehensive income (loss) (598 ) (1,037 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated comprehensive income 2,416 2,402 3,762 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. SCHEDULE II THE TRAVELERS COMPANIES, INC. CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED BALANCE SHEET At December 31, 2016 2015 Assets Fixed maturities 49 46 Equity securities 155 141 Short-term securities 1,627 1,546 Investment in subsidiaries 27,137 27,573 Other assets 68 58 ​ ​ ​ ​ ​ ​ ​ Total assets 29,036 29,364 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Debt 5,744 5,651 Other liabilities 82 127 ​ ​ ​ ​ ​ ​ ​ Total liabilities 5,826 5,778 ​ ​ ​ ​ ​ ​ ​ Shareholders' equity Common stock (1,750.0 shares authorized, 279.6 and 295.9 shares issued and outstanding) 22,614 22,172 Retained earnings 32,185 29,933 Accumulated other comprehensive loss (755 ) (157 ) Treasury stock, at cost (489.5 and 467.6 shares) (30,834 ) (28,362 ) ​ ​ ​ ​ ​ ​ ​ Total shareholders' equity 23,210 23,586 ​ ​ ​ ​ ​ ​ ​ Total liabilities and shareholders' equity 29,036 29,364 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. SCHEDULE II THE TRAVELERS COMPANIES, INC. CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED STATEMENT OF CASH FLOWS For the year ended December 31, 2016 2015 2014 Cash flows from operating activities Net income 3,014 3,439 3,692 Adjustments to reconcile net income to net cash provided by operating activities: Equity in net income of subsidiaries (3,154 ) (3,664 ) (3,904 ) Dividends received from consolidated subsidiaries 2,998 3,833 4,071 Capital received from subsidiaries — 3 — Deferred federal income tax expense (benefit) 12 (6 ) 51 Change in income taxes payable (48 ) 51 (87 ) Other 73 113 (13 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 2,895 3,769 3,810 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Net purchases of short-term securities (81 ) (16 ) (7 ) Other investments, net (8 ) (20 ) 5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in investing activities (89 ) (36 ) (2 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization (2,400 ) (3,150 ) (3,275 ) Treasury stock acquired—net employee share-based compensation (72 ) (74 ) (57 ) Dividends paid to shareholders (757 ) (739 ) (729 ) Payment of debt (400 ) (400 ) — Issuance of debt 491 392 — Issuance of common stock—employee share options 332 183 195 Other — 55 57 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,806 ) (3,733 ) (3,809 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net decrease in cash — — (1 ) Cash at beginning of year 2 2 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 2 2 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Cash received during the year for taxes 132 209 136 Cash paid during the year for interest 311 318 318 The condensed financial statements should be read in conjunction with the notes to the condensed financial information of the registrant, as well as the consolidated financial statements and notes thereto. SCHEDULE II THE TRAVELERS COMPANIES, INC. NOTES TO THE CONDENSED FINANCIAL INFORMATION OF REGISTRANT 1. GUARANTEES The Travelers Companies, Inc. (TRV) fully and unconditionally guarantees the payment of all principal, premiums, if any, and interest on certain debt obligations of its subsidiaries TPC and TIGHI. The guarantees pertain to the $200 million 7.75% notes due 2026 and the $500 million 6.375% notes due 2033. TRV also has contingent obligations for guarantees in connection with the selling of businesses to third parties and various indemnifications including indemnifications to service providers in the normal course of business. The guarantees and indemnification clauses are often standard contractual terms and include indemnifications for breaches of representations and warranties and in some cases obligations arising from certain liabilities. The terms of these provisions vary in duration and nature. Certain of the guarantees and indemnifications described above have no stated or notional amounts or limitation to the maximum potential future payments, and, accordingly, TRV is unable to provide an estimate of the maximum potential payments for such arrangements.

Schedule III

Schedule III	12 Months Ended
	Dec. 31, 2016
Schedule III
Schedule III [Text Block]	SCHEDULE III THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES Segment Deferred Claims and Unearned Earned Net Claims and Amortization Other Net 2016 Business and International Insurance 1,093 41,006 7,134 14,620 1,763 9,190 2,358 2,746 14,675 Bond & Specialty Insurance 232 2,944 1,308 2,088 210 572 397 389 2,099 Personal Insurance 598 3,979 3,887 7,826 329 5,308 1,230 988 8,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total—Reportable Segments 1,923 47,929 12,329 24,534 2,302 15,070 3,985 4,123 24,958 Other — 20 — — — — — 394 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated 1,923 47,949 12,329 24,534 2,302 15,070 3,985 4,517 24,958 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2015 Business and International Insurance 1,072 41,563 7,147 14,521 1,824 8,859 2,329 2,686 14,583 Bond & Specialty Insurance 225 3,157 1,292 2,085 223 643 393 389 2,081 Personal Insurance 552 3,552 3,532 7,268 332 4,221 1,163 988 7,457 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total—Reportable Segments 1,849 48,272 11,971 23,874 2,379 13,723 3,885 4,063 24,121 Other — 23 — — — — — 404 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated 1,849 48,295 11,971 23,874 2,379 13,723 3,885 4,467 24,121 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 Business and International Insurance 1,080 42,700 7,208 14,512 2,156 9,145 2,321 2,541 14,636 Bond & Specialty Insurance 222 3,435 1,286 2,076 252 481 388 403 2,103 Personal Insurance 533 3,689 3,345 7,125 379 4,244 1,173 989 7,165 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total—Reportable Segments 1,835 49,824 11,839 23,713 2,787 13,870 3,882 3,933 23,904 Other — 26 — — — — — 400 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidated 1,835 49,850 11,839 23,713 2,787 13,870 3,882 4,333 23,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) See note 2 of notes to the consolidated financial statements for discussion of the method used to allocate net investment income and invested assets to the identified segments. (2) Expense allocations are determined in accordance with prescribed statutory accounting practices. These practices make a reasonable allocation of all expenses to those product lines with which they are associated.

Schedule V

Schedule V	12 Months Ended
	Dec. 31, 2016
Schedule V
Schedule V [Text Block]	SCHEDULE V THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES Balance at Charged to Charged to Deductions(1) Balance 2016 Reinsurance recoverables 157 — — 41 116 Allowance for uncollectible: Premiums receivable from underwriting activities 65 35 — 39 61 Deductibles 35 5 — 6 34 2015 Reinsurance recoverables 203 — — 46 157 Allowance for uncollectible: Premiums receivable from underwriting activities 70 38 — 43 65 Deductibles 36 3 — 4 35 2014 Reinsurance recoverables 239 — — 36 203 Allowance for uncollectible: Premiums receivable from underwriting activities 75 44 — 49 70 Deductibles 39 — — 3 36 (1) Credited to the related asset account.

Schedule VI

Schedule VI	12 Months Ended
	Dec. 31, 2016
Schedule VI
Schedule VI [Text Block]	SCHEDULE VI THE TRAVELERS COMPANIES, INC. AND SUBSIDIARIES Claims and Paid Discount From Amortization Affiliation with Registrant(2) Deferred Claims and Unearned Earned Net Current Prior Net 2016 1,923 47,929 1,083 12,329 24,534 2,302 15,675 (680 ) 3,985 14,796 24,958 2015 1,849 48,272 1,066 11,971 23,874 2,379 14,471 (817 ) 3,885 14,474 24,121 2014 1,835 49,824 1,080 11,839 23,713 2,787 14,688 (885 ) 3,882 14,066 23,904 (1) Excludes accident and health insurance business. (2) Consolidated property-casualty insurance operations. (3) For a discussion of types of reserves discounted and discount rates used, see note 7 of notes to the consolidated financial statements.

Summary of Significant Accoun32

Summary of Significant Accounting Policies (policies)	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies disclosure
Accounting Policies, Basis of Presentation [Policy Text Block]	Basis of Presentation The consolidated financial statements include the accounts of The Travelers Companies, Inc. (together with its subsidiaries, the Company). The preparation of the consolidated financial statements in conformity with U.S. generally accepted accounting principles (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 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 and 2014 financial statements to conform to the 2016 presentation. All material intercompany transactions and balances have been eliminated.
Accounting Policies, Adoption of Accounting Standards [Policy Text Block]	Adoption of Accounting Standards 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. In August 2014, the FASB issued guidance to address the diversity in practice in determining when there is substantial doubt about an entity's ability to continue as a going concern and when an entity must disclose certain relevant conditions and events. The new guidance requires an entity to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued (or available to be issued). The new guidance allows the entity to consider the mitigating effects of management's plans that will alleviate the substantial doubt and requires certain disclosures when substantial doubt is alleviated as a result of consideration of management's plans. If conditions or events raise substantial doubt that is not alleviated, an entity should disclose that there is substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued (or available to be issued), along with the principal conditions or events that raise substantial doubt, management's evaluation of the significance of those conditions or events in relation to the entity's ability to meet its obligations and management's plans that are intended to mitigate those conditions. The updated guidance was effective for annual periods ending after December 15, 2016, and interim and annual periods thereafter. The adoption of this guidance did not have any effect on the Company's results of operations, financial position or liquidity. 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. 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. 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. 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. 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.
Accounting Policies, Investments [Policy Text Block]	Investments Fixed maturities include bonds, notes and redeemable preferred stocks. Fixed maturities, including instruments subject to securities lending agreements, are classified as available for sale and are reported at fair value, with unrealized investment gains and losses, net of income taxes, charged or credited directly to other comprehensive income. Equity securities, which include public common and non-redeemable preferred stocks, are classified as available for sale and are reported at fair value with unrealized gains and losses, net of income taxes, charged or credited directly to other comprehensive income. The Company's real estate investments include warehouses, office buildings and other commercial land and properties that are directly owned. Real estate is recorded on the purchase date at the purchase price, which generally represents fair value, and is supported by internal analysis or external appraisals that use discounted cash flow analyses and other acceptable valuation techniques. Real estate held for investment purposes is subsequently carried at cost less accumulated depreciation. Buildings are depreciated on a straight-line basis over the shorter of the expected useful life of the building or 39 years. Real estate held for sale is carried at lower of cost or fair value, less estimated costs to sell. Short-term securities have an original maturity of less than one year and are carried at amortized cost, which approximates fair value. Investments in Private Equity Limited Partnerships, Hedge Funds and Real Estate Partnerships The Company uses the equity method of accounting for investments in private equity limited partnerships, hedge funds and real estate partnerships. The partnerships and the hedge funds generally report investments on their balance sheet at fair value. The financial statements prepared by the investee are received by the Company on a lag basis, with the lag period generally dependent upon the type of underlying investments. The private equity and real estate partnerships provide financial information quarterly which is generally available to investors, including the Company, within three to six months following the date of the reporting period. The hedge funds provide financial information monthly, which is generally available to investors within one month following the date of the reporting period. The Company regularly requests financial information from the partnerships prior to the receipt of the partnerships' financial statements and records any material information obtained from these requests in its consolidated financial statements. Other Also included in other investments are non-public common equities, preferred equities and derivatives. Non-public common equities and preferred equities are reported at fair value with changes in fair value, net of income taxes, charged or credited directly to other comprehensive income. The Company's derivative financial instruments are carried at fair value, with the changes in fair value reflected in the consolidated statement of income in net realized investment gains (losses). For a further discussion of the derivatives used by the Company, see note 3.
Accounting Policies, Net Investment Income [Policy Text Block]	Net Investment Income Investment income from fixed maturities is recognized based on the constant effective yield method which includes an adjustment for estimated principal pre-payments, if any. The effective yield used to determine amortization for fixed maturities subject to prepayment risk (e.g., asset-backed, loan-backed and structured securities) is recalculated and adjusted periodically based upon actual historical and/or projected future cash flows, which are obtained from a widely-accepted securities data provider. The adjustments to the yield for highly rated prepayable fixed maturities are accounted for using the retrospective method. The adjustments to the yield for non-highly rated prepayable fixed maturities are accounted for using the prospective method. Dividends on equity securities (including those with transfer restrictions) are recognized in income when declared. Rental income on real estate is recognized on a straight-line basis over the lease term. See the section titled: Real Estate in note 3 for further discussion. Investments in private equity limited partnerships, hedge funds, real estate partnerships and joint ventures are accounted for using the equity method of accounting, whereby the Company's share of the investee's earnings or losses in the fund is reported in net investment income. Accrual of income is suspended on non-securitized fixed maturities that are in default, or on which it is likely that future payments will not be made as scheduled. Interest income on investments in default is recognized only when payments are received. Investments included in the consolidated balance sheet that were not income-producing for the preceding 12 months were not material. For fixed maturities where the Company records an other-than-temporary impairment, a determination is made as to the cause of the impairment and whether the Company expects a recovery in the value. For fixed maturities where the Company expects a recovery in value, not necessarily to par, the constant effective yield method is utilized, and the investment is amortized to the expected recovery amount.
Accounting Policies, Investment Gains and Losses [Policy Text Block]	Investment Gains and Losses Net realized investment gains and losses are included as a component of pre-tax revenues based upon specific identification of the investments sold on the trade date. Included in net realized investment gains (losses) are other-than-temporary impairment losses on invested assets other than those investments accounted for using the equity method of accounting as described in the "Investment Impairments" section that follows.
Accounting Policies, Investment Impairments [Policy Text Block]	Investment Impairments The Company conducts a periodic review to identify and evaluate invested assets having other-than-temporary impairments. Some of the factors considered in identifying other-than-temporary impairments include: (1) for fixed maturity investments, whether the Company intends to sell the investment or whether it is more likely than not that the Company will be required to sell the investment prior to an anticipated recovery in value; (2) for non-fixed maturity investments, the Company's ability and intent to retain the investment for a reasonable period of time sufficient to allow for an anticipated recovery in value; (3) the likelihood of the recoverability of principal and interest for fixed maturity securities (i.e., whether there is a credit loss) or cost for equity securities; (4) the length of time and extent to which the fair value has been less than amortized cost for fixed maturity securities or cost for equity securities; and (5) the financial condition, near-term and long-term prospects for the issuer, including the relevant industry conditions and trends, and implications of rating agency actions and offering prices. For fixed maturity investments that the Company does not intend to sell or for which it is more likely than not that the Company would not be required to sell before an anticipated recovery in value, the Company separates the credit loss component of the impairment from the amount related to all other factors and reports the credit loss component in net realized investment gains (losses). The impairment related to all other factors is reported in other comprehensive income. For equity securities (including public common and non-redeemable preferred stock) and for fixed maturity investments the Company intends to sell or for which it is more likely than not that the Company will be required to sell before an anticipated recovery in value, the full amount of the impairment is included in net realized investment gains (losses). Upon recognizing an other-than-temporary impairment, the new cost basis of the investment is the previous amortized cost basis less the other-than-temporary impairment recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value; however, for fixed maturity investments the difference between the new cost basis and the expected cash flows is accreted on a quarterly basis to net investment income over the remaining expected life of the investment. The Company determines the credit loss component of fixed maturity investments by utilizing discounted cash flow modeling to determine the present value of the security and comparing the present value with the amortized cost of the security. If the amortized cost is greater than the present value of the expected cash flows, the difference is considered a credit loss and recognized in net realized investment gains (losses). For non-structured fixed maturities (U.S. Treasury securities, obligations of U.S. government and government agencies and authorities, obligations of states, municipalities and political subdivisions, debt securities issued by foreign governments and certain corporate debt), the estimate of expected cash flows is determined by projecting a recovery value and a recovery time frame and assessing whether further principal and interest will be received. The determination of recovery value incorporates an issuer valuation assumption utilizing one or a combination of valuation methods as deemed appropriate by the Company. The Company determines the undiscounted recovery value by allocating the estimated value of the issuer to the Company's assessment of the priority of claims. The present value of the cash flows is determined by applying the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment) and an estimated recovery time frame. Generally, that time frame for securities for which the issuer is in bankruptcy is 12 months. For securities for which the issuer is financially troubled but not in bankruptcy, that time frame is generally 24 months. Included in the present value calculation are expected principal and interest payments; however, for securities for which the issuer is classified as bankrupt or in default, the present value calculation assumes no interest payments and a single recovery amount. In estimating the recovery value, significant judgment is involved in the development of assumptions relating to a myriad of factors related to the issuer including, but not limited to, revenue, margin and earnings projections, the likely market or liquidation values of assets, potential additional debt to be incurred pre- or post-bankruptcy/restructuring, the ability to shift existing or new debt to different priority layers, the amount of restructuring/bankruptcy expenses, the size and priority of unfunded pension obligations, litigation or other contingent claims, the treatment of intercompany claims and the likely outcome with respect to inter-creditor conflicts. For structured fixed maturity securities (primarily residential and commercial mortgage-backed securities and asset-backed securities), the Company estimates the present value of the security by projecting future cash flows of the assets underlying the securitization, allocating the flows to the various tranches based on the structure of the securitization and determining the present value of the cash flows using the effective yield of the security at the date of acquisition (or the most recent implied rate used to accrete the security if the implied rate has changed as a result of a previous impairment or changes in expected cash flows). The Company incorporates levels of delinquencies, defaults and severities as well as credit attributes of the remaining assets in the securitization, along with other economic data, to arrive at its best estimate of the parameters applied to the assets underlying the securitization. In order to project cash flows, the following assumptions are applied to the assets underlying the securitization: (1) voluntary prepayment rates, (2) default rates and (3) loss severity. The key assumptions made for the Prime, Alt-A and first-lien Sub-Prime mortgage-backed securities at December 31, 2016 were as follows: (at December 31, 2016) Prime Alt-A Sub-Prime Voluntary prepayment rates 0% - 35% 4% - 15% 3% - 12% Percentage of remaining pool liquidated due to defaults 0% - 46% 20% - 73% 22% - 52% Loss severity 30% - 65% 42% - 90% 75% - 110% On at least an annual basis, the Company obtains independent appraisals for substantially all of its real estate investments. In addition, the carrying value of all real estate investments is reviewed for impairment on a quarterly basis or when events or changes in circumstances indicate that the carrying amount may not be recoverable. The review for impairment considers the valuation from the independent appraisal, when applicable, and incorporates an estimate of the undiscounted cash flows expected to result from the use and eventual disposition of the real estate property. An impairment loss is recognized if the expected future undiscounted cash flows are less than the carrying value of the real estate property. The impairment loss is the amount by which the carrying amount exceeds fair value. The Company reviews its investments in private equity limited partnerships, hedge funds and real estate partnerships for impairment no less frequently than quarterly and monitors the performance throughout the year through discussions with the managers/general partners. If the Company becomes aware of an impairment of a partnership's investments at the balance sheet date prior to receiving the partnership's financial statements, it will recognize an impairment by recording a reduction in the carrying value of the partnership with a corresponding charge to net investment income. The Company may, from time to time, sell invested assets subsequent to the balance sheet date that it did not intend to sell at the balance sheet date. Conversely, the Company may not sell invested assets that it asserted that it intended to sell at the balance sheet date. Such changes in intent are due to events occurring subsequent to the balance sheet date. The types of events that may result in a change in intent include, but are not limited to, significant changes in the economic facts and circumstances related to the invested asset (e.g., a downgrade or upgrade from a rating agency), significant unforeseen changes in liquidity needs, or changes in tax laws or the regulatory environment.
Accounting Policies, Securities Lending [Policy Text Block]	Securities Lending The Company has engaged in securities lending activities from which it generates net investment income by lending certain of its investments to other institutions for short periods of time. Borrowers of these securities provide collateral equal to at least 102% of the market value of the loaned securities plus accrued interest. This collateral is held by a third-party custodian, and the Company has the right to access the collateral only in the event that the institution borrowing the Company's securities is in default under the lending agreement. Therefore, the Company does not recognize the receipt of the collateral held by the third-party custodian or the obligation to return the collateral. The loaned securities remain a recorded asset of the Company. The Company accepts only cash as collateral for securities on loan and restricts the manner in which that cash is invested.
Accounting Policies, Reinsurance Recoverables [Policy Text Block]	Reinsurance Recoverables Amounts recoverable from reinsurers are estimated in a manner consistent with the associated claim liability. The Company reports its reinsurance recoverables net of an allowance for estimated uncollectible reinsurance recoverables. The allowance is based upon the Company's ongoing review of amounts outstanding, length of collection periods, changes in reinsurer credit standing, disputes, applicable coverage defenses and other relevant factors. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance for estimated uncollectible reinsurance recoverables. Any subsequent collections of amounts previously written off are reported as part of claims and claim adjustment expenses. The Company evaluates and monitors the financial condition of its reinsurers under voluntary reinsurance arrangements to minimize its exposure to significant losses from reinsurer insolvencies.
Accounting Policies, Deferred Acquisition Costs [Policy Text Block]	Deferred Acquisition Costs Incremental direct costs of acquired, new and renewal insurance contracts, consisting of commissions (other than contingent commissions) and premium-related taxes, are capitalized and charged to expense pro rata over the contract periods in which the related premiums are earned. Deferred acquisition costs are reviewed to determine if they are recoverable from future income and, if not, are charged to expense. Future investment income attributable to related premiums is taken into account in measuring the recoverability of the carrying value of this asset. All other acquisition expenses are charged to operations as incurred.
Accounting Policies, Contractholder Receivables and Payables [Policy Text Block]	Contractholder Receivables and Payables Under certain workers' compensation insurance contracts with deductible features, the Company is obligated to pay the claimant for the full amount of the claim. The Company is subsequently reimbursed by the policyholder for the deductible amount. These amounts are included on a gross basis in the consolidated balance sheet in contractholder payables and contractholder receivables, respectively.
Accounting Policies, Goodwill and Other Intangible Assets [Policy Text Block]	Goodwill and Other Intangible Assets The Company performs a review, on at least an annual basis, of goodwill held by the reporting units which are the Company's three operating and reportable segments: Business and International Insurance; Bond & Specialty Insurance; and Personal Insurance. The Company estimates the fair value of its reporting units and compares it to their carrying value, including goodwill. If the carrying values of the reporting units were to exceed their fair value, the amount of the impairment would be calculated and goodwill adjusted accordingly. The Company uses a discounted cash flow model to estimate the fair value of its reporting units. The discounted cash flow model is an income approach to valuation that is based on a detailed cash flow analysis for deriving a current fair value of reporting units and is representative of the Company's reporting units' current and expected future financial performance. The discount rate assumptions reflect the Company's assessment of the risks inherent in the projected future cash flows and the Company's weighted-average cost of capital, and are compared against available market data for reasonableness. Other indefinite-lived intangible assets held by the Company are also reviewed for impairment on at least an annual basis. The classification of the asset as indefinite-lived is reassessed and an impairment is recognized if the carrying amount of the asset exceeds its fair value. Intangible assets that are deemed to have a finite useful life are amortized over their useful lives. The carrying amount of intangible assets with a finite useful life is regularly reviewed for indicators of impairment in value. Impairment is recognized only if the carrying amount of the intangible asset is not recoverable from its undiscounted cash flows and is measured as the difference between the carrying amount and the fair value of the asset. As a result of the reviews performed for the years ended December 31, 2016, 2015 and 2014, the Company determined that the estimated fair value substantially exceeded the respective carrying value of its reporting units for those years and that goodwill was not impaired. The Company also determined during its reviews for each year that its other indefinite-lived intangible assets and finite-lived intangible assets were not impaired.
Accounting Policies, Claims and Claim Adjustment Expense Reserves [Policy Text Block]	Claims and Claim Adjustment Expense Reserves Claims and claim adjustment expense reserves represent estimates for the ultimate cost of unpaid reported and unreported claims incurred and related expenses. The reserves are adjusted regularly based upon experience. Included in the claims and claim adjustment expense reserves in the consolidated balance sheet are reserves for long-term disability and annuity claim payments, primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, that are discounted to the present value of estimated future payments. The Company performs a continuing review of its claims and claim adjustment expense reserves, including its reserving techniques and the impact of reinsurance. The reserves are also reviewed regularly by qualified actuaries employed by the Company. Since the reserves are based on estimates, the ultimate liability may be more or less than such reserves. The effects of changes in such estimated reserves are included in the results of operations in the period in which the estimates are changed. Such changes in estimates could occur in a future period and may be material to the Company's results of operations and financial position in such period.
Accounting Policies, Other Liabilities [Policy Text Block]	Other Liabilities Included in other liabilities in the consolidated balance sheet is the Company's estimate of its liability for guaranty fund and other insurance-related assessments. The liability for expected state guaranty fund and other premium-based assessments is recognized as the Company writes or becomes obligated to write or renew the premiums on which the assessments are expected to be based. The liability for loss-based assessments is recognized as the related losses are incurred. At December 31, 2016 and 2015, the Company had a liability of $242 million and $241 million, respectively, for guaranty fund and other insurance-related assessments and related recoverables of $16 million and $18 million, respectively. The liability for such assessments and the related recoverables are not discounted for the time value of money. The loss-based assessments are expected to be paid over a period ranging from one year to the life expectancy of certain workers' compensation claimants and the recoveries are expected to occur over the same period of time. Also included in other liabilities is an accrual for policyholder dividends. Certain insurance contracts, primarily workers' compensation, are participating whereby dividends are paid to policyholders in accordance with contract provisions. Net written premiums for participating dividend policies were approximately 1%, 2% and 1% of total net written premiums for the years ended December 31, 2016, 2015 and 2014, respectively. Policyholder dividends are accrued against earnings using best available estimates of amounts to be paid. The liability accrued for policyholder dividends totaled $62 million and $57 million at December 31, 2016 and 2015, respectively.
Accounting Policies, Treasury Stock [Policy Text Block]	Treasury Stock The cost of common stock repurchased by the Company is reported as treasury stock and represents authorized and unissued shares of the Company under the Minnesota Business Corporation Act.
Accounting Policies, Statutory Accounting Practices [Policy Text Block]	Statutory Accounting Practices The Company's U.S. insurance subsidiaries, domiciled principally in the State of Connecticut, are required to prepare statutory financial statements in accordance with the accounting practices prescribed or permitted by the insurance departments of the states of domicile. Prescribed statutory accounting practices are those practices that are incorporated directly or by reference in state laws, regulations, and general administrative rules applicable to all insurance enterprises domiciled in a particular state. The State of Connecticut requires insurers domiciled in Connecticut to prepare their statutory financial statements in accordance with National Association of Insurance Commissioners' (NAIC) statutory accounting practices. Permitted statutory accounting practices are those practices that differ either from state-prescribed statutory accounting practices or NAIC statutory accounting practices. The Company does not apply any statutory accounting practices that would be considered a prescribed or permitted statutory accounting practice that differs from NAIC statutory accounting practices. The Company's non-U.S. insurance subsidiaries file financial statements prepared in accordance with the regulatory reporting requirements of their respective local jurisdiction.
Accounting Policies, Premiums and Unearned Premium Reserves [Policy Text Block]	Premiums and Unearned Premium Reserves Premiums are recognized as revenues pro rata over the policy period. Unearned premium reserves represent the unexpired portion of policy premiums. Accrued retrospective premiums are included in premium balances receivable. Premium balances receivable are reported net of an allowance for estimated uncollectible premium amounts. Ceded premiums are charged to income over the applicable term of the various reinsurance contracts with third party reinsurers. Prepaid reinsurance premiums represent the unexpired portion of premiums ceded to reinsurers and are reported as part of other assets.
Accounting Policies, Fee Income [Policy Text Block]	Fee Income Fee income includes servicing fees from carriers and revenues from large deductible policies and service contracts and is recognized pro rata over the contract or policy periods.
Accounting Policies, Other Revenues [Policy Text Block]	Other Revenues Other revenues include revenues from premium installment charges, which are recognized as collected, revenues of noninsurance subsidiaries other than fee income and gains and losses on dispositions of assets and redemption of debt, and other miscellaneous revenues including a gain recognized as a result of the settlement of a reinsurance dispute.
Accounting Policies, Income Taxes [Policy Text Block]	Income Taxes The Company recognizes deferred income tax assets and liabilities for the expected future tax effects attributable to temporary differences between the financial statement and tax return bases of assets and liabilities, based on enacted tax rates and other provisions of the tax law. The effect of a change in tax laws or rates on deferred tax assets and liabilities is recognized in income in the period in which such change is enacted. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized.
Accounting Policies, Foreign Currency Translation [Policy Text Block]	Foreign Currency Translation The Company assigns functional currencies to its foreign operations, which are generally the currencies of the local operating environment. Foreign currency amounts are remeasured to the functional currency, and the resulting foreign exchange gains or losses are reflected in earnings. Functional currency amounts are then translated into U.S. dollars. The foreign currency remeasurement and translation are calculated using current exchange rates for items reported in the balance sheets and average exchange rates for items recorded in earnings. The change in unrealized foreign currency translation gain or loss during the year, net of tax, is a component of other comprehensive income.
Accounting Policies, Share-Based Compensation [Policy Text Block]	Share-Based Compensation The Company has an employee stock incentive compensation plan that permits grants of nonqualified stock options, incentive stock options, stock appreciation rights, restricted stock, deferred stock, stock units, performance awards and other share-based or share-denominated awards with respect to the Company's common stock. Compensation cost is measured based on the grant-date fair value of an award, utilizing the assumptions discussed in note 13. Compensation cost is recognized for financial reporting purposes over the period in which the employee is required to provide service in exchange for the award (generally the vesting period). In connection with certain share-based awards, participants are entitled to receive dividends during the vesting period, either in cash or dividend equivalent shares, commensurate with the dividends paid to common shareholders. Dividends and dividend equivalent shares on awards that are expected to vest are recorded in retained earnings. Dividends paid on awards that are not expected to vest as part of the Company's forfeiture estimate are recorded as compensation expense.

