Chubb Limited (CB) 10-K 23 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 12, 2018	Jun. 30, 2017
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	CB
Entity Registrant Name	Chubb Ltd
Entity Central Index Key	896,159
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		464,091,254
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 67

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2017		Dec. 31, 2016
Assets
Fixed maturities available for sale, at fair value (amortized cost - $77,835 and $79,536) (includes hybrid financial instruments of $5 and $2)		$ 78,939		$ 80,115
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)		14,335		10,644
Equity securities, at fair value (cost – $737 and $706)		937		814
Short-term investments, at fair value and amortized cost		3,561		3,002
Other investments (cost – $4,417 and $4,270)		4,672		4,519
Total investments		102,444		99,094
Cash	[1]	728	[2]	985	[3],[4]
Securities lending collateral		1,737		1,092
Accrued investment income		909		918
Insurance and reinsurance balances receivable		9,334		8,970
Reinsurance recoverable on losses and loss expenses		15,034		13,577
Reinsurance recoverable on policy benefits	[5]	184		182
Deferred policy acquisition costs		4,723		4,314
Value of business acquired		326		355
Goodwill		15,541		15,332
Intangible Assets, Net (Excluding Goodwill)		6,513		6,763
Prepaid reinsurance premiums		2,529		2,448
Investments in partially-owned insurance companies		662		666
Other assets		6,358		5,090
Total assets		167,022		159,786
Liabilities
Unpaid losses and loss expenses		63,179		60,540
Unearned premiums		15,216		14,779
Future policy benefits		5,321		5,036
Insurance and reinsurance balances payable		5,868		5,637
Collateral held under securities lending agreements		1,737		1,093
Accounts payable, accrued expenses, and other liabilities		9,545		8,617
Deferred Income Tax Liabilities, Net		699		988
Repurchase agreements		1,408		1,403
Short-term debt		1,013		500
Long-term debt		11,556		12,610
Trust preferred securities		308		308
Total liabilities		115,850		111,511
Commitments and contingencies
Shareholders' equity
Common Shares (CHF 24.15 par value; 479,783,864 shares issued; 463,833,179 and 465,968,716 shares outstanding)		11,121		11,121
Common Shares in treasury (15,950,685 and 13,815,148 shares)		(1,944)		(1,480)
Additional Paid in Capital, Common Stock		13,978		15,335
Retained earnings		27,474		23,613
Accumulated other comprehensive income (loss) (AOCI)		543		(314)
Total shareholders' equity		51,172		48,275
Total liabilities and shareholders’ equity		$ 167,022		$ 159,786
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	(1) Net of a provision for uncollectible reinsurance.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) $ in Millions	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares
Statement of Financial Position [Abstract]
Fixed maturities available for sale, at amortized cost	$ 77,835	$ 79,536
Fixed maturities available for sale, hybrid financial instruments	5	2
Held-to-maturity Securities, Fair Value	14,474	10,670
Equity securities, at cost	737	706
Other investments, cost	$ 4,417	$ 4,270
Common Shares, shares issued | shares	479,783,864	479,783,864
Common Shares, shares outstanding | shares	463,833,179	465,968,716
Common Shares in treasury, shares | shares	15,950,685	13,815,148

Consolidated Statements Of Oper

Consolidated Statements Of Operations and Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Net premiums written	$ 29,244	$ 28,145	$ 17,713
(Increase) decrease in unearned premiums	(210)	604	(500)
Net premiums earned	29,034	28,749	17,213
Net investment income	3,125	2,865	2,194
Net realized gains (losses):
Other-than-temporary impairment (OTTI) losses gross	(46)	(111)	(151)
Portion of OTTI losses recognized in other comprehensive income (OCI)	1	8	39
Net OTTI losses recognized in income	(45)	(103)	(112)
Net realized gains (losses) excluding OTTI losses	129	(42)	(308)
Total Net realized gains (losses) including OTTI	84	(145)	(420)
Total revenues	32,243	31,469	18,987
Expenses
Losses and loss expenses	18,454	16,052	9,484
Policy benefits	676	588	543
Policy Acquisition Costs	5,781	5,904	2,941
Administrative expenses	2,833	3,081	2,270
Interest expense	607	605	300
Other (income) expense	(400)	(222)	(51)
Amortization of Purchased Intangibles	260	19	171
Chubb integration expenses	310	492	33
Total expenses	28,521	26,519	15,691
Income before income tax	3,722	4,950	3,296
Income tax expense	(139)	815	462
Net income	3,861	4,135	2,834
Other comprehensive income (loss)
Unrealized appreciation (depreciation)	618	(35)	(1,280)
Reclassification adjustment for net realized (gains) losses included in net income	15	119	151
Other comprehensive income (loss) after reclassification for net realized gains included in net income	633	84	(1,129)
Change in:
Cumulative foreign currency translation adjustment	471	(154)	(958)
Postretirement benefit liability adjustment	(16)	545	15
Other comprehensive income (loss), before income tax	1,088	475	(2,072)
Income tax (expense) benefit related to OCI items	(231)	(54)	146
Other comprehensive income (loss)	857	421	(1,926)
Comprehensive income	$ 4,718	$ 4,556	$ 908
Earnings per share
Basic earnings per share	$ 8.26	$ 8.94	$ 8.71
Diluted earnings per share	$ 8.19	$ 8.87	$ 8.62

Consolidated Statements of Ope5

Consolidated Statements of Operations and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income tax expense (benefit)	$ (13)	$ 28	$ (2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net unrealized appreciation on investments
Net realized gains (losses)	(15)	(119)	(151)
Income tax expense (benefit)	$ (13)	$ 28	$ (2)

Consolidated Statements Of Shar

Consolidated Statements Of Shareholders' Equity - USD ($) $ in Millions	Total	Common Shares	Common Shares in Treasury	Additional Paid-in Capital	Retained Earnings	Net unrealized appreciation on investments	Cumulative Translation Adjustment	Accumulated Defined Benefit Plans Adjustment [Member]	Accumulated Other Comprehensive Income	The Chubb Corporation [Member]Common Shares	The Chubb Corporation [Member]Additional Paid-in Capital
Balance – beginning of year at Dec. 31, 2014		$ 8,055	$ (1,448)	$ 5,145	$ 16,644	$ 1,851	$ (581)	$ (79)
Dividends declared on Common Shares – par value reduction		(222)
Common Shares repurchased			(734)
Shares issued for Chubb Corp acquisition										$ 0	$ 0
Net shares redeemed under employee share-based compensation plans			260	(160)
Stock Issued During Period, Value, Stock Options Exercised				(61)
Share-based compensation expense and other				184
Funding of dividends declared from Additional paid-in capital				(653)	653
Tax benefit on share-based compensation expense				26
Net income	$ 2,834				2,834
Dividends declared on Common Shares					(653)
Change in year, before reclassification from AOCI, net of income tax benefit (expense) of $(228), $72, and $154						(1,126)
Amounts reclassified from AOCI, net of income tax benefit (expense) of $(13), $28, and $(2)						149
Change in year, net of income tax benefit (expense) of $(241), $100, and $152						(977)
Change in year, net of income tax benefit of $5, $30, and nil							(958)
Change in year, net of income tax benefit (expense) of $5, $(184), and $(6)								9
Balance – Ending of year at Dec. 31, 2015	29,135	7,833	(1,922)	4,481	19,478	874	(1,539)	(70)	$ (735)
Common Shares repurchased			0
Shares issued for Chubb Corp acquisition										3,288	11,916
Net shares redeemed under employee share-based compensation plans			442	(382)							323
Stock Issued During Period, Value, Stock Options Exercised				(64)
Share-based compensation expense and other				313
Funding of dividends declared from Additional paid-in capital				(1,284)	1,284
Tax benefit on share-based compensation expense				32
Net income	4,135				4,135
Dividends declared on Common Shares					(1,284)
Change in year, before reclassification from AOCI, net of income tax benefit (expense) of $(228), $72, and $154						37
Amounts reclassified from AOCI, net of income tax benefit (expense) of $(13), $28, and $(2)						147
Change in year, net of income tax benefit (expense) of $(241), $100, and $152						184
Change in year, net of income tax benefit of $5, $30, and nil							(124)
Change in year, net of income tax benefit (expense) of $5, $(184), and $(6)								361
Balance – Ending of year at Dec. 31, 2016	48,275	11,121	(1,480)	15,335	23,613	1,058	(1,663)	291	(314)
Common Shares repurchased			(830)
Shares issued for Chubb Corp acquisition										$ 0	$ 0
Net shares redeemed under employee share-based compensation plans			366	(313)
Stock Issued During Period, Value, Stock Options Exercised				(58)
Share-based compensation expense and other				331
Funding of dividends declared from Additional paid-in capital				(1,317)	1,317
Net income	3,861				3,861
Dividends declared on Common Shares					(1,317)
Change in year, before reclassification from AOCI, net of income tax benefit (expense) of $(228), $72, and $154						390
Amounts reclassified from AOCI, net of income tax benefit (expense) of $(13), $28, and $(2)						2
Change in year, net of income tax benefit (expense) of $(241), $100, and $152						392
Change in year, net of income tax benefit of $5, $30, and nil							476
Change in year, net of income tax benefit (expense) of $5, $(184), and $(6)								(11)
Balance – Ending of year at Dec. 31, 2017	$ 51,172	$ 11,121	$ (1,944)	$ 13,978	$ 27,474	$ 1,450	$ (1,187)	$ 280	$ 543

Consolidated Statements Of Sha7

Consolidated Statements Of Shareholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income (Loss), Available-for-sale Securities, before Reclassification Adjustments, Tax	$ (228)	$ 72	$ 154
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	(13)	28	(2)
Net unrealized appreciation on investments, Change in year, income tax (expense) benefit	(241)	100	152
Cumulative translation adjustment, Change in year, income tax(expense) benefit	5	30	0
Pension liability adjustment, Change in year, income tax (expense) benefit	$ 5	$ (184)	$ (6)

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Cash flows from operating activities
Net income		$ 3,861		$ 4,135		$ 2,834
Adjustments to reconcile net income to net cash flows from operating activities
Net realized (gains) losses		(84)		145		420
Amortization of premiums/discounts on fixed maturities		694		737		158
Amortization of UPR related to the Chubb Corp acquisition and other intangibles		260		1,578		171
Deferred income taxes		(527)		96		113
Unpaid losses and loss expenses		2,137		332		(375)
Unearned premiums		264		(680)		335
Future policy benefits		217		188		216
Insurance and reinsurance balances payable		271		848		268
Accounts payable, accrued expenses, and other liabilities		(517)		(97)		179
Income taxes payable		(365)		147		(148)
Insurance and reinsurance balances receivable		(243)		(616)		(53)
Reinsurance recoverable on losses and loss expenses		(1,248)		(365)		218
Reinsurance recoverable on policy benefits				7		33
Deferred policy acquisition costs		(317)		(1,449)		(435)
Prepaid reinsurance premiums		(82)		18		(212)
Other		182		268		142
Net cash flows from operating activities		4,503		5,292		3,864
Cash flows from investing activities
Purchases of fixed maturities available for sale		(25,720)		(30,759)		(16,040)
Purchases of to be announced mortgage-backed securities		(27)		(56)		(31)
Purchases of fixed maturities held to maturity		(352)		(282)		(62)
Purchases of equity securities		(173)		(146)		(158)
Sales of fixed maturities available for sale		13,228		16,621		10,783
Sales of to be announced mortgage-backed securities		27		56		31
Sales of equity securities		187		1,000		183
Maturities and redemptions of fixed maturities available for sale		10,425		9,349		6,567
Maturities and redemptions of fixed maturities held to maturity		879		958		669
Net change in short-term investments		(537)		12,350		(8,216)
Net derivative instruments settlements		(265)		(168)		(21)
Acquisition of subsidiaries (net of cash acquired of $nil, $71, and $629)				(14,248)		264
Other		(114)		10		(263)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		(2,442)		(5,315)		(6,294)
Cash flows from financing activities
Dividends paid on Common Shares		(1,308)		(1,173)		(862)
Common Shares repurchased		(801)				(758)
Proceeds from issuance of long-term debt						6,090
Proceeds from issuance of repurchase agreements		2,353		2,310		2,029
Repayment of repurchase agreements		(2,348)		(2,311)		(2,027)
Repayments of Long-term Debt		(501)		0		(1,150)
Proceeds from share-based compensation plans		151		167		131
Policyholder contract deposits		442		522		503
Policyholder contract withdrawals		(307)		(253)		(221)
Other		0		(4)		(40)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(2,319)		(742)		3,695
Effect of foreign currency rate changes on cash and cash equivalents		1		(25)		(145)
Net increase (decrease) in cash		(257)		(790)		1,120
Cash – beginning of year		985	[1],[2],[3]	1,775	[2],[4]	655	[4]
Cash – end of year	[2]	728	[5]	985	[1],[3]	1,775	[4]
Supplemental cash flow information
Taxes paid		736		662		469
Interest paid		$ 644		$ 642		$ 259
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Consolidated Statements Of Cas9

Consolidated Statements Of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Cash Flows [Abstract]
Acquisition of subsidiaries, cash acquired	$ 0	$ 71	$ 629