Summary of Significant Accoun33

Summary of Significant Accounting Policies (table)	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies disclosure
Key assumptions used in estimation of present value of structured fixed maturity securities [Table Text Block]	(at December 31, 2016) Prime Alt-A Sub-Prime Voluntary prepayment rates 0% - 35% 4% - 15% 3% - 12% Percentage of remaining pool liquidated due to defaults 0% - 46% 20% - 73% 22% - 52% Loss severity 30% - 65% 42% - 90% 75% - 110%

Segment Information (tables)

Segment Information (tables)	12 Months Ended
	Dec. 31, 2016
Segment Information disclosure
Company's revenues and operating income by segment [Table Text Block]	(for the year ended December 31, in millions) Business and Bond & Personal Total 2016 Premiums 14,620 2,088 7,826 24,534 Net investment income 1,763 210 329 2,302 Fee income 442 — 16 458 Other revenues 176 20 56 252 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues(1) 17,001 2,318 8,227 27,546 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization and depreciation 2,956 457 1,391 4,804 Income tax expense 659 307 191 1,157 Operating income(1) 2,048 653 510 3,211 2015 Premiums 14,521 2,085 7,268 23,874 Net investment income 1,824 223 332 2,379 Fee income 445 — 15 460 Other revenues 23 22 48 93 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues(1) 16,813 2,330 7,663 26,806 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization and depreciation 2,907 467 1,322 4,696 Income tax expense 769 272 402 1,443 Operating income(1) 2,170 633 889 3,692 2014 Premiums 14,512 2,076 7,125 23,713 Net investment income 2,156 252 379 2,787 Fee income 438 — 12 450 Other revenues 46 19 80 145 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues(1) 17,152 2,347 7,596 27,095 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization and depreciation 2,909 482 1,347 4,738 Income tax expense 798 348 366 1,512 Operating income(1) 2,347 727 824 3,898 (1) Operating revenues for reportable business segments exclude net realized investment gains. Operating income for reportable business segments equals net income excluding the after-tax impact of net realized investment gains.
Net written premiums by market [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Business and International Insurance: Domestic: Select Accounts 2,729 2,716 2,707 Middle Market 6,463 6,302 6,077 National Accounts 1,058 1,048 1,047 First Party 1,601 1,564 1,579 Specialized Distribution 1,094 1,111 1,074 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Domestic 12,945 12,741 12,484 International 1,730 1,842 2,152 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Business and International Insurance 14,675 14,583 14,636 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Bond & Specialty Insurance 2,099 2,081 2,103 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Personal Insurance: Automobile 4,327 3,700 3,390 Homeowners and Other 3,857 3,757 3,775 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Personal Insurance 8,184 7,457 7,165 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated net written premiums 24,958 24,121 23,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Business segment reconciliations of revenue and income, net of tax [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Revenue reconciliation Earned premiums Business and International Insurance: Domestic: Workers' compensation 3,969 3,867 3,711 Commercial automobile 2,010 1,922 1,900 Commercial property 1,769 1,766 1,747 General liability 1,977 1,898 1,834 Commercial multi-peril 3,148 3,133 3,071 Other 31 39 42 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Domestic 12,904 12,625 12,305 International 1,716 1,896 2,207 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Business and International Insurance 14,620 14,521 14,512 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Bond & Specialty Insurance: Fidelity and surety 962 954 936 General liability 946 955 963 Other 180 176 177 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Bond & Specialty Insurance 2,088 2,085 2,076 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Personal Insurance: Automobile 4,013 3,512 3,316 Homeowners and Other 3,813 3,756 3,809 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Personal Insurance 7,826 7,268 7,125 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total earned premiums 24,534 23,874 23,713 Net investment income 2,302 2,379 2,787 Fee income 458 460 450 Other revenues 252 93 145 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating revenues for reportable segments 27,546 26,806 27,095 Other revenues 11 6 — Net realized investment gains 68 3 79 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated revenues 27,625 26,815 27,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income reconciliation, net of tax Total operating income for reportable segments 3,211 3,692 3,898 Interest Expense and Other(1) (244 ) (255 ) (257 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total operating income 2,967 3,437 3,641 Net realized investment gains 47 2 51 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated net income 3,014 3,439 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The primary component of Interest Expense and Other was after-tax interest expense of $236 million, $242 million and $240 million in 2016, 2015 and 2014, respectively.
Asset reconciliation [Table Text Block]	(at December 31, in millions) 2016 2015 Asset reconciliation: Business and International Insurance 79,468 79,692 Bond & Specialty Insurance 7,296 7,360 Personal Insurance 13,118 12,748 ​ ​ ​ ​ ​ ​ ​ Total assets for reportable segments 99,882 99,800 Other assets(1) 363 384 ​ ​ ​ ​ ​ ​ ​ Total consolidated assets 100,245 100,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The primary components of other assets at December 31, 2016 and 2015 were other intangible assets and deferred taxes.
Revenues of the Company's operations based on location [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 U.S. 25,904 25,127 25,103 Non-U.S.: Canada 1,154 1,202 1,474 Other Non-U.S. 567 486 597 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Non-U.S. 1,721 1,688 2,071 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 27,625 26,815 27,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Investments (tables)

Investments (tables)	12 Months Ended
	Dec. 31, 2016
Investments disclosure
Amortized cost and fair value of investments in fixed maturities [Table Text Block]	Gross Unrealized Amortized Cost Fair (at December 31, 2016, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,031 9 5 2,035 Obligations of states, municipalities and political subdivisions: Local general obligation 13,955 271 182 14,044 Revenue 10,910 215 147 10,978 State general obligation 1,717 36 22 1,731 Pre-refunded 4,968 190 1 5,157 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total obligations of states, municipalities and political subdivisions 31,550 712 352 31,910 Debt securities issued by foreign governments 1,631 34 3 1,662 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,614 100 6 1,708 All other corporate bonds 22,737 508 138 23,107 Redeemable preferred stock 87 6 — 93 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 59,650 1,369 504 60,515 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Unrealized Amortized Fair (at December 31, 2015, in millions) Gains Losses U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,202 8 16 2,194 Obligations of states, municipalities and political subdivisions: Local general obligation 12,744 577 3 13,318 Revenue 9,492 472 4 9,960 State general obligation 1,978 97 2 2,073 Pre-refunded 5,813 247 — 6,060 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total obligations of states, municipalities and political subdivisions 30,027 1,393 9 31,411 Debt securities issued by foreign governments 1,829 45 1 1,873 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,863 124 6 1,981 All other corporate bonds 22,854 523 288 23,089 Redeemable preferred stock 103 7 — 110 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 58,878 2,100 320 60,658 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Amortized cost and fair value of fixed maturities by contractual maturity [Table Text Block]	(at December 31, 2016, in millions) Amortized Fair Due in one year or less 5,619 5,677 Due after 1 year through 5 years 16,417 16,926 Due after 5 years through 10 years 14,258 14,449 Due after 10 years 21,742 21,755 ​ ​ ​ ​ ​ ​ ​ 58,036 58,807 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,614 1,708 ​ ​ ​ ​ ​ ​ ​ Total 59,650 60,515 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Cost and fair value of investments in equity securities [Table Text Block]	Gross (at December 31, 2016, in millions) Cost Gains Losses Fair Value Public common stock 390 216 3 603 Non-redeemable preferred stock 114 20 5 129 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 504 236 8 732 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Fair (at December 31, 2015, in millions) Cost Gains Losses Public common stock 386 164 7 543 Non-redeemable preferred stock 142 26 6 162 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 528 190 13 705 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Unrealized investment losses [Table Text Block]	Less than 12 months 12 months or longer Total (at December 31, 2016, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 1,124 5 — — 1,124 5 Obligations of states, municipalities and political subdivisions 9,781 352 12 — 9,793 352 Debt securities issued by foreign governments 360 3 — — 360 3 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 528 5 43 1 571 6 All other corporate bonds 6,470 115 437 23 6,907 138 Redeemable preferred stock — — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 18,263 480 492 24 18,755 504 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 45 2 10 1 55 3 Non-redeemable preferred stock 2 — 59 5 61 5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 47 2 69 6 116 8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 18,310 482 561 30 18,871 512 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less than 12 months 12 months or longer Total (at December 31, 2015, in millions) Fair Gross Fair Gross Fair Gross Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 1,820 15 28 1 1,848 16 Obligations of states, municipalities and political subdivisions 928 7 142 2 1,070 9 Debt securities issued by foreign governments 172 1 — — 172 1 Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 473 4 57 2 530 6 All other corporate bonds 7,725 197 710 91 8,435 288 Redeemable preferred stock 8 — — — 8 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 11,126 224 937 96 12,063 320 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 48 6 33 1 81 7 Non-redeemable preferred stock 47 3 38 3 85 6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 95 9 71 4 166 13 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,221 233 1,008 100 12,229 333 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Securities continuously in an unrealized loss position of greater than 20% of amortized cost by length of time [Table Text Block]	Period For Which Fair Value Is Less Than 80% of Amortized Cost (in millions) 3 Months Greater Than Greater Than Greater Than Total Fixed maturities Mortgage-backed securities — — — — — Other 1 — — 2 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 1 — — 2 3 Equity securities 1 — — — 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 2 — — 2 4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Impairment charges included in net realized investment gains [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities — — — Obligations of states, municipalities and political subdivisions — — — Debt securities issued by foreign governments — — — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities — — 1 All other corporate bonds 15 13 15 Redeemable preferred stock — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 15 13 16 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 9 37 9 Non-redeemable preferred stock 3 — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 12 37 9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments 2 2 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 29 52 26 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Cumulative amount of and the changes during the year in the credit losses of other-than-temporary impairments (OTTI) on fixed maturities recognized in the consolidated statement of income for which a portion of the OTTI was recognized in other comprehensive income (loss) [Table Text Block]	Year ended December 31, 2016 Cumulative Additions for Additions for Reductions Adjustments to Cumulative OTTI Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 32 — — — (1 ) 31 All other corporate bonds 51 13 — (7 ) (3 ) 54 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 83 13 — (7 ) (4 ) 85 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2015 Cumulative Additions for Additions for Reductions Adjustments to Cumulative OTTI Fixed maturities Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 40 — — (6 ) (2 ) 32 All other corporate bonds 59 2 — (4 ) (6 ) 51 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 99 2 — (10 ) (8 ) 83 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Net investment income [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Gross investment income Fixed maturities 1,981 2,091 2,244 Equity securities 37 39 40 Short-term securities 29 12 9 Real estate investments 51 48 44 Other investments 242 230 489 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross investment income 2,340 2,420 2,826 Investment expenses 38 41 39 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net investment income 2,302 2,379 2,787 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Changes in net unrealized investment gains [Table Text Block]	(at and for the year ended December 31, in millions) 2016 2015 2014 Changes in net unrealized investment gains Fixed maturities (915 ) (893 ) 913 Equity securities 51 (143 ) 63 Other investments 2 2 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in net pre-tax unrealized gains on investment securities (862 ) (1,034 ) 978 Related tax expense (benefit) (303 ) (357 ) 334 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in net unrealized gains on investment securities (559 ) (677 ) 644 Balance, beginning of year 1,289 1,966 1,322 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of year 730 1,289 1,966 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Fair Value Measurements (tables

Fair Value Measurements (tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Measurements disclosure
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities reported at fair value are measured [Table Text Block]	(at December 31, 2016, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,035 2,035 — — Obligations of states, municipalities and political subdivisions 31,910 — 31,898 12 Debt securities issued by foreign governments 1,662 — 1,662 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,708 — 1,704 4 All other corporate bonds 23,107 — 22,939 168 Redeemable preferred stock 93 3 90 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 60,515 2,038 58,293 184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 603 603 — — Non-redeemable preferred stock 129 51 78 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 732 654 78 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments 53 17 — 36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 61,300 2,709 58,371 220 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (at December 31, 2015, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities U.S. Treasury securities and obligations of U.S. government and government agencies and authorities 2,194 2,194 — — Obligations of states, municipalities and political subdivisions 31,411 — 31,398 13 Debt securities issued by foreign governments 1,873 — 1,873 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 1,981 — 1,957 24 All other corporate bonds 23,089 — 22,915 174 Redeemable preferred stock 110 3 100 7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 60,658 2,197 58,243 218 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities Public common stock 543 543 — — Non-redeemable preferred stock 162 55 107 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities 705 598 107 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments 56 18 — 38 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 61,419 2,813 58,350 256 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Changes in the Level 3 fair value category [Table Text Block]	(in millions) Fixed Other Total Balance at December 31, 2015 218 38 256 Total realized and unrealized investment gains (losses): Reported in net realized investment gains(1) 3 5 8 Reported in increases in other comprehensive income 2 3 5 Purchases, sales and settlements/maturities: Purchases 123 — 123 Sales (19 ) (10 ) (29 ) Settlements/maturities (66 ) — (66 ) Gross transfers into Level 3 19 — 19 Gross transfers out of Level 3 (96 ) — (96 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, 2016 184 36 220 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date — (2 ) (2 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities. (in millions) Fixed Other Total Balance at December 31, 2014 232 36 268 Total realized and unrealized investment gains (losses): Reported in net realized investment gains(1) 1 2 3 Reported in increases (decreases) in other comprehensive income (4 ) 1 (3 ) Purchases, sales and settlements/maturities: Purchases 202 1 203 Sales (7 ) (2 ) (9 ) Settlements/maturities (41 ) — (41 ) Gross transfers into Level 3 21 — 21 Gross transfers out of Level 3 (186 ) — (186 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at December 31, 2015 218 38 256 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date — (1 ) (1 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes impairments on investments held at the end of the period as well as amortization on fixed maturities.
Carrying value and fair value of financial instruments disclosed, but not carried, at fair value and the level within the fair value hierarchy at which such financial instruments are categorized [Table Text Block]	(at December 31, 2016, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets: Short-term securities 4,865 4,865 1,223 3,607 35 Financial liabilities: Debt 6,337 7,262 — 7,262 — Commercial paper 100 100 — 100 — (at December 31, 2015, in millions) Carrying Fair Level 1 Level 2 Level 3 Financial assets: Short-term securities 4,671 4,671 1,685 2,958 28 Financial liabilities: Debt 6,244 7,180 — 7,180 — Commercial paper 100 100 — 100 —

Reinsurance (tables)

Reinsurance (tables)	12 Months Ended
	Dec. 31, 2016
Reinsurance disclosure
Summary of reinsurance financial data [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Written premiums Direct 25,567 24,939 24,844 Assumed 928 843 788 Ceded (1,537 ) (1,661 ) (1,728 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net written premiums 24,958 24,121 23,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earned premiums Direct 25,262 24,740 24,810 Assumed 875 814 743 Ceded (1,603 ) (1,680 ) (1,840 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net earned premiums 24,534 23,874 23,713 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of assumed earned premiums to net earned premiums 3.6 % 3.4 % 3.1 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ceded claims and claim adjustment expenses incurred 762 1,034 953 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Reinsurance recoverables [Table Text Block]	(at December 31, in millions) 2016 2015 Gross reinsurance recoverables on paid and unpaid claims and claim adjustment expenses 3,181 3,848 Allowance for uncollectible reinsurance (116 ) (157 ) ​ ​ ​ ​ ​ ​ ​ Net reinsurance recoverables 3,065 3,691 Mandatory pools and associations 2,054 2,015 Structured settlements 3,168 3,204 ​ ​ ​ ​ ​ ​ ​ Total reinsurance recoverables 8,287 8,910 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Goodwill and Other Intangible38

Goodwill and Other Intangible Assets (tables)	12 Months Ended
	Dec. 31, 2016
Goodwill and Other Intangible Assets disclosure
Goodwill by segment [Table Text Block]	(at December 31, in millions) 2016 2015 Business and International Insurance(1) 2,446 2,439 Bond & Specialty Insurance 496 496 Personal Insurance 612 612 Other 26 26 ​ ​ ​ ​ ​ ​ ​ Total 3,580 3,573 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes goodwill associated with the Company's international business which is subject to the impact of changes in foreign currency exchange rates.
Other intangible assets subject to amortization [Table Text Block]	(at December 31, 2016, in millions) Gross Accumulated Net Subject to amortization(1) 210 159 51 Not subject to amortization 217 — 217 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 427 159 268 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (at December 31, 2015, in millions) Gross Accumulated Net Subject to amortization(1) 210 148 62 Not subject to amortization 217 — 217 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 427 148 279 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Intangible assets subject to amortization are comprised of fair value adjustments on claims and claim adjustment expense reserves, reinsurance recoverables and other contract and customer-related intangibles. Fair value adjustments recorded in connection with insurance acquisitions were based on management's estimate of nominal claims and claim adjustment expense reserves and reinsurance recoverables. The method used calculated a risk adjustment to a risk-free discounted reserve that would, if reserves ran off as expected, produce results that yielded the assumed cost-of-capital on the capital supporting the loss reserves. The fair value adjustments are reported as other intangible assets on the consolidated balance sheet, and the amounts measured in accordance with the acquirer's accounting policies for insurance contracts have been reported as part of the claims and claim adjustment expense reserves and reinsurance recoverables. The intangible assets are being recognized into income over the expected payment pattern. Because the time value of money and the risk adjustment (cost of capital) components of the intangible assets run off at different rates, the amount recognized in income may be a net benefit in some periods and a net expense in other periods.
Other intangible assets not subject to amortization [Table Text Block]	(at December 31, 2016, in millions) Gross Accumulated Net Subject to amortization(1) 210 159 51 Not subject to amortization 217 — 217 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 427 159 268 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (at December 31, 2015, in millions) Gross Accumulated Net Subject to amortization(1) 210 148 62 Not subject to amortization 217 — 217 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 427 148 279 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Intangible assets subject to amortization are comprised of fair value adjustments on claims and claim adjustment expense reserves, reinsurance recoverables and other contract and customer-related intangibles. Fair value adjustments recorded in connection with insurance acquisitions were based on management's estimate of nominal claims and claim adjustment expense reserves and reinsurance recoverables. The method used calculated a risk adjustment to a risk-free discounted reserve that would, if reserves ran off as expected, produce results that yielded the assumed cost-of-capital on the capital supporting the loss reserves. The fair value adjustments are reported as other intangible assets on the consolidated balance sheet, and the amounts measured in accordance with the acquirer's accounting policies for insurance contracts have been reported as part of the claims and claim adjustment expense reserves and reinsurance recoverables. The intangible assets are being recognized into income over the expected payment pattern. Because the time value of money and the risk adjustment (cost of capital) components of the intangible assets run off at different rates, the amount recognized in income may be a net benefit in some periods and a net expense in other periods.

Insurance Claim Reserves (table

Insurance Claim Reserves (tables)	12 Months Ended
	Dec. 31, 2016
Insurance Claim Reserves disclosure
Claims and claim adjustment expense reserves [Table Text Block]	(at December 31, in millions) 2016 2015 Property-casualty 47,929 48,272 Accident and health 20 23 ​ ​ ​ ​ ​ ​ ​ Total 47,949 48,295 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Reconciliation of beginning and ending property casualty reserve balances for claims and claim adjustment expenses [Table Text Block]	(at and for the year ended December 31, in millions) 2016 2015 2014 Claims and claim adjustment expense reserves at beginning of year 48,272 49,824 50,865 Less reinsurance recoverables on unpaid losses 8,449 8,788 9,280 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net reserves at beginning of year 39,823 41,036 41,585 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Estimated claims and claim adjustment expenses for claims arising in the current year 15,675 14,471 14,688 Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (680 ) (817 ) (885 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total increases 14,995 13,654 13,803 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and claim adjustment expense payments for claims arising in: Current year 6,220 5,725 5,895 Prior years 8,576 8,749 8,171 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total payments 14,796 14,474 14,066 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Acquisition(1) — 2 — Unrealized foreign exchange gain (74 ) (395 ) (286 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net reserves at end of year 39,948 39,823 41,036 Plus reinsurance recoverables on unpaid losses 7,981 8,449 8,788 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and claim adjustment expense reserves at end of year 47,929 48,272 49,824 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Amount represents acquired net claims and claim adjustment expense reserves of Travelers Participações em Seguros Brasil S.A. at October 1, 2015.
Summary of claims and claim adjustment expense reserves, including certain components, for the Company's major product lines by reporting segment [Table Text Block]	At December 31, 2016 (in millions) Net Undiscounted Discount Subtotal: Reinsurance Claims and Business and International Insurance General liability 7,034 (168 ) 6,866 712 7,578 Commercial property 866 — 866 194 1,060 Commercial multi-peril 3,414 — 3,414 81 3,495 Commercial automobile 2,270 — 2,270 256 2,526 Workers' compensation(1) 15,439 (832 ) 14,607 729 15,336 International—Canada 1,482 — 1,482 157 1,639 Bond & Specialty Insurance General liability 2,042 — 2,042 82 2,124 Fidelity and surety 450 — 450 17 467 Personal Insurance Automobile 2,277 — 2,277 465 2,742 Homeowners (excluding Other) 742 — 742 2 744 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal—claims and allocated claim adjustment expenses for the products presented in the development tables below 36,016 (1,000 ) 35,016 2,695 37,711 Other insurance contracts(2) 2,955 (3 ) 2,952 2,058 5,010 Unallocated loss adjustment expense reserves 1,936 — 1,936 40 1,976 Structured settlements(3) — — — 3,168 3,168 Other 44 — 44 20 64 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total property-casualty 40,951 (1,003 ) 39,948 7,981 47,929 Accident and health — — — 20 20 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 40,951 (1,003 ) 39,948 8,001 47,949 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Net discount amount includes discount of $80 million on reinsurance recoverables for long-term disability and annuity claim payments. (2) Primarily includes residual market, non-Canadian international and runoff assumed reinsurance business. (3) Includes structured settlements in cases where the Company did not receive a release from the claimant.
Allocated claim adjustment expense, by accident year, on a historical basis for incurred and paid claims on an undiscounted, net of reinsurance basis [Table Text Block]	Business and International Insurance General Liability (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,136 1,162 1,087 1,089 968 919 888 883 865 824 78 23,840 2008 1,143 1,209 1,222 1,079 1,041 994 946 931 935 88 25,385 1,060 1,071 1,028 960 869 837 809 796 95 25,457 2010 1,028 1,031 1,021 959 927 912 918 108 27,678 1,004 1,074 1,065 998 972 935 146 27,210 2012 989 985 935 913 892 184 24,384 965 975 958 940 256 21,836 2014 976 989 983 438 20,926 998 956 592 18,771 2016 1,075 908 13,810 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 9,254 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 32 134 316 467 549 632 682 697 713 726 2008 35 154 359 497 615 694 734 759 799 35 167 314 446 543 613 643 667 2010 35 139 324 487 629 702 756 Liability for Claims 2011 47 187 355 539 660 725 And Allocated Claim 2012 32 150 295 489 589 Adjustment Expenses, 2013 35 175 363 498 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 37 163 321 36 137 2007 - Before 2016 35 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,253 4,001 3,033 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 3.9 % 13.3 % 19.1 % 17.6 % 12.4 % 8.4 % 5.0 % 2.5 % 3.1 % 1.6 % Commercial Property (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,054 988 924 889 895 13 28,183 2013 789 755 737 731 10 22,141 936 860 836 15 21,490 2015 786 750 28 19,859 896 131 19,327 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 4,108 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 453 770 845 865 872 Adjustment Expenses, 2013 389 610 683 703 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 464 710 775 2015 376 615 2012 - Before 2016 441 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,406 702 164 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 51.7 % 31.8 % 8.7 % 2.5 % 0.8 % Commercial Multi-Peril (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,490 1,430 1,364 1,402 1,398 1,375 1,373 1,369 1,376 1,369 51 96,767 2008 1,725 1,674 1,683 1,688 1,674 1,684 1,674 1,688 1,681 47 108,382 1,484 1,506 1,501 1,498 1,511 1,514 1,514 1,509 42 103,198 2010 1,711 1,826 1,832 1,861 1,895 1,892 1,898 51 111,586 2,235 2,244 2,269 2,286 2,296 2,287 66 125,358 2012 1,885 1,883 1,903 1,888 1,888 88 104,419 1,615 1,623 1,620 1,609 122 82,936 2014 1,663 1,627 1,625 193 76,833 1,568 1,625 354 68,278 2016 1,662 658 56,471 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 17,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 498 824 982 1,110 1,208 1,256 1,278 1,296 1,307 1,312 2008 712 1,103 1,264 1,396 1,490 1,551 1,581 1,602 1,617 603 958 1,121 1,264 1,360 1,408 1,436 1,449 2010 709 1,180 1,395 1,579 1,698 1,763 1,798 Liability for Claims 2011 1,060 1,573 1,803 1,979 2,088 2,156 And Allocated Claim 2012 795 1,246 1,424 1,590 1,699 Adjustment Expenses, 2013 644 987 1,167 1,304 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 628 956 1,154 595 970 2007 - Before 2016 585 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 14,044 3,109 305 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 39.5 % 22.9 % 10.8 % 8.8 % 6.0 % 3.3 % 1.8 % 1.1 % 0.9 % 0.4 % Commercial Automobile (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,294 1,350 1,327 1,325 1,337 35 214,780 2013 1,235 1,236 1,240 1,245 67 197,041 1,165 1,166 1,168 131 184,067 2015 1,198 1,215 246 179,963 1,290 516 173,790 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 6,255 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 467 753 960 1,134 1,235 Adjustment Expenses, 2013 435 675 884 1,039 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 397 618 821 2015 409 658 2012 - Before 2016 416 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 4,169 2,086 184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 34.0 % 20.0 % 16.6 % 12.7 % 7.6 % Workers' Compensation (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,554 1,519 1,484 1,448 1,390 1,373 1,358 1,340 1,328 1,341 217 103,064 2008 1,714 1,745 1,734 1,683 1,639 1,634 1,621 1,617 1,617 237 107,565 1,799 1,778 1,746 1,753 1,753 1,766 1,775 1,750 272 104,229 2010 1,886 2,042 2,035 2,056 2,049 2,052 2,055 354 116,837 2,284 2,303 2,347 2,350 2,379 2,385 430 135,061 2012 2,447 2,456 2,457 2,456 2,445 519 133,417 2,553 2,545 2,540 2,506 651 128,111 2014 2,554 2,553 2,547 839 123,110 2,644 2,585 1,142 120,681 2016 2,768 1,651 108,357 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 21,999 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 216 450 589 683 747 802 845 880 910 936 2008 274 571 752 875 961 1,036 1,088 1,130 1,162 288 623 828 961 1,065 1,137 1,193 1,235 2010 341 750 978 1,133 1,246 1,321 1,385 Liability for Claims 2011 420 911 1,185 1,365 1,487 1,583 And Allocated Claim 2012 443 940 1,217 1,394 1,536 Adjustment Expenses, 2013 458 954 1,237 1,413 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 455 944 1,224 430 893 2007 - Before 2016 421 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,788 10,211 5,228 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 17.0 % 19.2 % 11.2 % 7.4 % 5.4 % 4.1 % 3.2 % 2.5 % 2.1 % 1.9 % International—Canada (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 632 626 616 608 607 609 611 608 601 597 4 66,327 2008 681 685 670 665 658 655 651 646 642 5 71,803 724 718 707 714 714 702 696 690 13 71,671 2010 715 722 721 735 724 715 706 20 71,437 723 696 686 682 678 669 30 72,063 2012 664 642 631 611 616 50 67,320 723 717 701 685 56 71,183 2014 665 678 682 83 67,935 597 610 112 58,238 2016 612 102 54,948 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 6,509 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 228 355 410 450 488 524 547 561 570 578 2008 256 406 460 501 543 579 603 616 622 274 419 479 525 573 608 630 648 2010 258 403 465 522 573 615 641 Liability for Claims 2011 253 380 432 481 538 571 And Allocated Claim 2012 225 336 389 435 482 Adjustment Expenses, 2013 260 388 439 494 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 252 382 445 228 346 2007 - Before 2016 295 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,122 1,387 95 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 38.9 % 20.0 % 8.5 % 7.2 % 7.2 % 5.5 % 3.6 % 2.3 % 1.2 % 1.4 % The incurred and paid amounts have been translated from the local currency to U.S. dollars using the December 31, 2016 spot rate for all years presented in the table above in order to isolate changes in foreign exchange rates from loss development. General Liability (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 584 571 638 582 551 511 479 467 462 454 4 11,018 2008 579 769 743 697 716 712 672 643 631 24 6,463 592 624 665 686 680 660 655 641 24 6,287 2010 571 612 679 679 661 668 653 18 5,655 565 596 639 632 601 545 34 5,191 2012 538 591 614 605 601 137 4,824 510 565 606 630 204 4,371 2014 549 571 563 232 4,182 528 524 272 3,814 2016 512 405 2,676 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,754 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 35 134 229 303 357 373 393 400 410 415 2008 47 157 281 387 471 529 562 579 590 36 167 310 390 460 497 563 592 2010 33 152 291 396 482 565 597 Liability for Claims 2011 33 143 249 324 414 447 And Allocated Claim 2012 38 160 255 342 383 Adjustment Expenses, 2013 34 154 252 352 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 38 150 239 38 141 2007 - Before 2016 30 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,786 1,968 74 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 6.3 % 19.7 % 18.8 % 15.1 % 12.1 % 7.5 % 6.2 % 3.0 % 1.9 % 1.1 % Fidelity and Surety (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 255 262 249 175 140 9 1,148 2013 240 246 199 146 6 1,006 223 212 165 32 992 2015 217 191 79 768 226 128 595 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 868 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 42 108 124 110 111 Adjustment Expenses, 2013 37 113 128 131 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 58 96 111 2015 32 75 2012 - Before 2016 54 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 482 386 64 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 26.1 % 36.2 % 10.1 % (3.6)%(1 ) 0.8 % (1) Includes recovery activity. Automobile (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,417 2,454 2,448 2,432 2,428 15 793,669 2013 2,108 2,095 2,049 2,044 36 694,650 2,014 1,994 1,981 75 669,990 2015 2,186 2,244 224 755,762 2,779 646 839,962 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,476 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 1,503 1,983 2,189 2,311 2,376 Adjustment Expenses, 2013 1,251 1,628 1,814 1,935 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 1,193 1,564 1,763 2015 1,319 1,768 2012 - Before 2016 1,610 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 9,452 2,024 253 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 60.0 % 19.2 % 9.2 % 5.5 % 2.7 % Homeowners (excluding Other) (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,136 2,056 2,029 2,018 2,019 1 259,006 2013 1,488 1,397 1,365 1,375 4 149,373 1,515 1,450 1,453 9 151,517 2015 1,438 1,454 28 144,367 1,556 307 129,630 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 7,857 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 1,508 1,901 1,964 1,993 2,008 Adjustment Expenses, 2013 994 1,269 1,317 1,344 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 1,053 1,338 1,402 2015 994 1,333 2012 - Before 2016 1,049 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 7,136 721 21 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 71.1 % 20.6 % 3.7 % 1.7 % 0.7 %
Historical average annual percentage payout of incurred claims by age of accident year [Table Text Block]	Business and International Insurance General Liability (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,136 1,162 1,087 1,089 968 919 888 883 865 824 78 23,840 2008 1,143 1,209 1,222 1,079 1,041 994 946 931 935 88 25,385 1,060 1,071 1,028 960 869 837 809 796 95 25,457 2010 1,028 1,031 1,021 959 927 912 918 108 27,678 1,004 1,074 1,065 998 972 935 146 27,210 2012 989 985 935 913 892 184 24,384 965 975 958 940 256 21,836 2014 976 989 983 438 20,926 998 956 592 18,771 2016 1,075 908 13,810 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 9,254 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 32 134 316 467 549 632 682 697 713 726 2008 35 154 359 497 615 694 734 759 799 35 167 314 446 543 613 643 667 2010 35 139 324 487 629 702 756 Liability for Claims 2011 47 187 355 539 660 725 And Allocated Claim 2012 32 150 295 489 589 Adjustment Expenses, 2013 35 175 363 498 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 37 163 321 36 137 2007 - Before 2016 35 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,253 4,001 3,033 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 3.9 % 13.3 % 19.1 % 17.6 % 12.4 % 8.4 % 5.0 % 2.5 % 3.1 % 1.6 % Commercial Property (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,054 988 924 889 895 13 28,183 2013 789 755 737 731 10 22,141 936 860 836 15 21,490 2015 786 750 28 19,859 896 131 19,327 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 4,108 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 453 770 845 865 872 Adjustment Expenses, 2013 389 610 683 703 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 464 710 775 2015 376 615 2012 - Before 2016 441 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,406 702 164 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 51.7 % 31.8 % 8.7 % 2.5 % 0.8 % Commercial Multi-Peril (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,490 1,430 1,364 1,402 1,398 1,375 1,373 1,369 1,376 1,369 51 96,767 2008 1,725 1,674 1,683 1,688 1,674 1,684 1,674 1,688 1,681 47 108,382 1,484 1,506 1,501 1,498 1,511 1,514 1,514 1,509 42 103,198 2010 1,711 1,826 1,832 1,861 1,895 1,892 1,898 51 111,586 2,235 2,244 2,269 2,286 2,296 2,287 66 125,358 2012 1,885 1,883 1,903 1,888 1,888 88 104,419 1,615 1,623 1,620 1,609 122 82,936 2014 1,663 1,627 1,625 193 76,833 1,568 1,625 354 68,278 2016 1,662 658 56,471 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 17,153 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 498 824 982 1,110 1,208 1,256 1,278 1,296 1,307 1,312 2008 712 1,103 1,264 1,396 1,490 1,551 1,581 1,602 1,617 603 958 1,121 1,264 1,360 1,408 1,436 1,449 2010 709 1,180 1,395 1,579 1,698 1,763 1,798 Liability for Claims 2011 1,060 1,573 1,803 1,979 2,088 2,156 And Allocated Claim 2012 795 1,246 1,424 1,590 1,699 Adjustment Expenses, 2013 644 987 1,167 1,304 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 628 956 1,154 595 970 2007 - Before 2016 585 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 14,044 3,109 305 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 39.5 % 22.9 % 10.8 % 8.8 % 6.0 % 3.3 % 1.8 % 1.1 % 0.9 % 0.4 % Commercial Automobile (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,294 1,350 1,327 1,325 1,337 35 214,780 2013 1,235 1,236 1,240 1,245 67 197,041 1,165 1,166 1,168 131 184,067 2015 1,198 1,215 246 179,963 1,290 516 173,790 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 6,255 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 467 753 960 1,134 1,235 Adjustment Expenses, 2013 435 675 884 1,039 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 397 618 821 2015 409 658 2012 - Before 2016 416 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 4,169 2,086 184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 34.0 % 20.0 % 16.6 % 12.7 % 7.6 % Workers' Compensation (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,554 1,519 1,484 1,448 1,390 1,373 1,358 1,340 1,328 1,341 217 103,064 2008 1,714 1,745 1,734 1,683 1,639 1,634 1,621 1,617 1,617 237 107,565 1,799 1,778 1,746 1,753 1,753 1,766 1,775 1,750 272 104,229 2010 1,886 2,042 2,035 2,056 2,049 2,052 2,055 354 116,837 2,284 2,303 2,347 2,350 2,379 2,385 430 135,061 2012 2,447 2,456 2,457 2,456 2,445 519 133,417 2,553 2,545 2,540 2,506 651 128,111 2014 2,554 2,553 2,547 839 123,110 2,644 2,585 1,142 120,681 2016 2,768 1,651 108,357 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 21,999 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 216 450 589 683 747 802 845 880 910 936 2008 274 571 752 875 961 1,036 1,088 1,130 1,162 288 623 828 961 1,065 1,137 1,193 1,235 2010 341 750 978 1,133 1,246 1,321 1,385 Liability for Claims 2011 420 911 1,185 1,365 1,487 1,583 And Allocated Claim 2012 443 940 1,217 1,394 1,536 Adjustment Expenses, 2013 458 954 1,237 1,413 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 455 944 1,224 430 893 2007 - Before 2016 421 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,788 10,211 5,228 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 17.0 % 19.2 % 11.2 % 7.4 % 5.4 % 4.1 % 3.2 % 2.5 % 2.1 % 1.9 % International—Canada (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 632 626 616 608 607 609 611 608 601 597 4 66,327 2008 681 685 670 665 658 655 651 646 642 5 71,803 724 718 707 714 714 702 696 690 13 71,671 2010 715 722 721 735 724 715 706 20 71,437 723 696 686 682 678 669 30 72,063 2012 664 642 631 611 616 50 67,320 723 717 701 685 56 71,183 2014 665 678 682 83 67,935 597 610 112 58,238 2016 612 102 54,948 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 6,509 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 228 355 410 450 488 524 547 561 570 578 2008 256 406 460 501 543 579 603 616 622 274 419 479 525 573 608 630 648 2010 258 403 465 522 573 615 641 Liability for Claims 2011 253 380 432 481 538 571 And Allocated Claim 2012 225 336 389 435 482 Adjustment Expenses, 2013 260 388 439 494 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 252 382 445 228 346 2007 - Before 2016 295 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,122 1,387 95 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 38.9 % 20.0 % 8.5 % 7.2 % 7.2 % 5.5 % 3.6 % 2.3 % 1.2 % 1.4 % The incurred and paid amounts have been translated from the local currency to U.S. dollars using the December 31, 2016 spot rate for all years presented in the table above in order to isolate changes in foreign exchange rates from loss development. General Liability (dollars in millions) For the Years Ended December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 584 571 638 582 551 511 479 467 462 454 4 11,018 2008 579 769 743 697 716 712 672 643 631 24 6,463 592 624 665 686 680 660 655 641 24 6,287 2010 571 612 679 679 661 668 653 18 5,655 565 596 639 632 601 545 34 5,191 2012 538 591 614 605 601 137 4,824 510 565 606 630 204 4,371 2014 549 571 563 232 4,182 528 524 272 3,814 2016 512 405 2,676 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 5,754 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year 35 134 229 303 357 373 393 400 410 415 2008 47 157 281 387 471 529 562 579 590 36 167 310 390 460 497 563 592 2010 33 152 291 396 482 565 597 Liability for Claims 2011 33 143 249 324 414 447 And Allocated Claim 2012 38 160 255 342 383 Adjustment Expenses, 2013 34 154 252 352 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 38 150 239 38 141 2007 - Before 2016 30 2016 2007 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,786 1,968 74 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Unaudited Years 1 2 3 4 5 6 7 8 9 10 6.3 % 19.7 % 18.8 % 15.1 % 12.1 % 7.5 % 6.2 % 3.0 % 1.9 % 1.1 % Fidelity and Surety (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 255 262 249 175 140 9 1,148 2013 240 246 199 146 6 1,006 223 212 165 32 992 2015 217 191 79 768 226 128 595 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 868 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 42 108 124 110 111 Adjustment Expenses, 2013 37 113 128 131 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 58 96 111 2015 32 75 2012 - Before 2016 54 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 482 386 64 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 26.1 % 36.2 % 10.1 % (3.6)%(1 ) 0.8 % (1) Includes recovery activity. Automobile (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,417 2,454 2,448 2,432 2,428 15 793,669 2013 2,108 2,095 2,049 2,044 36 694,650 2,014 1,994 1,981 75 669,990 2015 2,186 2,244 224 755,762 2,779 646 839,962 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 11,476 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 1,503 1,983 2,189 2,311 2,376 Adjustment Expenses, 2013 1,251 1,628 1,814 1,935 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 1,193 1,564 1,763 2015 1,319 1,768 2012 - Before 2016 1,610 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 9,452 2,024 253 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 60.0 % 19.2 % 9.2 % 5.5 % 2.7 % Homeowners (excluding Other) (dollars in millions) For the Years Ended December 31, 2012 2013 2014 2015 2016 Incurred Claims and Allocated Claims Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ IBNR Cumulative Reserves Number of Dec. 31, Reported Accident Year 2016 Claims ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,136 2,056 2,029 2,018 2,019 1 259,006 2013 1,488 1,397 1,365 1,375 4 149,373 1,515 1,450 1,453 9 151,517 2015 1,438 1,454 28 144,367 1,556 307 129,630 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 7,857 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Paid Claims and Allocated Claim Unaudited ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accident Year Liability for Claims 1,508 1,901 1,964 1,993 2,008 Adjustment Expenses, 2013 994 1,269 1,317 1,344 Net of Reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 1,053 1,338 1,402 2015 994 1,333 2012 - Before 2016 1,049 2016 2012 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 7,136 721 21 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Annual Percentage Payout of Unaudited Years 1 2 3 4 5 71.1 % 20.6 % 3.7 % 1.7 % 0.7 %