Summary of significant accounti

Summary of significant accounting policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies a) Basis of presentation Chubb Limited is a holding company incorporated in Zurich, Switzerland. Chubb Limited, through its subsidiaries, provides a broad range of insurance and reinsurance products to insureds worldwide. Our results are reported through the following business segments: North America Commercial P&C Insurance, North America Personal P&C Insurance, North America Agricultural Insurance, Overseas General Insurance, Global Reinsurance, and Life Insurance. Refer to Note 15 for additional information. The accompanying consolidated financial statements, which include the accounts of Chubb Limited and its subsidiaries (collectively, Chubb, we, us, or our), have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and, in the opinion of management, reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of the results and financial position for such periods. All significant intercompany accounts and transactions, including internal reinsurance transactions, have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Amounts included in the Consolidated financial statements reflect our best estimates and assumptions; actual amounts could differ materially from these estimates. Chubb's principal estimates include: • unpaid loss and loss expense reserves, including long-tail asbestos and environmental (A&E) reserves; • future policy benefits reserves; • the valuation of value of business acquired (VOBA) and amortization of deferred policy acquisition costs and VOBA; • reinsurance recoverable, including a provision for uncollectible reinsurance; • the assessment of risk transfer for certain structured insurance and reinsurance contracts; • the valuation of the investment portfolio and assessment of OTTI; • the valuation of deferred tax assets; • the valuation of derivative instruments related to guaranteed living benefits (GLB); • the valuation and amortization of purchased intangibles; and • the assessment of goodwill for impairment. b) Premiums Premiums are generally recorded as written upon inception of the policy. For multi-year policies for which premiums written are payable in annual installments, only the current annual premium is included as written at policy inception due to the ability of the insured/reinsured to commute or cancel coverage within the policy term. The remaining annual premiums are recorded as written at each successive anniversary date within the multi-year term. For P&C insurance and reinsurance products, premiums written are primarily earned on a pro-rata basis over the policy terms to which they relate. Unearned premiums represent the portion of premiums written applicable to the unexpired portion of the policies in force. For retrospectively-rated policies, written premiums are adjusted to reflect expected ultimate premiums consistent with changes to incurred losses, or other measures of exposure as stated in the policy, and earned over the policy coverage period. For retrospectively-rated multi-year policies, premiums recognized in the current period are computed using a with-and-without method as the difference between the ceding enterprise's total contract costs before and after the experience under the contract at the reporting date. Accordingly, for retrospectively-rated multi-year policies, additional premiums are generally written and earned when losses are incurred. Mandatory reinstatement premiums assessed on reinsurance policies are earned in the period of the loss event that gave rise to the reinstatement premiums. All remaining unearned premiums are recognized over the remaining coverage period. Premiums from long-duration contracts such as certain traditional term life, whole life, endowment, and long-duration personal accident and health (A&H) policies are generally recognized as revenue when due from policyholders. Traditional life policies include those contracts with fixed and guaranteed premiums and benefits. Benefits and expenses are matched with income to result in the recognition of profit over the life of the contracts. Retroactive loss portfolio transfer (LPT) contracts in which the insured loss events occurred prior to contract inception are evaluated to determine whether they meet criteria for reinsurance accounting. If reinsurance accounting is appropriate, written premiums are fully earned and corresponding losses and loss expenses recognized at contract inception. These contracts can cause significant variances in gross premiums written, net premiums written, net premiums earned, and net incurred losses in the years in which they are written. Reinsurance contracts sold not meeting criteria for reinsurance accounting are recorded using the deposit method as described below in Note 1 k). Reinsurance premiums assumed are based on information provided by ceding companies supplemented by our own estimates of premium when we have not received ceding company reports. Estimates are reviewed and adjustments are recorded in the period in which they are determined. Premiums are earned over the coverage terms of the related reinsurance contracts and range from one to three years. c) Deferred policy acquisition costs and value of business acquired Policy acquisition costs consist of commissions (direct and ceded), premium taxes, and certain underwriting costs related directly to the successful acquisition of new or renewal insurance contracts. A VOBA intangible asset is established upon the acquisition of blocks of long-duration contracts in a business combination and represents the present value of estimated net cash flows for the contracts in force at the acquisition date. Acquisition costs and VOBA, collectively policy acquisition costs, are deferred and amortized. Amortization is recorded in Policy acquisition costs in the Consolidated statements of operations. Policy acquisition costs on P&C contracts are generally amortized ratably over the period in which premiums are earned. Policy acquisition costs on traditional long-duration contracts are amortized over the estimated life of the contracts, generally in proportion to premium revenue recognized based upon the same assumptions used in estimating the liability for future policy benefits. For non-traditional long-duration contracts, we amortize policy acquisition costs over the expected life of the contracts in proportion to expected gross profits. The effect of changes in estimates of expected gross profits is reflected in the period the estimates are revised. Policy acquisition costs are reviewed to determine if they are recoverable from future income, including investment income. Unrecoverable policy acquisition costs are expensed in the period identified. Advertising costs are expensed as incurred except for direct-response campaigns that qualify for cost deferral, principally related to long-duration A&H business produced by the Overseas General Insurance segment, which are deferred and recognized as a component of Policy acquisition costs . For individual direct-response marketing campaigns that we can demonstrate have specifically resulted in incremental sales to customers and such sales have probable future economic benefits, incremental costs directly related to the marketing campaigns are capitalized as Deferred policy acquisition costs. Deferred policy acquisition costs, including deferred marketing costs, are reviewed regularly for recoverability from future income, including investment income, and amortized in proportion to premium revenue recognized, primarily over a ten -year period, the expected economic future benefit period based upon the same assumptions used in estimating the liability for future policy benefits. The expected future benefit period is evaluated periodically based on historical results and adjusted prospectively. The amount of deferred marketing costs reported in Deferred policy acquisition costs in the Consolidated balance sheets was $ 271 million and $ 256 million at December 31, 2017 and 2016 , respectively. Amortization expense for deferred marketing costs was $ 116 million, $ 92 million, and $ 78 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. d) Reinsurance Chubb assumes and cedes reinsurance with other insurance companies to provide greater diversification of business and minimize the net loss potential arising from large risks. Ceded reinsurance contracts do not relieve Chubb of its primary obligation to policyholders. For both ceded and assumed reinsurance, risk transfer requirements must be met in order to account for a contract as reinsurance, principally resulting in the recognition of cash flows under the contract as premiums and losses. To meet risk transfer requirements, a reinsurance contract must include insurance risk, consisting of both underwriting and timing risk, and a reasonable possibility of a significant loss for the assuming entity. To assess risk transfer for certain contracts, Chubb generally develops expected discounted cash flow analyses at contract inception. Deposit accounting is used for contracts that do not meet risk transfer requirements. Deposit accounting requires that consideration received or paid be recorded in the balance sheet as opposed to recording premiums written or losses incurred in the statement of operations. Non-refundable fees on deposit contracts are earned based on the terms of the contract described below in Note 1 k). Reinsurance recoverable includes balances due from reinsurance companies for paid and unpaid losses and loss expenses and future policy benefits that will be recovered from reinsurers, based on contracts in force. The method for determining the reinsurance recoverable on unpaid losses and loss expenses incurred but not reported (IBNR) involves actuarial estimates consistent with those used to establish the associated liability for unpaid losses and loss expenses as well as a determination of Chubb's ability to cede unpaid losses and loss expenses under the terms of the reinsurance agreement. Reinsurance recoverable is presented net of a provision for uncollectible reinsurance determined based upon a review of the financial condition of reinsurers and other factors. The provision for uncollectible reinsurance is based on an estimate of the reinsurance recoverable balance that will ultimately be unrecoverable due to reinsurer insolvency, a contractual dispute, or any other reason. The valuation of this provision includes several judgments including certain aspects of the allocation of reinsurance recoverable on IBNR claims by reinsurer and a default analysis to estimate uncollectible reinsurance. The primary components of the default analysis are reinsurance recoverable balances by reinsurer, net of collateral, and default factors used to determine the portion of a reinsurer's balance deemed uncollectible. The definition of collateral for this purpose requires some judgment and is generally limited to assets held in a Chubb-only beneficiary trust, letters of credit, and liabilities held with the same legal entity for which Chubb believes there is a contractual right of offset. The determination of the default factor is principally based on the financial strength rating of the reinsurer. Default factors require considerable judgment and are determined using the current financial strength rating, or rating equivalent, of each reinsurer as well as other key considerations and assumptions. The more significant considerations include, but are not necessarily limited to, the following: • For reinsurers that maintain a financial strength rating from a major rating agency, and for which recoverable balances are considered representative of the larger population (i.e., default probabilities are consistent with similarly rated reinsurers and payment durations conform to averages), the financial rating is based on a published source and the default factor is based on published default statistics of a major rating agency applicable to the reinsurer's particular rating class. When a recoverable is expected to be paid in a brief period of time by a highly rated reinsurer, such as certain property catastrophe claims, a default factor may not be applied; • For balances recoverable from reinsurers that are both unrated by a major rating agency and for which management is unable to determine a credible rating equivalent based on a parent, affiliate, or peer company, we determine a rating equivalent based on an analysis of the reinsurer that considers an assessment of the creditworthiness of the particular entity, industry benchmarks, or other factors as considered appropriate. We then apply the applicable default factor for that rating class. For balances recoverable from unrated reinsurers for which the ceded reserve is below a certain threshold, we generally apply a default factor of 34 percent, consistent with published statistics of a major rating agency; • For balances recoverable from reinsurers that are either insolvent or under regulatory supervision, we establish a default factor and resulting provision for uncollectible reinsurance based on reinsurer-specific facts and circumstances. Upon initial notification of an insolvency, we generally recognize an expense for a substantial portion of all balances outstanding, net of collateral, through a combination of write-offs of recoverable balances and increases to the provision for uncollectible reinsurance. When regulatory action is taken on a reinsurer, we generally recognize a default factor by estimating an expected recovery on all balances outstanding, net of collateral. When sufficient credible information becomes available, we adjust the provision for uncollectible reinsurance by establishing a default factor pursuant to information received; and • For other recoverables, management determines the provision for uncollectible reinsurance based on the specific facts and circumstances. The methods used to determine the reinsurance recoverable balance and related provision for uncollectible reinsurance are regularly reviewed and updated, and any resulting adjustments are reflected in earnings in the period identified. Prepaid reinsurance premiums represent the portion of premiums ceded to reinsurers applicable to the unexpired coverage terms of the reinsurance contracts in-force. The value of reinsurance business assumed of $ 18 million and $ 20 million at December 31, 2017 and 2016 , respectively, included in Other assets in the accompanying Consolidated balance sheets, represents the excess of estimated ultimate value of the liabilities assumed under retroactive reinsurance contracts over consideration received. The value of reinsurance business assumed is amortized and recorded to Losses and loss expenses based on the payment pattern of the losses assumed and ranges between 9 and 40 years. The unamortized value is reviewed regularly to determine if it is recoverable based upon the terms of the contract, estimated losses and loss expenses, and anticipated investment income. Unrecoverable amounts are expensed in the period identified. e) Investments Fixed maturities are classified as either available for sale or held to maturity. The available for sale portfolio is reported at fair value. The held to maturity portfolio includes securities for which we have the ability and intent to hold to maturity or redemption and is reported at amortized cost. Equity securities are classified as available for sale and are recorded at fair value. Short-term investments comprise securities due to mature within one year of the date of purchase and are recorded at fair value which typically approximates cost. Short-term investments include certain cash and cash equivalents, which are part of investment portfolios under the management of external investment managers. Other investments principally comprise life insurance policies, policy loans, trading securities, other direct equity investments, investment funds, and limited partnerships. • Life insurance policies are carried at policy cash surrender value and income is recorded in Other income (expense). • Policy loans are carried at outstanding balance and interest income is recorded to Net investment income. • Trading securities are recorded on a trade date basis and carried at fair value. Unrealized gains and losses on trading securities are reflected in Other (income) expense. • Other investments over which Chubb can exercise significant influence are accounted for using the equity method and income is recorded in Other (income) expense. • All other investments over which Chubb cannot exercise significant influence are carried at fair value with changes in fair value recognized through OCI. For these investments, investment income is recognized in Net investment income and realized gains are recognized as related distributions are received. • Partially-owned investment companies comprise entities in which we hold an ownership interest in excess of three percent. These investments as well as Chubb's investments in investment funds where our ownership interest is in excess of three percent are accounted for under the equity method because Chubb exerts significant influence. These investments apply investment company accounting to determine operating results, and Chubb retains the investment company accounting in applying the equity method. This means that investment income, realized gains or losses, and unrealized gains or losses are included in the portion of equity earnings reflected in Other (income) expense. As a result of the timing of the receipt of valuation data from the investment managers, these investments are generally reported on a three month lag. Investments in partially-owned insurance companies primarily represent direct investments in which Chubb has significant influence and, as such, meet the requirements for equity accounting. We report our share of the net income or loss of the partially-owned insurance companies in Other (income) expense. Realized gains or losses on sales of investments are determined on a first-in, first-out basis. Unrealized appreciation (depreciation) on investments is included as a separate component of AOCI in Shareholders' equity. We regularly review our investments for OTTI. Refer to Note 3 for additional information. With respect to securities where the decline in value is determined to be temporary and the security's value is not written down, a subsequent decision may be made to sell that security and realize a loss. Subsequent decisions on security sales are the result of changing or unforeseen facts and circumstances (i.e., arising from a large insured loss such as a catastrophe), deterioration of the creditworthiness of the issuer or its industry, or changes in regulatory requirements. We believe that subsequent decisions to sell such securities are consistent with the classification of the majority of the portfolio as available for sale. We use derivative instruments including futures, options, swaps, and foreign currency forward contracts for the purpose of managing certain investment portfolio risks and exposures. Refer to Note 10 for additional information. Derivatives are reported at fair value and are recorded in the accompanying Consolidated balance sheets in either Accounts payable, accrued expenses, and other liabilities or Other assets with changes in fair value included in Net realized gains (losses) in the Consolidated statements of operations. Collateral held by brokers equal to a percentage of the total value of open futures contracts is included in the investment portfolio. Net investment income includes interest and dividend income and amortization of fixed maturity market premiums and discounts and is net of investment management and custody fees. In addition, net investment income includes the amortization of the fair value adjustment related to the acquired invested assets of Chubb Corp. An adjustment of $1,652 million related to the fair value of Chubb Corp’s fixed maturities securities was recorded (fair value adjustment) at the date of acquisition. At December 31, 2017, the remaining balance of this fair value adjustment was $858 million which is expected to amortize over the next four years; however, the estimate could vary materially based on current market conditions, bond calls, and the duration of the acquired investment portfolio. In addition, sales of these acquired fixed maturities would also reduce the fair value adjustment balance. For mortgage-backed securities, and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any adjustments required due to the resultant change in effective yields and maturities are recognized prospectively. Prepayment fees or call premiums that are only payable when a security is called prior to its maturity are earned when received and reflected in Net investment income. Chubb participates in a securities lending program operated by a third-party banking institution whereby certain assets are loaned to qualified borrowers and from which we earn an incremental return. Borrowers provide collateral, in the form of either cash or approved securities, of 102 percent of the fair value of the loaned securities. Each security loan is deemed to be an overnight transaction. Cash collateral is invested in a collateral pool which is managed by the banking institution. The collateral pool is subject to written investment guidelines with key objectives which include the safeguard of principal and adequate liquidity to meet anticipated redemptions. The fair value of the loaned securities is monitored on a daily basis, with additional collateral obtained or refunded as the fair value of the loaned securities changes. The collateral is held by the third-party banking institution, and the collateral can only be accessed in the event that the institution borrowing the securities is in default under the lending agreement. As a result of these restrictions, we consider our securities lending activities to be non-cash investing and financing activities. An indemnification agreement with the lending agent protects us in the event a borrower becomes insolvent or fails to return any of the securities on loan. The fair value of the securities on loan is included in fixed maturities and equity securities. The securities lending collateral is reported as a separate line in the Consolidated balance sheets with a related liability reflecting our obligation to return the collateral plus interest. Similar to securities lending arrangements, securities sold under repurchase agreements, whereby Chubb sells securities and repurchases them at a future date for a predetermined price, are accounted for as collateralized investments and borrowings and are recorded at the contractual repurchase amounts plus accrued interest. Assets to be repurchased are the same, or substantially the same, as the assets transferred and the transferor, through right of substitution, maintains the right and ability to redeem the collateral on short notice. The fair value of the underlying securities is included in fixed maturities and equity securities. In contrast to securities lending programs, the use of cash received is not restricted. We report the obligation to return the cash as Repurchase agreements in the Consolidated balance sheets. Refer to Note 4 for a discussion on the determination of fair value for Chubb's various investment securities. f) Cash Cash includes cash on hand and deposits with an original maturity of three months or less at time of purchase. Cash held by external money managers is included in Short-term investments. We have agreements with a third-party bank provider which implemented two international multi-currency notional cash pooling programs. In each program, participating Chubb entities establish deposit accounts in different currencies with the bank provider and each day the credit or debit balances in every account are notionally translated into a single currency (U.S. dollars) and then notionally pooled. The bank extends overdraft credit to any participating Chubb entity as needed, provided that the overall notionally-pooled balance of all accounts in each pool at the end of each day is at least zero. Actual cash balances are not physically converted and are not commingled between legal entities. Any overdraft balances incurred under this program by a Chubb entity would be guaranteed by Chubb Limited (up to $ 300 million in the aggregate). Our syndicated letter of credit facility allows for same day drawings to fund a net pool overdraft should participating Chubb entities overdraw contributed funds from the pool. g) Goodwill and Other intangible assets Goodwill represents the excess of the cost of acquisitions over the fair value of net assets acquired and is not amortized. Goodwill is assigned at acquisition to the applicable reporting unit of the acquired entities giving rise to the goodwill. Goodwill impairment tests are performed annually or more frequently if circumstances indicate a possible impairment. For goodwill impairment testing, we use a qualitative assessment to determine whether it is more likely than not (i.e., more than a 50 percent probability) that the fair value of a reporting unit is greater than its carrying amount. If our assessment indicates less than a 50 percent probability that fair value exceeds carrying value, we quantitatively estimate a reporting unit's fair value. Goodwill recorded in connection with investments in partially-owned insurance companies is recorded in Investments in partially-owned insurance companies and is also measured for impairment annually. Indefinite lived intangible assets are not subject to amortization. Finite lived intangible assets are amortized over their useful lives, generally ranging from 1 to 30 years. Intangible assets are regularly reviewed for indicators of impairment. Impairment is recognized if the carrying amount is not recoverable from its undiscounted cash flows and is measured as the difference between the carrying amount and fair value. h) Unpaid losses and loss expenses A liability is established for the estimated unpaid losses and loss expenses under the terms of, and with respect to, Chubb's policies and agreements. Similar to premiums that are recognized as revenues over the coverage period of the policy, a liability for unpaid losses and loss expenses is recognized as expense when insured events occur over the coverage period of the policy. This liability includes a provision for both reported claims (case reserves) and incurred but not reported claims (IBNR reserves). IBNR reserve estimates are generally calculated by first projecting the ultimate cost of all losses that have occurred (expected losses), and then subtracting paid losses, case reserves, and loss expenses. The methods of determining such estimates and establishing the resulting liability are reviewed regularly and any adjustments are reflected in operations in the period in which they become known. Future developments may result in losses and loss expenses materially greater or less than recorded amounts. Except for net loss and loss expense reserves of $ 36 million net of discount, held at December 31, 2017 , representing certain structured settlements for which the timing and amount of future claim payments are reliably determinable and $ 41 million, net of discount, of certain reserves for unsettled claims that are discounted in statutory filings, Chubb does not discount its P&C loss reserves. This compares with reserves of $ 38 million for certain structured settlements and $ 50 million of certain reserves for unsettled claims at December 31, 2016 . Structured settlements represent contracts purchased from life insurance companies primarily to settle workers' compensation claims, where payments to the claimant by the life insurance company are expected to be made in the form of an annuity. Chubb retains the liability to the claimant in the event that the life insurance company fails to pay. At December 31, 2017 , the liability due to claimants was $ 586 million, net of discount, and reinsurance recoverables due from the life insurance companies was $ 550 million, net of discount. For structured settlement contracts where payments are guaranteed regardless of claimant life expectancy, the amounts recoverable from the life insurance companies at December 31, 2017 are included in Other assets in the Consolidated balance sheets, as they do not meet the requirements for reinsurance accounting. Included in Unpaid losses and loss expenses are liabilities for asbestos and environmental (A&E) claims and expenses. These unpaid losses and loss expenses are principally related to claims arising from remediation costs associated with hazardous waste sites and bodily-injury claims related to asbestos products and environmental hazards. The estimation of these liabilities is particularly sensitive to changes in the legal environment including specific settlements that may be used as precedents to settle future claims. However, Chubb does not anticipate future changes in laws and regulations in setting its A&E reserve levels. Also included in Unpaid losses and loss expenses is a fair value adjustment of $ 309 million at December 31, 2017 related to Chubb Corp’s historical unpaid losses and loss expenses. The estimated fair value consists of the present value of the expected net unpaid loss and loss adjustment expense payments adjusted for an estimated risk margin. The estimated cash flows are discounted at a risk free rate. The estimated risk margin varies based on the inherent risks associated with each type of reserve. The fair value is amortized through Amortization of purchased intangibles on the consolidated statements of operations over a range of 5 to 17 years, based on the estimated payout patterns of unpaid loss and loss expenses at the acquisition date. Prior period development arises from changes to loss estimates recognized in the current year that relate to loss reserves first reported in previous calendar years and excludes the effect of losses from the development of earned premiums from previous accident years. For purposes of analysis and disclosure, management views prior period development to be changes in the nominal value of loss estimates from period to period, net of premium and profit commission adjustments on loss sensitive contracts. Prior period development generally excludes changes in loss estimates that do not arise from the emergence of claims, such as those related to uncollectible reinsurance, interest, unallocated loss adjustment expenses, or foreign currency. Accordingly, specific items excluded from prior period development include the following: gains/losses related to foreign currency remeasurement; losses recognized from the early termination or commutation of reinsurance agreements that principally relate to the time value of money; changes in the value of reinsurance business assumed reflected in losses incurred but principally related to the time value of money; and losses that arise from changes in estimates of earned premiums from prior accident years. Except for foreign currency remeasurement, which is included in Net realized gains (losses), these items are included in current year losses. i) Future policy benefits The valuation of long-duration contract reserves requires management to make estimates and assumptions regarding expenses, mortality, persistency, and investment yields. Estimates are primarily based on historical experience and information provided by ceding companies and include a margin for adverse deviation. Interest rates used in calculating reserves range from less than 1.0 percent to 8.0 percent at both December 31, 2017 and 2016 . Actual results could differ materially from these estimates. Management monitors actual experience and where circumstances warrant, will revise assumptions and the related reserve estimates. Revisions are recorded in the period they are determined. Certain of our long-duration contracts are supported by assets that do not qualify for separate account reporting under GAAP. These assets are classifi

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisitions	Acquisitions The Chubb Corporation (Chubb Corp) On January 14, 2016, we completed the acquisition of Chubb Corp, a leading provider of middle-market commercial, specialty, surety, and personal insurance for $ 29.5 billion , comprising $ 14.3 billion in cash and $ 15.2 billion in newly-issued stock. In addition, we assumed outstanding equity awards to employees and directors with an attributed value of $ 323 million . The total consideration, including the assumption of equity awards, was $29.8 billion . We recognized goodwill of $ 10.5 billion , attributable to expected growth and profitability, none of which is expected to be deductible for income tax purposes. We financed the cash portion of the transaction through a combination of $ 9.0 billion sourced from various Chubb Limited and Chubb Corp companies plus $ 5.3 billion of senior notes, which were issued in November 2015. Refer to Note 9 for additional information on the senior notes. Upon completion of the merger, each Chubb Corp common share (other than shares held by certain legacy Chubb Corp employee benefit plans) was canceled and converted, in accordance with the procedures set forth in the merger agreement, into the right to receive (i) 0.6019 of a Chubb Limited common share and (ii) $62.93 in cash. In addition, replacement equity awards were issued by Chubb Limited to the holders of Chubb Corp's outstanding equity awards (stock options, restricted stock units, deferred stock units, deferred unit obligations, and performance units). We believe the Chubb Corp acquisition is highly complementary to our existing business lines, distribution channels, customer segments, and underwriting skills. Chubb Corp has a substantial presence in the U.S. with a broad variety of coverages serving large corporate and upper middle market accounts, middle market and small commercial accounts, and personal lines. Together we are one of the largest commercial insurers in the U.S. Internationally, where legacy ACE is a truly global insurer with extensive presence in 54 countries and territories, Chubb Corp's operations in 25 markets added to our presence and capabilities and positioned us to better pursue important market opportunities globally. The combined company is a leader in a number of global specialty and traditional products such as professional lines, risk management, workers' compensation, accident and health (A&H), and other property and general casualty lines. The table below details the purchase consideration and allocation of assets acquired and liabilities assumed: (in millions of U.S. dollars, except per share data) Purchase consideration Chubb Limited common shares Chubb Corp common shares outstanding 228 Per share exchange ratio 0.6019 Common shares issued by Chubb Limited 137 Common share price of Chubb Limited at January 14, 2016 $ 111.02 Fair value of common shares issued by Chubb Limited to common shareholders of Chubb Corp $ 15,204 Cash consideration Chubb Corp common shares outstanding 228 Agreed cash price per share paid to common shareholders of Chubb Corp $ 62.93 Cash consideration paid by Chubb Limited to common shareholders of Chubb Corp $ 14,319 Stock-based awards Fair value of equity awards issued (1) $ 323 Fair value of purchase consideration $ 29,846 Assets acquired and (liabilities) assumed Cash $ 71 Investments 42,967 Accrued investment income 359 Insurance and reinsurance balances receivable 3,095 Reinsurance recoverable on losses and loss expenses 1,676 Indefinite lived intangible assets 2,860 Finite lived intangible assets 4,795 Prepaid reinsurance premiums 280 Other assets 853 Unpaid losses and loss expenses (22,923 ) Unearned premiums (7,011 ) Insurance and reinsurance balances payable (603 ) Accounts payable, accrued expenses, and other liabilities (2,030 ) Deferred tax liabilities (1,292 ) Long-term debt (3,765 ) Total identifiable net assets acquired 19,332 Goodwill 10,514 Purchase price $ 29,846 (1) The fair value of the replacement equity awards was $525 million , of which $323 million was attributed to service periods prior to the acquisition and was included in the purchase consideration. Refer to Note 12 for further information on these replacement equity awards. The purchase price allocation to intangible assets recorded in connection with the Chubb Corp acquisition and their related useful lives are as follows: (in millions of U.S. dollars) Purchase price Allocation at January 14, 2016 Estimated useful life Definite life Unearned premium reserves (UPR) intangible asset $ 1,550 1 year Agency distribution relationships and renewal rights 3,150 24 years Internally developed technology 95 3 years Indefinite life Trademarks 2,800 Indefinite Licenses 50 Indefinite Syndicate capacity 10 Indefinite Total identified intangible assets $ 7,655 Refer to Note 6 for additional information on goodwill and intangible assets acquired. The following table summarizes the results of the acquired Chubb Corp operations since the acquisition date that have been included within our Consolidated statement of operations: (in millions of U.S. dollars) January 14, 2016 to December 31, 2016 Total revenues $ 12,376 Net income $ 1,756 The following table provides supplemental unaudited pro forma consolidated information for the years ended December 31, 2016 and 2015, as if Chubb Corp had been acquired as of January 1, 2015. The unaudited pro forma consolidated financial statements are presented solely for informational purposes and are not necessarily indicative of the consolidated results of operations that might have been achieved had the transaction been completed as of the date indicated, nor are they meant to be indicative of any anticipated consolidated future results of operations that the combined company will experience after the transaction. Year Ended December 31 (in millions of U.S. dollars, except per share data) 2016 2015 Total revenues $ 31,937 $ 32,622 Net income $ 4,183 $ 4,478 Earnings per share Basic earnings per share $ 8.95 $ 9.61 Diluted earnings per share $ 8.88 $ 9.52 Total revenues and net income were lower for the year ended December 31, 2016, compared to the prior year, primarily reflecting merger-related actions in 2016, which lowered net premiums earned. Fireman's Fund Insurance Company High Net Worth Personal Lines Insurance Business in the U.S. (Fireman's Fund) On April 1, 2015, we acquired the Fireman's Fund Insurance Company high net worth personal lines insurance business in the U.S., which included the renewal rights for new and existing business and reinsurance of all existing reserves for $365 million in cash. We acquired assets with a fair value of $753 million , consisting primarily of cash of $629 million and insurance and reinsurance balances receivable of $124 million . We assumed liabilities with a fair value of $863 million , consisting primarily of unpaid losses and loss expenses of $417 million and unearned premiums of $428 million . This acquisition generated $196 million of goodwill, attributable to expected growth and profitability, all of which is expected to be deductible for income tax purposes, and other intangible assets of $278 million , primarily related to renewal rights, based on Chubb’s purchase price allocation. The acquisition expanded our position in the high net worth personal lines insurers in the U.S. The Fireman’s Fund business was integrated into our existing high net worth personal lines business, offering a broad range of coverage including homeowners, automobile, umbrella and excess liability, collectibles, and yachts. Goodwill and other intangible assets arising from this acquisition are included in our North America Personal P&C Insurance segment. The Consolidated financial statements include results of acquired businesses from the acquisition dates.

Investments

Investments	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	Investments a) Transfers of securities During December 2017, we transferred securities, considered essential holdings in a diversified portfolio, with a total fair value of $4.3 billion from Fixed maturities available for sale to Fixed maturities held to maturity. These securities, which we have the intent and ability to hold to maturity, were transferred given the growth in our investment portfolio over the last several years, as well as continued efforts to manage the diversification of our global portfolio. The net unrealized appreciation at the date of the transfer continues to be reported in the carrying value of the transferred investments and is amortized through OCI over the remaining life of the securities using the effective interest method in a manner consistent with the amortization of any premium or discount. This transfer represents a non-cash transaction and does not impact the Consolidated statements of cash flows. b) Fixed maturities December 31, 2017 Amortized Cost Gross Unrealized Appreciation Gross Unrealized Depreciation Fair Value OTTI Recognized in AOCI (in millions of U.S. dollars) Available for sale U.S. Treasury and agency $ 3,701 $ 32 $ (35 ) $ 3,698 $ — Foreign 20,514 622 (106 ) 21,030 (1 ) Corporate securities 23,453 638 (95 ) 23,996 (4 ) Mortgage-backed securities 15,279 111 (100 ) 15,290 (1 ) States, municipalities, and political subdivisions 14,888 125 (88 ) 14,925 — $ 77,835 $ 1,528 $ (424 ) $ 78,939 $ (6 ) Held to maturity U.S. Treasury and agency $ 908 $ 12 $ (5 ) $ 915 $ — Foreign 1,738 27 (8 ) 1,757 — Corporate securities 3,159 67 (7 ) 3,219 — Mortgage-backed securities 2,724 23 (5 ) 2,742 — States, municipalities, and political subdivisions 5,806 50 (15 ) 5,841 — $ 14,335 $ 179 $ (40 ) $ 14,474 $ — December 31, 2016 Amortized Gross Gross Fair OTTI Recognized (in millions of U.S. dollars) Available for sale U.S. Treasury and agency $ 2,883 $ 32 $ (45 ) $ 2,870 $ — Foreign 20,929 636 (125 ) 21,440 (5 ) Corporate securities 23,736 580 (167 ) 24,149 (8 ) Mortgage-backed securities 14,066 135 (194 ) 14,007 (1 ) States, municipalities, and political subdivisions 17,922 72 (345 ) 17,649 — $ 79,536 $ 1,455 $ (876 ) $ 80,115 $ (14 ) Held to maturity U.S. Treasury and agency $ 655 $ 9 $ (3 ) $ 661 $ — Foreign 640 28 (1 ) 667 — Corporate securities 2,771 50 (26 ) 2,795 — Mortgage-backed securities 1,393 35 — 1,428 — States, municipalities, and political subdivisions 5,185 26 (92 ) 5,119 — $ 10,644 $ 148 $ (122 ) $ 10,670 $ — As discussed in Note 3 d), if a credit loss is incurred on an impaired fixed maturity, an OTTI is considered to have occurred and the portion of the impairment not related to credit losses (non-credit OTTI) is recognized in OCI. Included in the “OTTI Recognized in AOCI” columns above are the cumulative amounts of non-credit OTTI recognized in OCI adjusted for subsequent sales, maturities, and redemptions. OTTI recognized in AOCI does not include the impact of subsequent changes in fair value of the related securities. In periods subsequent to a recognition of OTTI in OCI, changes in the fair value of the related fixed maturities are reflected in Net unrealized appreciation on investments in the Consolidated statements of shareholders' equity. For the years ended December 31, 2017 and 2016 , $ 2 million of net unrealized depreciation and $ 62 million of net unrealized appreciation, respectively, related to such securities is included in OCI. At December 31, 2017 and 2016 , AOCI included cumulative net unrealized appreciation of $ 7 million and $ 10 million, respectively, related to securities remaining in the investment portfolio for which a non-credit OTTI was recognized. Mortgage-backed securities (MBS) issued by U.S. government agencies are combined with all other to be announced mortgage derivatives held (refer to Note 10 c) (iv)) and are included in the category, “Mortgage-backed securities”. Approximately 83 percent and 81 percent of the total mortgage-backed securities at December 31, 2017 and 2016 , respectively, are represented by investments in U.S. government agency bonds. The remainder of the mortgage exposure consists of collateralized mortgage obligations and non-government mortgage-backed securities, the majority of which provide a planned structure for principal and interest payments and carry a rating of AAA by the major credit rating agencies. The following table presents fixed maturities by contractual maturity: December 31 December 31 2017 2016 (in millions of U.S. dollars) Amortized Cost Fair Value Amortized Cost Fair Value Available for sale Due in 1 year or less $ 3,164 $ 3,182 $ 3,892 $ 3,913 Due after 1 year through 5 years 24,749 25,068 24,027 24,429 Due after 5 years through 10 years 25,388 25,704 27,262 27,379 Due after 10 years 9,255 9,695 10,289 10,387 62,556 63,649 65,470 66,108 Mortgage-backed securities 15,279 15,290 14,066 14,007 $ 77,835 $ 78,939 $ 79,536 $ 80,115 Held to maturity Due in 1 year or less $ 743 $ 746 $ 430 $ 435 Due after 1 year through 5 years 2,669 2,688 2,646 2,691 Due after 5 years through 10 years 4,744 4,756 2,969 2,944 Due after 10 years 3,455 3,542 3,206 3,172 11,611 11,732 9,251 9,242 Mortgage-backed securities 2,724 2,742 1,393 1,428 $ 14,335 $ 14,474 $ 10,644 $ 10,670 Expected maturities could differ from contractual maturities because borrowers may have the right to call or prepay obligations, with or without call or prepayment penalties. c) Equity securities December 31 December 31 (in millions of U.S. dollars) 2017 2016 Cost $ 737 $ 706 Gross unrealized appreciation 212 129 Gross unrealized depreciation (12 ) (21 ) Fair value $ 937 $ 814 d) Net realized gains (losses) In accordance with guidance related to the recognition and presentation of OTTI, when an impairment related to a fixed maturity has occurred, OTTI is required to be recorded in Net income if management has the intent to sell the security or it is more likely than not that we will be required to sell the security before the recovery of its amortized cost. Further, in cases where we do not intend to sell the security and it is more likely than not that we will not be required to sell the security, we must evaluate the security to determine the portion of the impairment, if any, related to credit losses. If a credit loss is incurred, an OTTI is considered to have occurred and any portion of the OTTI related to credit losses must be reflected in Net income, while the portion of OTTI related to all other factors is recognized in OCI. For fixed maturities held to maturity, OTTI recognized in OCI is accreted from AOCI to the amortized cost of the fixed maturity prospectively over the remaining term of the securities. Each quarter, securities in an unrealized loss position (impaired securities), including fixed maturities, securities lending collateral, equity securities, and other investments, are reviewed to identify impaired securities to be specifically evaluated for a potential OTTI. For all non-fixed maturities, OTTI is evaluated based on the following: • the amount of time a security has been in a loss position and the magnitude of the loss position; • the period in which cost is expected to be recovered, if at all, based on various criteria including economic conditions and other issuer-specific developments; and • our ability and intent to hold the security to the expected recovery period. As a general rule, we also consider that equity securities in an unrealized loss position for twelve consecutive months are other than temporarily impaired. For mutual funds included in equity securities in our Consolidated balance sheets, we employ analysis similar to fixed maturities, when applicable. Evaluation of potential credit losses related to fixed maturities We review each fixed maturity in an unrealized loss position to assess whether the security is a candidate for credit loss. Specifically, we consider credit rating, market price, and issuer-specific financial information, among other factors, to assess the likelihood of collection of all principal and interest as contractually due. Securities, for which we determine that credit loss is likely, are subjected to further analysis to estimate the credit loss recognized in Net income, if any. In general, credit loss recognized in Net income equals the difference between the security’s amortized cost and the net present value of its projected future cash flows discounted at the effective interest rate implicit in the debt security. All significant assumptions used in determining credit losses are subject to change as market conditions evolve. U.S. Treasury and agency obligations (including agency mortgage-backed securities); foreign government obligations; and states, municipalities, and political subdivisions obligations U.S. Treasury and agency obligations (including agency mortgage-backed securities); foreign government obligations; and states, municipalities, and political subdivisions obligations represent $ 311 million of gross unrealized loss at December 31, 2017 . These securities were evaluated for credit loss primarily using qualitative assessments of the likelihood of credit loss considering credit rating of the issuers and level of credit enhancement, if any. We concluded that the high level of creditworthiness of the issuers coupled with credit enhancement, where applicable, supports recognizing no credit loss in Net income. Corporate securities Projected cash flows for corporate securities (principally senior unsecured bonds) are driven primarily by assumptions regarding probability of default and also the timing and amount of recoveries associated with defaults. Chubb developed projected cash flows for corporate securities using market observable data, issuer-specific information, and credit ratings. We use historical default data by Moody’s Investors Service (Moody’s) rating category to calculate a 1-in-100 year probability of default, which results in a default assumption in excess of the historical mean default rate. Consistent with management's approach, Chubb assumed a 32 percent recovery rate (the par value of a defaulted security that will be recovered) across all rating categories, rather than using Moody's historical mean recovery rate of 42 percent . We believe that use of a default assumption, in excess of the historical mean, is conservative in light of current market conditions. The following table presents default assumptions by Moody's rating category (historical mean default rate provided for comparison): Moody's Rating Category 1-in-100 Year Default Rate Historical Mean Default Rate Investment Grade: Aaa-Baa 0.0-1.3% 0.0-0.3% Below Investment Grade: Ba 4.8 % 1.0 % B 12.1 % 3.2 % Caa-C 36.8 % 10.5 % Application of the methodology and assumptions described above resulted in credit losses recognized in Net income for corporate securities of $ 5 million, $ 30 million, and $ 50 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Mortgage-backed securities For mortgage-backed securities, credit impairment is assessed using a cash flow model that estimates the cash flows on the underlying mortgages, using the security-specific collateral and transaction structure. The model estimates cash flows from the underlying mortgage loans and distributes those cash flows to various tranches of securities, considering the transaction structure and any subordination and credit enhancements that exist in that structure. The cash flow model incorporates actual cash flows on the mortgage-backed securities through the current period and then projects the remaining cash flows using a number of assumptions, including default rates, prepayment rates, and loss severity rates (the par value of a defaulted security that will not be recovered) on foreclosed properties. We develop specific assumptions using market data, where available, and include internal estimates as well as estimates published by rating agencies and other third-party sources. We project default rates by mortgage sector considering current underlying mortgage loan performance, generally assuming lower loss severity for Prime sector bonds versus ALT-A and Sub-prime bonds. These estimates are extrapolated along a default timing curve to estimate the total lifetime pool default rate. Other assumptions used contemplate the actual collateral attributes, including geographic concentrations, rating agency loss projections, rating actions, and current market prices. If cash flow projections indicate that losses will exceed the credit enhancement for a given tranche, then we do not expect to recover our amortized cost basis, and we recognize an estimated credit loss in Net income. For the years ended December 31, 2017 and 2015 , there were no credit losses recognized in Net income for mortgage-backed securities. For the year ended December 31, 2016 , there was $ 1 million of credit losses recognized in Net income for mortgage-backed securities. The following table presents the Net realized gains (losses) and the losses included in Net realized gains (losses) and OCI as a result of conditions which caused us to conclude the decline in fair value of certain investments was “other-than-temporary” and the change in net unrealized appreciation (depreciation) of investments: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Fixed maturities: OTTI on fixed maturities, gross $ (24 ) $ (89 ) $ (142 ) OTTI on fixed maturities recognized in OCI (pre-tax) 1 8 39 OTTI on fixed maturities, net (23 ) (81 ) (103 ) Gross realized gains excluding OTTI 149 183 158 Gross realized losses excluding OTTI (157 ) (265 ) (235 ) Total fixed maturities (31 ) (163 ) (180 ) Equity securities: OTTI on equity securities (10 ) (8 ) (7 ) Gross realized gains excluding OTTI 28 65 47 Gross realized losses excluding OTTI (2 ) (13 ) (11 ) Total equity securities 16 44 29 OTTI on other investments (12 ) (14 ) (2 ) Foreign exchange gains (losses) 36 118 (80 ) Investment and embedded derivative instruments (11 ) (33 ) 32 Fair value adjustments on insurance derivative 364 53 (203 ) S&P put options and futures (261 ) (136 ) (10 ) Other derivative instruments (5 ) (10 ) (12 ) Other (12 ) (4 ) 6 Net realized gains (losses) 84 (145 ) (420 ) Change in net unrealized appreciation (depreciation) on investments: Fixed maturities available for sale 519 142 (1,119 ) Fixed maturities held to maturity 18 (59 ) 43 Equity securities 88 52 (17 ) Other 8 (51 ) (36 ) Income tax (expense) benefit (241 ) 100 152 Change in net unrealized appreciation (depreciation) on investments 392 184 (977 ) Total net realized gains (losses) and change in net unrealized appreciation (depreciation) on investments $ 476 $ 39 $ (1,397 ) The following table presents a roll-forward of pre-tax credit losses related to fixed maturities for which a portion of OTTI was recognized in OCI: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Balance of credit losses related to securities still held – beginning of year $ 35 $ 53 $ 28 Additions where no OTTI was previously recorded 4 17 41 Additions where an OTTI was previously recorded 2 14 9 Reductions for securities sold during the period (19 ) (49 ) (25 ) Balance of credit losses related to securities still held – end of year $ 22 $ 35 $ 53 e) Other investments December 31 December 31 2017 2016 (in millions of U.S. dollars) Fair Value Cost Fair Value Cost Investment funds $ 270 $ 123 $ 251 $ 126 Limited partnerships 549 441 730 607 Partially-owned investment companies 2,803 2,803 2,645 2,645 Life insurance policies 305 305 248 248 Policy loans 244 244 209 209 Trading securities 333 333 296 295 Other 168 168 140 140 Total $ 4,672 $ 4,417 $ 4,519 $ 4,270 Investment funds include one highly diversified fund investment as well as several direct funds that employ a variety of investment styles such as long/short equity and arbitrage/distressed. Included in limited partnerships and partially-owned investment companies are 138 individual limited partnerships covering a broad range of investment strategies including large cap buyouts, specialist buyouts, growth capital, distressed, mezzanine, real estate, and co-investments. The underlying portfolio consists of various public and private debt and equity securities of publicly traded and privately held companies and real estate assets. The underlying investments across various partnerships, geographies, industries, asset types, and investment strategies provide risk diversification within the limited partnership portfolio and the overall investment portfolio. Trading securities comprise $ 333 million of mutual funds supported by assets that do not qualify for separate account reporting under GAAP at December 31, 2017 compared with $ 271 million at December 31, 2016 . There were no trading securities held in rabbi trusts at December 31, 2017 , compared with $ 14 million of equity securities and $ 11 million of fixed maturities at December 31, 2016 . f) Investments in partially-owned insurance companies The following table presents Investments in partially-owned insurance companies: December 31, 2017 December 31, 2016 (in millions of U.S. dollars, except for percentages) Carrying Value Issued Share Capital Ownership Percentage Carrying Value Issued Share Capital Ownership Percentage Domicile Huatai Group $ 438 $ 616 20 % $ 447 $ 624 20 % China Huatai Life Insurance Company 105 495 20 % 99 428 20 % China Freisenbruch-Meyer 9 — 40 % 8 5 40 % Bermuda Chubb Arabia Cooperative Insurance Company 15 27 30 % 13 27 30 % Saudi Arabia Russian Reinsurance Company 2 4 23 % 2 4 23 % Russia ABR Reinsurance Ltd. 93 800 11 % 97 800 11 % Bermuda Total $ 662 $ 1,942 $ 666 $ 1,888 Huatai Group and Huatai Life Insurance Company provide a range of P&C, life, and investment products. g) Gross unrealized loss At December 31, 2017 , there were 9,828 fixed maturities out of a total of 30,932 fixed maturities in an unrealized loss position. The largest single unrealized loss in the fixed maturities was $7 million. There were 82 equity securities out of a total of 328 equity securities in an unrealized loss position. The largest single unrealized loss in the equity securities was $3 million. Fixed maturities in an unrealized loss position at December 31, 2017 , comprised both investment grade and below investment grade securities for which fair value declined primarily due to widening credit spreads since the date of purchase. The following tables present, for all securities in an unrealized loss position (including securities on loan), the aggregate fair value and gross unrealized loss by length of time the security has continuously been in an unrealized loss position: 0 – 12 Months Over 12 Months Total December 31, 2017 Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss (in millions of U.S. dollars) U.S. Treasury and agency $ 2,172 $ (14 ) $ 1,249 $ (26 ) $ 3,421 $ (40 ) Foreign 5,657 (65 ) 1,693 (49 ) 7,350 (114 ) Corporate securities 5,210 (56 ) 1,332 (46 ) 6,542 (102 ) Mortgage-backed securities 6,194 (31 ) 3,209 (74 ) 9,403 (105 ) States, municipalities, and political subdivisions 9,259 (71 ) 1,402 (32 ) 10,661 (103 ) Total fixed maturities 28,492 (237 ) 8,885 (227 ) 37,377 (464 ) Equity securities 115 (12 ) — — 115 (12 ) Other investments 78 (8 ) — — 78 (8 ) Total $ 28,685 $ (257 ) $ 8,885 $ (227 ) $ 37,570 $ (484 ) 0 – 12 Months Over 12 Months Total December 31, 2016 Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss (in millions of U.S. dollars) U.S. Treasury and agency $ 2,216 $ (48 ) $ — $ — $ 2,216 $ (48 ) Foreign 5,918 (99 ) 386 (27 ) 6,304 (126 ) Corporate securities 7,021 (149 ) 641 (44 ) 7,662 (193 ) Mortgage-backed securities 8,638 (189 ) 234 (5 ) 8,872 (194 ) States, municipalities, and political subdivisions 19,448 (435 ) 49 (2 ) 19,497 (437 ) Total fixed maturities 43,241 (920 ) 1,310 (78 ) 44,551 (998 ) Equity securities 199 (21 ) — — 199 (21 ) Other investments 201 (18 ) — — 201 (18 ) Total $ 43,641 $ (959 ) $ 1,310 $ (78 ) $ 44,951 $ (1,037 ) h) Net investment income Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Fixed maturities $ 2,987 $ 2,779 $ 2,157 Short-term investments 131 93 49 Equity securities 38 36 16 Other investments 133 98 86 Gross investment income (1) 3,289 3,006 2,308 Investment expenses (164 ) (141 ) (114 ) Net investment income (1) $ 3,125 $ 2,865 $ 2,194 (1) Includes amortization expense related to fair value adjustment of acquired invested assets related to the Chubb Corp acquisition $ (332 ) $ (393 ) $ — i) Restricted assets Chubb is required to maintain assets on deposit with various regulatory authorities to support its insurance and reinsurance operations. These requirements are generally promulgated in the statutory regulations of the individual jurisdictions. The assets on deposit are available to settle insurance and reinsurance liabilities. Chubb is also required to restrict assets pledged under repurchase agreements. We also use trust funds in certain large reinsurance transactions where the trust funds are set up for the benefit of the ceding companies and generally take the place of letter of credit (LOC) requirements. We also have investments in segregated portfolios primarily to provide collateral or guarantees for LOC and derivative transactions. Included in restricted assets at December 31, 2017 and 2016 , are investments, primarily fixed maturities, totaling $23.3 billion and $ 20.1 billion , and cash of $123 million and $103 million, respectively. The following table presents the components of restricted assets: December 31 December 31 (in millions of U.S. dollars) 2017 2016 Trust funds $ 17,011 $ 13,880 Deposits with U.S. regulatory authorities 2,345 2,203 Deposits with non-U.S. regulatory authorities 2,250 2,191 Assets pledged under repurchase agreements 1,434 1,461 Other pledged assets 414 435 $ 23,454 $ 20,170