Debt (tables)

Debt (tables)	12 Months Ended
	Dec. 31, 2016
Debt disclosure
Debt outstanding [Table Text Block]	(at December 31, in millions) 2016 2015 Short-term: Commercial paper 100 100 5.75% Senior notes due December 15, 2017 450 — 6.25% Senior notes due June 20, 2016 — 400 ​ ​ ​ ​ ​ ​ ​ Total short-term debt 550 500 ​ ​ ​ ​ ​ ​ ​ Long-term: 5.75% Senior notes due December 15, 2017 — 450 5.80% Senior notes due May 15, 2018 500 500 5.90% Senior notes due June 2, 2019 500 500 3.90% Senior notes due November 1, 2020 500 500 7.75% Senior notes due April 15, 2026 200 200 7.625% Junior subordinated debentures due December 15, 2027 125 125 6.375% Senior notes due March 15, 2033 500 500 6.75% Senior notes due June 20, 2036 400 400 6.25% Senior notes due June 15, 2037 800 800 5.35% Senior notes due November 1, 2040 750 750 4.60% Senior notes due August 1, 2043 500 500 4.30% Senior notes due August 25, 2045 400 400 8.50% Junior subordinated debentures due December 15, 2045 56 56 3.75% Senior notes dues May 15, 2046 500 — 8.312% Junior subordinated debentures due July 1, 2046 73 73 6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 107 107 ​ ​ ​ ​ ​ ​ ​ Total long-term debt 5,911 5,861 ​ ​ ​ ​ ​ ​ ​ Total debt principal 6,461 6,361 Unamortized fair value adjustment 47 49 Unamortized debt issuance costs (71 ) (66 ) ​ ​ ​ ​ ​ ​ ​ Total debt 6,437 6,344 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Merger-related unamortized fair value adjustments and the related effective interest rate [Table Text Block]	Unamortized Effective (in millions) Issue Rate Maturity Date 2016 2015 Subordinated debentures 7.625 % Dec. 2027 14 15 6.147 % 8.500 % Dec. 2045 15 15 6.362 % 8.312 % Jul. 2046 18 19 6.362 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 47 49 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Shareholders' Equity and Divi41

Shareholders' Equity and Dividend Availability (table)	12 Months Ended
	Dec. 31, 2016
Shareholders' Equity and Dividend Availability disclosure
Share repurchase activity and remaining repurchase capacity under the share repurchase authorization [Table Text Block]	(in millions, except per share amounts) Number of Cost of Average price Remaining capacity March 31, 2016 5.1 550 108.46 2,784 June 30, 2016 4.9 550 112.12 2,234 September 30, 2016 4.7 550 117.25 1,684 December 31, 2016 6.6 750 113.54 934 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 21.3 2,400 112.82 934 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Other Comprehensive Income an42

Other Comprehensive Income and Accumulated Other Comprehensive Income (tables)	12 Months Ended
	Dec. 31, 2016
Other Comprehensive Income and Accumulated Other Comprehensive Income disclosure
Changes in accumulated other comprehensive income (AOCI) [Table Text Block]	Changes in Net Unrealized Gains on Net Benefit Plan Net Total (in millions) Having No Credit Having Credit Losses Balance, December 31, 2013 1,125 197 (431 ) (81 ) 810 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) (OCI) before reclassifications 667 (2 ) (363 ) (250 ) 52 Amounts reclassified from AOCI (24 ) 3 39 — 18 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net OCI, current period 643 1 (324 ) (250 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2014 1,768 198 (755 ) (331 ) 880 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ OCI before reclassifications (641 ) (11 ) (18 ) (419 ) (1,089 ) Amounts reclassified from AOCI (27 ) 2 60 17 52 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net OCI, current period (668 ) (9 ) 42 (402 ) (1,037 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2015 1,100 189 (713 ) (733 ) (157 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ OCI before reclassifications (530 ) 4 (30 ) (49 ) (605 ) Amounts reclassified from AOCI (42 ) 9 40 — 7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net OCI, current period (572 ) 13 10 (49 ) (598 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2016 528 202 (703 ) (782 ) (755 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit) for each component [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (883 ) (1,020 ) 976 Income tax expense (benefit) (311 ) (352 ) 333 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes (572 ) (668 ) 643 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Having credit losses recognized in the consolidated statement of income 21 (14 ) 2 Income tax expense (benefit) 8 (5 ) 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 13 (9 ) 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net changes in benefit plan assets and obligations 16 66 (494 ) Income tax expense (benefit) 6 24 (170 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 10 42 (324 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net changes in unrealized foreign currency translation (41 ) (461 ) (289 ) Income tax expense (benefit) 8 (59 ) (39 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes (49 ) (402 ) (250 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income (loss) (887 ) (1,429 ) 195 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense (benefit) (289 ) (392 ) 125 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income (loss), net of taxes (598 ) (1,037 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Pre-tax components of the amounts reclassified from accumulated other comprehensive income and the related income tax (expense) benefit for each component [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Reclassification adjustments related to unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income(1) (64 ) (42 ) (36 ) Income tax expense(2) (22 ) (15 ) (12 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes (42 ) (27 ) (24 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Having credit losses recognized in the consolidated statement of income(1) 13 2 4 Income tax benefit(2) 4 — 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 9 2 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment related to benefit plan assets and obligations(3) 62 93 60 Income tax benefit(2) 22 33 21 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes 40 60 39 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment related to foreign currency translation(1) — 26 — Income tax benefit(2) — 9 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net of taxes — 17 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total reclassifications 11 79 28 Total income tax benefit 4 27 10 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total reclassifications, net of taxes 7 52 18 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) (Increases) decreases net realized investment gains on the consolidated statement of income. (2) (Increases) decreases income tax expense on the consolidated statement of income. (3) Increases (decreases) general and administrative expenses on the consolidated statement of income.

Earnings per Share (table)

Earnings per Share (table)	12 Months Ended
	Dec. 31, 2016
Earnings per Share disclosure
Earnings per share reconciliation [Table Text Block]	(for the year ended December 31, in millions, except per share amounts) 2016 2015 2014 Basic and Diluted Net income, as reported 3,014 3,439 3,692 Participating share-based awards—allocated income (22 ) (25 ) (27 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common shareholders—basic and diluted 2,992 3,414 3,665 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common Shares Basic Weighted average shares outstanding 288.1 310.6 338.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted Weighted average shares outstanding 288.1 310.6 338.8 Weighted average effects of dilutive securities: Stock options and performance shares 2.9 3.3 3.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 291.0 313.9 342.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income Per Common Share Basic 10.39 10.99 10.82 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted 10.28 10.88 10.70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes (tables)

Income Taxes (tables)	12 Months Ended
	Dec. 31, 2016
Income Taxes disclosure
Composition of income tax expense included in consolidated statement of income and shareholders' equity [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Composition of income tax expense included in the consolidated statement of income Current expense: Federal 899 1,144 1,216 Foreign 21 29 28 State 8 9 10 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total current tax expense 928 1,182 1,254 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred expense: Federal 110 117 121 Foreign 1 2 22 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax expense 111 119 143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense included in the consolidated statement of income 1,039 1,301 1,397 Composition of income tax expense (benefit) included in shareholders' equity Expense (benefit) relating to share-based compensation, the changes in unrealized gain on investments, unrealized loss on foreign exchange and other items in other comprehensive income (289 ) (448 ) 68 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense included in the consolidated financial statements 750 853 1,465 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Effective tax rate [Table Text Block]	(for the year ended December 31, in millions) 2016 2015 2014 Income before income taxes U.S. 3,946 4,621 4,899 Foreign 107 119 190 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income before income taxes 4,053 4,740 5,089 Effective tax rate Statutory tax rate 35 % 35 % 35 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Expected federal income tax expense 1,419 1,659 1,781 Tax effect of: Nontaxable investment income (323 ) (345 ) (379 ) Other, net (57 ) (13 ) (5 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income tax expense 1,039 1,301 1,397 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective tax rate 26 % 27 % 27 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Deferred tax assets and liabilities [Table Text Block]	(at December 31, in millions) 2016 2015 Deferred tax assets Claims and claim adjustment expense reserves 664 691 Unearned premium reserves 760 731 Compensation-related liabilities 268 326 Other 272 320 ​ ​ ​ ​ ​ ​ ​ Total gross deferred tax assets 1,964 2,068 Less: valuation allowance 3 — ​ ​ ​ ​ ​ ​ ​ Adjusted gross deferred tax assets 1,961 2,068 ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities Deferred acquisition costs 604 580 Investments 592 867 Internally developed software 157 134 Other 143 191 ​ ​ ​ ​ ​ ​ ​ Total gross deferred tax liabilities 1,496 1,772 ​ ​ ​ ​ ​ ​ ​ Net deferred tax asset 465 296 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Net operating loss amounts by jurisdiction and year of expiration [Table Text Block]	(in millions) Amount Year of Brazil 8 None United Kingdom 106 None
Reconciliation of unrecognized tax benefits [Table Text Block]	(in millions) 2016 2015 Balance at January 1 16 23 Additions for tax positions of prior years 3 2 Reductions for tax positions of prior years (6 ) (9 ) Additions based on tax positions related to current year — — ​ ​ ​ ​ ​ ​ ​ Balance at December 31 13 16 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Share-Based Incentive Compens45

Share-Based Incentive Compensation (tables)	12 Months Ended
	Dec. 31, 2016
Share-Based Incentive Compensation disclosure
Assumptions used in estimating fair value of options on grant date [Table Text Block]	(for the year ended December 31,) 2016 2015 2014 Assumptions used in estimating fair value of options on grant date Expected term of stock options 5 - 6 years 6 years 6 years Expected volatility of Company's stock 15.14% - 16.80% 19.29% 27.2% - 27.5% Weighted average volatility 16.79% 19.29% 27.5% Expected annual dividend per share $2.44 - $2.68 $2.20 $2.00 - $2.20 Risk-free rate 1.36% - 2.23% 1.31% 1.81% - 1.82%
Additional information regarding option grants [Table Text Block]	(for the year ended December 31,) 2016 2015 2014 Additional information Weighted average grant-date fair value of options granted (per share) $13.29 $15.78 $17.22 Total intrinsic value of options exercised during the year (in millions) $167 $120 $117 ​ ​ ​
Summary of stock option activity under the Company's 2014 Incentive Plan and legacy share-based incentive compensation plans [Table Text Block]	Stock Options Number Weighted Weighted Aggregate Outstanding, beginning of year 9,864,255 74.48 Original grants 2,847,398 106.21 Exercised (4,069,532 ) 69.13 Forfeited or expired (82,085 ) 97.44 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding, end of year 8,560,036 87.36 6.8 years 300 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vested at end of year(1) 5,588,061 80.74 6.0 years 233 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercisable at end of year 3,007,663 65.18 4.2 years 172 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Represents awards for which the requisite service has been rendered, including those that are retirement eligible.
Summary of restricted stock units, deferred stock units and performance share activity [Table Text Block]	Restricted and Deferred Stock Performance Shares Other Equity Instruments Number Weighted Average Number Weighted Average Nonvested, beginning of year 1,435,958 88.35 1,101,989 91.27 Granted 676,736 106.93 476,411 106.03 Vested (667,650 ) (1) 86.85 (818,360 ) (2) 84.43 Forfeited (68,552 ) 97.82 (63,495 ) 100.02 Performance-based adjustment — — 100,073 (3) 88.22 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nonvested, end of year 1,376,492 97.75 796,618 106.03 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Represents awards for which the requisite service has been rendered. (2) Reflects the number of performance shares attributable to the performance goals attained over the completed performance period (three years) and for which service conditions have been met. (3) Represents the current year change in estimated performance shares to reflect the attainment of performance goals for the awards that were granted in each of the years 2014 through 2016.

Pension Plans, Retirement Ben46

Pension Plans, Retirement Benefits and Savings Plans (tables)	12 Months Ended
	Dec. 31, 2016
Pension Plans, Retirement Benefits and Savings Plans disclosure
Summary of the funded status, obligations and amounts recognized in the consolidated balance sheet for the Company's benefit plans [Table Text Block]	Qualified Nonqualified Total (at and for the year ended December 31, in millions) 2016 2015 2016 2015 2016 2015 Change in projected benefit obligation: Benefit obligation at beginning of year 3,250 3,385 228 227 3,478 3,612 Benefits earned 111 124 7 7 118 131 Interest cost on benefit obligation 114 135 8 9 122 144 Actuarial loss (gain) 54 (203 ) 15 2 69 (201 ) Benefits paid (162 ) (191 ) (15 ) (8 ) (177 ) (199 ) Settlement — — (3 ) — (3 ) — Foreign currency exchange rate change — — (15 ) (9 ) (15 ) (9 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at end of year 3,367 3,250 225 228 3,592 3,478 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in plan assets: Fair value of plan assets at beginning of year 3,127 3,235 115 122 3,242 3,357 Actual return on plan assets 222 (17 ) 11 3 233 (14 ) Company contributions 200 100 14 7 214 107 Benefits paid (162 ) (191 ) (15 ) (8 ) (177 ) (199 ) Settlement — — (3 ) — (3 ) — Foreign currency exchange rate change — — (16 ) (9 ) (16 ) (9 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year 3,387 3,127 106 115 3,493 3,242 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Funded status of plan at end of year 20 (123 ) (119 ) (113 ) (99 ) (236 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in the consolidated balance sheet consist of: Accrued over-funded benefit plan assets 20 — 5 4 25 4 Accrued under-funded benefit plan liabilities — (123 ) (124 ) (117 ) (124 ) (240 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 20 (123 ) (119 ) (113 ) (99 ) (236 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive income consist of: Net actuarial loss 1,072 1,079 55 52 1,127 1,131 Prior service benefit (6 ) (8 ) — — (6 ) (8 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 1,066 1,071 55 52 1,121 1,123 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Postretirement (at and for the year ended December 31, in millions) 2016 2015 Change in projected benefit obligation: Benefit obligation at beginning of year 233 255 Benefits earned — — Interest cost on benefit obligation 8 10 Actuarial gain (17 ) (3 ) Benefits paid (11 ) (13 ) Plan amendments — (11 ) Foreign currency exchange rate change 1 (5 ) ​ ​ ​ ​ ​ ​ ​ Benefit obligation at end of year 214 233 ​ ​ ​ ​ ​ ​ ​ Change in plan assets: Fair value of plan assets at beginning of year 15 16 Actual return on plan assets — — Company contributions 10 12 Benefits paid (11 ) (13 ) ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year 14 15 ​ ​ ​ ​ ​ ​ ​ Funded status of plan at end of year (200 ) (218 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in the consolidated balance sheet consist of: Accrued under-funded benefit plan liability (200 ) (218 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive income consist of: Net actuarial (gain) loss (13 ) 4 Prior service benefit (31 ) (35 ) ​ ​ ​ ​ ​ ​ ​ Total (44 ) (31 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of the components of net periodic benefit cost and other amounts recognized in other comprehensive income related to the benefit plans [Table Text Block]	Pension Plans Postretirement (for the year ended December 31, in millions) 2016 2015 2014 2016 2015 2014 Net Periodic Benefit Cost: Service cost 118 131 110 — — — Interest cost on benefit obligation 122 144 150 8 10 10 Expected return on plan assets (230 ) (230 ) (218 ) — — — Curtailment — — (1 ) — — — Settlement 1 — 2 — — — Amortization of unrecognized: Prior service benefit (1 ) (1 ) — (3 ) (3 ) (2 ) Net actuarial loss (gain) 66 96 65 — 1 (3 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net periodic benefit cost 76 140 108 5 8 5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Changes in Benefit Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Prior service benefit — — (8 ) — (11 ) — Net actuarial loss (gain) 66 43 516 (17 ) (3 ) 50 Foreign currency exchange rate change (2 ) — — 1 — — Curtailment — — (2 ) — — — Settlement (1 ) — (2 ) — — — Amortization of prior service benefit 1 1 — 3 3 2 Amortization of net actuarial gain (loss) (66 ) (96 ) (65 ) — (1 ) 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other changes recognized in other comprehensive income (2 ) (52 ) 439 (13 ) (12 ) 55 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other changes recognized in net periodic benefit cost and other comprehensive income 74 88 547 (8 ) (4 ) 60 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Benefit obligations assumptions, net periodic benefit cost assumptions and health care cost trend rates [Table Text Block]	(at and for the year ended December 31,) 2016 2015 Assumptions used to determine benefit obligations Discount rate: Qualified domestic pension plan 4.23 % 4.50 % Nonqualified domestic pension plan 4.15 % 4.37 % Domestic postretirement benefit plan 4.10 % 4.35 % Future compensation increase rate 4.00 % 4.00 % Assumptions used to determine net periodic benefit cost Discount rate: Qualified domestic pension plan: Service cost 4.77 % 4.10 % Interest cost 3.64 % 4.10 % Nonqualified domestic pension plan: Service cost 4.53 % 4.10 % Interest cost 3.47 % 4.10 % Domestic postretirement benefit plan: Interest cost 3.53 % 4.10 % Expected long-term rate of return on assets: Pension plan 7.00 % 7.25 % Postretirement benefit plan 4.00 % 4.00 % Assumed health care cost trend rates Following year: Medical (before age 65) 6.50 % 6.75 % Medical (age 65 and older) 7.25 % 7.50 % Rate to which the cost trend rate is assumed to decline (ultimate trend rate) Year that the rate reaches the ultimate trend rate: Medical (before age 65) 2022 2022 Medical (age 65 and older) 2025 2025
Level within the fair value hierarchy at which the financial assets of the Company's pension plans are measured [Table Text Block]	(at December 31, 2016, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions 9 — 9 — Debt securities issued by foreign governments 14 — 14 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 12 — 12 — All other corporate bonds 511 — 511 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 546 — 546 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mutual funds Equity mutual funds 1,285 1,278 7 — Bond mutual funds 641 638 3 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total mutual funds 1,926 1,916 10 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities 747 747 — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments(1) 1 — — 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and short-term securities U.S. Treasury securities 45 45 — — Money market mutual funds 20 19 1 — Other 208 28 180 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and short-term securities 273 92 181 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,493 2,755 737 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value estimates of the two private equity funds comprising these investments are determined by an external fund manager based on recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the total fair value estimates are disclosed in Level 3. (at December 31, 2015, in millions) Total Level 1 Level 2 Level 3 Invested assets: Fixed maturities Obligations of states, municipalities and political subdivisions 17 — 17 — Debt securities issued by foreign governments 16 — 16 — Mortgage-backed securities, collateralized mortgage obligations and pass-through securities 16 — 16 — All other corporate bonds 491 — 491 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities 540 — 540 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mutual funds Equity mutual funds 1,237 1,231 6 — Bond mutual funds 649 646 3 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total mutual funds 1,886 1,877 9 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity securities 625 624 1 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other investments(1) 2 — — 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and short-term securities U.S. Treasury securities 25 25 — — Money market mutual funds 23 19 4 — Other 141 20 121 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and short-term securities 189 64 125 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total 3,242 2,565 675 2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value estimates of the two private equity funds comprising these investments are determined by an external fund manager based on recent filings, operating results, balance sheet stability, growth and other business and market sector fundamentals. Due to the significant unobservable inputs in these valuations, the total fair value estimates are disclosed in Level 3.
Estimated future benefit payments [Table Text Block]	Benefits Expected to be Paid (in millions) Pension Plans Postretirement 2017 230 13 2018 240 14 2019 247 14 2020 253 14 2021 258 14 2022 through 2026 1,327 71