Fair value measurements

Fair value measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements a ) Fair value hierarchy Fair value of financial assets and financial liabilities is estimated based on the framework established in the fair value accounting guidance. The guidance defines fair value as the price to sell an asset or transfer a liability (an exit price) in an orderly transaction between market participants and establishes a three-level valuation hierarchy based on the reliability of the inputs. The fair value hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. The three levels of the hierarchy are as follows: • Level 1 – Unadjusted quoted prices for identical assets or liabilities in active markets; • Level 2 – Includes, among other items, inputs other than quoted prices that are observable for the asset or liability such as interest rates and yield curves, quoted prices for similar assets and liabilities in active markets, and quoted prices for identical or similar assets and liabilities in markets that are not active; and • Level 3 – Inputs that are unobservable and reflect management’s judgments about assumptions that market participants would use in pricing an asset or liability. We categorize financial instruments within the valuation hierarchy at the balance sheet date based upon the lowest level of inputs that are significant to the fair value measurement. Accordingly, transfers between levels within the valuation hierarchy occur when there are significant changes to the inputs, such as increases or decreases in market activity, changes to the availability of current prices, changes to the transparency to underlying inputs, and whether there are significant variances in quoted prices. Transfers in and/or out of any level are assumed to occur at the end of the period. We use pricing services to obtain fair value measurements for the majority of our investment securities. Based on management’s understanding of the methodologies used, these pricing services only produce an estimate of fair value if there is observable market information that would allow them to make a fair value estimate. Based on our understanding of the market inputs used by the pricing services, all applicable investments have been valued in accordance with GAAP. We do not adjust prices obtained from pricing services. The following is a description of the valuation techniques and inputs used to determine fair values for financial instruments carried at fair value, as well as the general classification of such financial instruments pursuant to the valuation hierarchy. Fixed maturities We use pricing services to estimate fair value measurements for the majority of our fixed maturities. The pricing services use market quotations for fixed maturities that have quoted prices in active markets; such securities are classified within Level 1. For fixed maturities other than U.S. Treasury securities that generally do not trade on a daily basis, the pricing services prepare estimates of fair value measurements using their pricing applications, which include available relevant market information, benchmark curves, benchmarking of like securities, sector groupings, and matrix pricing. Additional valuation factors that can be taken into account are nominal spreads, dollar basis, and liquidity adjustments. The pricing services evaluate each asset class based on relevant market and credit information, perceived market movements, and sector news. The market inputs used 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 input is dependent on the asset class and the market conditions. Given the asset class, the priority of the use of inputs may change, or some market inputs may not be relevant. Additionally, fixed maturities valuation is more subjective when markets are less liquid due to the lack of market based inputs (i.e., stale pricing), which may increase the potential that an investment's estimated fair value is not reflective of the price at which an actual transaction would occur. The overwhelming majority of fixed maturities are classified within Level 2 because the most significant inputs used in the pricing techniques are observable. For a small number of fixed maturities, we obtain a single broker quote (typically from a market maker). Due to the disclaimers on the quotes that indicate that the price is indicative only, we include these fair value estimates in Level 3. Equity securities Equity securities with active markets are classified within Level 1 as fair values are based on quoted market prices. For equity securities in markets which are less active, fair values are based on market valuations and are classified within Level 2. Equity securities for which pricing is unobservable are classified within Level 3. Short-term investments Short-term investments, which comprise securities due to mature within one year of the date of purchase that are traded in active markets, are classified within Level 1 as fair values are based on quoted market prices. Securities such as commercial paper and discount notes are classified within Level 2 because these securities are typically not actively traded due to their approaching maturity and, as such, their cost approximates fair value. Short-term investments for which pricing is unobservable are classified within Level 3. Other investments Fair values for the majority of Other investments including investments in partially-owned investment companies, investment funds, and limited partnerships are based on their respective net asset values or equivalent (NAV) and are excluded from the fair value hierarchy table below. Certain of our long-duration contracts are supported by assets that do not qualify for separate account reporting under GAAP. These assets comprise mutual funds classified within Level 1 in the valuation hierarchy on the same basis as other equity securities traded in active markets. Other investments also include equity securities classified within Level 1, and fixed maturities, classified within Level 2, held in rabbi trusts maintained by Chubb for deferred compensation plans and are classified within the valuation hierarchy on the same basis as other equity securities and fixed maturities. Other investments for which pricing is unobservable are classified within Level 3. Securities lending collateral The underlying assets included in Securities lending collateral in the Consolidated balance sheets are fixed maturities which are classified in the valuation hierarchy on the same basis as other fixed maturities. Excluded from the valuation hierarchy is the corresponding liability related to Chubb’s obligation to return the collateral plus interest as it is reported at contract value and not fair value in the Consolidated balance sheets. Investment derivative instruments Actively traded investment derivative instruments, including futures, options, and forward contracts are classified within Level 1 as fair values are based on quoted market prices. The fair value of cross-currency swaps is based on market valuations and is classified within Level 2. Investment derivative instruments are recorded in either Other assets or Accounts payable, accrued expenses, and other liabilities in the Consolidated balance sheets. Other derivative instruments We generally maintain positions in other derivative instruments including exchange-traded equity futures contracts and option contracts designed to limit exposure to a severe equity market decline, which would cause an increase in expected claims and, therefore, an increase in reserves for our guaranteed minimum death benefits (GMDB) and guaranteed living benefits (GLB) reinsurance business. Our position in exchange-traded equity futures contracts is classified within Level 1. At December 31, 2017, we held no positions in option contracts on equity market indices. The fair value of the majority of the remaining positions in other derivative instruments is based on significant observable inputs including equity security and interest rate indices. Accordingly, these are classified within Level 2. Other derivative instruments based on unobservable inputs are classified within Level 3. Other derivative instruments are recorded in either Other assets or Accounts payable, accrued expenses, and other liabilities in the Consolidated balance sheets. Separate account assets Separate account assets represent segregated funds where investment risks are borne by the customers, except to the extent of certain guarantees made by Chubb. Separate account assets comprise mutual funds classified within Level 1 in the valuation hierarchy on the same basis as other equity securities traded in active markets. Separate account assets also include fixed maturities classified within Level 2 because the most significant inputs used in the pricing techniques are observable. Excluded from the valuation hierarchy are the corresponding liabilities as they are reported at contract value and not fair value in the Consolidated balance sheets. Separate account assets are recorded in Other assets in the Consolidated balance sheets. Guaranteed living benefits The GLB arises from life reinsurance programs covering living benefit guarantees whereby we assume the risk of guaranteed minimum income benefits (GMIB) and guaranteed minimum accumulation benefits (GMAB) associated with variable annuity contracts. GLB’s are recorded in Accounts payable, accrued expenses, and other liabilities and Future policy benefits in the Consolidated balance sheets. For GLB reinsurance, Chubb estimates fair value using an internal valuation model which includes current market information and estimates of policyholder behavior. All of the treaties contain claim limits, which are factored into the valuation model. The fair value depends on a number of factors, including interest rates, equity markets, credit risk, current account value, market volatility, expected annuitization rates and other policyholder behavior, and changes in policyholder mortality. The most significant policyholder behavior assumptions include lapse rates and the GMIB annuitization rates. Assumptions regarding lapse rates and GMIB annuitization rates differ by treaty, but the underlying methodologies to determine rates applied to each treaty are comparable. A lapse rate is the percentage of in-force policies surrendered in a given calendar year. All else equal, as lapse rates increase, ultimate claim payments will decrease. In general, the base lapse function assumes low lapse rates (ranging from about 3 percent to 9 percent per annum) during the surrender charge period of the GMIB contract, followed by a “spike” lapse rate (ranging from about 6 percent to 33 percent per annum) in the year immediately following the surrender charge period, and then reverting to an ultimate lapse rate (generally around 10 percent per annum), typically over a 2 -year period. This base rate is adjusted downward for policies with more valuable guarantees (policies with guaranteed values far in excess of their account values) by multiplying the base lapse rate by a factor ranging from 15 percent to 75 percent . Partial withdrawals and the impact of older policyholders with tax-qualified contracts (due to required minimum distributions) are also reflected in our modeling. The GMIB annuitization rate is the percentage of policies for which the policyholder will elect to annuitize using the guaranteed benefit provided under the GMIB. All else equal, as GMIB annuitization rates increase, ultimate claim payments will increase, subject to treaty claim limits. All GMIB reinsurance treaties include claim limits to protect Chubb in the event that actual annuitization behavior is significantly higher than expected. In general, Chubb assumes that GMIB annuitization rates will be higher for policies with more valuable guarantees (policies with guaranteed values far in excess of their account values). In addition, we also assume that GMIB annuitization rates are higher in the first year immediately following the waiting period (the first year the policies are eligible to annuitize using the GMIB) in comparison to all subsequent years. We do not yet have fully credible annuitization experience for all clients. The level of annuitization assumptions at December 31, 2017 are as follows: % of total GMIB guaranteed value Year of GMIB eligibility Maximum annuitization rate(s) (per year) Maximum annuitization rates based on 67% First year 2% - 52% Actual Experience Subsequent years 1% - 100% 3% First year N/A N/A (1) Subsequent years 12%, 100% Weighted average (2) 30% First year 25%, 56% Weighted average (2) Subsequent years 12%, 36% (1) Because all policies in this bracket are past the first year of eligibility, first year annuitization assumptions are no longer modeled. (2) Weighted average of two different annuitization rates. The effect of changes in key market factors on assumed lapse and annuitization rates reflect emerging trends using data available from cedants. For treaties with limited experience, rates are established in line with data received from other ceding companies adjusted, as appropriate, with industry estimates. The model and related assumptions are regularly re-evaluated by management and enhanced, as appropriate, based upon additional experience obtained related to policyholder behavior and availability of updated information such as market conditions, market participant assumptions, and demographics of in-force annuities. Because of the significant use of unobservable inputs including policyholder behavior, GLB reinsurance is classified within Level 3. In the fourth quarter of 2017, we completed a review of policyholder behavior related to annuitizations, partial withdrawals, lapses, and mortality for our variable annuity reinsurance business. • As annuitization experience continued to emerge, we refined our annuitization assumptions including age-based behavior, which generally lowered the annuitization rate. The change in annuitization assumptions decreased the fair value of GLB liabilities and generated a realized gain of approximately $117 million . • Reinsured policies allow for policyholders to make periodic withdrawals from their account values without lapsing the policy. The partial withdrawal results in a reduction to the associated guaranteed value that is either equal or proportional to the amount of the reduction in account value. Based on continued emerging experience, we refined our assumptions around the types of partial withdrawals according to their impact on guaranteed value. This resulted in an increase to the fair value of GLB liabilities generating a realized loss of approximately $43 million . • As lapse experience continued to emerge, we further refined our assumptions which resulted in a net increase to the fair value of GLB liabilities generating a realized loss of approximately $9 million . • We studied mortality experience for our variable annuity business for the first time this year and subsequently refined our mortality assumptions. The updated mortality rates increased the fair value of GLB liabilities generating a realized loss of approximately $25 million . In addition to the updates described above, we updated aspects of our valuation model relating to interest rates during the year ended December 31, 2017. This resulted in a decrease to the fair value of GLB liabilities generating a realized gain of approximately $94 million . During the year ended December 31, 2017 , we also made minor technical refinements to the internal valuation model which resulted in no material impact on the financial statements. Financial instruments measured at fair value on a recurring basis, by valuation hierarchy December 31, 2017 Level 1 Level 2 Level 3 Total (in millions of U.S. dollars) Assets: Fixed maturities available for sale U.S. Treasury and agency $ 3,129 $ 569 $ — $ 3,698 Foreign — 20,937 93 21,030 Corporate securities — 22,959 1,037 23,996 Mortgage-backed securities — 15,212 78 15,290 States, municipalities, and political subdivisions — 14,925 — 14,925 3,129 74,602 1,208 78,939 Equity securities 893 — 44 937 Short-term investments 2,309 1,252 — 3,561 Other investments (1) 466 305 263 1,034 Securities lending collateral — 1,737 — 1,737 Investment derivative instruments 18 — — 18 Other derivative instruments 1 — — 1 Separate account assets 2,635 99 — 2,734 Total assets measured at fair value (1) $ 9,451 $ 77,995 $ 1,515 $ 88,961 Liabilities: Investment derivative instruments $ 30 $ — $ — $ 30 Other derivative instruments 21 — 2 23 GLB (2) — — 204 204 Total liabilities measured at fair value $ 51 $ — $ 206 $ 257 (1) Excluded from the table above are partially-owned investments, investment funds, and limited partnerships of $3,623 million and other investments of $15 million at December 31, 2017 measured using NAV as a practical expedient. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information. December 31, 2016 Level 1 Level 2 Level 3 Total (in millions of U.S. dollars) Assets: Fixed maturities available for sale U.S. Treasury and agency $ 2,175 $ 695 $ — $ 2,870 Foreign — 21,366 74 21,440 Corporate securities — 23,468 681 24,149 Mortgage-backed securities — 13,962 45 14,007 States, municipalities, and political subdivisions — 17,649 — 17,649 2,175 77,140 800 80,115 Equity securities 773 — 41 814 Short-term investments 1,757 1,220 25 3,002 Other investments (1) 384 259 225 868 Securities lending collateral — 1,092 — 1,092 Investment derivative instruments 31 — — 31 Other derivative instruments 3 — — 3 Separate account assets 1,784 95 — 1,879 Total assets measured at fair value (1) $ 6,907 $ 79,806 $ 1,091 $ 87,804 Liabilities: Investment derivative instruments $ 54 $ — $ — $ 54 Other derivative instruments — — 13 13 GLB (2) — — 559 559 Total liabilities measured at fair value $ 54 $ — $ 572 $ 626 (1) Excluded from the table above are partially-owned investments, investment funds, and limited partnerships of $3,626 million and other investments of $25 million at December 31, 2016 measured using NAV as a practical expedient. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information. There were no transfers of financial instruments between Level 1 and Level 2 for the years ended December 31, 2017, 2016, and 2015. Fair value of alternative investments Alternative investments include investment funds, limited partnerships, and partially-owned investment companies measured at fair value using NAV as a practical expedient. The following table presents, by investment category, the expected liquidation period, fair value, and maximum future funding commitments of alternative investments: December 31 December 31 2017 2016 (in millions of U.S. dollars) Expected Liquidation Period of Underlying Assets Fair Value Maximum Future Funding Commitments Fair Value Maximum Future Funding Commitments Financial 5 to 9 Years $ 540 $ 330 $ 548 $ 428 Real Assets 3 to 7 Years 651 114 536 230 Distressed 3 to 7 Years 289 141 485 179 Private Credit 3 to 7 Years 187 327 236 259 Traditional 3 to 15 Years 1,656 3,149 1,550 930 Vintage 1 to 2 Years 30 — 21 14 Investment funds Not Applicable 270 — 251 — $ 3,623 $ 4,061 $ 3,627 $ 2,040 Included in all categories in the above table, except for Investment funds, are investments for which Chubb will never have the contractual option to redeem but receives distributions based on the liquidation of the underlying assets. Further, for all categories except for Investment funds, Chubb does not have the ability to sell or transfer the investments without the consent from the general partner of individual funds. Investment Category Consists of investments in private equity funds: Financial targeting financial services companies such as financial institutions and insurance services worldwide Real Assets targeting investments related to hard physical assets such as real estate, infrastructure, and natural resources Distressed targeting distressed corporate debt/credit and equity opportunities in the U.S. Private Credit targeting privately originated corporate debt investments including senior secured loans and subordinated bonds Traditional employing traditional private equity investment strategies such as buyout and growth equity globally Vintage made before 2002 or where the funds’ commitment periods had already expired Investment funds Chubb’s investment funds employ various investment strategies such as long/short equity and arbitrage/distressed. Included in this category are investments for which Chubb has the option to redeem at agreed upon value as described in each investment fund’s subscription agreement. Depending on the terms of the various subscription agreements, investment fund investments may be redeemed monthly, quarterly, semi-annually, or annually. If Chubb wishes to redeem an investment fund investment, it must first determine if the investment fund is still in a lock-up period (a time when Chubb cannot redeem its investment so that the investment fund manager has time to build the portfolio). If the investment fund is no longer in its lock-up period, Chubb must then notify the investment fund manager of its intention to redeem by the notification date prescribed by the subscription agreement. Subsequent to notification, the investment fund can redeem Chubb’s investment within several months of the notification. Notice periods for redemption of the investment funds range between 5 and 120 days. Chubb can redeem its investment funds without consent from the investment fund managers. Level 3 financial instruments The fair values of assets and liabilities measured at fair value using significant unobservable inputs (Level 3) consist of various inputs and assumptions that management makes when determining fair value. Management analyzes changes in fair value measurements classified within Level 3 by comparing pricing and returns of our investments to benchmarks, including month-over-month movements, investment credit spreads, interest rate movements, and credit quality of securities. The following table presents the significant unobservable inputs used in the Level 3 liability valuations. Excluded from the table below are inputs used to determine the fair value of Level 3 assets which are based on single broker quotes and contain no quantitative unobservable inputs developed by management. (in millions of U.S. dollars, except for percentages) Fair Value at December 31, 2017 Valuation Technique Significant Unobservable Inputs Ranges GLB (1) $ 204 Actuarial model Lapse rate 3% – 33% Annuitization rate 0% – 100% (1) Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits. The following tables present a reconciliation of the beginning and ending balances of financial instruments measured at fair value using significant unobservable inputs (Level 3): Assets Liabilities Available-for-Sale Debt Securities Equity securities Short-term investments Other investments Other derivative instruments GLB (2) Year Ended December 31, 2017 Foreign Corporate securities (1) MBS (in millions of U.S. dollars) Balance, beginning of year $ 74 $ 681 $ 45 $ 41 $ 25 $ 225 $ 13 $ 559 Transfers into Level 3 — 231 50 — — — — 9 Transfers out of Level 3 (3 ) (93 ) — — — — (9 ) — Change in Net Unrealized Gains (Losses) included in OCI 3 (12 ) — (1 ) — 6 — — Net Realized Gains/Losses — — — 2 — — (2 ) (364 ) Purchases 84 521 8 24 16 56 — — Sales (59 ) (111 ) (1 ) (22 ) — — — — Settlements (6 ) (180 ) (24 ) — (41 ) (24 ) — — Balance, end of year $ 93 $ 1,037 $ 78 $ 44 $ — $ 263 $ 2 $ 204 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (1 ) $ (2 ) $ — $ (1 ) $ — $ — $ (2 ) $ (364 ) (1) Transfers into and Purchases in Level 3 primarily consist of privately-placed fixed income securities. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information. Liabilities Available-for-Sale Debt Securities Equity securities Short-term investments Other Other derivative instruments GLB (1) Year Ended December 31, 2016 Foreign Corporate securities MBS (in millions of U.S. dollars) Balance, beginning of year $ 57 $ 174 $ 53 $ 16 $ — $ 212 — $ 6 $ 609 Transfers into Level 3 9 53 — — — — — — — Transfers out of Level 3 (24 ) (10 ) — — (50 ) — — — Change in Net Unrealized Gains (Losses) included in OCI 1 15 (1 ) 2 — (2 ) — — Net Realized Gains/Losses (6 ) (13 ) — 1 — 1 5 (50 ) Purchases (2) 70 566 1 27 75 33 2 — Sales (17 ) (59 ) (8 ) (5 ) — — — — Settlements (16 ) (45 ) — — — (19 ) — — Balance, end of year $ 74 $ 681 $ 45 $ 41 $ 25 $ 225 $ 13 $ 559 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (5 ) $ (11 ) $ — $ — $ — $ 1 $ 5 $ (50 ) (1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015 , which includes a fair value derivative adjustment of $559 million and $609 million , respectively. (2) Includes acquired invested assets as a result of the Chubb Corp acquisition. Assets Liabilities Available-for-Sale Debt Securities Other derivative instruments GLB (1) Year Ended December 31, 2015 Foreign Corporate securities MBS Equity securities Other investments (in millions of U.S. dollars) Balance, beginning of year $ 22 $ 187 $ 15 $ 2 $ 204 $ 4 $ 406 Transfers into Level 3 34 16 — — — — — Transfers out of Level 3 — — — — — — — Change in Net Unrealized Gains (Losses) included in OCI (2 ) (1 ) — 3 (6 ) — — Net Realized Gains/Losses (1 ) (4 ) — (2 ) — 2 203 Purchases 15 52 41 13 33 — — Sales (3 ) (28 ) (2 ) — — — — Settlements (8 ) (48 ) (1 ) (19 ) — Balance, end of year $ 57 $ 174 $ 53 $ 16 $ 212 $ 6 $ 609 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (1 ) $ (2 ) $ — $ (2 ) $ — $ 2 $ 203 (1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $ 406 million , respectively. b) Financial instruments disclosed, but not measured, at fair value Chubb uses various financial instruments in the normal course of its business. Our insurance contracts are excluded from fair value of financial instruments accounting guidance, and therefore, are not included in the amounts discussed below. The carrying values of cash, other assets, other liabilities, and other financial instruments not included below approximated their fair values. Investments in partially-owned insurance companies Fair values for investments in partially-owned insurance companies are based on Chubb’s share of the net assets based on the financial statements provided by those companies and are excluded from the valuation hierarchy tables below. Short- and long-term debt, repurchase agreements, and trust preferred securities Where practical, fair values for short-term debt, long-term debt, repurchase agreements, and trust preferred securities are estimated using discounted cash flow calculations based principally on observable inputs including incremental borrowing rates, which reflect Chubb’s credit rating, for similar types of borrowings with maturities consistent with those remaining for the debt being valued. The following tables present fair value, by valuation hierarchy, and carrying value of the financial instruments not measured at fair value: December 31, 2017 Fair Value Carrying Value (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total Assets: Fixed maturities held to maturity U.S. Treasury and agency $ 857 $ 58 $ — $ 915 $ 908 Foreign — 1,757 — 1,757 1,738 Corporate securities — 3,184 35 3,219 3,159 Mortgage-backed securities — 2,742 — 2,742 2,724 States, municipalities, and political subdivisions — 5,841 — 5,841 5,806 Total assets $ 857 $ 13,582 $ 35 $ 14,474 $ 14,335 Liabilities: Repurchase agreements $ — $ 1,408 $ — $ 1,408 $ 1,408 Short-term debt — 1,013 — 1,013 1,013 Long-term debt — 12,332 — 12,332 11,556 Trust preferred securities — 468 — 468 308 Total liabilities $ — $ 15,221 $ — $ 15,221 $ 14,285 December 31, 2016 Fair Value Carrying Value (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total Assets: Fixed maturities held to maturity U.S. Treasury and agency $ 555 $ 106 $ — $ 661 $ 655 Foreign — 667 — 667 640 Corporate securities — 2,782 13 2,795 2,771 Mortgage-backed securities — 1,428 — 1,428 1,393 States, municipalities, and political subdivisions — 5,119 — 5,119 5,185 Total assets $ 555 $ 10,102 $ 13 $ 10,670 $ 10,644 Liabilities: Repurchase agreements $ — $ 1,403 $ — $ 1,403 $ 1,403 Short-term debt — 503 — 503 500 Long-term debt — 12,998 — 12,998 12,610 Trust preferred securities — 456 — 456 308 Total liabilities $ — $ 15,360 $ — $ 15,360 $ 14,821

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2017
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance a) Consolidated reinsurance Chubb purchases reinsurance to manage various exposures including catastrophe risks. Although reinsurance agreements contractually obligate Chubb's reinsurers to reimburse it for the agreed-upon portion of its gross paid losses, they do not discharge Chubb's primary liability. The amounts for net premiums written and net premiums earned in the Consolidated statements of operations are net of reinsurance. The following table presents direct, assumed, and ceded premiums: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Premiums written Direct $ 33,137 $ 31,543 $ 19,879 Assumed 3,239 3,440 3,932 Ceded (7,132 ) (6,838 ) (6,098 ) Net $ 29,244 $ 28,145 $ 17,713 Premiums earned Direct $ 32,782 $ 31,811 $ 19,355 Assumed 3,332 3,744 3,676 Ceded (7,080 ) (6,806 ) (5,818 ) Net $ 29,034 $ 28,749 $ 17,213 Ceded losses and loss expenses incurred were $5.5 billion , $4.1 billion , and $3.1 billion for the years ended December 31, 2017 , 2016 , and 2015 , respectively. b) Reinsurance recoverable on ceded reinsurance December 31 December 31 (in millions of U.S. dollars) 2017 2016 Reinsurance recoverable on unpaid losses and loss expenses (1) $ 14,014 $ 12,708 Reinsurance recoverable on paid losses and loss expenses (1) 1,020 869 Reinsurance recoverable on losses and loss expenses (1) $ 15,034 $ 13,577 Reinsurance recoverable on policy benefits (1) $ 184 $ 182 (1) Net of a provision for uncollectible reinsurance. The increase in reinsurance recoverable on loss and loss expenses was principally related to the California wildfires and other catastrophe losses in 2017. We evaluate the financial condition of our reinsurers and potential reinsurers on a regular basis and also monitor concentrations of credit risk with reinsurers. The provision for uncollectible reinsurance is required principally due to the potential failure of reinsurers to indemnify Chubb, primarily because of disputes under reinsurance contracts and insolvencies. We have established provisions for amounts estimated to be uncollectible. At December 31, 2017 and 2016 , the provision for uncollectible reinsurance was $321 million and $ 300 million, respectively. The following tables present a listing, at December 31, 2017 , of the categories of Chubb's reinsurers: December 31, 2017 Gross Reinsurance Recoverable on Loss and Loss Expenses Provision for Uncollectible Reinsurance % of Gross Reinsurance Recoverable (in millions of U.S. dollars, except for percentages) Categories Largest reinsurers $ 5,190 $ 59 1.1 % Other reinsurers rated A- or better 5,898 58 1.0 % Other reinsurers with ratings lower than A- or not rated 681 75 11.0 % Pools 577 15 2.6 % Structured settlements 550 16 2.9 % Captives 2,199 18 0.8 % Other 260 80 30.8 % Total $ 15,355 $ 321 2.1 % Largest Reinsurers Berkshire Hathaway Insurance Group Lloyd's of London Swiss Re Group HDI Group (Hannover Re) Munich Re Group Categories of Chubb's reinsurers Comprises: Largest reinsurers • All groups of reinsurers or captives where the gross recoverable exceeds one percent of Chubb's total shareholders' equity. Other reinsurers rated A- or better • All reinsurers rated A- or better that were not included in the largest reinsurer category. Other reinsurers rated lower than A- or not rated • All reinsurers rated lower than A- or not rated that were not included in the largest reinsurer category. Pools • Related to Chubb's voluntary pool participation and Chubb's mandatory pool participation required by law in certain states. Structured settlements • Annuities purchased from life insurance companies to settle claims. Since we retain ultimate liability in the event that the life company fails to pay, we reflect the amounts as both a liability and a recoverable/receivable for GAAP purposes. Captives • Companies established and owned by our insurance clients to assume a significant portion of their direct insurance risk from Chubb; structured to allow clients to self-insure a portion of their reinsurance risk. It generally is our policy to obtain collateral equal to expected losses. Where appropriate, exceptions are granted but only with review and approval at a senior officer level. Excludes captives included in the largest reinsurer category. Other • Amounts recoverable that are in dispute or are from companies that are in supervision, rehabilitation, or liquidation. The provision for uncollectible reinsurance is principally based on an analysis of the credit quality of the reinsurer and collateral balances. We establish the provision for uncollectible reinsurance for the Other category based on a case-by-case analysis of individual situations including the merits of the underlying matter, credit and collateral analysis, and consideration of our collection experience in similar situations. c ) Assumed life reinsurance programs involving minimum benefit guarantees under variable annuity contracts The following table presents income and expenses relating to GMDB and GLB reinsurance. GLBs include GMIBs as well as some GMABs originating in Japan. Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 GMDB Net premiums earned $ 49 $ 55 $ 61 Policy benefits and other reserve adjustments $ 40 $ 45 $ 34 GLB Net premiums earned $ 110 $ 118 $ 121 Policy benefits and other reserve adjustments 105 52 45 Net realized gains (losses) 363 48 (203 ) Gain (loss) recognized in Net income $ 368 $ 114 $ (127 ) Net cash received and other 65 79 98 Net decrease (increase) in liability $ 303 $ 35 $ (225 ) Net realized gains (losses) in the table above include gains (losses) related to foreign exchange and fair value adjustments on insurance derivatives and exclude gains (losses) on S&P put options and futures used to partially offset the risk in the GLB reinsurance portfolio. Refer to Note 10 for additional information. At December 31, 2017 and 2016 , the reported liability for GMDB reinsurance was $129 million and $120 million, respectively. At December 31, 2017 and 2016 , the reported liability for GLB reinsurance was $550 million and $853 million, respectively, which includes a fair value derivative adjustment of $204 million and $559 million, respectively. Reported liabilities for both GMDB and GLB reinsurance are determined using internal valuation models. Such valuations require considerable judgment and are subject to significant uncertainty. The valuation of these products is subject to fluctuations arising from, among other factors, changes in interest rates, changes in equity markets, changes in credit markets, changes in the allocation of the investments underlying annuitants’ account values, and assumptions regarding future policyholder behavior. These models and the related assumptions are regularly reviewed by management and enhanced, as appropriate, based upon improvements in modeling assumptions and availability of updated information, such as market conditions and demographics of in-force annuities. Variable Annuity Net Amount at Risk The net amount at risk is defined as the present value of future claim payments assuming policy account values and guaranteed values are fixed at the valuation date ( December 31, 2017 and 2016 , respectively) and reinsurance coverage ends at the earlier of the maturity of the underlying variable annuity policy or the reinsurance treaty. In addition, the following assumptions were used: (in millions of U.S. dollars, except for percentages) Net amount at risk Reinsurance covering December 31, 2017 December 31, 2016 2017 Future claims discount rate Other assumptions Total claims at 100% mortality at December 31, 2017 (1) GMDB Risk Only $ 279 $ 341 4.00% - 4.50% No lapses or withdrawals $ 189 Mortality according to 100% of the Annuity 2000 mortality table GLB Risk Only $ 691 $ 800 4.25% - 4.75% No deaths, lapses or withdrawals N/A Annuitization at a frequency most disadvantageous to Chubb (2) Claim calculated using interest rates in line with rates used to calculate reserve Both Risks: (3) GMDB $ 81 $ 88 4.25% - 4.75% No lapses or withdrawals $ 18 Mortality according to 100% of the Annuity 2000 mortality table GLB $ 392 $ 464 4.25% - 4.75% Annuitization at a frequency most disadvantageous to Chubb (2) N/A Claim calculated using interest rates in line with rates used to calculate reserve (1) Takes into account all applicable reinsurance treaty claim limits. (2) Annuitization at a level that maximizes claims taking into account the treaty limits. (3) Covering both the GMDB and GLB risks on the same underlying policyholders. The average attained age of all policyholders for all risk categories above, weighted by the guaranteed value of each reinsured policy, is approximately 70 years.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets Disclosure [Text Block]	6 . Goodwill and Other intangible assets At December 31, 2017 and 2016 , Goodwill was $ 15.5 billion and $ 15.3 billion, respectively, and Other intangible assets were $ 6.5 billion and $ 6.8 billion, respectively. a) Goodwill The following table presents a roll-forward of Goodwill by segment: (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Reinsurance Life Insurance Chubb Consolidated Balance at December 31, 2015 $ 1,203 $ 196 $ 134 $ 2,078 $ 365 $ 820 $ 4,796 Acquisition of Chubb Corp 5,714 2,025 — 2,775 — — 10,514 Foreign exchange revaluation and other 44 14 — (36 ) — — 22 Balance at December 31, 2016 $ 6,961 $ 2,235 $ 134 $ 4,817 $ 365 $ 820 $ 15,332 Foreign exchange revaluation and other 15 5 — 187 — 2 209 Balance at December 31, 2017 $ 6,976 $ 2,240 $ 134 $ 5,004 $ 365 $ 822 $ 15,541 b) Other intangible assets The majority of the Other intangible assets balance at December 31, 2017 relates to the Chubb Corp acquisition and comprised of $ 3.5 billion that are subject to amortization, principally Agency distribution relationships and renewal rights, and $ 3.0 billion that are not subject to amortization, principally trademarks. This compares to $ 3.8 billion and $ 3.0 billion at December 31, 2016, respectively. Amortization of purchased intangibles Amortization expense related to purchased intangibles amounted to $260 million , $ 19 million, and $ 171 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The increase in amortization expense of purchased intangibles primarily reflects higher intangible amortization expense related to agency distribution relationships and renewal rights and lower amortization benefit from the fair value adjustment on Unpaid losses and loss expenses, both related to the Chubb Corp acquisition. The following table presents, as of December 31, 2017 , the expected estimated pre-tax amortization expense (benefit) of purchased intangibles, at current foreign currency exchange rates, for the next five years: Associated with the Chubb Corp Acquisition For the Year Ending December 31 (in millions of U.S. dollars) Agency distribution relationships and renewal rights Internally developed technology Fair value adjustment on Unpaid losses and loss expense (1) Total Other intangible assets Total Amortization of purchased intangibles 2018 $ 325 $ 32 $ (102 ) $ 255 $ 83 $ 338 2019 282 — (63 ) 219 75 294 2020 241 — (36 ) 205 67 272 2021 218 — (20 ) 198 61 259 2022 198 — (14 ) 184 57 241 Total $ 1,264 $ 32 $ (235 ) $ 1,061 $ 343 $ 1,404 (1) In connection with the Chubb Corp acquisition, we recorded an increase to Unpaid losses and loss expenses acquired to adjust the carrying value of Chubb Corp's historical unpaid losses and loss expenses to fair value as of the acquisition date. This fair value adjustment amortizes through Amortization of purchased intangibles on the Consolidated statements of operations over a range of 5 to 17 years. The balance of the fair value adjustment on Unpaid losses and loss expense at December 31, 2017 was $309 million . Refer to Note 1(h) for additional information. c) VOBA The following table presents a roll-forward of VOBA: (in millions of U.S. dollars) 2017 2016 2015 Balance, beginning of year $ 355 $ 395 $ 466 Amortization of VOBA (1) (35 ) (41 ) (42 ) Foreign exchange revaluation 6 1 (29 ) Balance, end of year $ 326 $ 355 $ 395 (1) Recognized in Policy acquisition costs in the Consolidated statements of operations. The following table presents, as of December 31, 2017, the expected estimated pre-tax amortization expense related to VOBA for the next five years: For the Year Ending December 31 VOBA (in millions of U.S. dollars) 2018 $ 32 2019 27 2020 25 2021 22 2022 20 Total $ 126