Consolidating Financial State47

Consolidating Financial Statements (Unaudited) (tables)	12 Months Ended
	Dec. 31, 2016
Consolidating Financial Statements of The Travelers Companies, Inc. and Subsidiaries (Unaudited) disclosure
Consolidating Statement of Income (Unaudited) [Table Text Block]	CONSOLIDATING STATEMENT OF INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Revenues Premiums 16,788 7,746 — — 24,534 Net investment income 1,569 720 13 — 2,302 Fee income 458 — — — 458 Net realized investment gains (losses)(1) 30 39 (1 ) — 68 Other revenues 248 36 — (21 ) 263 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 19,093 8,541 12 (21 ) 27,625 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and expenses Claims and claim adjustment expenses 10,232 4,838 — — 15,070 Amortization of deferred acquisition costs 2,702 1,283 — — 3,985 General and administrative expenses 2,928 1,242 5 (21 ) 4,154 Interest expense 48 — 315 — 363 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total claims and expenses 15,910 7,363 320 (21 ) 23,572 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes 3,183 1,178 (308 ) — 4,053 Income tax expense (benefit) 999 208 (168 ) — 1,039 Net income of subsidiaries — — 3,154 (3,154 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 2,184 970 3,014 (3,154 ) 3,014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2016, and the amounts comprising total OTTI that were recognized in net realized investment gains (losses) and in other comprehensive income (OCI), were as follows: (in millions) TPC Other TRV Eliminations Consolidated Total OTTI losses (19 ) (20 ) (1 ) — (40 ) OTTI losses recognized in net realized investment gains (losses) (13 ) (15 ) (1 ) — (29 ) OTTI losses recognized in OCI (6 ) (5 ) — — (11 ) CONSOLIDATING STATEMENT OF INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Revenues Premiums 16,254 7,620 — — 23,874 Net investment income 1,612 760 7 — 2,379 Fee income 460 — — — 460 Net realized investment gains (losses)(1) 13 (11 ) 1 — 3 Other revenues 78 21 — — 99 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 18,417 8,390 8 — 26,815 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and expenses Claims and claim adjustment expenses 9,208 4,515 — — 13,723 Amortization of deferred acquisition costs 2,627 1,258 — — 3,885 General and administrative expenses 2,853 1,225 16 — 4,094 Interest expense 48 — 325 — 373 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total claims and expenses 14,736 6,998 341 — 22,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes 3,681 1,392 (333 ) — 4,740 Income tax expense (benefit) 1,015 394 (108 ) — 1,301 Net income of subsidiaries — — 3,664 (3,664 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 2,666 998 3,439 (3,664 ) 3,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2015, and the amounts comprising total OTTI that were recognized in net realized investment gains (losses) and in other comprehensive income (OCI), were as follows: (in millions) TPC Other TRV Eliminations Consolidated Total OTTI losses (19 ) (35 ) — — (54 ) OTTI losses recognized in net realized investment gains (losses) (18 ) (34 ) — — (52 ) OTTI losses recognized in OCI (1 ) (1 ) — — (2 ) CONSOLIDATING STATEMENT OF INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Revenues Premiums 16,097 7,616 — — 23,713 Net investment income 1,874 907 6 — 2,787 Fee income 448 2 — — 450 Net realized investment gains(1) 12 64 3 — 79 Other revenues 125 20 — — 145 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues 18,556 8,609 9 — 27,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claims and expenses Claims and claim adjustment expenses 9,274 4,596 — — 13,870 Amortization of deferred acquisition costs 2,604 1,278 — — 3,882 General and administrative expenses 2,755 1,194 15 — 3,964 Interest expense 48 — 321 — 369 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total claims and expenses 14,681 7,068 336 — 22,085 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes 3,875 1,541 (327 ) — 5,089 Income tax expense (benefit) 1,095 417 (115 ) — 1,397 Net income of subsidiaries — — 3,904 (3,904 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 2,780 1,124 3,692 (3,904 ) 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Total other-than-temporary impairments (OTTI) for the year ended December 31, 2014, and the amounts comprising total OTTI that were recognized in net realized investment gains and in other comprehensive income (OCI), were as follows: (in millions) TPC Other TRV Eliminations Consolidated Total OTTI losses (16 ) (6 ) — — (22 ) OTTI losses recognized in net realized investment gains (19 ) (7 ) — — (26 ) OTTI gains recognized in OCI 3 1 — — 4
Consolidating Statement of Comprehensive Income (Unaudited) [Table Text Block]	CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Net income 2,184 970 3,014 (3,154 ) 3,014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (696 ) (198 ) 11 — (883 ) Having credit losses recognized in the consolidated statement of income 11 10 — — 21 Net changes in benefit plan assets and obligations 25 11 (20 ) — 16 Net changes in unrealized foreign currency translation 73 (114 ) — — (41 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss before income taxes and other comprehensive loss of subsidiaries (587 ) (291 ) (9 ) — (887 ) Income tax benefit (222 ) (66 ) (1 ) — (289 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss, net of taxes, before other comprehensive loss of subsidiaries (365 ) (225 ) (8 ) — (598 ) Other comprehensive loss of subsidiaries — — (590 ) 590 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss (365 ) (225 ) (598 ) 590 (598 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income 1,819 745 2,416 (2,564 ) 2,416 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Net income 2,666 998 3,439 (3,664 ) 3,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income (610 ) (407 ) (3 ) — (1,020 ) Having credit losses recognized in the consolidated statement of income (12 ) (2 ) — — (14 ) Net changes in benefit plan assets and obligations 2 — 64 — 66 Net changes in unrealized foreign currency translation (306 ) (155 ) — — (461 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) before income taxes and other comprehensive loss of subsidiaries (926 ) (564 ) 61 — (1,429 ) Income tax expense (benefit) (257 ) (156 ) 21 — (392 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss), net of taxes, before other comprehensive loss of subsidiaries (669 ) (408 ) 40 — (1,037 ) Other comprehensive loss of subsidiaries — — (1,077 ) 1,077 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss (669 ) (408 ) (1,037 ) 1,077 (1,037 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income 1,997 590 2,402 (2,587 ) 2,402 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Net income 2,780 1,124 3,692 (3,904 ) 3,692 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss): Changes in net unrealized gains on investment securities: Having no credit losses recognized in the consolidated statement of income 681 289 6 — 976 Having credit losses recognized in the consolidated statement of income 9 (7 ) — — 2 Net changes in benefit plan assets and obligations (15 ) (8 ) (471 ) — (494 ) Net changes in unrealized foreign currency translation (173 ) (116 ) — — (289 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss) before income taxes and other comprehensive income of subsidiaries 502 158 (465 ) — 195 Income tax expense (benefit) 207 81 (163 ) — 125 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss), net of taxes, before other comprehensive income of subsidiaries 295 77 (302 ) — 70 Other comprehensive income of subsidiaries — — 372 (372 ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income 295 77 70 (372 ) 70 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income 3,075 1,201 3,762 (4,276 ) 3,762 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Consolidating Balance Sheet (Unaudited) [Table Text Block]	CONSOLIDATING BALANCE SHEET (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $59,650) 42,014 18,452 49 — 60,515 Equity securities, available for sale, at fair value (cost $504) 169 408 155 — 732 Real estate investments 56 872 — — 928 Short-term securities 2,447 791 1,627 — 4,865 Other investments 2,569 878 1 — 3,448 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments 47,255 21,401 1,832 — 70,488 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash 141 164 2 — 307 Investment income accrued 441 183 6 — 630 Premiums receivable 4,545 2,177 — — 6,722 Reinsurance recoverables 5,664 2,623 — — 8,287 Ceded unearned premiums 536 53 — — 589 Deferred acquisition costs 1,741 182 — — 1,923 Deferred taxes 216 224 25 — 465 Contractholder receivables 3,656 953 — — 4,609 Goodwill 2,578 1,002 — — 3,580 Other intangible assets 202 66 — — 268 Investment in subsidiaries — — 27,137 (27,137 ) — Other assets 1,973 370 34 — 2,377 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets 68,948 29,398 29,036 (27,137 ) 100,245 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Claims and claim adjustment expense reserves 32,168 15,781 — — 47,949 Unearned premium reserves 8,575 3,754 — — 12,329 Contractholder payables 3,656 953 — — 4,609 Payables for reinsurance premiums 156 117 — — 273 Debt 693 — 5,744 — 6,437 Other liabilities 4,106 1,239 82 — 5,427 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities 49,354 21,844 5,826 — 77,024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shareholders' equity Common stock (1,750.0 shares authorized; 279.6 shares issued and outstanding) — 390 22,614 (390 ) 22,614 Additional paid-in capital 11,634 6,499 — (18,133 ) — Retained earnings 7,933 797 32,185 (8,719 ) 32,196 Accumulated other comprehensive income (loss) 27 (132 ) (755 ) 105 (755 ) Treasury stock, at cost (489.5 shares) — — (30,834 ) — (30,834 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total shareholders' equity 19,594 7,554 23,210 (27,137 ) 23,221 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and shareholders' equity 68,948 29,398 29,036 (27,137 ) 100,245 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CONSOLIDATING BALANCE SHEET (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Assets Fixed maturities, available for sale, at fair value (amortized cost $58,878) 42,289 18,323 46 — 60,658 Equity securities, available for sale, at fair value (cost $528) 189 375 141 — 705 Real estate investments 56 933 — — 989 Short-term securities 1,947 1,178 1,546 — 4,671 Other investments 2,516 930 1 — 3,447 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments 46,997 21,739 1,734 — 70,470 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash 225 153 2 — 380 Investment income accrued 453 185 4 — 642 Premiums receivable 4,336 2,101 — — 6,437 Reinsurance recoverables 5,849 3,061 — — 8,910 Ceded unearned premiums 610 46 — — 656 Deferred acquisition costs 1,660 189 — — 1,849 Deferred taxes 178 83 35 — 296 Contractholder receivables 3,387 987 — — 4,374 Goodwill 2,573 1,000 — — 3,573 Other intangible assets 203 76 — — 279 Investment in subsidiaries — — 27,573 (27,573 ) — Other assets 1,958 344 16 — 2,318 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets 68,429 29,964 29,364 (27,573 ) 100,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Claims and claim adjustment expense reserves 31,965 16,330 — — 48,295 Unearned premium reserves 8,335 3,636 — — 11,971 Contractholder payables 3,387 987 — — 4,374 Payables for reinsurance premiums 175 121 — — 296 Debt 693 — 5,651 — 6,344 Other liabilities 3,958 1,221 127 — 5,306 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities 48,513 22,295 5,778 — 76,586 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shareholders' equity Common stock (1,750.0 shares authorized; 295.9 shares issued and outstanding) — 390 22,172 (390 ) 22,172 Additional paid-in capital 11,634 6,499 — (18,133 ) — Retained earnings 7,888 688 29,933 (8,564 ) 29,945 Accumulated other comprehensive income (loss) 394 92 (157 ) (486 ) (157 ) Treasury stock, at cost (467.6 shares) — — (28,362 ) — (28,362 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total shareholders' equity 19,916 7,669 23,586 (27,573 ) 23,598 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and shareholders' equity 68,429 29,964 29,364 (27,573 ) 100,184 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Consolidating Statement of Cash Flows (Unaudited) [Table Text Block]	CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Cash flows from operating activities Net income 2,184 970 3,014 (3,154 ) 3,014 Net adjustments to reconcile net income to net cash provided by operating activities 1,085 66 (119 ) 156 1,188 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 3,269 1,036 2,895 (2,998 ) 4,202 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Proceeds from maturities of fixed maturities 6,589 2,380 6 — 8,975 Proceeds from sales of investments: Fixed maturities 768 647 2 — 1,417 Equity securities 47 45 — — 92 Real estate investments — 69 — — 69 Other investments 586 253 — — 839 Purchases of investments: Fixed maturities (7,921 ) (3,676 ) (12 ) — (11,609 ) Equity securities (6 ) (42 ) (3 ) — (51 ) Real estate investments (1 ) (47 ) — — (48 ) Other investments (453 ) (127 ) — — (580 ) Net sales (purchases) of short-term securities (501 ) 383 (81 ) — (199 ) Securities transactions in course of settlement 12 (32 ) (1 ) — (21 ) Other (334 ) (10 ) — — (344 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in investing activities (1,214 ) (157 ) (89 ) — (1,460 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization — — (2,400 ) — (2,400 ) Treasury stock acquired—net employee share-based compensation — — (72 ) — (72 ) Dividends paid to shareholders — — (757 ) — (757 ) Payment of debt — — (400 ) — (400 ) Issuance of debt — — 491 — 491 Issuance of common stock—employee share options — — 332 — 332 Dividends paid to parent company (2,140 ) (858 ) — 2,998 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,140 ) (858 ) (2,806 ) 2,998 (2,806 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash 1 (10 ) — — (9 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash (84 ) 11 — — (73 ) Cash at beginning of year 225 153 2 — 380 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 141 164 2 — 307 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Income taxes paid (received) 737 287 (132 ) — 892 Interest paid 47 — 311 — 358 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Cash flows from operating activities Net income 2,666 998 3,439 (3,664 ) 3,439 Net adjustments to reconcile net income to net cash provided by operating activities (577 ) 414 330 (172 ) (5 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 2,089 1,412 3,769 (3,836 ) 3,434 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Proceeds from maturities of fixed maturities 7,543 3,563 10 — 11,116 Proceeds from sales of investments: Fixed maturities 1,227 723 — — 1,950 Equity securities 25 34 — — 59 Real estate investments — 31 — — 31 Other investments 503 210 — — 713 Purchases of investments: Fixed maturities (8,276 ) (3,787 ) (27 ) — (12,090 ) Equity securities (3 ) (43 ) (3 ) — (49 ) Real estate investments (1 ) (122 ) — — (123 ) Other investments (423 ) (111 ) — — (534 ) Net sales (purchases) of short-term securities 179 (489 ) (16 ) — (326 ) Securities transactions in course of settlement (52 ) (61 ) — — (113 ) Acquisition, net of cash acquired (13 ) — — — (13 ) Other (343 ) 39 — — (304 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities 366 (13 ) (36 ) — 317 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization — — (3,150 ) — (3,150 ) Treasury stock acquired—net employee share-based compensation — — (74 ) — (74 ) Dividends paid to shareholders — — (739 ) — (739 ) Payment of debt — — (400 ) — (400 ) Issuance of debt — — 392 — 392 Issuance of common stock—employee share options — — 183 — 183 Excess tax benefits from share-based payment arrangements — — 55 — 55 Dividends paid to parent company (2,450 ) (1,383 ) — 3,833 — Capital contributions, loans and other transactions between subsidiaries — (3 ) — 3 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,450 ) (1,386 ) (3,733 ) 3,836 (3,733 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash (1 ) (11 ) — — (12 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase in cash 4 2 — — 6 Cash at beginning of year 221 151 2 — 374 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 225 153 2 — 380 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Income taxes paid (received) 1,032 384 (209 ) — 1,207 Interest paid 47 — 318 — 365 CONSOLIDATING STATEMENT OF CASH FLOWS (Unaudited) (in millions) TPC Other TRV Eliminations Consolidated Cash flows from operating activities Net income 2,780 1,124 3,692 (3,904 ) 3,692 Net adjustments to reconcile net income to net cash provided by operating activities 343 (293 ) 118 (167 ) 1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by operating activities 3,123 831 3,810 (4,071 ) 3,693 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from investing activities Proceeds from maturities of fixed maturities 6,625 4,258 11 — 10,894 Proceeds from sales of investments: Fixed maturities 595 453 1 — 1,049 Equity securities 111 43 4 — 158 Real estate investments 1 14 — — 15 Other investments 477 378 — — 855 Purchases of investments: Fixed maturities (6,856 ) (4,465 ) (4 ) — (11,325 ) Equity securities (3 ) (42 ) (7 ) — (52 ) Real estate investments (22 ) (26 ) — — (48 ) Other investments (405 ) (149 ) — — (554 ) Net purchases of short-term securities (268 ) (223 ) (7 ) — (498 ) Securities transactions in course of settlement 44 38 — — 82 Acquisition, net of cash acquired (9 ) (3 ) — (12 ) Other (350 ) (8 ) — — (358 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities (60 ) 268 (2 ) — 206 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash flows from financing activities Treasury stock acquired—share repurchase authorization — — (3,275 ) — (3,275 ) Treasury stock acquired—net employee share-based compensation — — (57 ) — (57 ) Dividends paid to shareholders — — (729 ) — (729 ) Issuance of common stock—employee share options — — 195 — 195 Excess tax benefits from share-based payment arrangements — — 57 — 57 Dividends paid to parent company (2,978 ) (1,093 ) — 4,071 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities (2,978 ) (1,093 ) (3,809 ) 4,071 (3,809 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash (1 ) (9 ) — — (10 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash 84 (3 ) (1 ) — 80 Cash at beginning of year 137 154 3 — 294 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash at end of year 221 151 2 — 374 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of cash flow information Income taxes paid (received) 947 336 (136 ) — 1,147 Interest paid 47 — 318 — 365

Selected Quarterly Financial 48

Selected Quarterly Financial Data (Unaudited) (table)	12 Months Ended
	Dec. 31, 2016
Selected Quarterly Financial Data (Unaudited) disclosure
Selected Quarterly Financial Data (Unaudited) disclosure [Table Text Block]	2016 (in millions, except per share amounts) First Second Third Fourth Total Total revenues 6,686 6,785 6,961 7,193 27,625 Total expenses 5,769 5,898 6,014 5,891 23,572 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes 917 887 947 1,302 4,053 Income tax expense 226 223 231 359 1,039 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 691 664 716 943 3,014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per share(1): Basic 2.33 2.27 2.48 3.32 10.39 Diluted 2.30 2.24 2.45 3.28 10.28 2015 (in millions, except per share amounts) First Second Third Fourth Total Total revenues 6,629 6,710 6,798 6,678 26,815 Total expenses 5,481 5,634 5,491 5,469 22,075 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes 1,148 1,076 1,307 1,209 4,740 Income tax expense 315 264 379 343 1,301 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income 833 812 928 866 3,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per share(1): Basic 2.58 2.56 3.00 2.87 10.99 Diluted 2.55 2.53 2.97 2.83 10.88 (1) Due to the averaging of shares, quarterly earnings per share may not add to the total for the full year.

Summary of Significant Accoun49

Summary of Significant Accounting Policies (details)	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies disclosure
Maximum useful life for buildings held in real estate investments	39 years
Maximum original maturity of short-term securities	1 year
Availability of financial information provided by private equity and real estate partnerships following the date of the reporting, minimum	3 months
Availability of financial information provided by private equity and real estate partnerships following the date of the reporting, maximum	6 months
Availability of financial information provided by hedge funds following the date of the reporting	1 month
Estimated recovery time for securities for which the issuer is in bankruptcy	12 months
Estimated recovery time for securities for which the issuer is financially troubled but not in bankruptcy	24 months

Summary of Significant Accoun50

Summary of Significant Accounting Policies (details) - Key Assumptions	12 Months Ended
	Dec. 31, 2016
Prime [Member] | Minimum [Member]
Key assumptions used in estimation of present value of structured fixed maturity securities
Voluntary prepayment rates	0.00%
Percentage of remaining pool liquidated due to defaults	0.00%
Loss severity	30.00%
Prime [Member] | Maxiumum [Member]
Key assumptions used in estimation of present value of structured fixed maturity securities
Voluntary prepayment rates	35.00%
Percentage of remaining pool liquidated due to defaults	46.00%
Loss severity	65.00%
Alt-A [Member] | Minimum [Member]
Key assumptions used in estimation of present value of structured fixed maturity securities
Voluntary prepayment rates	4.00%
Percentage of remaining pool liquidated due to defaults	20.00%
Loss severity	42.00%
Alt-A [Member] | Maxiumum [Member]
Key assumptions used in estimation of present value of structured fixed maturity securities
Voluntary prepayment rates	15.00%
Percentage of remaining pool liquidated due to defaults	73.00%
Loss severity	90.00%
Sub-Prime [Member] | Minimum [Member]
Key assumptions used in estimation of present value of structured fixed maturity securities
Voluntary prepayment rates	3.00%
Percentage of remaining pool liquidated due to defaults	22.00%
Loss severity	75.00%
Sub-Prime [Member] | Maxiumum [Member]
Key assumptions used in estimation of present value of structured fixed maturity securities
Voluntary prepayment rates	12.00%
Percentage of remaining pool liquidated due to defaults	52.00%
Loss severity	110.00%

Summary of Significant Accoun51

Summary of Significant Accounting Policies (details) - Additional Details $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)	Dec. 31, 2014
Summary of Significant Accounting Policies disclosure
Minimum collateral provided by borrowers of securities, as a percentage of the market value of the loaned securities plus accrued interest	102.00%
Number of reportable business segments | item	3
Liability for guaranty fund and other insurance-related assessments	$ 242	$ 241
Recoverables for liability for guaranty fund and other insurance-related assessments	$ 16	$ 18
Minimum expected payment period for loss-based assessments and recoveries	1 year	1 year
Net written premiums for participating dividend policies as a percent of total Company net written premiums	1.00%	2.00%	1.00%
Liability accrued for policyholder dividends	$ 62	$ 57
Percentage of capital provided by International for its syndicate at Lloyd's	100.00%
Number of principal business units through which the Company's syndicate at Lloyd's writes business | item	5

Summary of Significant Accoun52

Summary of Significant Accounting Policies (details) - Equity Method Investment	Dec. 31, 2016
JMalucelli - Brazilian joint venture [Member]
Equity method investment
Percent of common stock owned	49.50%
J. Malucelli Latam S.A. [Member]
Equity method investment
Percent of common stock owned	49.50%

Summary of Significant Accoun53

Summary of Significant Accounting Policies (details) - Acquisition	Oct. 01, 2015
Travelers Participacoes em Seguros Brasil S.A. [Member]
Business Acquisition
Percentage of common stock acquired	100.00%

Segment Information (details)

Segment Information (details) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Segment reporting information
Number of reportable business segments | item										3
Premiums										$ 24,534	$ 23,874	$ 23,713
Net investment income										2,302	2,379	2,787
Fee income										458	460	450
Other revenues										263	99	145
Income tax expense		$ 359	$ 231	$ 223	$ 226	$ 343	$ 379	$ 264	$ 315	1,039	1,301	1,397
Operating income (loss)										2,967	3,437	3,641
Net realized investment gains	[1]									68	3	79
Total revenues		7,193	6,961	6,785	6,686	6,678	6,798	6,710	6,629	27,625	26,815	27,174
Net realized investment gains, net of tax										47	2	51
Net income		$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	3,014	3,439	3,692
Property casualty [Member]
Segment reporting information
Premiums										24,534	23,874	23,713
Net investment income										2,302	2,379	2,787
Domestic [Member]
Segment reporting information
Total revenues										25,904	25,127	25,103
International [Member]
Segment reporting information
Total revenues										1,721	1,688	2,071
Reportable Segments [Member]
Segment reporting information
Premiums										24,534	23,874	23,713
Net investment income										2,302	2,379	2,787
Fee income										458	460	450
Other revenues										252	93	145
Total operating revenues										27,546	26,806	27,095
Amortization and depreciation										4,804	4,696	4,738
Income tax expense										1,157	1,443	1,512
Operating income (loss)										3,211	3,692	3,898
Reportable Segments [Member] | Business and International Insurance [Member]
Segment reporting information
Premiums										14,620	14,521	14,512
Net investment income										1,763	1,824	2,156
Fee income										442	445	438
Other revenues										176	23	46
Total operating revenues										17,001	16,813	17,152
Amortization and depreciation										2,956	2,907	2,909
Income tax expense										659	769	798
Operating income (loss)										2,048	2,170	2,347
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member]
Segment reporting information
Premiums										12,904	12,625	12,305
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member] | Workers' compensation [Member]
Segment reporting information
Premiums										3,969	3,867	3,711
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member] | Automobile [Member]
Segment reporting information
Premiums										2,010	1,922	1,900
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member] | Commercial property [Member]
Segment reporting information
Premiums										1,769	1,766	1,747
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member] | General liability [Member]
Segment reporting information
Premiums										1,977	1,898	1,834
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member] | Commercial multi-peril [Member]
Segment reporting information
Premiums										3,148	3,133	3,071
Reportable Segments [Member] | Business and International Insurance [Member] | Domestic [Member] | Other [Member]
Segment reporting information
Premiums										31	39	42
Reportable Segments [Member] | Business and International Insurance [Member] | International [Member]
Segment reporting information
Premiums										1,716	1,896	2,207
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Segment reporting information
Premiums										2,088	2,085	2,076
Net investment income										210	223	252
Other revenues										20	22	19
Total operating revenues										2,318	2,330	2,347
Amortization and depreciation										457	467	482
Income tax expense										307	272	348
Operating income (loss)										653	633	727
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Segment reporting information
Premiums										946	955	963
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Segment reporting information
Premiums										962	954	936
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Other [Member]
Segment reporting information
Premiums										180	176	177
Reportable Segments [Member] | Personal Insurance [Member]
Segment reporting information
Premiums										7,826	7,268	7,125
Net investment income										329	332	379
Fee income										16	15	12
Other revenues										56	48	80
Total operating revenues										8,227	7,663	7,596
Amortization and depreciation										1,391	1,322	1,347
Income tax expense										191	402	366
Operating income (loss)										510	889	824
Reportable Segments [Member] | Personal Insurance [Member] | Automobile [Member]
Segment reporting information
Premiums										4,013	3,512	3,316
Reportable Segments [Member] | Personal Insurance [Member] | Homeowners and Other [Member]
Segment reporting information
Premiums										3,813	3,756	3,809
Other [Member]
Segment reporting information
Other revenues										11	6
Operating income (loss)										(244)	(255)	(257)
After-tax interest expense										$ 236	$ 242	$ 240
[1]	Total other-than-temporary impairment (OTTI) losses were $(40) million, $(54) million and $(22) million for the years ended December 31, 2016, 2015 and 2014, respectively. Of total OTTI, credit losses of $(29) million, $(52) million and $(26) million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $(11) million, $(2) million and $4 million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.

Segment Information (details) -

Segment Information (details) - Net Written Premiums - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment reporting information
Net written premiums	$ 24,958	$ 24,121	$ 23,904
Business and International Insurance [Member]
Segment reporting information
Net written premiums	14,675	14,583	14,636
Business and International Insurance [Member] | Domestic [Member]
Segment reporting information
Net written premiums	12,945	12,741	12,484
Business and International Insurance [Member] | Domestic [Member] | Select Accounts [Member]
Segment reporting information
Net written premiums	2,729	2,716	2,707
Business and International Insurance [Member] | Domestic [Member] | Middle Market [Member]
Segment reporting information
Net written premiums	6,463	6,302	6,077
Business and International Insurance [Member] | Domestic [Member] | National Accounts [Member]
Segment reporting information
Net written premiums	1,058	1,048	1,047
Business and International Insurance [Member] | Domestic [Member] | First Party [Member]
Segment reporting information
Net written premiums	1,601	1,564	1,579
Business and International Insurance [Member] | Domestic [Member] | Specialized Distribution [Member]
Segment reporting information
Net written premiums	1,094	1,111	1,074
Business and International Insurance [Member] | International [Member]
Segment reporting information
Net written premiums	1,730	1,842	2,152
Bond & Specialty Insurance [Member]
Segment reporting information
Net written premiums	2,099	2,081	2,103
Personal Insurance [Member]
Segment reporting information
Net written premiums	8,184	7,457	7,165
Personal Insurance [Member] | Automobile [Member]
Segment reporting information
Net written premiums	4,327	3,700	3,390
Personal Insurance [Member] | Homeowners and Other [Member]
Segment reporting information
Net written premiums	$ 3,857	$ 3,757	$ 3,775

Segment Information (details)56

Segment Information (details) - Assets by Segment - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Assets by segment
Total assets	$ 100,245	$ 100,184
Reportable Segments [Member]
Assets by segment
Total assets	99,882	99,800
Reportable Segments [Member] | Business and International Insurance [Member]
Assets by segment
Total assets	79,468	79,692
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Assets by segment
Total assets	7,296	7,360
Reportable Segments [Member] | Personal Insurance [Member]
Assets by segment
Total assets	13,118	12,748
Other assets [Member]
Assets by segment
Total assets	$ 363	$ 384

Segment Information (details)57

Segment Information (details) - Enterprise-Wide Disclosures - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues based on location
Benchmark percentage of revenue transactions from a single customer									10.00%	10.00%	10.00%
Total revenues	$ 7,193	$ 6,961	$ 6,785	$ 6,686	$ 6,678	$ 6,798	$ 6,710	$ 6,629	$ 27,625	$ 26,815	$ 27,174
U.S. [Member]
Revenues based on location
Total revenues									25,904	25,127	25,103
Non-U.S. [Member]
Revenues based on location
Total revenues									1,721	1,688	2,071
Canada [Member]
Revenues based on location
Total revenues									1,154	1,202	1,474
Other Non-U.S. [Member]
Revenues based on location
Total revenues									$ 567	$ 486	$ 597

Investments (details)

Investments (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments disclosure
Fixed maturities, due in one year or less, amortized cost	$ 5,619
Fixed maturities, due after 1 year through 5 years, amortized cost	16,417
Fixed maturities, due after 5 years through 10 years, amortized cost	14,258
Fixed maturities, due after 10 years, amortized cost	21,742
Fixed maturities excluding mortgage-backed securities, collateralized mortgage obligations and pass-through securities, amortized cost	58,036
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities, amortized cost	1,614
Fixed maturities, amortized cost	59,650	$ 58,878
Fixed maturities, due in one year or less, fair value	5,677
Fixed maturities, due after 1 year through 5 years, fair value	16,926
Fixed maturities, due after 5 years through 10 years, fair value	14,449
Fixed maturities, due after 10 years, fair value	21,755
Fixed maturities excluding mortgage-backed securities, collateralized mortgage obligations and pass-through securities, fair value	58,807
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities, fair value	1,708
Fixed maturities, at fair value	60,515	60,658
Securities on loan as part of a tri-party lending agreement	286	269
Proceeds from sales of fixed maturities classified as available for sale	1,417	1,950	$ 1,049
Insurance subsidiaries' securities on deposit at financial institutions in certain states pursuant to the respective states' insurance regulatory requirements	4,560	4,680
Fair value of funds deposited with third parties to be used as collateral to secure various liabilities on behalf of insureds, cedants and other creditors	35	28
Fair value of other investments pledged as collateral securing outstanding letters of credit	3	21
Fair value of owned securities held by an insurance subsidiary pledged into a Lloyd's trust account to support capital requirements for the Company's operations at Lloyd's	97	140
Proceeds from sales of equity securities	92	59	158
Proceeds from sale of real estate investments	69	31	$ 15
Accumulated depreciation on real estate held for investment purposes	332	320
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2017	84
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2018	74
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2019	62
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2020	46
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2021	34
Future minimum rental income expected on operating leases relating to the Company's real estate properties for 2022 and thereafter	$ 45
Maximum original maturity of short-term securities	1 year
Combined average days to maturity of short-term securities (in days)	80 days
Amortized cost of short-term securities (which approximates fair value)	$ 4,870	$ 4,670

Investments (details) - Investm

Investments (details) - Investment Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investment disclosure details
Fixed maturities, amortized cost	$ 59,650	$ 58,878
Gross unrealized gains	1,369	2,100
Gross unrealized losses	504	320
Fixed maturities, at fair value	60,515	60,658
Equity securities, cost	504	528
Gross unrealized gains	236	190
Gross unrealized losses	8	13
Equity securities, at fair value	732	705
Continuous unrealized loss position less than 12 months, fair value	18,310	11,221
Continuous unrealized loss position less than 12 months, gross unrealized losses	482	233
Continuous unrealized loss position 12 months or longer, fair value	561	1,008
Continuous unrealized loss position 12 months or longer, gross unrealized losses	30	100
Continuous unrealized loss position, total, fair value	18,871	12,229
Continuous unrealized loss position, total, gross unrealized losses	512	333
Available-for-sale securities for which fair value is less than 80% of amortized cost, 3 months or less	2
Available-for-sale securities for which fair value is less than 80% of amortized cost, greater than 12 months	2
Available-for-sale securities for which fair value is less than 80% of amortized cost, total	$ 4
Unrealized investment losses for securities for which fair value is less than 80% of amortized cost, as a percentage of the combined fixed maturity and equity security portfolios on a pretax basis (less than)	1.00%
Unrealized investment losses for securities for which fair value is less than 80% of amortized cost, as a percentage of shareholders' equity on an after-tax basis (less than)	1.00%
Below investment grade [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 1,760	1,710
Fixed maturities [Member]
Investment disclosure details
Gross realized gains	79	95	$ 44
Gross realized losses	20	14	12
Continuous unrealized loss position less than 12 months, fair value	18,263	11,126
Continuous unrealized loss position less than 12 months, gross unrealized losses	480	224
Continuous unrealized loss position 12 months or longer, fair value	492	937
Continuous unrealized loss position 12 months or longer, gross unrealized losses	24	96
Continuous unrealized loss position, total, fair value	18,755	12,063
Continuous unrealized loss position, total, gross unrealized losses	504	320
Available-for-sale securities for which fair value is less than 80% of amortized cost, 3 months or less	1
Available-for-sale securities for which fair value is less than 80% of amortized cost, greater than 12 months	2
Available-for-sale securities for which fair value is less than 80% of amortized cost, total	3
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	2,031	2,202
Gross unrealized gains	9	8
Gross unrealized losses	5	16
Fixed maturities, at fair value	2,035	2,194
Continuous unrealized loss position less than 12 months, fair value	1,124	1,820
Continuous unrealized loss position less than 12 months, gross unrealized losses	5	15
Continuous unrealized loss position 12 months or longer, fair value		28
Continuous unrealized loss position 12 months or longer, gross unrealized losses		1
Continuous unrealized loss position, total, fair value	1,124	1,848
Continuous unrealized loss position, total, gross unrealized losses	5	16
Obligations of states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	31,550	30,027
Gross unrealized gains	712	1,393
Gross unrealized losses	352	9
Fixed maturities, at fair value	31,910	31,411
Continuous unrealized loss position less than 12 months, fair value	9,781	928
Continuous unrealized loss position less than 12 months, gross unrealized losses	352	7
Continuous unrealized loss position 12 months or longer, fair value	12	142
Continuous unrealized loss position 12 months or longer, gross unrealized losses		2
Continuous unrealized loss position, total, fair value	9,793	1,070
Continuous unrealized loss position, total, gross unrealized losses	352	9
Obligations of states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	13,955	12,744
Gross unrealized gains	271	577
Gross unrealized losses	182	3
Fixed maturities, at fair value	14,044	13,318
Obligations of states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	10,910	9,492
Gross unrealized gains	215	472
Gross unrealized losses	147	4
Fixed maturities, at fair value	10,978	9,960
Obligations of states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,717	1,978
Gross unrealized gains	36	97
Gross unrealized losses	22	2
Fixed maturities, at fair value	1,731	2,073
Obligations of states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	4,968	5,813
Gross unrealized gains	190	247
Gross unrealized losses	1
Fixed maturities, at fair value	5,157	6,060
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,631	1,829
Gross unrealized gains	34	45
Gross unrealized losses	3	1
Fixed maturities, at fair value	1,662	1,873
Continuous unrealized loss position less than 12 months, fair value	360	172
Continuous unrealized loss position less than 12 months, gross unrealized losses	3	1
Continuous unrealized loss position, total, fair value	360	172
Continuous unrealized loss position, total, gross unrealized losses	3	1
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,614	1,863
Gross unrealized gains	100	124
Gross unrealized losses	6	6
Fixed maturities, at fair value	1,708	1,981
Continuous unrealized loss position less than 12 months, fair value	528	473
Continuous unrealized loss position less than 12 months, gross unrealized losses	5	4
Continuous unrealized loss position 12 months or longer, fair value	43	57
Continuous unrealized loss position 12 months or longer, gross unrealized losses	1	2
Continuous unrealized loss position, total, fair value	571	530
Continuous unrealized loss position, total, gross unrealized losses	6	6
Residential mortgage-backed pass-through securities classified as available-for-sale, GNMA, FNMA, FHLMC and Canadian Government [Member]
Investment disclosure details
Fixed maturities, at fair value	563	676
Residential collateralized mortgage obligations [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 1,150	$ 1,300
Percent guaranteed by or fully collateralized by securities issued by GNMA, FNMA or FHLMC	51.00%	48.00%
Non-guaranteed residential collateralized mortgage obligations [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 566	$ 683
All other corporate bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	22,737	22,854
Gross unrealized gains	508	523
Gross unrealized losses	138	288
Fixed maturities, at fair value	23,107	23,089
Continuous unrealized loss position less than 12 months, fair value	6,470	7,725
Continuous unrealized loss position less than 12 months, gross unrealized losses	115	197
Continuous unrealized loss position 12 months or longer, fair value	437	710
Continuous unrealized loss position 12 months or longer, gross unrealized losses	23	91
Continuous unrealized loss position, total, fair value	6,907	8,435
Continuous unrealized loss position, total, gross unrealized losses	138	288
Commercial mortgage-backed securities [Member]
Investment disclosure details
Fixed maturities, at fair value	938	865
Commercial mortgage-backed securities, containing guarantees by the U.S. government or a government-sponsored enterprise [Member]
Investment disclosure details
Fixed maturities, at fair value	290	303
Commercial mortgage-backed securities, non-guaranteed securities [Member]
Investment disclosure details
Fixed maturities, at fair value	648	562
Other fixed maturities [Member]
Investment disclosure details
Available-for-sale securities for which fair value is less than 80% of amortized cost, 3 months or less	1
Available-for-sale securities for which fair value is less than 80% of amortized cost, greater than 12 months	2
Available-for-sale securities for which fair value is less than 80% of amortized cost, total	3
Redeemable preferred stock [Member]
Investment disclosure details
Fixed maturities, amortized cost	87	103
Gross unrealized gains	6	7
Fixed maturities, at fair value	93	110
Continuous unrealized loss position less than 12 months, fair value		8
Continuous unrealized loss position, total, fair value		8
Equity securities [Member]
Investment disclosure details
Gross realized gains	17	16	27
Gross realized losses	3	10	3
Continuous unrealized loss position less than 12 months, fair value	47	95
Continuous unrealized loss position less than 12 months, gross unrealized losses	2	9
Continuous unrealized loss position 12 months or longer, fair value	69	71
Continuous unrealized loss position 12 months or longer, gross unrealized losses	6	4
Continuous unrealized loss position, total, fair value	116	166
Continuous unrealized loss position, total, gross unrealized losses	8	13
Available-for-sale securities for which fair value is less than 80% of amortized cost, 3 months or less	1
Available-for-sale securities for which fair value is less than 80% of amortized cost, total	1
Public common stock [Member]
Investment disclosure details
Equity securities, cost	390	386
Gross unrealized gains	216	164
Gross unrealized losses	3	7
Equity securities, at fair value	603	543
Continuous unrealized loss position less than 12 months, fair value	45	48
Continuous unrealized loss position less than 12 months, gross unrealized losses	2	6
Continuous unrealized loss position 12 months or longer, fair value	10	33
Continuous unrealized loss position 12 months or longer, gross unrealized losses	1	1
Continuous unrealized loss position, total, fair value	55	81
Continuous unrealized loss position, total, gross unrealized losses	3	7
Non-redeemable preferred stock [Member]
Investment disclosure details
Equity securities, cost	114	142
Gross unrealized gains	20	26
Gross unrealized losses	5	6
Equity securities, at fair value	129	162
Continuous unrealized loss position less than 12 months, fair value	2	47
Continuous unrealized loss position less than 12 months, gross unrealized losses		3
Continuous unrealized loss position 12 months or longer, fair value	59	38
Continuous unrealized loss position 12 months or longer, gross unrealized losses	5	3
Continuous unrealized loss position, total, fair value	61	85
Continuous unrealized loss position, total, gross unrealized losses	5	6
Real estate [Member]
Investment disclosure details
Gross realized gains	7	4	6
Gross realized losses	$ 0	$ 0	$ 0