Unpaid losses and loss expenses

Unpaid losses and loss expenses	12 Months Ended
	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Abstract]
Unpaid Losses and Loss Expenses	Unpaid losses and loss expenses Chubb establishes reserves for the estimated unpaid ultimate liability for losses and loss expenses under the terms of its policies and agreements. Reserves include estimates for both claims that have been reported and for IBNR claims, and include estimates of expenses associated with processing and settling these claims. Reserves are recorded in Unpaid losses and loss expenses in the consolidated balance sheets. While we believe that our reserves for unpaid losses and loss expenses at December 31, 2017 are adequate, new information or trends may lead to future developments in incurred loss and loss expenses significantly greater or less than the reserves provided. Any such revisions could result in future changes in estimates of losses or reinsurance recoverable and would be reflected in our results of operations in the period in which the estimates are changed. The following table presents a reconciliation of Unpaid losses and loss expenses: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Gross unpaid losses and loss expenses, beginning of year $ 60,540 $ 37,303 $ 38,315 Reinsurance recoverable on unpaid losses (1) (12,708 ) (10,741 ) (11,307 ) Net unpaid losses and loss expenses, beginning of year 47,832 26,562 27,008 Acquisition of subsidiaries — 21,402 417 Total 47,832 47,964 27,425 Net losses and loss expenses incurred in respect of losses occurring in: Current year 19,391 17,256 10,030 Prior years (2) (937 ) (1,204 ) (546 ) Total 18,454 16,052 9,484 Net losses and loss expenses paid in respect of losses occurring in: Current year 6,575 5,899 4,053 Prior years 10,873 9,816 5,612 Total 17,448 15,715 9,665 Foreign currency revaluation and other 327 (469 ) (682 ) Net unpaid losses and loss expenses, end of year 49,165 47,832 26,562 Reinsurance recoverable on unpaid losses (1) 14,014 12,708 10,741 Gross unpaid losses and loss expenses, end of year $ 63,179 $ 60,540 $ 37,303 (1) Net of provision for uncollectible reinsurance. (2) Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments, and earned premiums totaling $108 million , $69 million , and nil, for 2017, 2016, and 2015, respectively. The increase in gross and net unpaid losses and loss expenses in 2017 primarily reflects the significant catastrophe events, principally from California wildfires, hurricanes Harvey, Irma, and Maria and the earthquakes in Mexico. The increase in gross and net unpaid losses and loss expenses in 2016 reflects the acquisition of Chubb Corp. The loss development tables under section c) below, present Chubb’s historical incurred and paid claims development by broad product line through December 31, 2017 , net of reinsurance, as well as the cumulative number of reported claims, IBNR balances, and other supplementary information. The following table presents a reconciliation of the loss development tables to the liability for unpaid losses and loss expenses in the consolidated balance sheet: Reconciliation of Reserve Balances to Liability for Unpaid Loss and Loss Expenses (in millions of U.S. dollars) December 31, 2017 Presented in the loss development tables: North America Commercial P&C Insurance — Workers' Compensation $ 8,873 North America Commercial P&C Insurance — Liability 16,631 North America Commercial P&C Insurance — Other Casualty 1,789 North America Commercial P&C Insurance — Non-Casualty 2,398 North America Personal P&C Insurance 2,421 Overseas General Insurance — Casualty 6,026 Overseas General Insurance — Non-Casualty 2,549 Global Reinsurance — Casualty 1,340 Global Reinsurance — Non-Casualty 371 Excluded from the loss development tables: Other 4,302 Net unpaid loss and allocated loss adjustment expense 46,700 Ceded unpaid loss and allocated loss adjustment expense: North America Commercial P&C Insurance — Workers' Compensation $ 1,737 North America Commercial P&C Insurance — Liability 4,133 North America Commercial P&C Insurance — Other Casualty 813 North America Commercial P&C Insurance — Non-Casualty 1,336 North America Personal P&C Insurance 503 Overseas General Insurance — Casualty 2,550 Overseas General Insurance — Non-Casualty 1,269 Global Reinsurance — Casualty 76 Global Reinsurance — Non-Casualty 142 Other 1,628 Ceded unpaid loss and allocated loss adjustment expense 14,187 Unpaid loss and loss expense on other than short-duration contracts (1) 810 Unpaid unallocated loss adjustment expenses 1,482 Unpaid losses and loss expenses $ 63,179 (1) Primarily includes the claims reserve of our international A&H business and Life Insurance segment reserves. Business excluded from the loss development tables “Other” shown in the reconciliation table above comprises businesses excluded from the loss development tables below: • North America Agricultural Insurance segment business, which is short-tailed with the majority of the liabilities expected to be resolved in the ensuing twelve months; • Corporate segment business, which includes run-off liabilities such as asbestos and environmental and other mass tort exposures and which impact accident years older than those shown in the exhibits below; • Life Insurance segment business, which is generally written using long-duration contracts; and • Certain subsets of our business due to data limitations or unsuitability to the development table presentation, including: ◦ We underwrite loss portfolio transfers at various times; by convention, all premium and losses associated with these transactions are recorded to the policy period of the transaction, even though the accident dates of the claims covered may be a decade or more in the past. We also underwrite certain high attachment, high limit, multiple-line and excess of aggregate coverages for large commercial clients. Changes in incurred loss and cash flow patterns are volatile and sufficiently different from those of typical insureds. This category includes the loss portfolio transfer of Fireman’s Fund personal lines run-off liabilities and Alternative Risk Solutions business within the North America Commercial P&C segment; ◦ 2015 and prior paid history on a subset of previously acquired international businesses, within the Overseas General Insurance segment, due to limitations on the data prior to the acquisition; ◦ Reinsurance recoverable bad debt; ◦ Purchase accounting adjustments related to unpaid losses and loss expenses for Chubb Corp. a) Description of Reserving Methodologies Our recorded reserves represent management's best estimate of the provision for unpaid claims as of the balance sheet date. Management's best estimate is developed after collaboration with actuarial, underwriting, claims, legal, and finance departments and culminates with the input of reserve committees. Each business unit reserve committee includes the participation of the relevant parties from actuarial, finance, claims, and unit senior management and has the responsibility for finalizing, recommending and approving the estimate to be used as management's best estimate. Reserves are further reviewed by Chubb's Chief Actuary and senior management. The objective of such a process is to determine a single estimate that we believe represents a better estimate than any other and which is viewed by management to be the best estimate of ultimate loss settlements. This estimate is based on a combination of exposure and experience-based actuarial methods (described below) and other considerations such as claims reviews, reinsurance recovery assumptions and/or input from other knowledgeable parties such as underwriting. Exposure-based methods are most commonly used on relatively immature origin years (i.e., the year in which the losses were incurred — “accident year” or “report year”), while experience-based methods provide a view based on the projection of loss experience that has emerged as of the valuation date. Greater reliance is placed upon experience-based methods as the pool of emerging loss experience grows and where it is deemed sufficiently credible and reliable as the basis for the estimate. In comparing the held reserve for any given origin year to the actuarial projections, judgment is required as to the credibility, uncertainty and inherent limitations of applying actuarial techniques to historical data to project future loss experience. Examples of factors that impact such judgments include, but are not limited to, the following: • nature and complexity of underlying coverage provided and net limits of exposure provided; • segmentation of data to provide sufficient homogeneity and credibility for loss projection methods; • extent of credible internal historical loss data and reliance upon industry information as required; • historical variability of actual loss emergence compared with expected loss emergence; • extent of emerged loss experience relative to the remaining expected period of loss emergence; • rate monitor information for new and renewal business; • facts and circumstances of large claims; • impact of applicable reinsurance recoveries; and • nature and extent of underlying assumptions. We have actuarial staff within each of our business units who analyze loss reserves (including loss expenses) and regularly project estimates of ultimate losses and the corresponding indications of the required IBNR reserve. Our reserving approach is a comprehensive ground-up process using data at a detailed level that reflects the specific types and coverages of the diverse products written by our various operations. The data presented in this disclosure was prepared on a more aggregated basis and with a focus on changes in incurred loss estimates over time as well as associated cash flows. We note that data prepared on this basis may not demonstrate the full spectrum of characteristics that are evident in the more detailed level studied internally. We perform an actuarial reserve review for each product line at least once a year. For most product lines, one or more standard actuarial reserving methods may be used to determine estimates of ultimate losses and loss expenses, and from these estimates, a single actuarial central estimate is selected. The actuarial central estimate is an input to the reserve committee process described above. For the few product lines that do not lend themselves to standard actuarial reserving methods, appropriate techniques are applied to produce the actuarial central estimates. For example, run-off asbestos and environmental liability estimates are better suited to the application of account-specific exposure-based analyses to best evaluate their associated aggregate reserve levels. b) Standard actuarial reserving methods Standard actuarial reserving methods include, but are not limited to, expected loss ratio, paid and reported loss development, and Bornhuetter-Ferguson methods. A general description of these methods is provided below. In addition to these standard methods, depending upon the product line characteristics and available data, we may use other recognized actuarial methods and approaches. Implicit in the standard actuarial methods that we generally utilize is the need for two fundamental assumptions: first, the pattern by which losses are expected to emerge over time for each origin year, and second the expected loss ratio for each origin year. The expected loss ratio for any particular origin year is selected after consideration of a number of factors, including historical loss ratios adjusted for rate changes, premium and loss trends, industry benchmarks, the results of policy level loss modeling at the time of underwriting, and/or other more subjective considerations for the product line (e.g., terms and conditions) and external environment as noted above. The expected loss ratio for a given origin year is initially established at the start of the origin year as part of the planning process. This analysis is performed in conjunction with underwriters and management. The expected loss ratio method arrives at an ultimate loss estimate by multiplying the expected ultimate loss ratio by the corresponding premium base. This method is most commonly used as the basis for the actuarial central estimate for immature origin periods on product lines where the actual paid or reported loss experience is not yet deemed sufficiently credible to serve as the principal basis for the selection of ultimate losses. The expected loss ratio for a given origin year may be modified over time if the underlying assumptions differ from the original assumptions (e.g., the assessment of prior year loss ratios, loss trend, rate changes, actual claims, or other information). Our selected paid and reported development patterns provide a benchmark against which the actual emerging loss experience can be monitored. Where possible, development patterns are selected based on historical loss emergence by origin year. For product lines where the historical data is viewed to have low statistical credibility, the selected development patterns also reflect relevant industry benchmarks and/or experience from similar product lines written elsewhere within Chubb. This most commonly occurs for relatively new product lines that have limited historical data or for high severity/low frequency portfolios where our historical experience exhibits considerable volatility and/or lacks credibility. The paid and reported loss development methods convert the selected loss emergence pattern to a set of multiplicative factors which are then applied to actual paid or reported losses to arrive at an estimate of ultimate losses for each period. Due to their multiplicative nature, the paid and reported loss development methods will leverage differences between actual and expected loss emergence. These methods tend to be utilized for more mature origin periods and for those portfolios where the loss emergence has been relatively consistent over time. The Bornhuetter-Ferguson method is a combination of the expected loss ratio method and the loss development method, where the loss development method is given more weight as the origin year matures. This approach allows a logical transition between the expected loss ratio method which is generally utilized at earlier maturities and the loss development methods which are typically utilized at later maturities. We usually apply this method using reported loss data although paid data may also be used. Short-tail business Short-tail business generally describes product lines for which losses are typically known and paid shortly after the loss actually occurs. This would include, for example, most property, personal accident, and automobile physical damage policies that we write. Due to the short reporting and development pattern for these product lines, the uncertainty associated with our estimate of ultimate losses for any particular accident period diminishes relatively quickly as actual loss experience emerges. We typically assign credibility to methods that incorporate actual loss emergence, such as the paid and reported loss development and Bornhuetter-Ferguson methods, sooner than would be the case for long-tail lines at a similar stage of development for a given origin year. The reserving process for short-tail losses arising from catastrophic events typically involves an assessment by the claims department, in conjunction with underwriters and actuaries, of our exposure and estimated losses immediately following an event and then subsequent revisions of the estimated losses as our insureds provide updated actual loss information. Long-tail business Long-tail business describes lines of business for which specific losses may not be known/reported for some period and for which claims can take significant time to settle/close. This includes most casualty lines such as general liability, D&O, and workers' compensation. There are various factors contributing to the uncertainty and volatility of long-tail business. Among these are: • The nature and complexity of underlying coverage provided and net limits of exposure provided; • Our historical loss data and experience is sometimes too immature and lacking in credibility to rely upon for reserving purposes. Where this is the case, in our reserve analysis we may utilize industry loss ratios or industry benchmark development patterns that we believe reflect the nature and coverage of the underwritten business and its future development, where available. For such product lines, actual loss experience may differ from industry loss statistics as well as loss experience for previous underwriting years; • The difficulty in estimating loss trends, claims inflation (e.g., medical and judicial) and underlying economic conditions; • The need for professional judgment to estimate loss development patterns beyond that represented by historical data using supplemental internal or industry data, extrapolation, or a blend of both; • The need to address shifts in mix over time when applying historical paid and reported loss development patterns from older origin years to more recent origin years. For example, changes over time in the processes and procedures for establishing case reserves can distort reported loss development patterns or changes in ceded reinsurance structures by origin year can alter the development of paid and reported losses; • Loss reserve analyses typically require loss or other data be grouped by common characteristics in some manner. If data from two combined lines of business exhibit different characteristics, such as loss payment patterns, the credibility of the reserve estimate could be affected. Additionally, since casualty lines of business can have significant intricacies in the terms and conditions afforded to the insured, there is an inherent risk as to the homogeneity of the underlying data used in performing reserve analyses; and • The applicability of the price change data used to estimate ultimate loss ratios for most recent origin years. As described above, various factors are considered when determining appropriate data, assumptions, and methods used to establish the loss reserve estimates for long-tail product lines. These factors may also vary by origin year for given product lines. The derivation of loss development patterns from data and the selection of a tail factor to project ultimate losses from actual loss emergence require considerable judgment, particularly with respect to the extent to which historical loss experience is relied upon to support changes in key reserving assumptions. c) Loss Development Tables The tables were designed to present business with similar risk characteristics which exhibit like development patterns and generally similar trends, in order to provide insight into the nature, amount, timing and uncertainty of cash flows related to our claims liabilities. Each table follows a similar format and reflects the following: • The incurred loss triangle includes both reported case reserves and IBNR liabilities. • Both the incurred and paid loss triangles include allocated loss adjustment expense (i.e., defense and investigative costs particular to individual claims) but exclude unallocated loss adjustment expense (i.e., the costs associated with internal claims staff and third-party administrators). • The amounts in both triangles for the years ended December 31, 2008 , to December 31, 2016 and average historical claim duration as of December 31, 2017 , are presented as supplementary information. • All data presented in the triangles is net of reinsurance recoverables. • The IBNR reserves shown to the right of each incurred loss development exhibit reflect the net IBNR recorded as of December 31, 2017 . • The tables are presented retrospectively with respect to acquisitions where these are material and doing so is practicable. Most notably, the Chubb Corp acquisition is presented retrospectively. The unaudited consolidated data is presented solely for informational purposes and is not necessarily indicative of the consolidated data that might have been observed had the transactions been completed prior to the date indicated. Historical dollar amounts are presented in this footnote on a constant-currency basis, which is achieved by assuming constant foreign exchange rates for all periods in the loss triangles, translating prior period amounts using the same local currency exchange rates as the current year end. The impact of this conversion is to show the change between periods exclusive of the effect of fluctuations in exchange rates, which would otherwise distort the change in incurred loss and cash flow patterns shown. The change in incurred loss shown will differ from other U.S. GAAP disclosures of incurred prior period reserve development amounts, which include the effect of fluctuations in exchanges rates. We provided guidance above on key assumptions that should be considered when reviewing this disclosure and information relating to how loss reserve estimates are developed. We believe the information provided in the “Loss Development Tables” section of the disclosure is of limited use for independent analysis or application of standard actuarial estimations. Cumulative Number of Reported Claims Reported claim counts, on a cumulative basis, are provided to the far right of each paid loss development table. We generally consider a reported claim to be one claim per coverage per claimant. We exclude claims closed without payment. Use of the presented claim counts in analysis of company experience has significant limitations, including: • High deductible workers' compensation claim counts include claims below the applicable policy deductible. • Professional liability and certain other lines have a high proportion of claims reported which will be closed without any payment; shifts in total reported counts may not meaningfully impact reported and ultimate loss experience. • Claims for certain events and/or product lines, such as portions of assumed reinsurance and A&H business, are not reported on an individual basis, but rather in bulk and thus not available for inclusion in this disclosure. For certain A&H business, where bulk reporting affected only the oldest few accident years, presented claim counts for these years were estimated. • Each of the segments below typically has a mixture of primary and excess experience which has shifted over time. Reported claim counts include open claims which have case reserves and exclude claims that have been incurred but not reported. As such the reported claims are consistent with reported losses, which can be calculated by subtracting incurred but not reported losses from incurred losses. Reported claim counts are inconsistent with losses in the incurred loss triangle, which include incurred but not reported losses, and are also inconsistent with losses in the paid loss triangle, which exclude case reserves. North America Commercial P&C Insurance — Workers' Compensation — Long-tail During the year ended December 31, 2017, we refined our loss development groupings based on the similarity of loss payout characteristics. The new groupings were applied consistently to all years presented. This product line has a substantial geographic spread and a broad mix across industries. Types of coverage include risk management business predominantly with high deductible policies, loss sensitive business (i.e., retrospectively-rated policies), business fronted for captives, as well as excess and primary guaranteed cost coverages. The triangle below shows all loss and allocated expense development for the workers' compensation product line. In our prior period development disclosure, we exclude any loss development where there is a directly related premium adjustment. For workers' compensation, changes in the exposure base due to payroll audits will drive changes in ultimate losses. In addition, we record involuntary pool assumptions (premiums and losses) on a lagged basis. Both of these items will influence the development in the triangle, particularly the first prior accident year, and are included in the reconciliation table presented on page F-65. North America Commercial P&C Insurance — Workers' Compensation — Long-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 1,084 $ 1,042 $ 1,043 $ 1,037 $ 1,036 $ 1,010 $ 1,009 $ 1,004 $ 986 $ 993 $ 214 2009 1,029 998 997 990 980 977 966 972 965 233 2010 1,049 1,037 1,050 1,065 1,064 1,052 1,028 1,020 262 2011 1,037 1,030 1,046 1,049 1,053 1,022 1,012 294 2012 1,050 1,011 1,030 1,040 1,011 989 326 2013 1,109 1,108 1,122 1,127 1,085 368 2014 1,207 1,201 1,217 1,214 553 2015 1,282 1,259 1,271 631 2016 1,367 1,367 806 2017 1,411 1,080 Total $ 11,327 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 124 $ 275 $ 371 $ 439 $ 503 $ 546 $ 578 $ 607 $ 632 $ 651 333 2009 107 258 348 416 475 519 550 597 617 282 2010 123 300 411 493 551 592 617 641 304 2011 119 294 411 484 533 567 595 287 2012 111 271 365 436 486 532 288 2013 107 286 422 506 553 300 2014 113 295 410 484 337 2015 116 301 418 339 2016 122 326 310 2017 120 307 Total $ 4,937 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 2,483 All Accident years $ 8,873 Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (35 ) All Accident years $ (108 ) North America Commercial P&C Insurance — Workers' Compensation — Long-tail (continued) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 10 % 16 % 10 % 7 % 5 % 4 % 3 % 3 % 2 % 2 % North America Commercial P&C Insurance — Liability — Long-tail During the year ended December 31, 2017, we refined our loss development groupings based on the similarity of loss payout characteristics. The new groupings were applied consistently to all years presented. This line consists of primary and excess liability exposures, including medical liability, and professional lines, including directors and officers (D&O) liability, errors and omissions (E&O) liability, employment practices liability (EPL), fidelity bonds, and fiduciary liability. The primary and excess liability business represents the largest part of these exposures. The former includes both monoline and commercial package liability. The latter includes a substantial proportion of commercial umbrella, excess and high excess business, where loss activity can produce significant volatility in the loss triangles at later ages within an accident year (and sometimes across years) due to the size of the limits afforded and the complex nature of the underlying losses. This line includes management and professional liability products provided to a wide variety of clients, from national accounts to small firms along with private and not-for-profit organizations, distributed through brokers, agents, wholesalers and MGAs. Many of these coverages, particularly D&O and E&O, are typically written on a claims-made form. While most of the coverages are underwritten on a primary basis, there are significant amounts of excess exposure with large policy limits. Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 3,792 $ 3,823 $ 3,812 $ 3,791 $ 3,652 $ 3,412 $ 3,352 $ 3,278 $ 3,174 $ 3,157 $ 245 2009 3,798 3,783 3,770 3,743 3,642 3,392 3,316 3,244 3,103 250 2010 3,578 3,583 3,601 3,559 3,419 3,250 3,128 3,107 423 2011 3,500 3,585 3,629 3,664 3,593 3,498 3,383 589 2012 3,552 3,628 3,613 3,564 3,524 3,426 856 2013 3,546 3,541 3,542 3,532 3,430 1,090 2014 3,535 3,585 3,674 3,717 1,526 2015 3,559 3,708 3,818 1,941 2016 3,533 3,594 2,381 2017 3,386 2,994 Total $ 34,121 North America Commercial P&C Insurance — Liability — Long-tail (continued) Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 147 $ 580 $ 1,110 $ 1,643 $ 1,992 $ 2,323 $ 2,558 $ 2,657 $ 2,753 $ 2,836 21 2009 135 587 1,160 1,672 2,019 2,357 2,545 2,678 2,730 21 2010 126 611 1,108 1,559 1,893 2,259 2,426 2,527 20 2011 160 652 1,209 1,805 2,214 2,476 2,659 20 2012 166 656 1,172 1,680 2,092 2,326 20 2013 130 548 1,192 1,597 2,007 20 2014 164 679 1,250 1,804 21 2015 138 605 1,206 23 2016 171 663 24 2017 161 19 Total $ 18,919 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 1,429 All Accident years $ 16,631 Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (154 ) All Accident years $ (434 ) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 4 % 14 % 17 % 15 % 12 % 9 % 6 % 4 % 2 % 3 % North America Commercial P&C Insurance — Other Casualty — Long-tail During the year ended December 31, 2017, we refined our loss development groupings based on the similarity of loss payout characteristics. The new groupings were applied consistently to all years presented. This product line consists of the remaining commercial casualty coverages such as automobile liability and aviation. There is also a small portion of commercial multi-peril (CMP) business in accident years 2014 and prior . The paid and reported data are impacted by some catastrophe loss activity primarily on the CMP exposures just noted. North America Commercial P&C Insurance — Other-Casualty — Long-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 693 $ 733 $ 700 $ 661 $ 644 $ 647 $ 643 $ 646 $ 641 $ 637 $ 13 2009 594 584 550 531 488 454 447 445 441 2 2010 610 604 598 543 503 475 477 489 33 2011 577 586 578 545 530 521 513 33 2012 632 604 575 559 518 517 27 2013 526 530 522 515 468 60 2014 592 581 579 594 147 2015 486 469 501 191 2016 503 494 249 2017 531 387 Total $ 5,185 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 144 $ 342 $ 446 $ 520 $ 566 $ 591 $ 602 $ 610 $ 618 $ 617 20 2009 70 206 287 337 374 402 414 423 428 15 2010 97 236 322 364 392 434 444 449 15 2011 86 235 341 400 437 461 466 16 2012 69 223 319 386 435 470 16 2013 69 197 271 348 385 18 2014 80 220 317 391 17 2015 47 137 215 15 2016 52 146 15 2017 66 13 Total $ 3,633 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 237 All Accident years $ 1,789 Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 14 All Accident years $ — North America Commercial P&C Insurance — Other-Casualty — Long-tail (continued) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 15 % 26 % 17 % 12 % 8 % 6 % 2 % 1 % 1 % — % North America Commercial P&C Insurance — Non-Casualty — Short-tail During the year ended December 31, 2017, we refined our loss development groupings based on the similarity of loss payout characteristics. The new groupings were applied consistently to all years presented. This product line represents first party commercial product lines that are short-tailed in nature, such as property, inland marine, ocean marine, surety and A&H. There is a wide diversity of products, primary and excess coverag