Investments (details) - Impairm

Investments (details) - Impairment Charges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Impairment charges
Impairment charges	$ 29	$ 52	$ 26
Fixed maturities [Member]
Impairment charges
Impairment charges	15	13	16
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Impairment charges
Impairment charges			1
All other corporate bonds [Member]
Impairment charges
Impairment charges	15	13	15
Equity securities [Member]
Impairment charges
Impairment charges	12	37	9
Public common stock [Member]
Impairment charges
Impairment charges	9	37	9
Non-redeemable preferred stock [Member]
Impairment charges
Impairment charges	3
Other investments [Member]
Impairment charges
Impairment charges	$ 2	$ 2	$ 1

Investments (details) - OTTI Ro

Investments (details) - OTTI Rollforward - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Roll-forward of the credit losses on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income (loss) [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	$ 83	$ 99
Additions for OTTI securities where no credit losses were previously recognized	13	2
Reductions due to sales/defaults of credit-impaired securities	(7)	(10)
Adjustments to book value of credit-impaired securities due to changes in cash flows	(4)	(8)
Cumulative OTTI credit losses recognized for securities still held, end of period	85	83
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Roll-forward of the credit losses on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income (loss) [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	32	40
Reductions due to sales/defaults of credit-impaired securities		(6)
Adjustments to book value of credit-impaired securities due to changes in cash flows	(1)	(2)
Cumulative OTTI credit losses recognized for securities still held, end of period	31	32
All other corporate bonds [Member]
Roll-forward of the credit losses on fixed maturities recognized in the consolidated statement of income for which a portion of the other-than-temporary impairment was recognized in other comprehensive income (loss) [Roll Forward]
Cumulative OTTI credit losses recognized for securities held, beginning of period	51	59
Additions for OTTI securities where no credit losses were previously recognized	13	2
Reductions due to sales/defaults of credit-impaired securities	(7)	(4)
Adjustments to book value of credit-impaired securities due to changes in cash flows	(3)	(6)
Cumulative OTTI credit losses recognized for securities still held, end of period	$ 54	$ 51

Investments (details) - Concent

Investments (details) - Concentrations and Credit Quality - Credit Concentration Risk [Member] - Stockholders' Equity, Total [Member] - Minimum [Member]	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Concentration risk as a percentage of shareholders' equity	5.00%	5.00%
Obligations of the Canadian government [Member]
Investment disclosure details
Concentration risk as a percentage of shareholders' equity		5.00%

Investments (details) - Net Inv

Investments (details) - Net Investment Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net investment income
Gross investment income	$ 2,340	$ 2,420	$ 2,826
Investment expenses	38	41	39
Net investment income	2,302	2,379	2,787
Fixed maturities [Member]
Net investment income
Gross investment income	1,981	2,091	2,244
Equity securities [Member]
Net investment income
Gross investment income	37	39	40
Short-term securities [Member]
Net investment income
Gross investment income	29	12	9
Real estate [Member]
Net investment income
Gross investment income	51	48	44
Other investments [Member]
Net investment income
Gross investment income	$ 242	$ 230	$ 489

Investments (details) - Changes

Investments (details) - Changes in Net Unrealized Investment Gains - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains	$ (887)	$ (1,429)	$ 195
Income tax expense (benefit)	(289)	(392)	125
Change in net unrealized gain on investment securities, net of tax	(598)	(1,037)	70
Balance, beginning of year	(157)
Balance, end of year	(755)	(157)
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains	(887)	(1,429)	195
Income tax expense (benefit)	(289)	(392)	125
Change in net unrealized gain on investment securities, net of tax	(598)	(1,037)	70
Changes in Net Unrealized Gains on Investment Securities [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains	(862)	(1,034)	978
Income tax expense (benefit)	(303)	(357)	334
Change in net unrealized gain on investment securities, net of tax	(559)	(677)	644
Balance, beginning of year	1,289	1,966	1,322
Balance, end of year	730	1,289	1,966
Changes in Net Unrealized Gains on Investment Securities [Member] | Fixed maturities [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains	(915)	(893)	913
Changes in Net Unrealized Gains on Investment Securities [Member] | Equity securities [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains	51	(143)	63
Changes in Net Unrealized Gains on Investment Securities [Member] | Other investments [Member]
Changes in net unrealized investment gains [Roll Forward]
Changes in net unrealized investment gains	$ 2	$ 2	$ 2

Investments (details) - Derivat

Investments (details) - Derivatives - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Futures [Member] | U.S. Treasury notes contracts [Member]
Derivatives
Notional value of open contracts	$ 400	$ 400

Fair Value Measurements (detail

Fair Value Measurements (details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fair Value Measurements disclosure
Percent of fixed maturities for which a pricing service estimates fair value	98.00%	98.00%
Percent change in monthly price at which securities are further evaluated	10.00%
Fair value of the fixed maturities for which the Company used an internal pricing matrix	$ 99	$ 101
Fair value of the fixed maturities for which the Company received a broker quote	$ 85	$ 117
Percent of short-term securities for which a pricing service estimates fair value	98.00%	99.00%
Percent of debt, including commercial paper, for which a pricing service estimates fair value	100.00%	100.00%

Fair Value Measurements (deta67

Fair Value Measurements (details) - Fair Value Hierarchy - Recurring basis [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	$ 61,300	$ 61,419
Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	2,709	2,813
Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	58,371	58,350
Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	220	256
Fixed maturities [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	60,515	60,658
Convertible bonds held containing embedded conversion options that are valued separately from the host bond contract and disclosed in Level 2	0	2
Fixed maturities [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	2,038	2,197
Fixed maturities [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	58,293	58,243
Convertible bonds held containing embedded conversion options that are valued separately from the host bond contract and disclosed in Level 2	0	2
Fixed maturities [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	184	218
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	2,035	2,194
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	2,035	2,194
Obligations of states, municipalities and political subdivisions [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	31,910	31,411
Obligations of states, municipalities and political subdivisions [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	31,898	31,398
Obligations of states, municipalities and political subdivisions [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	12	13
Debt securities issued by foreign governments [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	1,662	1,873
Debt securities issued by foreign governments [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	1,662	1,873
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	1,708	1,981
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	1,704	1,957
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	4	24
All other corporate bonds [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	23,107	23,089
All other corporate bonds [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	22,939	22,915
All other corporate bonds [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	168	174
Redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	93	110
Redeemable preferred stock [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	3	3
Redeemable preferred stock [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	90	100
Redeemable preferred stock [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis		7
Equity securities [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	732	705
Equity securities [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	654	598
Equity securities [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	78	107
Public common stock [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	603	543
Public common stock [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	603	543
Non-redeemable preferred stock [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	129	162
Non-redeemable preferred stock [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	51	55
Non-redeemable preferred stock [Member] | Level 2 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	78	107
Other investments [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	53	56
Other investments [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	17	18
Other investments [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	36	38
Investments in various publicly-traded securities, including mutual funds and other small holdings disclosed in Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	17	18
Investments in various publicly-traded securities, including mutual funds and other small holdings disclosed in Level 1 [Member] | Level 1 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	17	18
Investment in non-public common and preferred equity securities where the fair value estimate is determined either internally or by an external fund manager and therefore disclosed in Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	36	38
Investment in non-public common and preferred equity securities where the fair value estimate is determined either internally or by an external fund manager and therefore disclosed in Level 3 [Member] | Level 3 [Member]
Level within the fair value hierarchy at which the Company's financial assets are measured
Total invested assets measured on a recurring basis	$ 36	$ 38

Fair Value Measurements (deta68

Fair Value Measurements (details) - Changes in Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	$ 256	$ 268
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	8	3
Level 3 fair value category, total unrealized investment gains (losses) reported in increases (decreases) in other comprehensive income	5	(3)
Level 3 fair value category purchases	123	203
Level 3 fair value category sales	(29)	(9)
Level 3 fair value category settlements/maturities	(66)	(41)
Gross transfers into Level 3	19	21
Gross transfers out of Level 3	(96)	(186)
Level 3 fair value category, ending balance	220	256
Level 3 fair value category, amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	(2)	(1)
Fixed maturities [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	218	232
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	3	1
Level 3 fair value category, total unrealized investment gains (losses) reported in increases (decreases) in other comprehensive income	2	(4)
Level 3 fair value category purchases	123	202
Level 3 fair value category sales	(19)	(7)
Level 3 fair value category settlements/maturities	(66)	(41)
Gross transfers into Level 3	19	21
Gross transfers out of Level 3	(96)	(186)
Level 3 fair value category, ending balance	184	218
Other investments [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	38	36
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	5	2
Level 3 fair value category, total unrealized investment gains (losses) reported in increases (decreases) in other comprehensive income	3	1
Level 3 fair value category purchases		1
Level 3 fair value category sales	(10)	(2)
Level 3 fair value category, ending balance	36	38
Level 3 fair value category, amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	$ (2)	$ (1)

Fair Value Measurements Footnot

Fair Value Measurements Footnote (details) - Financial Instruments - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Financial Instruments
Short-term securities	$ 4,865	$ 4,671
Commercial paper amount	100	100
Fair Value [Member]
Financial Instruments
Short-term securities	4,865	4,671
Debt	7,262	7,180
Commercial paper amount	100	100
Fair Value [Member] | Level 1 [Member]
Financial Instruments
Short-term securities	1,223	1,685
Fair Value [Member] | Level 2 [Member]
Financial Instruments
Short-term securities	3,607	2,958
Debt	7,262	7,180
Commercial paper amount	100	100
Fair Value [Member] | Level 3 [Member]
Financial Instruments
Short-term securities	35	28
Carrying Value [Member]
Financial Instruments
Short-term securities	4,865	4,671
Debt	6,337	6,244
Commercial paper amount	$ 100	$ 100

Reinsurance (details)

Reinsurance (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance disclosure
Percentage of residual market business written directly by the Company for mandatory pools and associations and then ceded to the mandatory pool	100.00%
Written premiums, direct	$ 25,567	$ 24,939	$ 24,844
Written premiums, assumed	928	843	788
Written premiums, ceded	(1,537)	(1,661)	(1,728)
Total net written premiums	24,958	24,121	23,904
Earned premiums, direct	25,262	24,740	24,810
Earned premiums, assumed	875	814	743
Earned premiums, ceded	(1,603)	(1,680)	(1,840)
Total net earned premiums	$ 24,534	$ 23,874	$ 23,713
Percentage of assumed earned premiums to net earned premiums	3.60%	3.40%	3.10%
Ceded claims and claim adjustment expenses incurred	$ 762	$ 1,034	$ 953
Gross reinsurance recoverables on paid and unpaid claims and claim adjustment expenses	3,181	3,848
Allowance for uncollectible reinsurance	(116)	(157)
Net reinsurance recoverables	3,065	3,691
Reinsurance recoverables, mandatory pools and associations	2,054	2,015
Reinsurance recoverables, structured settlements	3,168	3,204
Total reinsurance recoverables	8,287	$ 8,910
Terrorism Risk Insurance Program, annual aggregate industry loss minimum in order for a loss to be covered, next fiscal year	140
Terrorism Risk Insurance Program, ultimate annual aggregate industry loss minimum in order for a loss to be covered	$ 200
Terrorism Risk Insurance Program, percentage of subject losses reimbursed by the Federal Government, after insurer deductible, subject to annual cap, next fiscal year	83.00%
Terrorism Risk Insurance Program, remaining life of the program (in years)	4 years
Terrorism Risk Insurance Program, ultimate percentage of subject losses reimbursed by the Federal Government, after insurer deductible, subject to annual cap	80.00%
Terrorism Risk Insurance Program, percentage of insurer's direct earned premiums for covered lines for the preceding calendar year at which the deductible is set	20.00%
Terrorism Risk Insurance Program, Company's estimated deductible for the next fiscal year	$ 2,450
Terrorism Risk Insurance Program, annual cap limiting amount of aggregate subject losses for all participating insurers	$ 100,000

Goodwill (details)

Goodwill (details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Goodwill by segment
Goodwill	$ 3,580	$ 3,573
Reportable Segments [Member] | Business and International Insurance [Member]
Goodwill by segment
Goodwill	2,446	2,439
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill	496	496
Reportable Segments [Member] | Personal Insurance [Member]
Goodwill by segment
Goodwill	612	612
Other [Member]
Goodwill by segment
Goodwill	$ 26	$ 26

Goodwill (details) - Other Inta

Goodwill (details) - Other Intangible Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 210	$ 210
Intangible assets subject to amortization, accumulated amortization	159	148
Intangible assets subject to amortization, net	51	62
Amortization expense for other intangible assets	11	$ 26	$ 46
Estimated intangible asset amortization expense, 2017	9
Estimated intangible asset amortization expense, 2018	8
Estimated intangible asset amortization expense, 2019	6
Estimated intangible asset amortization expense, 2020	5
Estimated intangible asset amortization expense, 2021	$ 5

Goodwill (details) - Total Inta

Goodwill (details) - Total Intangibles - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Other Intangible Assets disclosure
Intangible assets not subject to amortization	$ 217	$ 217
Total other intangible assets, gross carrying amount	427	427
Total other intangible assets, accumulated amortization	159	148
Total other intangible assets, net	$ 268	$ 279

Insurance Claim Reserves (detai

Insurance Claim Reserves (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Insurance Claim Reserves disclosure
Amount of decrease in gross claims and claim adjustment expense reserves	$ 343	$ 1,550
Amount of decrease in reinsurance recoverables on unpaid losses	$ 468	$ 339
Reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, discount rate (percent)	5.00%	5.00%
Reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies, net of discount	$ 2,170	$ 2,130
Discount included in reserves for long-term disability and annuity claim payments primarily arising from workers' compensation insurance and workers' compensation excess insurance policies	1,083	1,066
Accretion of discount	50	51	$ 50
Asbestos and environmental claims reserves, balance	$ 1,710	$ 2,170

Insurance Claim Reserves (det75

Insurance Claim Reserves (details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	$ 48,295	$ 49,850
Net reserves at end of year	39,948
Reinsurance recoverables on unpaid losses	8,001
Claims and claim adjustment expense reserves at end of year	47,949	48,295	$ 49,850
Property casualty [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	48,272	49,824	50,865
Reinsurance recoverables on unpaid losses	8,449	8,788	9,280
Net reserves at beginning of year	39,823	41,036	41,585
Estimated claims and claim adjustment expenses for claims arising in the current year	15,675	14,471	14,688
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years	(680)	(817)	(885)
Total increases	14,995	13,654	13,803
Claims and claim adjustment expense payments for claims arising in current year	6,220	5,725	5,895
Claims and claim adjustment expense payments for claims arising in prior years	8,576	8,749	8,171
Total payments	14,796	14,474	14,066
Acquisition		2
Unrealized foreign exchange gain	(74)	(395)	(286)
Net reserves at end of year	39,948	39,823	41,036
Reinsurance recoverables on unpaid losses	7,981	8,449	8,788
Claims and claim adjustment expense reserves at end of year	47,929	48,272	$ 49,824
Accident and health [Member]
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]
Claims and claim adjustment expense reserves at beginning of year	23
Reinsurance recoverables on unpaid losses	20
Claims and claim adjustment expense reserves at end of year	$ 20	$ 23

Insurance Claim Reserves Footno

Insurance Claim Reserves Footnote (details) - Asbestos Payment - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Asbestos Direct Action Litigation [Member]
Loss Contingencies [Line Items]
Settlement payment	$ 579		$ 579
PPG Industries, Inc Litigation [Member]
Loss Contingencies [Line Items]
Settlement payment		$ 524

Insurance Claim Reserves (det77

Insurance Claim Reserves (details) - Prior Year Reserve Development by Segment - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	$ 771	$ 941	$ 941
Business and International Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	484	405	322
Increase to net favorable prior year reserve development related to workers' compensation reinsurance pool for accident years 1996 and prior			162
Bond & Specialty Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	326	258	450
Personal Insurance [Member]
Liability for claims and claim adjustment expense
Net favorable (unfavorable) prior year reserve development impacting the Company's results of operations	$ (39)	$ 278	$ 169

Insurance Claim Reserves (det78

Insurance Claim Reserves (details) - Claims and Claim Adjustment Expenses Reserves Summary - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	$ 40,951
Discount (Net of Reinsurance)	(1,003)
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	39,948
Reinsurance Recoverables on Unpaid Losses	8,001
Claims and Claim Adjustment Reserves	47,949	$ 48,295	$ 49,850
Discount on reinsurance recoverables for long-term disability and annuity claim payments included in discount (net of reinsurance)	80
Property casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	40,951
Discount (Net of Reinsurance)	(1,003)
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	39,948	39,823	41,036	$ 41,585
Reinsurance Recoverables on Unpaid Losses	7,981	8,449	8,788	9,280
Claims and Claim Adjustment Reserves	47,929	48,272	49,824	$ 50,865
Accident and health [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Reinsurance Recoverables on Unpaid Losses	20
Claims and Claim Adjustment Reserves	20	23
Business and International Insurance [Member] | General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	7,034
Business and International Insurance [Member] | Commercial property [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	866
Business and International Insurance [Member] | Commercial multi-peril [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,414
Business and International Insurance [Member] | Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,270
Business and International Insurance [Member] | Workers' compensation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	15,439
Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,482
Bond & Specialty Insurance [Member] | General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,042
Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	450
Personal Insurance [Member] | Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,277
Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	742
Reportable Segments [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Claims and Claim Adjustment Reserves	47,929	48,272	49,824
Reportable Segments [Member] | Property casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	36,016
Discount (Net of Reinsurance)	(1,000)
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	35,016
Reinsurance Recoverables on Unpaid Losses	2,695
Claims and Claim Adjustment Reserves	37,711
Reportable Segments [Member] | Business and International Insurance [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Claims and Claim Adjustment Reserves	41,006	41,563	42,700
Reportable Segments [Member] | Business and International Insurance [Member] | General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	7,034
Discount (Net of Reinsurance)	(168)
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	6,866
Reinsurance Recoverables on Unpaid Losses	712
Claims and Claim Adjustment Reserves	7,578
Reportable Segments [Member] | Business and International Insurance [Member] | Commercial property [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	866
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	866
Reinsurance Recoverables on Unpaid Losses	194
Claims and Claim Adjustment Reserves	1,060
Reportable Segments [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	3,414
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	3,414
Reinsurance Recoverables on Unpaid Losses	81
Claims and Claim Adjustment Reserves	3,495
Reportable Segments [Member] | Business and International Insurance [Member] | Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,270
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	2,270
Reinsurance Recoverables on Unpaid Losses	256
Claims and Claim Adjustment Reserves	2,526
Reportable Segments [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	15,439
Discount (Net of Reinsurance)	(832)
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	14,607
Reinsurance Recoverables on Unpaid Losses	729
Claims and Claim Adjustment Reserves	15,336
Reportable Segments [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,482
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	1,482
Reinsurance Recoverables on Unpaid Losses	157
Claims and Claim Adjustment Reserves	1,639
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Claims and Claim Adjustment Reserves	2,944	3,157	3,435
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,042
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	2,042
Reinsurance Recoverables on Unpaid Losses	82
Claims and Claim Adjustment Reserves	2,124
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	450
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	450
Reinsurance Recoverables on Unpaid Losses	17
Claims and Claim Adjustment Reserves	467
Reportable Segments [Member] | Personal Insurance [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Claims and Claim Adjustment Reserves	3,979	$ 3,552	$ 3,689
Reportable Segments [Member] | Personal Insurance [Member] | Automobile [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,277
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	2,277
Reinsurance Recoverables on Unpaid Losses	465
Claims and Claim Adjustment Reserves	2,742
Reportable Segments [Member] | Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	742
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	742
Reinsurance Recoverables on Unpaid Losses	2
Claims and Claim Adjustment Reserves	744
Reconciling Items [Member] | Other insurance contracts [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	2,955
Discount (Net of Reinsurance)	(3)
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	2,952
Reinsurance Recoverables on Unpaid Losses	2,058
Claims and Claim Adjustment Reserves	5,010
Reconciling Items [Member] | Unallocated loss adjustment expense reserve [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	1,936
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	1,936
Reinsurance Recoverables on Unpaid Losses	40
Claims and Claim Adjustment Reserves	1,976
Reconciling Items [Member] | Structured settements [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Reinsurance Recoverables on Unpaid Losses	3,168
Claims and Claim Adjustment Reserves	3,168
Reconciling Items [Member] | Other [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Net Undiscounted Claims and Claim Adjustment Expense Reserves	44
Subtotal: Net Claims and Allocated Claim Adjustment Expense Reserves	44
Reinsurance Recoverables on Unpaid Losses	20
Claims and Claim Adjustment Reserves	$ 64