Taxation

Taxation	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Taxation	Taxation Under current Swiss law, a resident company is subject to income tax at the federal, cantonal, and communal levels that is levied on net worldwide income. Income attributable to permanent establishments or real estate located abroad is excluded from the Swiss tax base. Chubb Limited is a holding company and, therefore, is exempt from cantonal and communal income tax. As a result, Chubb Limited is subject to Swiss income tax only at the federal level. Furthermore, participation relief (i.e., tax relief) is granted to Chubb Limited at the federal level for qualifying dividend income and capital gains related to the sale of qualifying participations (i.e., subsidiaries). It is expected that the participation relief will result in a full exemption of participation income from federal income tax. Chubb Limited is subject to an annual cantonal and communal capital tax on the taxable equity of Chubb Limited in Switzerland. Chubb has two Swiss operating subsidiaries, an insurance company, Chubb Insurance (Switzerland) Limited and a reinsurance company, Chubb Reinsurance (Switzerland) Limited. Both are subject to federal, cantonal, and communal income tax and to annual cantonal and communal capital tax. Under current Bermuda law, Chubb Limited and its Bermuda subsidiaries are not required to pay any taxes on income or capital gains. If a Bermuda law were enacted that would impose taxes on income or capital gains, Chubb Limited and the Bermuda subsidiaries have received an undertaking from the Minister of Finance in Bermuda that would exempt such companies from Bermudian taxation until March 2035. Income from Chubb's operations at Lloyd's is subject to United Kingdom (U.K.) corporation taxes. Lloyd's is required to pay U.S. income tax on U.S. connected income (U.S. income) written by Lloyd's syndicates. Lloyd's has a closing agreement with the Internal Revenue Service (IRS) whereby the amount of tax due on this business is calculated by Lloyd's and remitted directly to the IRS. These amounts are then charged to the accounts of Chubb's Corporate Members in proportion to their participation in the relevant syndicates. Chubb's Corporate Members are subject to this arrangement but, as U.K. domiciled companies, will receive U.K. corporation tax credits for any U.S. income tax incurred up to the value of the equivalent U.K. corporation income tax charge on the U.S. income. Chubb Group Holdings and its respective subsidiaries are subject to income taxes imposed by U.S. authorities and file a consolidated U.S. tax return. As part of the Chubb Corp acquisition, immediately following the merger, Chubb Corp merged with and into Chubb INA Holdings Inc., and therefore, joined the Chubb Group Holdings consolidated return. Should Chubb Group Holdings pay a dividend to Chubb Limited, withholding taxes would apply. Currently, however, no withholding taxes are accrued with respect to such un-remitted earnings as management has no intention of remitting these earnings. Similarly, no taxes have been provided on the un-remitted earnings of certain foreign subsidiaries (Hong Kong and Korea life companies) as management has no intention of remitting these earnings. The cumulative amount that would be subject to withholding tax, if distributed, as well as the determination of the associated tax liability are not practicable to compute; however, such amount would be material to Chubb. Certain international operations of Chubb are also subject to income taxes imposed by the jurisdictions in which they operate. Chubb's domestic operations are in Switzerland, the jurisdiction where we are legally organized, incorporated, and registered. The following table presents pre-tax income and the related provision for income taxes: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Pre-tax income: Switzerland $ 527 $ 766 $ 469 Outside Switzerland 3,195 4,184 2,827 Total pre-tax income $ 3,722 $ 4,950 $ 3,296 Provision for income taxes Current tax expense: Switzerland $ 46 $ 97 $ 38 Outside Switzerland 313 727 266 Total current tax expense 359 824 304 Deferred tax expense (benefit): Switzerland 2 (27 ) 4 Outside Switzerland (500 ) 18 154 Total deferred tax expense (benefit) (498 ) (9 ) 158 Provision for income taxes $ (139 ) $ 815 $ 462 The most significant jurisdictions contributing to the overall taxation of Chubb are calculated using the following rates in 2017: Switzerland 7.83 percent , Bermuda 0.0 percent , U.S. 35.0 percent , and U.K. 19.0 percent . Effective January 1, 2018, the U.S. corporate rate was reduced to 21 percent. The following table presents a reconciliation of the difference between the provision for income taxes and the expected tax provision at the Swiss statutory income tax rate: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Expected tax provision at Swiss statutory tax rate $ 291 $ 388 $ 258 Permanent differences: Taxes on earnings subject to rate other than Swiss statutory rate 263 582 193 Tax-exempt interest and dividends received deduction, net of proration (199 ) (200 ) (32 ) Net withholding taxes 30 20 35 Excess tax benefit on share-based compensation (48 ) — — Impact of 2017 Tax Act (450 ) — — Corporate owned life insurance (37 ) — — Other 11 25 8 Total provision for income taxes $ (139 ) $ 815 $ 462 The following table presents the components of net deferred tax assets and liabilities: December 31 December 31 (in millions of U.S. dollars) 2017 2016 Deferred tax assets: Loss reserve discount $ 715 $ 1,269 Unearned premiums reserve 231 498 Foreign tax credits 340 2,115 Provision for uncollectible balances 45 72 Loss carry-forwards 90 92 Debt related amounts 77 219 Compensation related amounts 260 449 Cumulative translation adjustments 30 59 Other, net 70 69 Total deferred tax assets 1,858 4,842 Deferred tax liabilities: Deferred policy acquisition costs 635 842 Other intangible assets, including VOBA 1,437 2,352 Un-remitted foreign earnings 66 2,001 Investments 53 406 Unrealized appreciation on investments 184 60 Depreciation 83 91 Total deferred tax liabilities 2,458 5,752 Valuation allowance 99 78 Net deferred tax assets (liabilities) $ (699 ) $ (988 ) The 2017 Tax Act, enacted on December 22, 2017, among other things, reduces the U.S. federal income tax rate to 21 percent from 35 percent effective in 2018. We have not completed our assessment of the effects of the 2017 Tax Act; however, we have made our best estimate of those effects based on our current understanding of the provisions in the Act. Accordingly, we recorded a $450 million income tax transition benefit in the fourth quarter of 2017 on a provisional basis, principally reflecting the reduction in the U.S. corporate tax rate from 35 percent to 21 percent . This is comprised of a $743 million reduction in the deferred tax liabilities principally related to certain intangible assets, a $371 million reduction in net deferred tax assets related to other net assets, and a net benefit of $78 million related to the impact of excess foreign tax credits generated by the deemed repatriation rules and the impact of the reduced rate on our foreign branches. We have computed these amounts based on the best available information and our understanding of the 2017 Tax Act. As we complete our analysis of the 2017 Tax Act, collect and prepare necessary data and interpret any additional guidance issued by the IRS, the Treasury Department and other standard setting agencies, we may make adjustments to the provisional amounts. Those adjustments may materially impact our provision for income taxes in the period in which the adjustments are made. The valuation allowance of $ 99 million at December 31, 2017 , and $ 78 million at December 31, 2016 , reflects management's assessment, based on available information, that it is more likely than not that a portion of the deferred tax assets will not be realized due to the potential inability to utilize foreign tax credits in the U.S. and the inability of certain foreign subsidiaries to generate sufficient taxable income. Adjustments to the valuation allowance are made when there is a change in management's assessment of the amount of deferred tax assets that are realizable. At December 31, 2017 , Chubb has net operating loss carry-forwards of $ 329 million which, if unused, will expire starting in 2018, and a foreign tax credit carry-forward in the amount of $ 340 million which, if unused, will expire in the years 2022 through 2027. The following table presents a reconciliation of the beginning and ending amount of gross unrecognized tax benefits: December 31 December 31 (in millions of U.S. dollars) 2017 2016 Balance, beginning of year $ 17 $ 16 Additions based on tax positions related to the current year 3 3 Additions based on tax positions related to prior years (1) — 2 Reductions for tax positions of prior years (4 ) (4 ) Reductions for the lapse of the applicable statutes of limitations (3 ) — Balance, end of year $ 13 $ 17 (1) Assumed in connection with the Chubb Corp acquisition in 2016. At December 31, 2017 and 2016 , the total amount of unrecognized tax benefits that would affect the effective tax rate, if recognized, were $13 million and $ 17 million , respectively. Chubb recognizes accruals for interest and penalties, if any, related to unrecognized tax benefits in income tax expense in the Consolidated statements of operations. For the years ended December 31, 2017 , 2016 , and 2015 , tax-related interest expense (income) and penalties reported in the Consolidated statements of operations was $1 million for each of the three years. At December 31, 2017 and 2016 , liabilities for tax-related interest and penalties in our Consolidated balance sheets were $ 3 million and $4 million , respectively. In September 2016, the IRS completed its examination of Chubb Group Holdings’ (formerly ACE Group Holdings) federal tax returns for the 2010-2012 tax years. No material adjustments resulted from this examination. During 2017, the IRS commenced its field examination of Chubb Group Holdings federal income tax returns for 2014 and 2015 and Chubb Corp’s federal tax return for 2014 which were still ongoing at December 31, 2017. It is reasonably possible that over the next twelve months, the amount of unrecognized tax benefits may change resulting from the re-evaluation of unrecognized tax benefits arising from examinations of taxing authorities and the closing of tax statutes of limitations. With few exceptions, Chubb is no longer subject to state and local and non-U.S. income tax examinations for years before 2010.

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt December 31 December 31 (in millions of U.S. dollars) 2017 2016 Early Redemption Option Repurchase agreements (weighted average interest rate of 1.5% in 2017 and 0.8% in 2016) $ 1,408 $ 1,403 None Short-term debt Chubb INA senior notes: $500 million 5.7% due February 2017 $ — $ 500 Make-whole premium plus 0.20% $300 million 5.8% due March 2018 300 — Make-whole premium plus 0.35% $600 million 5.75% due May 2018 610 — Make-whole premium plus 0.30% $100 million 6.6% due August 2018 103 — None Total short-term debt $ 1,013 $ 500 Long-term debt Chubb INA senior notes: $300 million 5.8% due March 2018 $ — $ 300 Make-whole premium plus 0.35% $600 million 5.75% due May 2018 — 635 Make-whole premium plus 0.30% $100 million 6.6% due August 2018 — 107 None $500 million 5.9% due June 2019 499 498 Make-whole premium plus 0.40% $1,300 million 2.3% due November 2020 1,296 1,294 Make-whole premium plus 0.15% $1,000 million 2.875% due November 2022 995 994 Make-whole premium plus 0.20% $475 million 2.7% due March 2023 472 471 Make-whole premium plus 0.10% $700 million 3.35% due May 2024 695 695 Make-whole premium plus 0.15% $800 million 3.15% due March 2025 795 794 Make-whole premium plus 0.15% $1,500 million 3.35% due May 2026 1,489 1,488 Make-whole premium plus 0.20% $100 million 8.875% due August 2029 100 100 None $200 million 6.8% due November 2031 254 257 Make-whole premium plus 0.25% $300 million 6.7% due May 2036 297 297 Make-whole premium plus 0.20% $800 million 6.0% due May 2037 971 980 Make-whole premium plus 0.20% $600 million 6.5% due May 2038 768 776 Make-whole premium plus 0.30% $475 million 4.15% due March 2043 469 469 Make-whole premium plus 0.15% $1,500 million 4.35% due November 2045 1,482 1,482 Make-whole premium plus 0.25% Chubb INA $1,000 million 6.375% capital securities due March 2067 (1) 964 962 Make-whole premium plus 0.25%-0.50% Other long-term debt (2.75% to 7.1% due December 2019 to September 2020) 10 11 None Total long-term debt $ 11,556 $ 12,610 Trust preferred securities Chubb INA capital securities due April 2030 $ 308 $ 308 Redemption prices (2) (1) 6.375% interest rate through April 14, 2017; interest rate equal to three-month LIBOR rate plus 2.25% thereafter. The current interest rate at the time of this filing is 3.97% . (2) Redemption prices are equal to accrued and unpaid interest to the redemption date plus the greater of (i) 100 percent of the principal amount thereof, or (ii) sum of present value of scheduled payments of principal and interest on the capital securities from the redemption date to April 1, 2030. a) Repurchase agreements Chubb has executed repurchase agreements with certain counterparties under which Chubb agreed to sell securities and repurchase them at a future date for a predetermined price. b) Short-term debt Short-term debt comprises the current maturities of our long-term debt instruments described below. These short-term debt instruments were reclassified from long-term debt during 2017 and are reflected in the table above. c) Long-term debt Certain of Chubb INA's senior notes and capital securities are redeemable at any time at Chubb INA's option subject to the provisions described in the table above. A "make-whole" premium is the present value of the remaining principal and interest discounted at the applicable U.S. Treasury rate. The senior notes and capital securities are also redeemable at par plus accrued and unpaid interest in the event of certain changes in tax law. The senior notes do not have the benefit of any sinking fund. These senior unsecured notes are guaranteed on a senior basis by Chubb Limited and they rank equally with all of Chubb's other senior obligations. They also contain customary limitations on lien provisions as well as customary events of default provisions which, if breached, could result in the accelerated maturity of such senior debt. We have outstanding $ 1.0 billion of unsecured junior subordinated capital securities at December 31, 2017 , which were assumed by Chubb INA in connection with the Chubb Corp acquisition. Effective April 15, 2017, the interest rate on our $1.0 billion of unsecured junior subordinated capital securities converted to a floating rate, equal to the three-month LIBOR plus 2.25 percentage points. Previously, these capital securities carried interest at a rate of 6.375 percent. The current interest rate at the time of this filing on these securities is 3.97 percent . The scheduled maturity date for these securities is April 15, 2037. In August 2017, Chubb eliminated the Replacement Capital Covenant (RCC) associated with these capital securities which benefited the holders of the 6.8 percent debentures due November 2031. The RCC was eliminated through a consent solicitation process whereby the holders of the 6.8 percent debentures agreed to waive their rights under the RCC in exchange for a nominal fee. Chubb received the requisite number of consents required to eliminate the RCC and as a result, the RCC was terminated in August 2017. d) Trust preferred securities In March 2000, ACE Capital Trust II, a Delaware statutory business trust, publicly issued $ 300 million of 9.7 percent Capital Securities (the Capital Securities) due to mature in April 2030. At the same time, Chubb INA purchased $ 9.2 million of common securities of ACE Capital Trust II. The sole assets of ACE Capital Trust II consist of $ 309 million principal amount of 9.7 percent Junior Subordinated Deferrable Interest Debentures (the Subordinated Debentures) issued by Chubb INA due to mature in April 2030. Distributions on the Capital Securities are payable semi-annually and may be deferred for up to ten consecutive semi-annual periods (but no later than April 1, 2030). Any deferred payments would accrue interest compounded semi-annually if Chubb INA defers interest on the Subordinated Debentures. Interest on the Subordinated Debentures is payable semi-annually. Chubb INA may defer such interest payments (but no later than April 1, 2030), with such deferred payments accruing interest compounded semi-annually. The Capital Securities and the ACE Capital Trust II Common Securities will be redeemed upon repayment of the Subordinated Debentures. Chubb Limited has guaranteed, on a subordinated basis, Chubb INA's obligations under the Subordinated Debentures, and distributions and other payments due on the Capital Securities. These guarantees, when taken together with Chubb's obligations under expense agreements entered into with ACE Capital Trust II, provide a full and unconditional guarantee of amounts due on the Capital Securities.