Insurance Claim Reserves (det79

Insurance Claim Reserves (details) - Claim Development $ in Millions	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)	Dec. 31, 2009USD ($)	Dec. 31, 2008USD ($)	Dec. 31, 2007USD ($)
Claims Development
Total net liability (Audited)	$ 40,951
Property casualty [Member]
Claims Development
Total net liability (Audited)	40,951
Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	9,254
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	5,253
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	4,001
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	3,033
Total net liability (Audited)	7,034
Business and International Insurance [Member] | Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	4,108
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	3,406
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	702
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	164
Total net liability (Audited)	866
Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	17,153
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	14,044
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	3,109
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	305
Total net liability (Audited)	3,414
Business and International Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	6,255
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	4,169
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	2,086
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	184
Total net liability (Audited)	2,270
Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	21,999
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	11,788
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	10,211
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	5,228
Total net liability (Audited)	15,439
Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	6,509
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	5,122
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	1,387
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	95
Total net liability (Audited)	1,482
Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	5,754
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	3,786
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	1,968
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	74
Total net liability (Audited)	2,042
Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	868
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	482
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	386
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	64
Total net liability (Audited)	450
Personal Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	11,476
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	9,452
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	2,024
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	253
Total net liability (Audited)	2,277
Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	7,857
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	7,136
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Disclosed Accident Years (Audited)	721
Liability for Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance, Before Disclosed Accident Years (Audited)	21
Total net liability (Audited)	742
Short-duration Insurance Contracts, Accident Year 2007 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	824	$ 865	$ 883	$ 888	$ 919	$ 968	$ 1,089	$ 1,087	$ 1,162	$ 1,136
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	726	713	697	682	632	549	467	316	134	32
IBNR Reserves Dec. 31, 2016 (Audited)	$ 78
Cumulative Number of Reported Claims (Audited) | item	23,840
Short-duration Insurance Contracts, Accident Year 2007 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,369	1,376	1,369	1,373	1,375	1,398	1,402	1,364	1,430	1,490
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,312	1,307	1,296	1,278	1,256	1,208	1,110	982	824	498
IBNR Reserves Dec. 31, 2016 (Audited)	$ 51
Cumulative Number of Reported Claims (Audited) | item	96,767
Short-duration Insurance Contracts, Accident Year 2007 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,341	1,328	1,340	1,358	1,373	1,390	1,448	1,484	1,519	1,554
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	936	910	880	845	802	747	683	589	450	216
IBNR Reserves Dec. 31, 2016 (Audited)	$ 217
Cumulative Number of Reported Claims (Audited) | item	103,064
Short-duration Insurance Contracts, Accident Year 2007 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 597	601	608	611	609	607	608	616	626	632
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	578	570	561	547	524	488	450	410	355	228
IBNR Reserves Dec. 31, 2016 (Audited)	$ 4
Cumulative Number of Reported Claims (Audited) | item	66,327
Short-duration Insurance Contracts, Accident Year 2007 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 454	462	467	479	511	551	582	638	571	584
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	415	410	400	393	373	357	303	229	134	$ 35
IBNR Reserves Dec. 31, 2016 (Audited)	$ 4
Cumulative Number of Reported Claims (Audited) | item	11,018
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 935	931	946	994	1,041	1,079	1,222	1,209	1,143
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	799	759	734	694	615	497	359	154	35
IBNR Reserves Dec. 31, 2016 (Audited)	$ 88
Cumulative Number of Reported Claims (Audited) | item	25,385
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,681	1,688	1,674	1,684	1,674	1,688	1,683	1,674	1,725
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,617	1,602	1,581	1,551	1,490	1,396	1,264	1,103	712
IBNR Reserves Dec. 31, 2016 (Audited)	$ 47
Cumulative Number of Reported Claims (Audited) | item	108,382
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,617	1,617	1,621	1,634	1,639	1,683	1,734	1,745	1,714
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,162	1,130	1,088	1,036	961	875	752	571	274
IBNR Reserves Dec. 31, 2016 (Audited)	$ 237
Cumulative Number of Reported Claims (Audited) | item	107,565
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 642	646	651	655	658	665	670	685	681
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	622	616	603	579	543	501	460	406	256
IBNR Reserves Dec. 31, 2016 (Audited)	$ 5
Cumulative Number of Reported Claims (Audited) | item	71,803
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 631	643	672	712	716	697	743	769	579
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	590	579	562	529	471	387	281	157	$ 47
IBNR Reserves Dec. 31, 2016 (Audited)	$ 24
Cumulative Number of Reported Claims (Audited) | item	6,463
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 796	809	837	869	960	1,028	1,071	1,060
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	667	643	613	543	446	314	167	35
IBNR Reserves Dec. 31, 2016 (Audited)	$ 95
Cumulative Number of Reported Claims (Audited) | item	25,457
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,509	1,514	1,514	1,511	1,498	1,501	1,506	1,484
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,449	1,436	1,408	1,360	1,264	1,121	958	603
IBNR Reserves Dec. 31, 2016 (Audited)	$ 42
Cumulative Number of Reported Claims (Audited) | item	103,198
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,750	1,775	1,766	1,753	1,753	1,746	1,778	1,799
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,235	1,193	1,137	1,065	961	828	623	288
IBNR Reserves Dec. 31, 2016 (Audited)	$ 272
Cumulative Number of Reported Claims (Audited) | item	104,229
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 690	696	702	714	714	707	718	724
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	648	630	608	573	525	479	419	274
IBNR Reserves Dec. 31, 2016 (Audited)	$ 13
Cumulative Number of Reported Claims (Audited) | item	71,671
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 641	655	660	680	686	665	624	592
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	592	563	497	460	390	310	167	$ 36
IBNR Reserves Dec. 31, 2016 (Audited)	$ 24
Cumulative Number of Reported Claims (Audited) | item	6,287
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 918	912	927	959	1,021	1,031	1,028
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	756	702	629	487	324	139	35
IBNR Reserves Dec. 31, 2016 (Audited)	$ 108
Cumulative Number of Reported Claims (Audited) | item	27,678
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,898	1,892	1,895	1,861	1,832	1,826	1,711
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,798	1,763	1,698	1,579	1,395	1,180	709
IBNR Reserves Dec. 31, 2016 (Audited)	$ 51
Cumulative Number of Reported Claims (Audited) | item	111,586
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,055	2,052	2,049	2,056	2,035	2,042	1,886
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,385	1,321	1,246	1,133	978	750	341
IBNR Reserves Dec. 31, 2016 (Audited)	$ 354
Cumulative Number of Reported Claims (Audited) | item	116,837
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 706	715	724	735	721	722	715
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	641	615	573	522	465	403	258
IBNR Reserves Dec. 31, 2016 (Audited)	$ 20
Cumulative Number of Reported Claims (Audited) | item	71,437
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 653	668	661	679	679	612	571
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	597	565	482	396	291	152	$ 33
IBNR Reserves Dec. 31, 2016 (Audited)	$ 18
Cumulative Number of Reported Claims (Audited) | item	5,655
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 935	972	998	1,065	1,074	1,004
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	725	660	539	355	187	47
IBNR Reserves Dec. 31, 2016 (Audited)	$ 146
Cumulative Number of Reported Claims (Audited) | item	27,210
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,287	2,296	2,286	2,269	2,244	2,235
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	2,156	2,088	1,979	1,803	1,573	1,060
IBNR Reserves Dec. 31, 2016 (Audited)	$ 66
Cumulative Number of Reported Claims (Audited) | item	125,358
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,385	2,379	2,350	2,347	2,303	2,284
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,583	1,487	1,365	1,185	911	420
IBNR Reserves Dec. 31, 2016 (Audited)	$ 430
Cumulative Number of Reported Claims (Audited) | item	135,061
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 669	678	682	686	696	723
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	571	538	481	432	380	253
IBNR Reserves Dec. 31, 2016 (Audited)	$ 30
Cumulative Number of Reported Claims (Audited) | item	72,063
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 545	601	632	639	596	565
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	447	414	324	249	143	$ 33
IBNR Reserves Dec. 31, 2016 (Audited)	$ 34
Cumulative Number of Reported Claims (Audited) | item	5,191
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 892	913	935	985	989
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	589	489	295	150	32
IBNR Reserves Dec. 31, 2016 (Audited)	$ 184
Cumulative Number of Reported Claims (Audited) | item	24,384
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business and International Insurance [Member] | Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 895	889	924	988	1,054
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	872	865	845	770	453
IBNR Reserves Dec. 31, 2016 (Audited)	$ 13
Cumulative Number of Reported Claims (Audited) | item	28,183
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,888	1,888	1,903	1,883	1,885
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,699	1,590	1,424	1,246	795
IBNR Reserves Dec. 31, 2016 (Audited)	$ 88
Cumulative Number of Reported Claims (Audited) | item	104,419
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business and International Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,337	1,325	1,327	1,350	1,294
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,235	1,134	960	753	467
IBNR Reserves Dec. 31, 2016 (Audited)	$ 35
Cumulative Number of Reported Claims (Audited) | item	214,780
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,445	2,456	2,457	2,456	2,447
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,536	1,394	1,217	940	443
IBNR Reserves Dec. 31, 2016 (Audited)	$ 519
Cumulative Number of Reported Claims (Audited) | item	133,417
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 616	611	631	642	664
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	482	435	389	336	225
IBNR Reserves Dec. 31, 2016 (Audited)	$ 50
Cumulative Number of Reported Claims (Audited) | item	67,320
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 601	605	614	591	538
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	383	342	255	160	38
IBNR Reserves Dec. 31, 2016 (Audited)	$ 137
Cumulative Number of Reported Claims (Audited) | item	4,824
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 140	175	249	262	255
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	111	110	124	108	42
IBNR Reserves Dec. 31, 2016 (Audited)	$ 9
Cumulative Number of Reported Claims (Audited) | item	1,148
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Personal Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,428	2,432	2,448	2,454	2,417
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	2,376	2,311	2,189	1,983	1,503
IBNR Reserves Dec. 31, 2016 (Audited)	$ 15
Cumulative Number of Reported Claims (Audited) | item	793,669
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,019	2,018	2,029	2,056	2,136
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	2,008	1,993	1,964	1,901	$ 1,508
IBNR Reserves Dec. 31, 2016 (Audited)	$ 1
Cumulative Number of Reported Claims (Audited) | item	259,006
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 940	958	975	965
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	498	363	175	35
IBNR Reserves Dec. 31, 2016 (Audited)	$ 256
Cumulative Number of Reported Claims (Audited) | item	21,836
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business and International Insurance [Member] | Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 731	737	755	789
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	703	683	610	389
IBNR Reserves Dec. 31, 2016 (Audited)	$ 10
Cumulative Number of Reported Claims (Audited) | item	22,141
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,609	1,620	1,623	1,615
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,304	1,167	987	644
IBNR Reserves Dec. 31, 2016 (Audited)	$ 122
Cumulative Number of Reported Claims (Audited) | item	82,936
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business and International Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,245	1,240	1,236	1,235
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,039	884	675	435
IBNR Reserves Dec. 31, 2016 (Audited)	$ 67
Cumulative Number of Reported Claims (Audited) | item	197,041
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,506	2,540	2,545	2,553
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,413	1,237	954	458
IBNR Reserves Dec. 31, 2016 (Audited)	$ 651
Cumulative Number of Reported Claims (Audited) | item	128,111
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 685	701	717	723
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	494	439	388	260
IBNR Reserves Dec. 31, 2016 (Audited)	$ 56
Cumulative Number of Reported Claims (Audited) | item	71,183
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 630	606	565	510
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	352	252	154	34
IBNR Reserves Dec. 31, 2016 (Audited)	$ 204
Cumulative Number of Reported Claims (Audited) | item	4,371
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 146	199	246	240
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	131	128	113	37
IBNR Reserves Dec. 31, 2016 (Audited)	$ 6
Cumulative Number of Reported Claims (Audited) | item	1,006
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Personal Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,044	2,049	2,095	2,108
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,935	1,814	1,628	1,251
IBNR Reserves Dec. 31, 2016 (Audited)	$ 36
Cumulative Number of Reported Claims (Audited) | item	694,650
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,375	1,365	1,397	1,488
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,344	1,317	1,269	$ 994
IBNR Reserves Dec. 31, 2016 (Audited)	$ 4
Cumulative Number of Reported Claims (Audited) | item	149,373
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 983	989	976
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	321	163	37
IBNR Reserves Dec. 31, 2016 (Audited)	$ 438
Cumulative Number of Reported Claims (Audited) | item	20,926
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business and International Insurance [Member] | Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 836	860	936
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	775	710	464
IBNR Reserves Dec. 31, 2016 (Audited)	$ 15
Cumulative Number of Reported Claims (Audited) | item	21,490
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,625	1,627	1,663
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,154	956	628
IBNR Reserves Dec. 31, 2016 (Audited)	$ 193
Cumulative Number of Reported Claims (Audited) | item	76,833
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business and International Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,168	1,166	1,165
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	821	618	397
IBNR Reserves Dec. 31, 2016 (Audited)	$ 131
Cumulative Number of Reported Claims (Audited) | item	184,067
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,547	2,553	2,554
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,224	944	455
IBNR Reserves Dec. 31, 2016 (Audited)	$ 839
Cumulative Number of Reported Claims (Audited) | item	123,110
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 682	678	665
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	445	382	252
IBNR Reserves Dec. 31, 2016 (Audited)	$ 83
Cumulative Number of Reported Claims (Audited) | item	67,935
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 563	571	549
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	239	150	38
IBNR Reserves Dec. 31, 2016 (Audited)	$ 232
Cumulative Number of Reported Claims (Audited) | item	4,182
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 165	212	223
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	111	96	58
IBNR Reserves Dec. 31, 2016 (Audited)	$ 32
Cumulative Number of Reported Claims (Audited) | item	992
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Personal Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,981	1,994	2,014
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,763	1,564	1,193
IBNR Reserves Dec. 31, 2016 (Audited)	$ 75
Cumulative Number of Reported Claims (Audited) | item	669,990
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,453	1,450	1,515
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,402	1,338	$ 1,053
IBNR Reserves Dec. 31, 2016 (Audited)	$ 9
Cumulative Number of Reported Claims (Audited) | item	151,517
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 956	998
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	137	36
IBNR Reserves Dec. 31, 2016 (Audited)	$ 592
Cumulative Number of Reported Claims (Audited) | item	18,771
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business and International Insurance [Member] | Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 750	786
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	615	376
IBNR Reserves Dec. 31, 2016 (Audited)	$ 28
Cumulative Number of Reported Claims (Audited) | item	19,859
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,625	1,568
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	970	595
IBNR Reserves Dec. 31, 2016 (Audited)	$ 354
Cumulative Number of Reported Claims (Audited) | item	68,278
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business and International Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,215	1,198
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	658	409
IBNR Reserves Dec. 31, 2016 (Audited)	$ 246
Cumulative Number of Reported Claims (Audited) | item	179,963
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,585	2,644
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	893	430
IBNR Reserves Dec. 31, 2016 (Audited)	$ 1,142
Cumulative Number of Reported Claims (Audited) | item	120,681
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 610	597
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	346	228
IBNR Reserves Dec. 31, 2016 (Audited)	$ 112
Cumulative Number of Reported Claims (Audited) | item	58,238
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 524	528
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	141	38
IBNR Reserves Dec. 31, 2016 (Audited)	$ 272
Cumulative Number of Reported Claims (Audited) | item	3,814
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 191	217
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	75	32
IBNR Reserves Dec. 31, 2016 (Audited)	$ 79
Cumulative Number of Reported Claims (Audited) | item	768
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Personal Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,244	2,186
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,768	1,319
IBNR Reserves Dec. 31, 2016 (Audited)	$ 224
Cumulative Number of Reported Claims (Audited) | item	755,762
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,454	1,438
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,333	$ 994
IBNR Reserves Dec. 31, 2016 (Audited)	$ 28
Cumulative Number of Reported Claims (Audited) | item	144,367
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business and International Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,075
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	35
IBNR Reserves Dec. 31, 2016 (Audited)	$ 908
Cumulative Number of Reported Claims (Audited) | item	13,810
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business and International Insurance [Member] | Commercial property [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 896
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	441
IBNR Reserves Dec. 31, 2016 (Audited)	$ 131
Cumulative Number of Reported Claims (Audited) | item	19,327
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business and International Insurance [Member] | Commercial multi-peril [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,662
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	585
IBNR Reserves Dec. 31, 2016 (Audited)	$ 658
Cumulative Number of Reported Claims (Audited) | item	56,471
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business and International Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,290
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	416
IBNR Reserves Dec. 31, 2016 (Audited)	$ 516
Cumulative Number of Reported Claims (Audited) | item	173,790
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business and International Insurance [Member] | Workers' compensation [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,768
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	421
IBNR Reserves Dec. 31, 2016 (Audited)	$ 1,651
Cumulative Number of Reported Claims (Audited) | item	108,357
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 612
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	295
IBNR Reserves Dec. 31, 2016 (Audited)	$ 102
Cumulative Number of Reported Claims (Audited) | item	54,948
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Bond & Specialty Insurance [Member] | General liability [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 512
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	30
IBNR Reserves Dec. 31, 2016 (Audited)	$ 405
Cumulative Number of Reported Claims (Audited) | item	2,676
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 226
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	54
IBNR Reserves Dec. 31, 2016 (Audited)	$ 128
Cumulative Number of Reported Claims (Audited) | item	595
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Personal Insurance [Member] | Automobile [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 2,779
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,610
IBNR Reserves Dec. 31, 2016 (Audited)	$ 646
Cumulative Number of Reported Claims (Audited) | item	839,962
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Claims Development
Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	$ 1,556
Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance (Audited for 2016)	1,049
IBNR Reserves Dec. 31, 2016 (Audited)	$ 307
Cumulative Number of Reported Claims (Audited) | item	129,630

Insurance Claim Reserves Foot80

Insurance Claim Reserves Footnote (details) - Historical Claim Duration	Dec. 31, 2016
Business and International Insurance [Member] | General liability [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	3.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	13.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	19.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	17.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	12.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	8.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	5.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	2.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	3.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.60%
Business and International Insurance [Member] | Commercial property [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	51.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	31.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	8.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	2.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.80%
Business and International Insurance [Member] | Commercial multi-peril [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	39.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	22.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	10.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	8.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	6.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	3.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	1.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	1.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.40%
Business and International Insurance [Member] | Automobile [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	34.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	16.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	12.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	7.60%
Business and International Insurance [Member] | Workers' compensation [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	17.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	19.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	11.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	5.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	4.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	3.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	2.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	2.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.90%
Business and International Insurance [Member] | International - Canada [Member] | Property casualty [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	38.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	8.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	7.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	5.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	3.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	2.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.40%
Bond & Specialty Insurance [Member] | General liability [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	6.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	19.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	18.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	15.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	12.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	7.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	6.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	3.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.10%
Bond & Specialty Insurance [Member] | Fidelity and surety [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	26.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	36.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	10.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	(3.60%)
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.80%
Personal Insurance [Member] | Automobile [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	60.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	19.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	9.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	5.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	2.70%
Personal Insurance [Member] | Homeowners (excluding Other) [Member]
Historical Claims Duration
Short-duration Insurance Contracts, Historical Claims Duration, Year One	71.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	3.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	1.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.70%

Insurance Claim Reserves (det81

Insurance Claim Reserves (details) - Asbestos and Environmental Reserves - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Asbestos Direct Action Litigation [Member]
Liability for claims and claim adjustment expense
Reduction to net favorable prior year reserve development due to interest awarded as part of damages relating to a legal matter	$ 77
Settlement amount	$ 502
Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves		$ 225	$ 224	$ 250
Net losses paid		$ 708	$ 770	$ 242
Percent of total asbestos net paid losses related to policyholders with whom the Company had entered into settlement agreements limiting the Company's liability		69.00%	69.00%	8.00%
Asbestos reserves [Member] | Asbestos Direct Action Litigation [Member]
Liability for claims and claim adjustment expense
Settlement amount			$ 502
Asbestos reserves [Member] | PPG Industries, Inc Litigation [Member]
Liability for claims and claim adjustment expense
Settlement amount		$ 518
Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves		82	72	$ 87
Business and International Insurance [Member] | Asbestos reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves		225	224	250
Business and International Insurance [Member] | Asbestos reserves [Member] | Asbestos Direct Action Litigation [Member]
Liability for claims and claim adjustment expense
Reduction to net favorable prior year reserve development due to interest awarded as part of damages relating to a legal matter				77
Business and International Insurance [Member] | Environmental reserves [Member]
Liability for claims and claim adjustment expense
Increase (decrease) to asbestos and environmental reserves		$ 82	$ 72	$ 87

Debt (details)

Debt (details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 20, 2016	Dec. 31, 2015
Debt disclosure
Commercial paper amount	$ 100		$ 100
Total short-term debt	550		500
Schedule of debt
Total long-term debt	5,911		5,861
Total debt principal	6,461		6,361
Unamortized fair value adjustment, debt	47		49
Unamortized debt issuance costs	(71)		(66)
Total debt	6,437		6,344
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	700
6.25% Senior notes due June 20, 2016 [Member]
Schedule of debt
Current maturities of long-term debt			$ 400
Interest rate (percent)		6.25%	6.25%
5.75% Senior notes due December 15, 2017 [Member]
Schedule of debt
Current maturities of long-term debt	$ 450
Total long-term debt			$ 450
Interest rate (percent)	5.75%		5.75%
5.80% Senior notes due May 15, 2018 [Member]
Schedule of debt
Total long-term debt	$ 500		$ 500
Interest rate (percent)	5.80%		5.80%
5.90% Senior notes due June 2, 2019 [Member]
Schedule of debt
Total long-term debt	$ 500		$ 500
Interest rate (percent)	5.90%		5.90%
3.90% Senior notes due November 1, 2020 [Member]
Schedule of debt
Total long-term debt	$ 500		$ 500
Interest rate (percent)	3.90%		3.90%
7.75% Senior notes due April 15, 2026 [Member]
Schedule of debt
Total long-term debt	$ 200		$ 200
Interest rate (percent)	7.75%		7.75%
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
7.625% Junior subordinated debentures due December 15, 2027 [Member]
Schedule of debt
Total long-term debt	125		$ 125
Unamortized fair value adjustment, debt	$ 14		$ 15
Interest rate (percent)	7.625%		7.625%
6.375% Senior notes due March 15, 2033 [Member]
Schedule of debt
Total long-term debt	$ 500		$ 500
Interest rate (percent)	6.375%		6.375%
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 500
6.75% Senior notes due June 20, 2036 [Member]
Schedule of debt
Total long-term debt	$ 400		$ 400
Interest rate (percent)	6.75%		6.75%
6.25% Senior notes due June 15, 2037 [Member]
Schedule of debt
Total long-term debt	$ 800		$ 800
Interest rate (percent)	6.25%		6.25%
5.35% Senior notes due November 1, 2040 [Member]
Schedule of debt
Total long-term debt	$ 750		$ 750
Interest rate (percent)	5.35%		5.35%
4.60% Senior notes due August 1, 2043 [Member]
Schedule of debt
Total long-term debt	$ 500		$ 500
Interest rate (percent)	4.60%		4.60%
4.30% Senior notes due August 25, 2045 [Member]
Schedule of debt
Total long-term debt	$ 400		$ 400
Interest rate (percent)	4.30%		4.30%
8.50% Junior subordinated debentures due December 15, 2045 [Member]
Schedule of debt
Total long-term debt	$ 56		$ 56
Unamortized fair value adjustment, debt	$ 15		$ 15
Interest rate (percent)	8.50%		8.50%
3.75% Senior notes due May 15, 2046 [Member]
Schedule of debt
Total long-term debt	$ 500
Interest rate (percent)	3.75%
8.312% Junior subordinated debentures due July 1, 2046 [Member]
Schedule of debt
Total long-term debt	$ 73		$ 73
Unamortized fair value adjustment, debt	$ 18		$ 19
Interest rate (percent)	8.312%		8.312%
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member]
Schedule of debt
Total long-term debt	$ 107		$ 107
Interest rate (percent)	6.25%		6.25%

Debt (details) - Debt Issuance

Debt (details) - Debt Issuance - USD ($) $ in Millions	May 11, 2016	Aug. 25, 2015	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument
Net proceeds of issuance, after original issuance discount and deduction of underwriting expenses and commissions and other expenses			$ 491	$ 392
Senior notes [Member]
Debt Instrument
Debt, principal amount	$ 500	$ 400
Interest rate (percent)	3.75%	4.30%
Net proceeds of issuance, after original issuance discount and deduction of underwriting expenses and commissions and other expenses	$ 491	$ 392
Percentage of principal amount at which redemption price may be set	100.00%	100.00%
Basis points added to current treasury rate used in calculation of alternative redemption price	0.20%	0.25%

Debt (details) - Repayment

Debt (details) - Repayment - USD ($) $ in Millions	Jun. 20, 2016	Dec. 01, 2015	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument
Debt, principal amount repaid			$ 400	$ 400
6.25% Senior notes due June 20, 2016 [Member]
Debt Instrument
Debt, principal amount repaid	$ 400
Interest rate (percent)	6.25%			6.25%
5.50% Senior notes due December 1, 2015 [Member]
Debt Instrument
Debt, principal amount repaid		$ 400
Interest rate (percent)		5.50%

Debt (details) - Junior Sub Deb

Debt (details) - Junior Sub Debt $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)
Debt Instrument
Unamortized fair value adjustment, debt	$ 47	$ 49
Junior subordinated debt [Member]
Debt Instrument
Number of junior subordinated debentures that are not fixed-to-floating rate debentures | item	3
Number of separate trusts that issued preferred securities and used proceeds to purchase the Company's subordinated debentures that are not fixed-to-floating rate | item	3
Impact of amortization of the fair value adjustment on interest expense	$ 2	$ 1
7.625% Junior subordinated debentures due December 15, 2027 [Member]
Debt Instrument
Interest rate (percent)	7.625%	7.625%
Debt, effective interest rate (percent)	6.147%	6.147%
Unamortized fair value adjustment, debt	$ 14	$ 15
8.50% Junior subordinated debentures due December 15, 2045 [Member]
Debt Instrument
Interest rate (percent)	8.50%	8.50%
Debt, effective interest rate (percent)	6.362%	6.362%
Unamortized fair value adjustment, debt	$ 15	$ 15
8.312% Junior subordinated debentures due July 1, 2046 [Member]
Debt Instrument
Interest rate (percent)	8.312%	8.312%
Debt, effective interest rate (percent)	6.362%	6.362%
Unamortized fair value adjustment, debt	$ 18	$ 19
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member]
Debt Instrument
Number of consecutive years before Company is required to settle deferred interest	5 years
Number of consecutive years Company may defer interest without giving rise to an event of default	10 years
Interest rate (percent)	6.25%	6.25%
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Minimum [Member]
Debt Instrument
Number of occasions the Company may defer payment of interest | item	1
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Period from issuance to March 14, 2017 [Member]
Debt Instrument
Interest rate (percent)	6.25%
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Period from March 15, 2017 until redemption [Member]
Debt Instrument
Percentage of principal amount at which redemption price may be set	100.00%
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Period from March 15, 2017 until redemption [Member] | LIBOR [Member]
Debt Instrument
Maturity of LIBOR rate used	three-month LIBOR
Basis spread on variable rate	2.215%
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Period from March 15, 2037 until redemption [Member]
Debt Instrument
Days in period during which Company will be required to raise proceeds to repay debentures if Company chooses not to redeem the debentures	180 days
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Period from March 15, 2037 until redemption [Member] | Minimum [Member]
Debt Instrument
Days before scheduled maturity date that Company's 180-day period must end	10 days
6.25% Fixed-to-floating rate junior subordinated debentures due March 15, 2067 [Member] | Period from March 15, 2037 until redemption [Member] | Maxiumum [Member]
Debt Instrument
Days before scheduled maturity date that Company's 180-day period must end	15 days

Debt (details) - Maturities

Debt (details) - Maturities $ in Millions	Dec. 31, 2016USD ($)
Maturities of long-term debt
Amount of debt obligations, other than commercial paper, due in 2017	$ 450
Amount of debt obligations, other than commercial paper, due in 2018	500
Amount of debt obligations, other than commercial paper, due in 2019	500
Amount of debt obligations, other than commercial paper, due in 2020	500
Amount of debt obligations, other than commercial paper, due in 2021	$ 0

Debt (details) - Line of Credit

Debt (details) - Line of Credit - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Line of credit
Years from effective date to expiration date of previous universal shelf registration statement	3 years
Line of credit [Member]
Line of credit
Credit agreement, term (in years)	5 years
Credit agreement, maximum borrowing capacity	$ 1,000
Credit agreement, covenant terms	Pursuant to the credit agreement covenants, the Company must maintain a minimum consolidated net worth, defined as shareholders' equity determined in accordance with GAAP plus (a) trust preferred securities (not to exceed 15% of total capital) and (b) mandatorily convertible securities (combined with trust preferred securities, not to exceed 25% of total capital) less goodwill and other intangible assets, of $13.73 billion. In addition, the credit agreement contains other customary restrictive covenants as well as certain customary events of default, including with respect to a change in control, which is defined to include the acquisition of 35% or more of the Company's voting stock and certain changes in the composition of the Company's board of directors.
Credit agreement, threshold of consolidated net worth	$ 13,730
Credit agreement, compliance	At December 31, 2016, the Company was in compliance with these covenants.
Line of credit [Member] | Minimum [Member]
Line of credit
Percentage of Company's voting stock acquired by outside entity that would be considered a change in control	35.00%
Line of credit [Member] | Maxiumum [Member]
Line of credit
Maximum percentage of trust preferred securities relative to total capital in determining consolidated net worth	15.00%
Maximum percentage of trust preferred securities and mandatorily convertible securities relative to total capital in determining consolidated net worth	25.00%
Line of credit [Member] | LIBOR [Member]
Line of credit
Credit agreement, cost of borrowing, basis points above LIBOR	1.125%
Line of credit [Member] | LIBOR [Member] | Minimum [Member]
Line of credit
Credit agreement, cost of borrowing, basis points above LIBOR	0.875%
Line of credit [Member] | LIBOR [Member] | Maxiumum [Member]
Line of credit
Credit agreement, cost of borrowing, basis points above LIBOR	1.50%
Commercial Paper [Member]
Line of credit
Credit agreement, maximum borrowing capacity	$ 800
Commercial Paper [Member] | Minimum [Member]
Line of credit
Interest rate on commercial paper	0.35%	0.09%
Commercial Paper [Member] | Maxiumum [Member]
Line of credit
Interest rate on commercial paper	0.55%	0.30%

Shareholders' Equity and Divi88

Shareholders' Equity and Dividend Availability (details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Shareholders' Equity and Dividend Availability disclosure
Number of authorized shares	1,755				1,755
Number of authorized shares, preferred shares	5				5
Number of authorized shares, voting common stock	1,745				1,745
Number of authorized shares, undesignated shares	5				5
Number of shares purchased (in shares)	6.6	4.7	4.9	5.1	21.3
Cost of shares repurchased	$ 750	$ 550	$ 550	$ 550	$ 2,400
Average price paid per share	$ 113.54	$ 117.25	$ 112.12	$ 108.46	$ 112.82
Remaining capacity under share repurchase authorization	$ 934	$ 1,684	$ 2,234	$ 2,784	$ 934
Cost of shares acquired to cover tax withholding costs and exercise costs					$ 72	$ 74

Shareholders' Equity and Divi89

Shareholders' Equity and Dividend Availability (details) - Dividend Availability $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)item$ / shares	Dec. 31, 2015USD ($)item$ / shares	Dec. 31, 2014USD ($)item$ / shares
Statutory accounting principals
Dividends received by TRV and its two non-insurance holding companies from their U.S. insurance subsidiaries	$ 3,050	$ 3,750	$ 4,100
Cash dividends declared per common share | $ / shares	$ 2.62	$ 2.38	$ 2.15
Cash dividends paid	$ 757	$ 739	$ 729
Insurance subsidiaries [Member]
Statutory accounting principals
Statutory net income of the Company's domestic and international insurance subsidiaries	3,200	3,800	$ 3,970
Statutory capital and surplus of the Company's domestic and international insurance subsidiaries	$ 20,760	$ 20,570
Travelers [Member]
Statutory accounting principals
Number of non-insurance holding companies underneath TRV | item	2	2	2
Cash dividends declared per common share | $ / shares	$ 2.62	$ 2.38	$ 2.15
Cash dividends paid	$ 757	$ 739	$ 729
Connecticut Insurance Department [Member] | Insurance subsidiaries [Member]
Statutory accounting principals
Maximum amount of dividends available to be paid by subsidiaries to their parent without prior approval of the Connecticut Insurance Department	$ 3,690

Other Comprehensive Income an90

Other Comprehensive Income and Accumulated Other Comprehensive Income (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive income [Roll Forward]
Shareholders' equity, beginning of year	$ 23,598	$ 24,836
Other comprehensive income (loss), net of taxes	(598)	(1,037)	$ 70
Shareholders' equity, end of year	23,221	23,598	24,836
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(887)	(1,429)	195
Income tax expense (benefit), other comprehensive income (loss)	(289)	(392)	125
Other comprehensive income (loss), net of taxes	(598)	(1,037)	70
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income [Roll Forward]
Shareholders' equity, beginning of year	(157)	880	810
Other comprehensive income (loss) before reclassifications	(605)	(1,089)	52
Amounts reclassified from accumulated other comprehensive income	7	52	18
Other comprehensive income (loss), net of taxes	(598)	(1,037)	70
Shareholders' equity, end of year	(755)	(157)	880
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(887)	(1,429)	195
Income tax expense (benefit), other comprehensive income (loss)	(289)	(392)	125
Other comprehensive income (loss), net of taxes	(598)	(1,037)	70
Changes in Net Unrealized Gains on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Shareholders' equity, beginning of year	1,100	1,768	1,125
Other comprehensive income (loss) before reclassifications	(530)	(641)	667
Amounts reclassified from accumulated other comprehensive income	(42)	(27)	(24)
Other comprehensive income (loss), net of taxes	(572)	(668)	643
Shareholders' equity, end of year	528	1,100	1,768
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(883)	(1,020)	976
Income tax expense (benefit), other comprehensive income (loss)	(311)	(352)	333
Other comprehensive income (loss), net of taxes	(572)	(668)	643
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Shareholders' equity, beginning of year	189	198	197
Other comprehensive income (loss) before reclassifications	4	(11)	(2)
Amounts reclassified from accumulated other comprehensive income	9	2	3
Other comprehensive income (loss), net of taxes	13	(9)	1
Shareholders' equity, end of year	202	189	198
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	21	(14)	2
Income tax expense (benefit), other comprehensive income (loss)	8	(5)	1
Other comprehensive income (loss), net of taxes	13	(9)	1
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income [Roll Forward]
Shareholders' equity, beginning of year	(713)	(755)	(431)
Other comprehensive income (loss) before reclassifications	(30)	(18)	(363)
Amounts reclassified from accumulated other comprehensive income	40	60	39
Other comprehensive income (loss), net of taxes	10	42	(324)
Shareholders' equity, end of year	(703)	(713)	(755)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	16	66	(494)
Income tax expense (benefit), other comprehensive income (loss)	6	24	(170)
Other comprehensive income (loss), net of taxes	10	42	(324)
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income [Roll Forward]
Shareholders' equity, beginning of year	(733)	(331)	(81)
Other comprehensive income (loss) before reclassifications	(49)	(419)	(250)
Amounts reclassified from accumulated other comprehensive income		17
Other comprehensive income (loss), net of taxes	(49)	(402)	(250)
Shareholders' equity, end of year	(782)	(733)	(331)
Pre-tax components of other comprehensive income (loss) and related tax expense (benefit)
Other comprehensive income (loss) before income taxes	(41)	(461)	(289)
Income tax expense (benefit), other comprehensive income (loss)	8	(59)	(39)
Other comprehensive income (loss), net of taxes	$ (49)	$ (402)	$ (250)

Other Comprehensive Income an91

Other Comprehensive Income and Accumulated Other Comprehensive Income (details) - Reclassifications - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement	[1]									$ (68)	$ (3)	$ (79)
Reclassification adjustment impacting general and administrative expense on the income statement										4,154	4,094	3,964
Total reclassifications		$ (1,302)	$ (947)	$ (887)	$ (917)	$ (1,209)	$ (1,307)	$ (1,076)	$ (1,148)	(4,053)	(4,740)	(5,089)
Income tax benefit		(359)	(231)	(223)	(226)	(343)	(379)	(264)	(315)	(1,039)	(1,301)	(1,397)
Amounts reclassified from accumulated other comprehensive income, net of taxes		$ (943)	$ (716)	$ (664)	$ (691)	$ (866)	$ (928)	$ (812)	$ (833)	(3,014)	(3,439)	(3,692)
Accumulated Other Comprehensive Income (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Total reclassifications										11	79	28
Income tax benefit										4	27	10
Amounts reclassified from accumulated other comprehensive income, net of taxes										7	52	18
Changes in Net Unrealized Gains on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement										(64)	(42)	(36)
Income tax benefit										(22)	(15)	(12)
Amounts reclassified from accumulated other comprehensive income, net of taxes										(42)	(27)	(24)
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement										13	2	4
Income tax benefit										4		1
Amounts reclassified from accumulated other comprehensive income, net of taxes										9	2	3
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting general and administrative expense on the income statement										62	93	60
Income tax benefit										22	33	21
Amounts reclassified from accumulated other comprehensive income, net of taxes										$ 40	60	$ 39
Net Unrealized Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement											26
Income tax benefit											9
Amounts reclassified from accumulated other comprehensive income, net of taxes											$ 17
[1]	Total other-than-temporary impairment (OTTI) losses were $(40) million, $(54) million and $(22) million for the years ended December 31, 2016, 2015 and 2014, respectively. Of total OTTI, credit losses of $(29) million, $(52) million and $(26) million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $(11) million, $(2) million and $4 million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.

Earnings per Share (details)

Earnings per Share (details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings per Share disclosure
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Participating share-based awards - allocated income									(22)	(25)	(27)
Net income available to common shareholders -- basic									2,992	3,414	3,665
Net income available to common shareholders -- diluted									$ 2,992	$ 3,414	$ 3,665
Weighted average shares outstanding, basic									288.1	310.6	338.8
Weighted average effects of dilutive securities, stock options and performance shares (in shares)									2.9	3.3	3.7
Weighted average shares outstanding, diluted									291	313.9	342.5
Net income per common share, basic	$ 3.32	$ 2.48	$ 2.27	$ 2.33	$ 2.87	$ 3	$ 2.56	$ 2.58	$ 10.39	$ 10.99	$ 10.82
Net income per common share, diluted	$ 3.28	$ 2.45	$ 2.24	$ 2.30	$ 2.83	$ 2.97	$ 2.53	$ 2.55	$ 10.28	$ 10.88	$ 10.70

Income Taxes (details)

Income Taxes (details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes disclosure
Current income tax expense included in consolidated statement of income, federal									$ 899	$ 1,144	$ 1,216
Current income tax expense included in consolidated statement of income, foreign									21	29	28
Current income tax expense included in consolidated statement of income, state									8	9	10
Total current tax expense									928	1,182	1,254
Deferred income tax expense included in consolidated statement of income, federal									110	117	121
Deferred income tax expense included in consolidated statement of income, foreign									1	2	22
Total deferred tax expense									111	119	143
Total income tax expense included in consolidated statement of income	$ 359	$ 231	$ 223	$ 226	$ 343	$ 379	$ 264	$ 315	1,039	1,301	1,397
Expense (benefit) relating to share-based compensation, the changes in unrealized gain on investments, unrealized loss on foreign exchange and other items in other comprehensive income									(289)	(448)	68
Total income tax expense included in consolidated financial statements									750	853	1,465
U.S. income before income taxes									3,946	4,621	4,899
Foreign income before income taxes									107	119	190
Income before income taxes	1,302	$ 947	$ 887	$ 917	1,209	$ 1,307	$ 1,076	$ 1,148	$ 4,053	$ 4,740	$ 5,089
Statutory tax rate (percent)									35.00%	35.00%	35.00%
Expected federal income tax expense									$ 1,419	$ 1,659	$ 1,781
Tax effect of nontaxable investment income									(323)	(345)	(379)
Tax effect of other, net									$ (57)	$ (13)	$ (5)
Effective tax rate (percent)									26.00%	27.00%	27.00%
Income taxes paid									$ 892	$ 1,207	$ 1,147
Current income tax payable	72				50				72	50
Deferred tax assets, claims and claim adjustment expense reserves	664				691				664	691
Deferred tax assets, unearned premium reserves	760				731				760	731
Deferred tax assets, compensation-related liabilities	268				326				268	326
Deferred tax assets, other	272				320				272	320
Total gross deferred tax assets	1,964				2,068				1,964	2,068
Less: valuation allowance	3								3
Adjusted gross deferred tax assets	1,961				2,068				1,961	2,068
Deferred tax liabilities, deferred acquisition costs	604				580				604	580
Deferred tax liabilities, investments	592				867				592	867
Deferred tax liabilities, internally-developed software	157				134				157	134
Deferred tax liabilities, other	143				191				143	191
Total gross deferred tax liabilities	1,496				1,772				1,496	1,772
Net deferred tax asset	465				$ 296				465	$ 296
Increase in valuation allowance									3
Amount of the Company's foreign operations' undistributed earnings for which U.S. income taxes have not been recognized	$ 358								$ 358

Income Taxes (details) - NOL Ca

Income Taxes (details) - NOL Carryforwards $ in Millions	Dec. 31, 2016USD ($)
Brazil [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	$ 8
United Kingdom [Member]
Net Operating Loss Carryforward
Net operating loss carryforward	$ 106

Income Taxes (details) - Additi

Income Taxes (details) - Additional Tax Details - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits, balance at January 1	$ 16	$ 23
Additions for tax positions of prior years	3	2
Reductions for tax positions of prior years	(6)	(9)
Unrecognized tax benefits, balance at December 31	13	16	$ 23
Unrecognized tax benefits that, if recognized, would affect the annual effective tax rate	7	4
Amount of unrecognized tax benefits that are tax positions for which the ultimate deductibility is certain, but for which there is uncertainty about the timing of deductibility	6	12
Amount of interest recognized on unrecognized tax benefits in income taxes	31		$ 31
Amount of interest benefit recognized on unrecognized tax benefits in income taxes		(32)
Accrued payment of interest balance for unrecognized tax benefits	$ 57	$ 26

Share-Based Incentive Compens96

Share-Based Incentive Compensation (details) - USD ($) $ / shares in Units, $ in Millions	Feb. 09, 2017	May 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of stock option activity
Stock options outstanding, beginning of year, number (in shares)			9,864,255
Stock options granted, number (in shares)			2,847,398
Stock options exercised, number (in shares)			(4,069,532)
Stock options forfeited or expired, number (in shares)			(82,085)
Stock options outstanding, end of year, number (in shares)			8,560,036	9,864,255
Stock options outstanding, beginning of year, weighted average exercise price (per share)			$ 74.48
Stock options granted, weighted average exercise price (per share)			106.21
Stock options exercised, weighted average exercise price (per share)			69.13
Stock options forfeited or expired, weighted average exercise price (per share)			97.44
Stock options outstanding, end of year, weighted average exercise price (per share)			$ 87.36	$ 74.48
Stock options outstanding, weighted average contractual life remaining			6 years 9 months 18 days
Stock options outstanding, aggregate intrinsic value			$ 300
Stock options vested at end of year, number (in shares)			5,588,061
Stock options vested at end of year, weighted average exercise price (per share)			$ 80.74
Stock options vested at end of year, weighted average contractual life remaining			6 years
Stock options vested at end of year, aggregate intrinsic value			$ 233
Stock options exercisable at end of year, number (in shares)			3,007,663
Stock options exercisable at end of year, weighted average exercise price (per share)			$ 65.18
Stock options exercisable at end of year, weighted average contractual life remaining			4 years 2 months 12 days
Stock options exercisable at end of year, aggregate intrinsic value			$ 172
Stock option grants [Member]
Assumptions used in estimating fair value of options
Expected term of stock options				6 years	6 years
Expected volatility of the Company's stock (percent)				19.29%
Weighted average volatility (percent)			16.79%	19.29%	27.50%
Expected annual dividend per share				$ 2.20
Risk-free rate				1.31%
Summary of stock option activity
Stock options granted, weighted average grant-date fair value of options granted (per share)			$ 13.29	$ 15.78	$ 17.22
Total intrinsic value of options exercised during the year			$ 167	$ 120	$ 117
Stock option grants [Member] | Minimum [Member]
Assumptions used in estimating fair value of options
Expected term of stock options			5 years
Expected volatility of the Company's stock (percent)			15.14%		27.20%
Expected annual dividend per share			$ 2.44		$ 2
Risk-free rate			1.36%		1.81%
Stock option grants [Member] | Maxiumum [Member]
Assumptions used in estimating fair value of options
Expected term of stock options			6 years
Expected volatility of the Company's stock (percent)			16.80%		27.50%
Expected annual dividend per share			$ 2.68		$ 2.20
Risk-free rate			2.23%		1.82%
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member]
Share-based compensation plan description
Number of shares of the Company's common stock originally authorized for grant under the 2014 Incentive Plan			10,000,000
Additional number of shares of the Company's common stock authorized for grant under the 2014 Incentive Plan		4,400,000
Number of shares of the Company's common stock authorized for grant under the 2014 Incentive Plan			14,400,000
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] | Stock option grants [Member]
Share-based compensation plan description
Option term			10 years
General vesting period			3 years
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] | Stock option grants [Member] | Subsequent Event [Member]
Summary of stock option activity
Stock options granted, number (in shares)	2,106,022
Stock options granted, weighted average exercise price (per share)	$ 118.78
Stock options granted, weighted average grant-date fair value of options granted (per share)	$ 16.15
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] | Director deferred stock awards [Member]
Share-based compensation plan description
Number of days prior to date of annual meeting in year following date of grant in which annual deferred stock awards vest in full			1 day
Number of months after termination of service as a director before distributions of deferreed stock awards begin			6 months

Share-Based Incentive Compens97

Share-Based Incentive Compensation (details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	Feb. 09, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted stock units, deferred stock units and performance share awards [Member]
Share-based compensation
Fair value of shares that vested during the year		$ 175	$ 179	$ 147
Restricted stock units, deferred stock units and performance share awards [Member] | Subsequent Event [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, granted, number	960,515
Other equity instruments, granted, weighted average grant-date fair value	$ 118.78
Restricted and deferred stock units [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, nonvested, number, beginning of year		1,435,958
Other equity instruments, granted, number		676,736
Other equity instruments, vested, number		(667,650)
Other equity instruments, forfeited, number		(68,552)
Other equity instruments, nonvested, number, end of year		1,376,492	1,435,958
Other equity instruments, nonvested, weighted average grant-date fair value, beginning of year		$ 88.35
Other equity instruments, granted, weighted average grant-date fair value		106.93
Other equity instruments, vested, weighted average grant-date fair value		86.85
Other equity instruments, forfeited, weighted average grant-date fair value		97.82
Other equity instruments, nonvested, weighted average grant-date fair value, end of year		$ 97.75	$ 88.35
Other equity instruments, nonvested dividend equivalents, number, beginning of year		396
Other equity instruments, nonvested dividend equivalents, number, end of year		408	396
Restricted and deferred stock units [Member] | Subsequent Event [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, granted, number	567,006
Restricted stock units [Member]
Share-based compensation
Award vesting period		3 years
Performance shares [Member]
Share-based compensation
Award vesting period		3 years
Peformance period		3 years
Summary of other equity instruments [Roll Forward]
Other equity instruments, nonvested, number, beginning of year		1,101,989
Other equity instruments, granted, number		476,411
Other equity instruments, vested, number		(818,360)
Other equity instruments, forfeited, number		(63,495)
Other equity instruments, performance-based adjustment, number		100,073
Other equity instruments, nonvested, number, end of year		796,618	1,101,989
Other equity instruments, nonvested, weighted average grant-date fair value, beginning of year		$ 91.27
Other equity instruments, granted, weighted average grant-date fair value		106.03
Other equity instruments, vested, weighted average grant-date fair value		84.43
Other equity instruments, forfeited, weighted average grant-date fair value		100.02
Other equity instruments, performance-based adjustment, weighted average grant-date fair value		88.22
Other equity instruments, nonvested, weighted average grant-date fair value, end of year		$ 106.03	$ 91.27
Other equity instruments, nonvested dividend equivalents, number, beginning of year		40,663
Other equity instruments, nonvested dividend equivalents, number, end of year		28,480	40,663
Performance shares [Member] | Subsequent Event [Member]
Summary of other equity instruments [Roll Forward]
Other equity instruments, granted, number	393,509
Performance shares [Member] | Feburary 2015, 2016 and 2017 Awards [Member] | Minimum [Member]
Share-based compensation
Percentage of performance shares to vest		50.00%
Performance shares [Member] | Feburary 2015, 2016 and 2017 Awards [Member] | Maxiumum [Member]
Share-based compensation
Percentage of performance shares to vest		150.00%

Share-Based Incentive Compensta

Share-Based Incentive Compenstaion (details) - Cost Recognition - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based compensation
Total compensation cost recognized in earnings for all share-based incentive compensation awards	$ 155	$ 141	$ 138
Tax benefit recognized in earnings related to compensation costs	52	47	47
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	$ 124
Weighted-average period of recognition for unrecognized compensation cost (in years)	1 year 8 months 12 days
Cash received from the exercise of employee stock options under share-based compensation plans	$ 332	183	195
Tax benefit for tax deductions from employee stock options	$ 58	41
Minimum [Member]
Share-based compensation
Estimated annual forfeiture rate reflected in share-based compensation cost (percent)	3.00%
Maxiumum [Member]
Share-based compensation
Estimated annual forfeiture rate reflected in share-based compensation cost (percent)	4.00%
Performance shares [Member]
Share-based compensation
Estimated attainment of performance shares at grant date (percent)	100.00%
Compensation cost adjustments for the updated estimate of performance shares due to attaining certain performance levels	$ 11	$ 8	$ 14

Pension Plans, Retirement Ben99

Pension Plans, Retirement Benefits and Savings Plans (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	$ 3,478	$ 3,612
Benefits earned	118	131	$ 110
Interest cost on benefit obligation	122	144	150
Actuarial loss (gain)	69	(201)
Benefits paid	(177)	(199)
Settlement	(3)
Foreign currency exchange rate change, change in projected benefit obligation	(15)	(9)
Benefit obligation, balance, end of year	3,592	3,478	3,612
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	3,242	3,357
Actual return on plan assets	233	(14)
Company contributions	214	107
Benefits paid	(177)	(199)
Settlement	(3)
Foreign currency exchange rate change, change in plan assets	(16)	(9)
Fair value of plan assets, balance, end of year	3,493	3,242	3,357
Funded status of plan at end of year	(99)	(236)
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	25	4
Accrued under-funded benefit plan liabilities	(124)	(240)
Total amount recognized in the consolidated balance sheet	(99)	(236)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial (gain) loss	1,127	1,131
Prior service benefit	(6)	(8)
Total amount recognized in accumulated other comprehensive income	1,121	1,123
Qualified Domestic Pension Plan [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	3,250	3,385
Benefits earned	111	124
Interest cost on benefit obligation	114	135
Actuarial loss (gain)	54	(203)
Benefits paid	(162)	(191)
Benefit obligation, balance, end of year	3,367	3,250	3,385
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	3,127	3,235
Actual return on plan assets	222	(17)
Company contributions	200	100	200
Benefits paid	(162)	(191)
Fair value of plan assets, balance, end of year	3,387	3,127	3,235
Funded status of plan at end of year	20	(123)
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	20
Accrued under-funded benefit plan liabilities		(123)
Total amount recognized in the consolidated balance sheet	20	(123)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial (gain) loss	1,072	1,079
Prior service benefit	(6)	(8)
Total amount recognized in accumulated other comprehensive income	1,066	1,071
Nonqualified and Foreign Pension Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	228	227
Benefits earned	7	7
Interest cost on benefit obligation	8	9
Actuarial loss (gain)	15	2
Benefits paid	(15)	(8)
Settlement	(3)
Foreign currency exchange rate change, change in projected benefit obligation	(15)	(9)
Benefit obligation, balance, end of year	225	228	227
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	115	122
Actual return on plan assets	11	3
Company contributions	14	7
Benefits paid	(15)	(8)
Settlement	(3)
Foreign currency exchange rate change, change in plan assets	(16)	(9)
Fair value of plan assets, balance, end of year	106	115	122
Funded status of plan at end of year	(119)	(113)
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	5	4
Accrued under-funded benefit plan liabilities	(124)	(117)
Total amount recognized in the consolidated balance sheet	(119)	(113)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial (gain) loss	55	52
Total amount recognized in accumulated other comprehensive income	55	52
Postretirement Benefit Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	233	255
Interest cost on benefit obligation	8	10	10
Actuarial loss (gain)	(17)	(3)
Benefits paid	(11)	(13)
Plan amendments		(11)
Foreign currency exchange rate change, change in projected benefit obligation	1	(5)
Benefit obligation, balance, end of year	214	233	255
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	15	16
Company contributions	10	12
Benefits paid	(11)	(13)
Fair value of plan assets, balance, end of year	14	15	$ 16
Funded status of plan at end of year	(200)	(218)
Amounts recognized in the consolidated balance sheet consist of:
Accrued under-funded benefit plan liabilities	(200)	(218)
Total amount recognized in the consolidated balance sheet	(200)	(218)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial (gain) loss	(13)	4
Prior service benefit	(31)	(35)
Total amount recognized in accumulated other comprehensive income	$ (44)	$ (31)

Pension Plans, Retirement Be100

Pension Plans, Retirement Benefits and Savings Plans (details) - Additional Pension Disclosures - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	$ (16)	$ (66)	$ 494
Pension Plans [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	3,480	3,370
Aggregate projected benefit obligation for pension plans with an accumulated benefit obligation in excess of plan assets	200	3,470
Aggregate accumulated benefit obligation for pension plans with an accumulated benefit obligation in excess of plan assets	200	3,360
Fair value of plan assets for pension plans with an accumulated benefit obligation in excess of plan assets	100	3,230
Components of net periodic benefit cost
Service cost	118	131	110
Interest cost on benefit obligation	122	144	150
Expected return on plan assets	(230)	(230)	(218)
Net periodic benefit cost, curtailment			(1)
Net periodic benefit cost, settlement	1		2
Net periodic benefit cost, amortization of unrecognized prior service benefit	(1)	(1)
Net periodic benefit cost, amortization of unrecognized net actuarial loss (gain)	66	96	65
Net periodic benefit cost	76	140	108
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, prior service benefit			(8)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, net actuarial loss (gain)	66	43	516
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, foreign currency exchange rate change	(2)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, curtailment			(2)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, settlement	(1)		(2)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of prior service benefit	1	1
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of net actuarial gain (loss)	(66)	(96)	(65)
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	(2)	(52)	439
Total other changes recognized in net periodic benefit cost and other comprehensive income	74	88	547
Estimated net actuarial gain (loss) that will be amortized from other comprehensive income into net periodic benefit cost over the next fiscal year	(75)
Estimated prior service benefit to be amortized over the next fiscal year	1
Qualified Domestic Pension Plan [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	3,260	3,150
Required contributions made	0	0	0
Required contributions during next fiscal year	0
Components of net periodic benefit cost
Service cost	111	124
Interest cost on benefit obligation	114	135
Nonqualified and Foreign Pension Plans [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	220	220
Components of net periodic benefit cost
Service cost	7	7
Interest cost on benefit obligation	8	9
Foreign Pension Plan [Member]
Defined benefit plan disclosure
Required contributions during next fiscal year	0
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost
Interest cost on benefit obligation	8	10	10
Net periodic benefit cost, amortization of unrecognized prior service benefit	(3)	(3)	(2)
Net periodic benefit cost, amortization of unrecognized net actuarial loss (gain)		1	(3)
Net periodic benefit cost	5	8	5
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, prior service benefit		(11)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, net actuarial loss (gain)	(17)	(3)	50
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, foreign currency exchange rate change	1
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of prior service benefit	3	3	2
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of net actuarial gain (loss)		(1)	3
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	(13)	(12)	55
Total other changes recognized in net periodic benefit cost and other comprehensive income	(8)	$ (4)	$ 60
Estimated prior service benefit to be amortized over the next fiscal year	3
Postretirement Benefit Plans [Member] | Maxiumum [Member]
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Estimated net actuarial gain (loss) that will be amortized from other comprehensive income into net periodic benefit cost over the next fiscal year	$ 1

Pension Plans, Retirement Be101

Pension Plans, Retirement Benefits and Savings Plans (details) - Change in Estimation - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Accounting Estimate
Increase in diluted net income per share	$ 3.28	$ 2.45	$ 2.24	$ 2.30	$ 2.83	$ 2.97	$ 2.53	$ 2.55	$ 10.28	$ 10.88	$ 10.70
Qualified Domestic Pension Plan [Member]
Change in Accounting Estimate
Reduction to service cost									$ (111)	$ (124)
Reduction to interest cost									$ (114)	$ (135)
Weighted average discount rate used to measure service cost (percent)									4.77%	4.10%
Weighted average discount rate used to measure interest cost (percent)									3.64%	4.10%
Nonqualified Domestic Pension Plan [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									4.53%	4.10%
Weighted average discount rate used to measure interest cost (percent)									3.47%	4.10%
Domestic Postretirement Benefit Plans [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure interest cost (percent)									3.53%	4.10%
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Impact of Change in Estimation Approach [Member]
Change in Accounting Estimate
Reduction to service cost									$ 6
Reduction to interest cost									$ 30
Increase in diluted net income per share									$ 0.08
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Current Estimation Approach [Member] | Qualified Domestic Pension Plan [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									4.77%
Weighted average discount rate used to measure interest cost (percent)									3.64%
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Current Estimation Approach [Member] | Nonqualified Domestic Pension Plan [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									4.53%
Weighted average discount rate used to measure interest cost (percent)									3.47%
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Current Estimation Approach [Member] | Domestic Postretirement Benefit Plans [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									0.00%
Weighted average discount rate used to measure interest cost (percent)									3.53%
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Prior Estimation Approach [Member] | Qualified Domestic Pension Plan [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									4.50%
Weighted average discount rate used to measure interest cost (percent)									4.50%
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Prior Estimation Approach [Member] | Nonqualified Domestic Pension Plan [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									4.37%
Weighted average discount rate used to measure interest cost (percent)									4.37%
Change in Assumptions for Pension Plans and Postretirement Benefit Plans [Member] | Prior Estimation Approach [Member] | Domestic Postretirement Benefit Plans [Member]
Change in Accounting Estimate
Weighted average discount rate used to measure service cost (percent)									4.35%
Weighted average discount rate used to measure interest cost (percent)									4.35%

Pension Plans, Retirement Be102

Pension Plans, Retirement Benefits and Savings Plans (details) - Assumptions - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, future compensation increase rate (percent)	4.00%	4.00%
Pension Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	7.00%	7.25%
Qualified Domestic Pension Plan [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	4.23%	4.50%
Assumptions used to determine net periodic benefit cost, discount rate used to measure service cost (percent)	4.77%	4.10%
Assumptions used to determine net periodic benefit cost, discount rate to measure interest cost (percent)	3.64%	4.10%
Nonqualified Domestic Pension Plan [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	4.15%	4.37%
Assumptions used to determine net periodic benefit cost, discount rate used to measure service cost (percent)	4.53%	4.10%
Assumptions used to determine net periodic benefit cost, discount rate to measure interest cost (percent)	3.47%	4.10%
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	4.00%	4.00%
Impact to accumulated postretirement benefit obligation from increasing the assumed health care cost trend rate by 1%	$ 20
Impact to the aggregate of the service and interest cost components of net postretirement benefit expense from increasing the assumed health care cost trend rate by 1%	1
Impact to accumulated postretirement benefit obligation from decreasing the assumed health care cost trend rate by 1%	17
Impact to the aggregate of the service and interest cost components of net postretirement benefit expense from decreasing the assumed health care cost trend rate by 1%	$ 1
Domestic Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	4.10%	4.35%
Assumptions used to determine net periodic benefit cost, discount rate to measure interest cost (percent)	3.53%	4.10%
Assumed health care cost trend rates, rate to which the cost trend rate is assumed to decline (ultimate trend rate) (percent)	5.00%	5.00%
Postretirement Benefit Plan Before Age 65 [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	6.50%	6.75%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2,022	2,022
Postretirement Benefit Plan Age 65 and Older [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	7.25%	7.50%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2,025	2,025

Pension Plans, Retirement Be103

Pension Plans, Retirement Benefits and Savings Plans (details) - Miscellaneous Fair Value Disclosures - item	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Qualified Domestic Pension Plan [Member] | Equity securities [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	55.00%
Maximum investment in class of securities (as a percentage)	65.00%
Qualified Domestic Pension Plan [Member] | Fixed income securities [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	20.00%
Maximum investment in class of securities (as a percentage)	40.00%
Qualified Domestic Pension Plan [Member] | Private equity funds [Member]
Defined benefit plan disclosure
Number of private equity funds included in pension plan assets	2	2
Number of private equity funds included in pension plan assets focused on financial companies	1
Qualified Domestic Pension Plan [Member] | Long-term growth [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	85.00%
Maximum investment in class of securities (as a percentage)	90.00%
Qualified Domestic Pension Plan [Member] | Near-term benefit payments [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	10.00%
Maximum investment in class of securities (as a percentage)	15.00%
Postretirement Benefit Plans [Member] | Fixed income securities [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	25.00%
Maximum investment in class of securities (as a percentage)	75.00%
Postretirement Benefit Plans [Member] | Long-term growth [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	35.00%
Maximum investment in class of securities (as a percentage)	65.00%
Postretirement Benefit Plans [Member] | Near-term benefit payments [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	35.00%
Maximum investment in class of securities (as a percentage)	60.00%

Pension Plans, Retirement Be104

Pension Plans, Retirement Benefits and Savings Plans (details) - Fair Value - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	$ 3,493	$ 3,242	$ 3,357
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	14	15	$ 16
Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	2,755	2,565
Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	737	675
Level 2 [Member] | Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	14	15
Level 3 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1	2
Fixed maturities [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	546	540
Fixed maturities [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	546	540
Obligations of states, municipalities and political subdivisions [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	9	17
Obligations of states, municipalities and political subdivisions [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	9	17
Debt securities issued by foreign governments [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	14	16
Debt securities issued by foreign governments [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	14	16
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	12	16
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	12	16
All other corporate bonds [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	511	491
All other corporate bonds [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	511	491
Total mutual funds [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,926	1,886
Total mutual funds [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,916	1,877
Total mutual funds [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	10	9
Equity mutual funds [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,285	1,237
Equity mutual funds [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1,278	1,231
Equity mutual funds [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	7	6
Bond mutual funds [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	641	649
Bond mutual funds [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	638	646
Bond mutual funds [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	3	3
Equity securities [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	747	625
Equity securities [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	747	624
Equity securities [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets		1
Other investments [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1	2
Other investments [Member] | Level 3 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1	2
Cash and short-term securities [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	273	189
Cash and short-term securities [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	92	64
Cash and short-term securities [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	181	125
Cash and short-term securities, U.S. Treasury securities [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	45	25
Cash and short-term securities, U.S. Treasury securities [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	45	25
Money market mutual funds [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	20	23
Money market mutual funds [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	19	19
Money market mutual funds [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	1	4
Cash and short-term securities, other [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	208	141
Cash and short-term securities, other [Member] | Level 1 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	28	20
Cash and short-term securities, other [Member] | Level 2 [Member] | Pension Plans [Member]
Defined benefit plan disclosure
Fair value of plan assets	$ 180	$ 121

Pension Plans Retirement Benefi

Pension Plans Retirement Benefits and Savings Plans (details) - Future Payments $ in Millions	Dec. 31, 2016USD ($)
Pension Plans [Member]
Estimated Future Benefit Payments
Benefits expected to be paid, 2017	$ 230
Benefits expected to be paid, 2018	240
Benefits expected to be paid, 2019	247
Benefits expected to be paid, 2020	253
Benefits expected to be paid, 2021	258
Benefits expected to be paid, 2022 through 2026	1,327
Postretirement Benefit Plans [Member]
Estimated Future Benefit Payments
Benefits expected to be paid, 2017	13
Benefits expected to be paid, 2018	14
Benefits expected to be paid, 2019	14
Benefits expected to be paid, 2020	14
Benefits expected to be paid, 2021	14
Benefits expected to be paid, 2022 through 2026	$ 71

Pension Plans, Retirement Be106

Pension Plans, Retirement Benefits and Savings Plans (details) - Savings Plan - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Savings Plan
Expense related to all savings plans	$ 114,000,000	$ 109,000,000	$ 103,000,000
The Travelers 401(k) Savings Plan [Member]
Savings Plan
Maximum annual match	$ 6,000
Vesting percentage of employer match after vesting period	100.00%
Vesting period	3 years
The Travelers 401(k) Savings Plan [Member] | Maxiumum [Member]
Savings Plan
Matching contribution as a percent of eligible pay	5.00%

Leases (details)

Leases (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Leases disclosure
Rent expense	$ 197	$ 202	$ 215
Future minimum annual rental payments due for 2017	147
Future minimum annual rental payments due for 2018	118
Future minimum annual rental payments due for 2019	100
Future minimum annual rental payments due for 2020	80
Future minimum annual rental payments due for 2021	60
Future minimum annual rental payments due for 2022 and thereafter	100
Approximate aggregate future sublease rental income that will partially offset the lease commitments	$ 4

Contingencies, Commitments a108

Contingencies, Commitments and Guarantees (details) - Asbestos Direct Action Litigation [Member] $ in Millions	1 Months Ended	12 Months Ended	24 Months Ended
	Jan. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2002item
Loss Contingencies
Number of purported class action suits filed against the Company and other insurers in state court in West Virginia, Massachusetts and Hawaii relative to asbestos direct action litigation | item			2
Settlement amount	$ 502
Total settlement amount	579	$ 579
Interest related to settlement award	$ 77

Contingencies, Commitments a109

Contingencies, Commitments and Guarantees (details) - Gain Contingencies $ in Millions	3 Months Ended	76 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2016USD ($)item	Nov. 07, 2016item	Nov. 06, 2016USD ($)	Dec. 31, 2015USD ($)
Gain Contingencies
Reinsurance recoverables	$ 8,287	$ 8,287			$ 8,910
United States Fidelity & Guaranty Company v. American Re-Insurance Company, et al. [Member]
Gain Contingencies
Number of discrete issues for which the Court of Appeals remanded the case for trial | item	2	2
Number of reinsurer defendants | item	2	2	3
Number of reinsurers against which judgment was entered in a reinsurance dispute who are subsidiaries of the same company | item	2	2
Number of reinsurers with whom the Company reached a settlement agreeement | item			1
Payment received from settlement fund (pre-tax)	$ 126
Payment received from settlement fund (after-tax)	82
Reinsurance recoverables	$ 31	$ 31		$ 238
Total settlement amount		69
Settlement amount, reinsurance recoverables		31
Interest related to settlement award		$ 38
Annual interest rate accruing on judgment not yet paid		9.00%

Contingencies, Commitments a110

Contingencies, Commitments and Guarantees (details) - Commitments - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Contingencies and Commitments disclosure
Unfunded commitments to private equity limited partnerships and real estate partnerships	$ 1,600	$ 1,710

Contingencies, Commitments a111

Contingencies, Commitments and Guarantees (details) - Guarantees $ in Millions	Dec. 31, 2016USD ($)
Indemnifications related to the sale of businesses [Member]
Guarantor obligations
Maximum amount of contingent obligation	$ 358
Amount recognized on balance sheet for contingent obligation	2
Guarantees of certain investments and third-party loans [Member]
Guarantor obligations
Maximum amount of contingent obligation	150
Amount indemnified by a third party	75
Guarantees of certain insurance policy obligations [Member]
Guarantor obligations
Maximum amount of contingent obligation	480
Amount indemnified by a third party	$ 480

Consolidating Financial Stat112

Consolidating Financial Statements (Unaudited) (details) $ in Millions	Dec. 31, 2016USD ($)
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

Consolidating Financial Stat113

Consolidating Financial Statements (details) - Consolidating Statement of Income (Unaudited) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidating Statement of Income
Premiums										$ 24,534	$ 23,874	$ 23,713
Net investment income										2,302	2,379	2,787
Fee income										458	460	450
Net realized investment gains (losses)	[1]									68	3	79
Other revenues										263	99	145
Total revenues		$ 7,193	$ 6,961	$ 6,785	$ 6,686	$ 6,678	$ 6,798	$ 6,710	$ 6,629	27,625	26,815	27,174
Claims and claim adjustment expenses										15,070	13,723	13,870
Amortization of deferred acquisition costs										3,985	3,885	3,882
General and administrative expenses										4,154	4,094	3,964
Interest expense										363	373	369
Total claims and expenses		5,891	6,014	5,898	5,769	5,469	5,491	5,634	5,481	23,572	22,075	22,085
Income before income taxes		1,302	947	887	917	1,209	1,307	1,076	1,148	4,053	4,740	5,089
Income tax expense (benefit)		359	231	223	226	343	379	264	315	1,039	1,301	1,397
Net income		$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	3,014	3,439	3,692
Total other-than-temporary impairment losses										(40)	(54)	(22)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(29)	(52)	(26)
Other-than-temporary impairment gains (losses) recognized in other comprehensive income										(11)	(2)	4
TPC [Member]
Consolidating Statement of Income
Premiums										16,788	16,254	16,097
Net investment income										1,569	1,612	1,874
Fee income										458	460	448
Net realized investment gains (losses)										30	13	12
Other revenues										248	78	125
Total revenues										19,093	18,417	18,556
Claims and claim adjustment expenses										10,232	9,208	9,274
Amortization of deferred acquisition costs										2,702	2,627	2,604
General and administrative expenses										2,928	2,853	2,755
Interest expense										48	48	48
Total claims and expenses										15,910	14,736	14,681
Income before income taxes										3,183	3,681	3,875
Income tax expense (benefit)										999	1,015	1,095
Net income										2,184	2,666	2,780
Total other-than-temporary impairment losses										(19)	(19)	(16)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(13)	(18)	(19)
Other-than-temporary impairment gains (losses) recognized in other comprehensive income										(6)	(1)	3
Other Subsidiaries [Member]
Consolidating Statement of Income
Premiums										7,746	7,620	7,616
Net investment income										720	760	907
Fee income												2
Net realized investment gains (losses)										39	(11)	64
Other revenues										36	21	20
Total revenues										8,541	8,390	8,609
Claims and claim adjustment expenses										4,838	4,515	4,596
Amortization of deferred acquisition costs										1,283	1,258	1,278
General and administrative expenses										1,242	1,225	1,194
Total claims and expenses										7,363	6,998	7,068
Income before income taxes										1,178	1,392	1,541
Income tax expense (benefit)										208	394	417
Net income										970	998	1,124
Total other-than-temporary impairment losses										(20)	(35)	(6)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(15)	(34)	(7)
Other-than-temporary impairment gains (losses) recognized in other comprehensive income										(5)	(1)	1
Travelers [Member]
Consolidating Statement of Income
Net investment income										13	7	6
Net realized investment gains (losses)										(1)	1	3
Total revenues										12	8	9
General and administrative expenses										5	16	15
Interest expense										315	325	321
Total claims and expenses										320	341	336
Income before income taxes										(308)	(333)	(327)
Income tax expense (benefit)										(168)	(108)	(115)
Net income of subsidiaries										3,154	3,664	3,904
Net income										3,014	3,439	3,692
Total other-than-temporary impairment losses										(1)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(1)	0	0
Other-than-temporary impairment gains (losses) recognized in other comprehensive income										0	0	0
Eliminations [Member]
Consolidating Statement of Income
Other revenues										(21)
Total revenues										(21)
General and administrative expenses										(21)
Total claims and expenses										(21)
Net income of subsidiaries										(3,154)	(3,664)	(3,904)
Net income										$ (3,154)	$ (3,664)	$ (3,904)
[1]	Total other-than-temporary impairment (OTTI) losses were $(40) million, $(54) million and $(22) million for the years ended December 31, 2016, 2015 and 2014, respectively. Of total OTTI, credit losses of $(29) million, $(52) million and $(26) million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $(11) million, $(2) million and $4 million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.

Consolidating Financial Stat114

Consolidating Financial Statements (details) - Consolidating Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidating Statement of Comprehensive Income
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(883)	(1,020)	976
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									21	(14)	2
Net changes in benefit plan assets and obligations									16	66	(494)
Net changes in unrealized foreign currency translation									(41)	(461)	(289)
Other comprehensive income (loss) before income taxes									(887)	(1,429)	195
Income tax expense (benefit)									(289)	(392)	125
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(598)	(1,037)	70
Other comprehensive income (loss), net of taxes									(598)	(1,037)	70
Comprehensive income									2,416	2,402	3,762
TPC [Member]
Consolidating Statement of Comprehensive Income
Net income									2,184	2,666	2,780
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(696)	(610)	681
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									11	(12)	9
Net changes in benefit plan assets and obligations									25	2	(15)
Net changes in unrealized foreign currency translation									73	(306)	(173)
Other comprehensive income (loss) before income taxes									(587)	(926)	502
Income tax expense (benefit)									(222)	(257)	207
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(365)	(669)	295
Other comprehensive income (loss), net of taxes									(365)	(669)	295
Comprehensive income									1,819	1,997	3,075
Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income									970	998	1,124
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(198)	(407)	289
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									10	(2)	(7)
Net changes in benefit plan assets and obligations									11		(8)
Net changes in unrealized foreign currency translation									(114)	(155)	(116)
Other comprehensive income (loss) before income taxes									(291)	(564)	158
Income tax expense (benefit)									(66)	(156)	81
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(225)	(408)	77
Other comprehensive income (loss), net of taxes									(225)	(408)	77
Comprehensive income									745	590	1,201
Travelers [Member]
Consolidating Statement of Comprehensive Income
Net income									3,014	3,439	3,692
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									11	(3)	6
Net changes in benefit plan assets and obligations									(20)	64	(471)
Other comprehensive income (loss) before income taxes									(9)	61	(465)
Income tax expense (benefit)									(1)	21	(163)
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(8)	40	(302)
Other comprehensive income (loss) of subsidiaries									(590)	(1,077)	372
Other comprehensive income (loss), net of taxes									(598)	(1,037)	70
Comprehensive income									2,416	2,402	3,762
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income									(3,154)	(3,664)	(3,904)
Other comprehensive income (loss) of subsidiaries									590	1,077	(372)
Other comprehensive income (loss), net of taxes									590	1,077	(372)
Comprehensive income									$ (2,564)	$ (2,587)	$ (4,276)

Consolidating Financial Stat115

Consolidating Financial Statements (details) - Consolidating Balance Sheet (Unaudited) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidating Balance Sheet
Fixed maturities, available for sale, at fair value	$ 60,515	$ 60,658
Equity securities, available for sale, at fair value	732	705
Real estate investments	928	989
Short-term securities	4,865	4,671
Other investments	3,448	3,447
Total investments	70,488	70,470
Cash	307	380	$ 374	$ 294
Investment income accrued	630	642
Premiums receivable	6,722	6,437
Reinsurance recoverables	8,287	8,910
Ceded unearned premiums	589	656
Deferred acquisition costs	1,923	1,849	1,835
Deferred taxes	465	296
Contractholder receivables	4,609	4,374
Goodwill	3,580	3,573
Other intangible assets	268	279
Other assets	2,377	2,318
Total assets	100,245	100,184
Claims and claim adjustment expense reserves	47,949	48,295	49,850
Unearned premium reserves	12,329	11,971	11,839
Contractholder payables	4,609	4,374
Payables for reinsurance premiums	273	296
Debt	6,437	6,344
Other liabilities	5,427	5,306
Total liabilities	77,024	76,586
Common stock	22,614	22,172
Retained earnings	32,196	29,945
Accumulated other comprehensive income (loss)	(755)	(157)
Treasury stock, at cost	(30,834)	(28,362)
Total shareholders' equity	23,221	23,598	24,836
Total liabilities and shareholders' equity	100,245	100,184
Fixed maturities, available for sale, amortized cost	59,650	58,878
Equity securities, available for sale, cost	$ 504	$ 528
Common stock, shares authorized	1,750	1,750
Common stock, shares issued	279.6	295.9
Common stock, shares outstanding	279.6	295.9
Treasury stock, at cost, shares	489.5	467.6
TPC [Member]
Consolidating Balance Sheet
Fixed maturities, available for sale, at fair value	$ 42,014	$ 42,289
Equity securities, available for sale, at fair value	169	189
Real estate investments	56	56
Short-term securities	2,447	1,947
Other investments	2,569	2,516
Total investments	47,255	46,997
Cash	141	225	221	137
Investment income accrued	441	453
Premiums receivable	4,545	4,336
Reinsurance recoverables	5,664	5,849
Ceded unearned premiums	536	610
Deferred acquisition costs	1,741	1,660
Deferred taxes	216	178
Contractholder receivables	3,656	3,387
Goodwill	2,578	2,573
Other intangible assets	202	203
Other assets	1,973	1,958
Total assets	68,948	68,429
Claims and claim adjustment expense reserves	32,168	31,965
Unearned premium reserves	8,575	8,335
Contractholder payables	3,656	3,387
Payables for reinsurance premiums	156	175
Debt	693	693
Other liabilities	4,106	3,958
Total liabilities	49,354	48,513
Additional paid-in capital	11,634	11,634
Retained earnings	7,933	7,888
Accumulated other comprehensive income (loss)	27	394
Total shareholders' equity	19,594	19,916
Total liabilities and shareholders' equity	68,948	68,429
Other Subsidiaries [Member]
Consolidating Balance Sheet
Fixed maturities, available for sale, at fair value	18,452	18,323
Equity securities, available for sale, at fair value	408	375
Real estate investments	872	933
Short-term securities	791	1,178
Other investments	878	930
Total investments	21,401	21,739
Cash	164	153	151	154
Investment income accrued	183	185
Premiums receivable	2,177	2,101
Reinsurance recoverables	2,623	3,061
Ceded unearned premiums	53	46
Deferred acquisition costs	182	189
Deferred taxes	224	83
Contractholder receivables	953	987
Goodwill	1,002	1,000
Other intangible assets	66	76
Other assets	370	344
Total assets	29,398	29,964
Claims and claim adjustment expense reserves	15,781	16,330
Unearned premium reserves	3,754	3,636
Contractholder payables	953	987
Payables for reinsurance premiums	117	121
Other liabilities	1,239	1,221
Total liabilities	21,844	22,295
Common stock	390	390
Additional paid-in capital	6,499	6,499
Retained earnings	797	688
Accumulated other comprehensive income (loss)	(132)	92
Total shareholders' equity	7,554	7,669
Total liabilities and shareholders' equity	29,398	29,964
Travelers [Member]
Consolidating Balance Sheet
Fixed maturities, available for sale, at fair value	49	46
Equity securities, available for sale, at fair value	155	141
Short-term securities	1,627	1,546
Other investments	1	1
Total investments	1,832	1,734
Cash	2	2	$ 2	$ 3
Investment income accrued	6	4
Deferred taxes	25	35
Investment in subsidiaries	27,137	27,573
Other assets	34	16
Total assets	29,036	29,364
Debt	5,744	5,651
Other liabilities	82	127
Total liabilities	5,826	5,778
Common stock	22,614	22,172
Retained earnings	32,185	29,933
Accumulated other comprehensive income (loss)	(755)	(157)
Treasury stock, at cost	(30,834)	(28,362)
Total shareholders' equity	23,210	23,586
Total liabilities and shareholders' equity	$ 29,036	$ 29,364
Common stock, shares authorized	1,750	1,750
Common stock, shares issued	279.6	295.9
Common stock, shares outstanding	279.6	295.9
Treasury stock, at cost, shares	489.5	467.6
Eliminations [Member]
Consolidating Balance Sheet
Investment in subsidiaries	$ (27,137)	$ (27,573)
Total assets	(27,137)	(27,573)
Common stock	(390)	(390)
Additional paid-in capital	(18,133)	(18,133)
Retained earnings	(8,719)	(8,564)
Accumulated other comprehensive income (loss)	105	(486)
Total shareholders' equity	(27,137)	(27,573)
Total liabilities and shareholders' equity	$ (27,137)	$ (27,573)

Consolidating Financial Stat116

Consolidating Financial Statements (details) - Consolidating Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidating Statement of Cash Flows
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Net adjustments to reconcile net income to net cash provided by operating activities									1,188	(5)	1
Net cash provided by operating activities									4,202	3,434	3,693
Proceeds from maturities of fixed maturities									8,975	11,116	10,894
Proceeds from sales of investments, fixed maturities									1,417	1,950	1,049
Proceeds from sales of investments, equity securities									92	59	158
Proceeds from sales of investments, real estate investments									69	31	15
Proceeds from sales of investments, other investments									839	713	855
Purchases of investments, fixed maturities									(11,609)	(12,090)	(11,325)
Purchases of investments, equity securities									(51)	(49)	(52)
Purchases of investments, real estate investments									(48)	(123)	(48)
Purchases of investments, other investments									(580)	(534)	(554)
Net sales (purchases) of short-term securities									(199)	(326)	(498)
Securities transactions in course of settlement									(21)	(113)	82
Acquisition, net of cash acquired										(13)	(12)
Other investing activities									(344)	(304)	(358)
Net cash provided by (used in) investing activities									(1,460)	317	206
Treasury stock acquired - share repurchase authorization									(2,400)	(3,150)	(3,275)
Treasury stock acquired - net employee share-based compensation									(72)	(74)	(57)
Dividends paid to shareholders									(757)	(739)	(729)
Payment of debt									(400)	(400)
Issuance of debt									491	392
Issuance of common stock - employee share options									332	183	195
Excess tax benefits from share-based payment arrangements										55	57
Net cash used in financing activities									(2,806)	(3,733)	(3,809)
Effect of exchange rate changes on cash									(9)	(12)	(10)
Net increase (decrease) in cash									(73)	6	80
Cash at beginning of year				380				374	380	374	294
Cash at end of year	307				380				307	380	374
Income taxes paid (received)									892	1,207	1,147
Interest paid									358	365	365
TPC [Member]
Consolidating Statement of Cash Flows
Net income									2,184	2,666	2,780
Net adjustments to reconcile net income to net cash provided by operating activities									1,085	(577)	343
Net cash provided by operating activities									3,269	2,089	3,123
Proceeds from maturities of fixed maturities									6,589	7,543	6,625
Proceeds from sales of investments, fixed maturities									768	1,227	595
Proceeds from sales of investments, equity securities									47	25	111
Proceeds from sales of investments, real estate investments											1
Proceeds from sales of investments, other investments									586	503	477
Purchases of investments, fixed maturities									(7,921)	(8,276)	(6,856)
Purchases of investments, equity securities									(6)	(3)	(3)
Purchases of investments, real estate investments									(1)	(1)	(22)
Purchases of investments, other investments									(453)	(423)	(405)
Net sales (purchases) of short-term securities									(501)	179	(268)
Securities transactions in course of settlement									12	(52)	44
Acquisition, net of cash acquired										(13)	(9)
Other investing activities									(334)	(343)	(350)
Net cash provided by (used in) investing activities									(1,214)	366	(60)
Dividends paid to parent company									(2,140)	(2,450)	(2,978)
Net cash used in financing activities									(2,140)	(2,450)	(2,978)
Effect of exchange rate changes on cash									1	(1)	(1)
Net increase (decrease) in cash									(84)	4	84
Cash at beginning of year				225				221	225	221	137
Cash at end of year	141				225				141	225	221
Income taxes paid (received)									737	1,032	947
Interest paid									47	47	47
Other Subsidiaries [Member]
Consolidating Statement of Cash Flows
Net income									970	998	1,124
Net adjustments to reconcile net income to net cash provided by operating activities									66	414	(293)
Net cash provided by operating activities									1,036	1,412	831
Proceeds from maturities of fixed maturities									2,380	3,563	4,258
Proceeds from sales of investments, fixed maturities									647	723	453
Proceeds from sales of investments, equity securities									45	34	43
Proceeds from sales of investments, real estate investments									69	31	14
Proceeds from sales of investments, other investments									253	210	378
Purchases of investments, fixed maturities									(3,676)	(3,787)	(4,465)
Purchases of investments, equity securities									(42)	(43)	(42)
Purchases of investments, real estate investments									(47)	(122)	(26)
Purchases of investments, other investments									(127)	(111)	(149)
Net sales (purchases) of short-term securities									383	(489)	(223)
Securities transactions in course of settlement									(32)	(61)	38
Acquisition, net of cash acquired											(3)
Other investing activities									(10)	39	(8)
Net cash provided by (used in) investing activities									(157)	(13)	268
Dividends paid to parent company									(858)	(1,383)	(1,093)
Capital contributions, loans and other transactions between subsidiaries										(3)
Net cash used in financing activities									(858)	(1,386)	(1,093)
Effect of exchange rate changes on cash									(10)	(11)	(9)
Net increase (decrease) in cash									11	2	(3)
Cash at beginning of year				153				151	153	151	154
Cash at end of year	164				153				164	153	151
Income taxes paid (received)									287	384	336
Travelers [Member]
Consolidating Statement of Cash Flows
Net income									3,014	3,439	3,692
Net adjustments to reconcile net income to net cash provided by operating activities									(119)	330	118
Net cash provided by operating activities									2,895	3,769	3,810
Proceeds from maturities of fixed maturities									6	10	11
Proceeds from sales of investments, fixed maturities									2		1
Proceeds from sales of investments, equity securities											4
Purchases of investments, fixed maturities									(12)	(27)	(4)
Purchases of investments, equity securities									(3)	(3)	(7)
Net sales (purchases) of short-term securities									(81)	(16)	(7)
Securities transactions in course of settlement									(1)
Net cash provided by (used in) investing activities									(89)	(36)	(2)
Treasury stock acquired - share repurchase authorization									(2,400)	(3,150)	(3,275)
Treasury stock acquired - net employee share-based compensation									(72)	(74)	(57)
Dividends paid to shareholders									(757)	(739)	(729)
Payment of debt									(400)	(400)
Issuance of debt									491	392
Issuance of common stock - employee share options									332	183	195
Excess tax benefits from share-based payment arrangements										55	57
Net cash used in financing activities									(2,806)	(3,733)	(3,809)
Net increase (decrease) in cash											(1)
Cash at beginning of year				$ 2				$ 2	2	2	3
Cash at end of year	$ 2				$ 2				2	2	2
Income taxes paid (received)									(132)	(209)	(136)
Interest paid									311	318	318
Eliminations [Member]
Consolidating Statement of Cash Flows
Net income									(3,154)	(3,664)	(3,904)
Net adjustments to reconcile net income to net cash provided by operating activities									156	(172)	(167)
Net cash provided by operating activities									(2,998)	(3,836)	(4,071)
Dividends paid to parent company									2,998	3,833	4,071
Capital contributions, loans and other transactions between subsidiaries										3
Net cash used in financing activities									$ 2,998	$ 3,836	$ 4,071

Selected Quarterly Financial117

Selected Quarterly Financial Data (Unaudited) (details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Data (Unaudited) disclosure
Total revenues	$ 7,193	$ 6,961	$ 6,785	$ 6,686	$ 6,678	$ 6,798	$ 6,710	$ 6,629	$ 27,625	$ 26,815	$ 27,174
Total expenses	5,891	6,014	5,898	5,769	5,469	5,491	5,634	5,481	23,572	22,075	22,085
Income before income taxes	1,302	947	887	917	1,209	1,307	1,076	1,148	4,053	4,740	5,089
Income tax expense	359	231	223	226	343	379	264	315	1,039	1,301	1,397
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Net income per share, basic	$ 3.32	$ 2.48	$ 2.27	$ 2.33	$ 2.87	$ 3	$ 2.56	$ 2.58	$ 10.39	$ 10.99	$ 10.82
Net income per common share, diluted	$ 3.28	$ 2.45	$ 2.24	$ 2.30	$ 2.83	$ 2.97	$ 2.53	$ 2.55	$ 10.28	$ 10.88	$ 10.70

Schedule II (details) - Condens

Schedule II (details) - Condensed Income Statement - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Statement of Income
Net investment income										$ 2,302	$ 2,379	$ 2,787
Net realized investment gains (losses)	[1]									68	3	79
Total revenues		$ 7,193	$ 6,961	$ 6,785	$ 6,686	$ 6,678	$ 6,798	$ 6,710	$ 6,629	27,625	26,815	27,174
Interest expense										363	373	369
Expenses, other										4,154	4,094	3,964
Total claims and expenses		5,891	6,014	5,898	5,769	5,469	5,491	5,634	5,481	23,572	22,075	22,085
Income before income taxes		1,302	947	887	917	1,209	1,307	1,076	1,148	4,053	4,740	5,089
Income tax expense (benefit)		359	231	223	226	343	379	264	315	1,039	1,301	1,397
Net income		$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	3,014	3,439	3,692
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(29)	(52)	(26)
Other-than-temporary impairment gains or losses recognized in other comprehensive income (loss)										(11)	(2)	4
Travelers [Member]
Condensed Statement of Income
Net investment income										13	7	6
Net realized investment gains (losses)										(1)	1	3
Total revenues										12	8	9
Interest expense										315	325	321
Expenses, other										5	16	15
Total claims and expenses										320	341	336
Income before income taxes										(308)	(333)	(327)
Income tax expense (benefit)										(168)	(108)	(115)
Loss before net income of subsidiaries										(140)	(225)	(212)
Net income of subsidiaries										3,154	3,664	3,904
Net income										3,014	3,439	3,692
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(1)	0	0
Other-than-temporary impairment gains or losses recognized in other comprehensive income (loss)										$ 0	$ 0	$ 0
[1]	Total other-than-temporary impairment (OTTI) losses were $(40) million, $(54) million and $(22) million for the years ended December 31, 2016, 2015 and 2014, respectively. Of total OTTI, credit losses of $(29) million, $(52) million and $(26) million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in net realized investment gains. In addition, unrealized gains (losses) from other changes in total OTTI of $(11) million, $(2) million and $4 million for the years ended December 31, 2016, 2015 and 2014, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.

Schedule II (details) - Cond119

Schedule II (details) - Condensed Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Statement of Comprehensive Income
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									(883)	(1,020)	976
Net changes in benefit plan assets and obligations									16	66	(494)
Other comprehensive income (loss) before income taxes									(887)	(1,429)	195
Income tax expense (benefit)									(289)	(392)	125
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(598)	(1,037)	70
Other comprehensive income (loss), net of taxes									(598)	(1,037)	70
Comprehensive income									2,416	2,402	3,762
Travelers [Member]
Condensed Statement of Comprehensive Income
Net income									3,014	3,439	3,692
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									11	(3)	6
Net changes in benefit plan assets and obligations									(20)	64	(471)
Other comprehensive income (loss) before income taxes									(9)	61	(465)
Income tax expense (benefit)									(1)	21	(163)
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									(8)	40	(302)
Other comprehensive income (loss) of subsidiaries									(590)	(1,077)	372
Other comprehensive income (loss), net of taxes									(598)	(1,037)	70
Comprehensive income									$ 2,416	$ 2,402	$ 3,762

Schedule II (details) - Cond120

Schedule II (details) - Condensed Balance Sheet - USD ($) shares in Millions, $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Balance Sheet
Fixed maturities, at fair value	$ 60,515	$ 60,658
Equity securities	732	705
Short-term securities	4,865	4,671
Total assets	100,245	100,184
Debt	6,437	6,344
Total liabilities	77,024	76,586
Common stock (1,750.0 shares authorized; 279.6 and 295.9 shares issued and outstanding)	22,614	22,172
Retained earnings	32,196	29,945
Accumulated other comprehensive loss	(755)	(157)
Treasury stock, at cost (489.5 and 467.6 shares)	(30,834)	(28,362)
Total shareholders' equity	23,221	23,598	$ 24,836
Total liabilities and shareholders' equity	$ 100,245	$ 100,184
Common stock, shares authorized	1,750	1,750
Common stock, shares issued	279.6	295.9
Common stock, shares outstanding	279.6	295.9
Treasury stock, at cost, shares	489.5	467.6
Travelers [Member]
Condensed Balance Sheet
Fixed maturities, at fair value	$ 49	$ 46
Equity securities	155	141
Short-term securities	1,627	1,546
Investment in subsidiaries	27,137	27,573
Other assets	68	58
Total assets	29,036	29,364
Debt	5,744	5,651
Other liabilities	82	127
Total liabilities	5,826	5,778
Common stock (1,750.0 shares authorized; 279.6 and 295.9 shares issued and outstanding)	22,614	22,172
Retained earnings	32,185	29,933
Accumulated other comprehensive loss	(755)	(157)
Treasury stock, at cost (489.5 and 467.6 shares)	(30,834)	(28,362)
Total shareholders' equity	23,210	23,586
Total liabilities and shareholders' equity	$ 29,036	$ 29,364
Common stock, shares authorized	1,750	1,750
Common stock, shares issued	279.6	295.9
Common stock, shares outstanding	279.6	295.9
Treasury stock, at cost, shares	489.5	467.6

Schedule II (details) - Cond121

Schedule II (details) - Condensed Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Statement of Cash Flows
Net income	$ 943	$ 716	$ 664	$ 691	$ 866	$ 928	$ 812	$ 833	$ 3,014	$ 3,439	$ 3,692
Deferred federal income tax expense (benefit)									110	117	121
Other operating activities									189	56	63
Net cash provided by operating activities									4,202	3,434	3,693
Net purchases of short-term securities									(199)	(326)	(498)
Net cash provided by (used in) investing activities									(1,460)	317	206
Treasury stock acquired - share repurchase authorization									(2,400)	(3,150)	(3,275)
Treasury stock acquired - net employee share-based compensation									(72)	(74)	(57)
Dividends paid to shareholders									(757)	(739)	(729)
Payment of debt									(400)	(400)
Issuance of debt									491	392
Issuance of common stock - employee share options									332	183	195
Net cash used in financing activities									(2,806)	(3,733)	(3,809)
Net increase (decrease) in cash									(73)	6	80
Cash at beginning of year				380				374	380	374	294
Cash at end of year	307				380				307	380	374
Cash received during the year for taxes									(892)	(1,207)	(1,147)
Cash paid during the year for interest									358	365	365
Travelers [Member]
Condensed Statement of Cash Flows
Net income									3,014	3,439	3,692
Equity in net income of subsidiaries									(3,154)	(3,664)	(3,904)
Dividends received from consolidated subsidiaries									2,998	3,833	4,071
Capital received from subsidiaries										3
Deferred federal income tax expense (benefit)									12	(6)	51
Change in income taxes payable									(48)	51	(87)
Other operating activities									73	113	(13)
Net cash provided by operating activities									2,895	3,769	3,810
Net purchases of short-term securities									(81)	(16)	(7)
Other investments, net									(8)	(20)	5
Net cash provided by (used in) investing activities									(89)	(36)	(2)
Treasury stock acquired - share repurchase authorization									(2,400)	(3,150)	(3,275)
Treasury stock acquired - net employee share-based compensation									(72)	(74)	(57)
Dividends paid to shareholders									(757)	(739)	(729)
Payment of debt									(400)	(400)
Issuance of debt									491	392
Issuance of common stock - employee share options									332	183	195
Other financing activities										55	57
Net cash used in financing activities									(2,806)	(3,733)	(3,809)
Net increase (decrease) in cash											(1)
Cash at beginning of year				$ 2				$ 2	2	2	3
Cash at end of year	$ 2				$ 2				2	2	2
Cash received during the year for taxes									132	209	136
Cash paid during the year for interest									$ 311	$ 318	$ 318

Schedule II (details) - Guarant

Schedule II (details) - Guarantees Footnote	12 Months Ended
	Dec. 31, 2016
Schedule II
Schedule II Guarantees Footnote [Text Block]	1. GUARANTEES The Travelers Companies, Inc. (TRV) fully and unconditionally guarantees the payment of all principal, premiums, if any, and interest on certain debt obligations of its subsidiaries TPC and TIGHI. The guarantees pertain to the $200 million 7.75% notes due 2026 and the $500 million 6.375% notes due 2033. TRV also has contingent obligations for guarantees in connection with the selling of businesses to third parties and various indemnifications including indemnifications to service providers in the normal course of business. The guarantees and indemnification clauses are often standard contractual terms and include indemnifications for breaches of representations and warranties and in some cases obligations arising from certain liabilities. The terms of these provisions vary in duration and nature. Certain of the guarantees and indemnifications described above have no stated or notional amounts or limitation to the maximum potential future payments, and, accordingly, TRV is unable to provide an estimate of the maximum potential payments for such arrangements.

Schedule II (details) - Guar123

Schedule II (details) - Guarantees Footnote (details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Guarantor obligations
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 700
7.75% Senior notes due April 15, 2026 [Member]
Guarantor obligations
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
Interest rate (percent)	7.75%	7.75%
6.375% Senior notes due March 15, 2033 [Member]
Guarantor obligations
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 500
Interest rate (percent)	6.375%	6.375%
Guarantees on payment of principal, premiums and interest on certain debt obligations [Member] | Travelers [Member] | 7.75% Senior notes due April 15, 2026 [Member]
Guarantor obligations
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
Interest rate (percent)	7.75%
Guarantees on payment of principal, premiums and interest on certain debt obligations [Member] | Travelers [Member] | 6.375% Senior notes due March 15, 2033 [Member]
Guarantor obligations
Amount of certain debt obligations of TPC that are unconditionally guaranteed by The Travelers Companies, Inc.	$ 500
Interest rate (percent)	6.375%

Schedule III (details)

Schedule III (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule III
Deferred acquisition costs	$ 1,923	$ 1,849	$ 1,835
Claims and claim adjustment expense reserves	47,949	48,295	49,850
Unearned premiums	12,329	11,971	11,839
Earned premiums	24,534	23,874	23,713
Net investment income	2,302	2,379	2,787
Claims and claim adjustment expenses	15,070	13,723	13,870
Amortization of deferred acquisition costs	3,985	3,885	3,882
Other operating expenses	4,517	4,467	4,333
Net written premiums	24,958	24,121	23,904
Business and International Insurance [Member]
Schedule III
Net written premiums	14,675	14,583	14,636
Bond & Specialty Insurance [Member]
Schedule III
Net written premiums	2,099	2,081	2,103
Personal Insurance [Member]
Schedule III
Net written premiums	8,184	7,457	7,165
Reportable Segments [Member]
Schedule III
Deferred acquisition costs	1,923	1,849	1,835
Claims and claim adjustment expense reserves	47,929	48,272	49,824
Unearned premiums	12,329	11,971	11,839
Earned premiums	24,534	23,874	23,713
Net investment income	2,302	2,379	2,787
Claims and claim adjustment expenses	15,070	13,723	13,870
Amortization of deferred acquisition costs	3,985	3,885	3,882
Other operating expenses	4,123	4,063	3,933
Net written premiums	24,958	24,121	23,904
Reportable Segments [Member] | Business and International Insurance [Member]
Schedule III
Deferred acquisition costs	1,093	1,072	1,080
Claims and claim adjustment expense reserves	41,006	41,563	42,700
Unearned premiums	7,134	7,147	7,208
Earned premiums	14,620	14,521	14,512
Net investment income	1,763	1,824	2,156
Claims and claim adjustment expenses	9,190	8,859	9,145
Amortization of deferred acquisition costs	2,358	2,329	2,321
Other operating expenses	2,746	2,686	2,541
Net written premiums	14,675	14,583	14,636
Reportable Segments [Member] | Bond & Specialty Insurance [Member]
Schedule III
Deferred acquisition costs	232	225	222
Claims and claim adjustment expense reserves	2,944	3,157	3,435
Unearned premiums	1,308	1,292	1,286
Earned premiums	2,088	2,085	2,076
Net investment income	210	223	252
Claims and claim adjustment expenses	572	643	481
Amortization of deferred acquisition costs	397	393	388
Other operating expenses	389	389	403
Net written premiums	2,099	2,081	2,103
Reportable Segments [Member] | Personal Insurance [Member]
Schedule III
Deferred acquisition costs	598	552	533
Claims and claim adjustment expense reserves	3,979	3,552	3,689
Unearned premiums	3,887	3,532	3,345
Earned premiums	7,826	7,268	7,125
Net investment income	329	332	379
Claims and claim adjustment expenses	5,308	4,221	4,244
Amortization of deferred acquisition costs	1,230	1,163	1,173
Other operating expenses	988	988	989
Net written premiums	8,184	7,457	7,165
Other [Member]
Schedule III
Claims and claim adjustment expense reserves	20	23	26
Other operating expenses	$ 394	$ 404	$ 400

Schedule V (details)

Schedule V (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance recoverables [Member]
Schedule V [Roll Forward]
Valuation and qualifying accounts, balance at beginning of period	$ 157	$ 203	$ 239
Valuation and qualifying accounts, deductions	41	46	36
Valuation and qualifying accounts, balance at end of period	116	157	203
Allowance for uncollectible premiums receivable from underwriting activities [Member]
Schedule V [Roll Forward]
Valuation and qualifying accounts, balance at beginning of period	65	70	75
Valuation and qualifying accounts, charged to costs and expenses	35	38	44
Valuation and qualifying accounts, deductions	39	43	49
Valuation and qualifying accounts, balance at end of period	61	65	70
Allowance for uncollectible deductibles [Member]
Schedule V [Roll Forward]
Valuation and qualifying accounts, balance at beginning of period	35	36	39
Valuation and qualifying accounts, charged to costs and expenses	5	3
Valuation and qualifying accounts, deductions	6	4	3
Valuation and qualifying accounts, balance at end of period	$ 34	$ 35	$ 36

Schedule VI (details)

Schedule VI (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplementary Information Concerning Property-Casualty Insurance Operations
Deferred acquisition costs	$ 1,923	$ 1,849	$ 1,835
Claims and claim adjustment expense reserves	47,949	48,295	49,850
Discount from reserves for unpaid claims	1,083	1,066
Unearned premiums	12,329	11,971	11,839
Earned premiums	24,534	23,874	23,713
Net investment income	2,302	2,379	2,787
Amortization of deferred acquisition costs	3,985	3,885	3,882
Net written premiums	24,958	24,121	23,904
Property casualty [Member]
Supplementary Information Concerning Property-Casualty Insurance Operations
Deferred acquisition costs	1,923	1,849	1,835
Claims and claim adjustment expense reserves	47,929	48,272	49,824	$ 50,865
Discount from reserves for unpaid claims	1,083	1,066	1,080
Unearned premiums	12,329	11,971	11,839
Earned premiums	24,534	23,874	23,713
Net investment income	2,302	2,379	2,787
Claims and claim adjustment expenses incurred related to current year	15,675	14,471	14,688
Claims and claim adjustment expenses incurred related to prior year	(680)	(817)	(885)
Amortization of deferred acquisition costs	3,985	3,885	3,882
Paid claims and claim adjustment expenses	14,796	14,474	14,066
Net written premiums	$ 24,958	$ 24,121	$ 23,904