Commitments, contingencies, and

Commitments, contingencies, and guarantees	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments, contingencies, and guarantees	Commitments, contingencies, and guarantees a) Derivative instruments Foreign currency management As a global company, Chubb entities transact business in multiple currencies. Our policy is to generally match assets, liabilities, and required capital for each individual jurisdiction in local currency, which would include the use of derivatives discussed below. We do not hedge our net asset non-U.S. dollar capital positions; however, we do consider economic hedging for planned cross border transactions. Derivative instruments employed Chubb maintains positions in derivative instruments such as futures, options, swaps, and foreign currency forward contracts for which the primary purposes are to manage duration and foreign currency exposure, yield enhancement, or to obtain an exposure to a particular financial market. Chubb also maintains positions in convertible securities that contain embedded derivatives. Investment derivative instruments are recorded in either Other assets (OA) or Accounts payable, accrued expenses, and other liabilities (AP), convertible bonds are recorded in Fixed maturities available for sale (FM AFS), and convertible equity securities are recorded in Equity securities (ES) in the Consolidated balance sheets. These are the most numerous and frequent derivative transactions. In addition, Chubb from time to time purchases to be announced mortgage-backed securities (TBAs) as part of its investing activities. Under reinsurance programs covering GLBs, Chubb assumes the risk of GLBs, including GMIB and GMAB, associated with variable annuity contracts. The GMIB risk is triggered if, at the time the contract holder elects to convert the accumulated account value to a periodic payment stream (annuitize), the accumulated account value is not sufficient to provide a guaranteed minimum level of monthly income. The GMAB risk is triggered if, at contract maturity, the contract holder’s account value is less than a guaranteed minimum value. The GLB reinsurance product meets the definition of a derivative instrument. Benefit reserves in respect of GLBs are classified as Future policy benefits (FPB) while the fair value derivative adjustment is classified within AP. Chubb also generally maintains positions in exchange-traded equity futures contracts on equity market indices to limit equity exposure in the GMDB and GLB blocks of business. All derivative instruments are carried at fair value with changes in fair value recorded in Net realized gains (losses) in the Consolidated statements of operations. None of the derivative instruments are designated as hedges for accounting purposes. The following table presents the balance sheet locations, fair values of derivative instruments in an asset or (liability) position, and notional values/payment provisions of our derivative instruments: December 31, 2017 December 31, 2016 Consolidated Fair Value Notional Fair Value Notional Derivative Asset Derivative (Liability) Derivative Asset Derivative (Liability) (in millions of U.S. dollars) Investment and embedded derivative instruments: Foreign currency forward contracts OA / (AP) $ 14 $ (27 ) $ 2,064 $ 25 $ (50 ) $ 2,220 Cross-currency swaps OA / (AP) — — 45 — — 95 Options/Futures contracts on notes and bonds OA / (AP) 4 (3 ) 1,007 6 (4 ) 2,344 Convertible securities (1) FM AFS/ES 5 — 6 2 — 7 $ 23 $ (30 ) $ 3,122 $ 33 $ (54 ) $ 4,666 Other derivative instruments: Futures contracts on equities (2) OA / (AP) $ — $ (21 ) $ 1,553 $ 1 $ — $ 1,316 Other OA / (AP) 1 (2 ) 75 2 (13 ) 214 $ 1 $ (23 ) $ 1,628 $ 3 $ (13 ) $ 1,530 GLB (3) (AP) / (FPB) $ — $ (550 ) $ 1,083 $ — $ (853 ) $ 1,264 (1) Includes fair value of embedded derivatives. (2) Related to GMDB and GLB blocks of business. (3) Includes both future policy benefits reserves and fair value derivative adjustment. Refer to Note 5 c ) for additional information. Note that the payment provision related to GLB is the net amount at risk. The concept of a notional value does not apply to the GLB reinsurance contracts. At December 31, 2017 and 2016 , derivative liabilities of $ 24 million and $10 million , respectively, included in the table above were subject to a master netting agreement. The remaining derivatives included in the table above were not subject to a master netting agreement. b) Secured borrowings Chubb participates in a securities lending program operated by a third-party banking institution whereby certain assets are loaned to qualified borrowers and from which we earn an incremental return. At December 31, 2017 and 2016 , our securities lending collateral was $1,737 million and $1,092 million , respectively, and our securities lending payable, reflecting our obligation to return the collateral plus interest, was $1,737 million and $1,093 million , respectively. The securities lending collateral can only be drawn down by Chubb in the event that the institution borrowing the securities is in default under the lending agreement. An indemnification agreement with the lending agent protects us in the event a borrower becomes insolvent or fails to return any of the securities on loan. The collateral is recorded in Securities lending collateral and the liability is recorded in Securities lending payable in the Consolidated balance sheets. The following table presents the carrying value of collateral held under securities lending agreements by investment category and remaining contractual maturity of the underlying agreements: Remaining contractual maturity December 31 2017 December 31 2016 (in millions of U.S. dollars) Overnight and Continuous Collateral held under securities lending agreements: Cash $ 828 $ 423 U.S. Treasury and agency 36 54 Foreign 712 578 Corporate securities — 37 Mortgage-backed securities 74 — Equity securities 87 — $ 1,737 $ 1,092 Gross amount of recognized liability for securities lending payable $ 1,737 $ 1,093 Difference (1) $ — $ (1 ) (1) The carrying value of the securities lending collateral held is $1 million lower than the securities lending payable at December 31, 2016 due to accrued interest recorded in the securities lending payable. At December 31, 2017 and 2016 , our repurchase agreement obligations of $1,408 million and $ 1,403 million , respectively, were fully collateralized. In contrast to securities lending programs, the use of cash received is not restricted for the repurchase obligations. The fair value of the underlying securities sold remains in Fixed maturities available for sale, and the repurchase agreement obligation is recorded in Repurchase agreements in the Consolidated balance sheets. The following table presents the carrying value of collateral pledged under repurchase agreements by investment category and remaining contractual maturity of the underlying agreements: Remaining contractual maturity December 31, 2017 December 31, 2016 Up to 30 Days Greater than 90 Days Up to 30 Days Greater than 90 Days Total (in millions of U.S. dollars) Total Collateral pledged under repurchase agreements: Cash $ — $ — $ — $ — $ 1 $ 1 U.S. Treasury and agency 9 230 239 230 10 240 Mortgage-backed securities 369 826 1,195 339 881 1,220 $ 378 $ 1,056 $ 1,434 $ 569 $ 892 $ 1,461 Gross amount of recognized liabilities for repurchase agreements $ 1,408 $ 1,403 Difference (1) $ 26 $ 58 (1) Per the repurchase agreements, the amount of collateral posted is required to exceed the amount of gross liability. Potential risks exist in our secured borrowing transactions due to market conditions and counterparty exposure. With collateral that we pledge, there is a risk that the collateral may not be returned at the expiration of the agreement. If the counterparty fails to return the collateral, Chubb will have free use of the borrowed funds until our collateral is returned. In addition, we may encounter the risk that Chubb may not be able to renew outstanding borrowings with a new term or with an existing counterparty due to market conditions including a decrease in demand as well as more restrictive terms from banks due to increased regulatory and capital constraints. Should this condition occur, Chubb may seek alternative borrowing sources or reduce borrowings. Additionally, increased margins and collateral requirements due to market conditions would increase our restricted assets as we are required to provide additional collateral to support the transaction. The following table presents net realized gains (losses) related to derivative instrument activity in the Consolidated statements of operations: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Investment and embedded derivative instruments: Foreign currency forward contracts $ 9 $ (31 ) $ 31 All other futures contracts and options (21 ) (10 ) 9 Convertible securities (1) 1 8 (8 ) Total investment and embedded derivative instruments $ (11 ) $ (33 ) $ 32 GLB and other derivative instruments: GLB (2) $ 364 $ 53 $ (203 ) Futures contracts on equities (3) (261 ) (136 ) (8 ) Other (5 ) (10 ) (14 ) Total GLB and other derivative instruments $ 98 $ (93 ) $ (225 ) $ 87 $ (126 ) $ (193 ) (1) Includes embedded derivatives. (2) Excludes foreign exchange gains (losses) related to GLB. (3) Related to GMDB and GLB blocks of business. c) Derivative instrument objectives (i) Foreign currency exposure management A foreign currency forward contract (forward) is an agreement between participants to exchange specific foreign currencies at a future date. Chubb uses forwards to minimize the effect of fluctuating foreign currencies as discussed above. (ii) Duration management and market exposure Futures Futures contracts give the holder the right and obligation to participate in market movements, determined by the index or underlying security on which the futures contract is based. Settlement is made daily in cash by an amount equal to the change in value of the futures contract times a multiplier that scales the size of the contract. Exchange-traded futures contracts on money market instruments, notes and bonds are used in fixed maturity portfolios to more efficiently manage duration, as substitutes for ownership of the money market instruments, bonds and notes without significantly increasing the risk in the portfolio. Investments in futures contracts may be made only to the extent that there are assets under management not otherwise committed. Exchange-traded equity futures contracts are used to limit exposure to a severe equity market decline, which would cause an increase in expected claims and therefore, an increase in reserves for GMDB and GLB reinsurance business. Options An option contract conveys to the holder the right, but not the obligation, to purchase or sell a specified amount or value of an underlying security at a fixed price. Option contracts are used in the investment portfolio as protection against unexpected shifts in interest rates, which would affect the duration of the fixed maturity portfolio. By using options in the portfolio, the overall interest rate sensitivity of the portfolio can be reduced. Option contracts may also be used as an alternative to futures contracts in the synthetic strategy as described above. The price of an option is influenced by the underlying security, expected volatility, time to expiration, and supply and demand. The credit risk associated with the above derivative financial instruments relates to the potential for non-performance by counterparties. Although non-performance is not anticipated, in order to minimize the risk of loss, management monitors the creditworthiness of its counterparties and obtains collateral. The performance of exchange-traded instruments is guaranteed by the exchange on which they trade. For non-exchange-traded instruments, the counterparties are principally banks which must meet certain criteria according to our investment guidelines. Cross-currency swaps Cross-currency swaps are agreements under which two counterparties exchange interest payments and principal denominated in different currencies at a future date. We use cross-currency swaps to reduce the foreign currency and interest rate risk by converting cash flows back into local currency. We invest in foreign currency denominated investments to improve credit diversification and also to obtain better duration matching to our liabilities that is limited in the local currency market. Other Included within Other are derivatives intended to reduce potential losses which may arise from certain exposures in our insurance business. The economic benefit provided by these derivatives is similar to purchased reinsurance. For example, Chubb may enter into crop derivative contracts to protect underwriting results in the event of a significant decline in commodity prices. (iii) Convertible security investments A convertible security is a debt instrument or preferred stock that can be converted into a predetermined amount of the issuer’s equity. The convertible option is an embedded derivative within the host instruments which are classified in the investment portfolio as either available for sale or as an equity security. Chubb purchases convertible securities for their total return and not specifically for the conversion feature. (iv) TBA By acquiring TBAs, we make a commitment to purchase a future issuance of mortgage-backed securities. For the period between purchase of the TBAs and issuance of the underlying security, we account for our position as a derivative in the consolidated financial statements. Chubb purchases TBAs both for their total return and for the flexibility they provide related to our mortgage-backed security strategy. (v) GLB Under the GLB program, as the assuming entity, Chubb is obligated to provide coverage until the expiration or maturity of the underlying deferred annuity contracts or the expiry of the reinsurance treaty. Premiums received under the reinsurance treaties are classified as premium. Expected losses allocated to premiums received are classified as Future policy benefits and valued similar to GMDB reinsurance. Other changes in fair value, principally arising from changes in expected losses allocated to expected future premiums, are classified as Net realized gains (losses). Fair value represents management’s estimate of an exit price and thus, includes a risk margin. We may recognize a realized loss for other changes in fair value due to adverse changes in the capital markets (e.g., declining interest rates and/or declining equity markets) and changes in actual or estimated future policyholder behavior (e.g., increased annuitization or decreased lapse rates) although we expect the business to be profitable. We believe this presentation provides the most meaningful disclosure of changes in the underlying risk within the GLB reinsurance programs for a given reporting period. d) Concentrations of credit risk Our investment portfolio is managed following prudent standards of diversification. Specific provisions limit the allowable holdings of a single issue and issuer. We believe that there are no significant concentrations of credit risk associated with our investments. Our three largest exposures by issuer at December 31, 2017 , were Wells Fargo & Co., JP Morgan Chase & Co., and Anheuser-Busch InBev NV. Our largest exposure by industry at December 31, 2017 was financial services. We market our insurance and reinsurance worldwide primarily through insurance and reinsurance brokers. We assume a degree of credit risk associated with brokers with whom we transact business. No broker or one insured accounted for more than 10 percent of gross written premium for the years ended December 31, 2017, 2016, and 2015. e) Fixed maturities At December 31, 2017 , we have commitments to purchase fixed income securities of $1,020 million over the next several years. f) Other investments At December 31, 2017 , included in Other investments in the Consolidated balance sheet are investments in limited partnerships and partially-owned investment companies with a carrying value of $3.4 billion. In connection with these investments, we have commitments that may require funding of up to $4.1 billion over the next several years. g) Letters of credit On October 25, 2017, we replaced our $1.5 billion letter of credit/revolver facility that was set to expire in November 2017 with an amended and restated credit facility that provides for up to $1.0 billion of availability, all of which may be used for the issuance of letters of credit and for revolving loans. We have the ability to increase the capacity under our existing credit facility to $2.0 billion under certain conditions, but any such increase would not raise the sub-limit for revolving loans above $1.0 billion . The letter of credit facility required that we maintain certain financial covenants, all of which we met at December 31, 2017 . At December 31, 2017, outstanding LOCs issued under this facility were $250 million . h) Legal proceedings Our insurance subsidiaries are subject to claims litigation involving disputed interpretations of policy coverages and, in some jurisdictions, direct actions by allegedly-injured persons seeking damages from policyholders. These lawsuits, involving claims on policies issued by our subsidiaries which are typical to the insurance industry in general and in the normal course of business, are considered in our loss and loss expense reserves. In addition to claims litigation, we are subject to lawsuits and regulatory actions in the normal course of business that do not arise from or directly relate to claims on insurance policies. This category of business litigation typically involves, among other things, allegations of underwriting errors or misconduct, employment claims, regulatory activity, or disputes arising from our business ventures. In the opinion of management, our ultimate liability for these matters could be, but we believe is not likely to be, material to our consolidated financial condition and results of operations. i) Lease commitments We lease office space and equipment under operating leases which expire at various dates through 2033. Rent expense was $ 211 million, $ 209 million, and $ 126 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Future minimum lease payments under the leases are expected to be as follows: For the years ending December 31 (in millions of U.S. dollars) 2018 $ 181 2019 153 2020 133 2021 114 2022 89 Thereafter 230 Total minimum future lease commitments $ 900

Shareholders' equity

Shareholders' equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Shareholders' equity	Shareholders’ equity a) Common Shares All of Chubb’s Common Shares are authorized under Swiss corporate law. Though the par value of Common Shares is stated in Swiss francs, Chubb continues to use U.S. dollars as its reporting currency for preparing the consolidated financial statements. Under Swiss corporate law, we are generally prohibited from issuing Common Shares below their par value. If there were a need to raise common equity at a time when the trading price of Chubb's Common Shares is below par value, we would need in advance to obtain shareholder approval to decrease the par value of the Common Shares. Dividend approval At our May 2016 and 2015 annual general meetings, our shareholders approved an annual dividend for the following year of up to $2.76 and $2.68 per share, respectively, which was paid in four quarterly installments of $0.69 per share and $0.67 per share, respectively, at dates determined by the Board of Directors (Board) after the annual general meeting by way of a distribution from capital contribution reserves, transferred to free reserves for payment. At our May 2017 annual general meeting, our shareholders approved an annual dividend for the following year of up to $ 2.84 per share, expected to be paid in four quarterly installments of $ 0.71 per share after the annual general meeting by way of distribution from capital contribution reserves, transferred to free reserves for payment. The Board will determine the record and payment dates at which the annual dividend may be paid until the date of the 2018 annual general meeting, and is authorized to abstain from distributing a dividend at its discretion. The first three quarterly installments each of $ 0.71 per share, have been distributed by the Board as expected. Dividend distributions Under Swiss corporate law, dividends, including distributions through a reduction in par value (par value reduction), must be stated in Swiss francs though dividend payments are made by Chubb in U.S. dollars. Dividend distributions following Chubb's redomestication to Switzerland have generally been made by way of par value reduction (under the methods approved by our shareholders at our annual general meetings) and had the effect of reducing par value per Common Share each time a dividend was distributed. We may also issue dividends without subjecting them to withholding tax by way of distributions from capital contribution reserves and payment out of free reserves. We employed this method of dividends for the annual dividends approved in May 2015, 2016 and 2017 as noted above. The following table presents dividend distributions per Common Share in Swiss francs (CHF) and U.S. dollars (USD): Year Ended December 31 2017 2016 2015 CHF USD CHF USD CHF USD Dividends - par value reduction — $ — — $ — 0.62 $ 0.65 Dividends - distributed from capital contribution reserves 2.76 2.82 2.70 2.74 1.94 2.01 Total dividend distributions per common share 2.76 $ 2.82 2.70 $ 2.74 2.56 $ 2.66 b) Shares issued, outstanding, authorized, and conditional Year Ended December 31 2017 2016 2015 Shares issued, beginning of year 479,783,864 342,832,412 342,832,412 Shares issued for Chubb Corp acquisition — 136,951,452 — Shares issued, end of year 479,783,864 479,783,864 342,832,412 Common Shares in treasury, end of year (at cost) (15,950,685 ) (13,815,148 ) (18,268,971 ) Shares issued and outstanding, end of year 463,833,179 465,968,716 324,563,441 Increases in Common Shares in treasury are due to open market repurchases of Common Shares and the surrender of Common Shares to satisfy tax withholding obligations in connection with the vesting of restricted stock and the forfeiture of unvested restricted stock. Decreases in Common Shares in treasury are principally due to grants of restricted stock, exercises of stock options, and purchases under the Employee Stock Purchase Plan (ESPP). Authorized share capital for general purposes The Board has shareholder-approved authority as set forth in the Articles of Association to increase for general purposes Chubb's share capital from time to time until May 19, 2018, by the issuance of up to 200,000,000 fully paid up Common Shares, with a par value equal to the par value of Chubb's Common Shares as set forth in the Articles of Association at the time of any such issuance. Chubb intends to seek shareholder approval at its 2018 annual general meeting for a new pool of authorized share capital for general purposes to replace the existing 200,000,000 share pool when it expires. Conditional share capital for bonds and similar debt instruments Chubb's share capital may be increased through the issuance of a maximum of 33,000,000 fully paid up Common Shares (with a par value of CHF 24.15 as of December 31, 2017) through the exercise of conversion and/or option or warrant rights granted in connection with bonds, notes, or similar instruments, issued or to be issued by Chubb, including convertible debt instruments. Conditional share capital for employee benefit plans Chubb's share capital may be increased through the issuance of a maximum of 25,410,929 fully paid up Common Shares (with a par value of CHF 24.15 as of December 31, 2017) in connection with the exercise of option rights granted to any employee of Chubb, and any consultant, director, or other person providing services to Chubb. c) Chubb Limited securities repurchases From time to time, we repurchase shares as part of our capital management program and to partially offset potential dilution from the exercise of stock options and the granting of restricted stock under share-based compensation plans. Our Board of Directors has authorized share repurchase programs as follows: • $ 1.5 billion of Chubb Common Shares from January 1, 2015 through December 31, 2015 • $ 1.0 billion of Chubb Common Shares from November 17, 2016 through December 31, 2017 • $1.0 billion of Chubb Common Shares from January 1, 2018 through December 31, 2018 Share repurchases may be in the open market, in privately negotiated transactions, block trades, accelerated repurchases and/or through option or other forward transactions. The following table presents repurchases of Chubb's Common Shares conducted in a series of open market transactions under the Board authorizations: Year Ended December 31 (in millions of U.S. dollars, except share data) 2017 2016 2015 Number of shares repurchased 5,866,612 — 6,677,663 Cost of shares repurchased $ 830 $ — $ 734 d) General restrictions The holders of the Common Shares are entitled to receive dividends as approved by the shareholders. Holders of Common Shares are allowed one vote per share provided that, if the controlled shares of any shareholder constitute ten percent or more of the outstanding Common Shares of Chubb, only a fraction of the vote will be allowed so as not to exceed ten percent in aggregate. Entry of acquirers of Common Shares as shareholders with voting rights in the share register may be refused if it would confer voting rights with respect to ten percent or more of the registered share capital recorded in the commercial register.

Share-based compensation

Share-based compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation	Share-based compensation Chubb has share-based compensation plans which currently provide the Board the ability to grant awards of stock options, restricted stock, and restricted stock units to its employees, consultants, and members of the Board. In connection with the Chubb Corp acquisition in 2016, we assumed outstanding equity awards consisting of service-based restricted stock units, performance-based restricted stock units, and stock options issued by Chubb Corp to employees and directors with a fair value of $525 million , of which $323 million is attributed to purchase consideration for the acquisition. These awards were generally granted with a 3-year vesting period, and the stock options generally have a 10-year term. In May 2016, our shareholders approved the Chubb Limited 2016 Long-Term Incentive Plan (the 2016 LTIP), which replaced both the ACE Limited 2004 LTIP (the 2004 LTIP) and The Chubb Corporation Long-Term Incentive Plan (2014). The 2016 LTIP is substantially similar to the 2004 LTIP in its operation and the types of awards that may be granted. Under the 2016 LTIP, Common Shares of Chubb were authorized to be issued pursuant to awards made as stock options, stock appreciation rights, performance shares, performance units, restricted stock, and restricted stock units. Chubb principally issues restricted stock grants and stock options on a graded vesting schedule. Chubb recognizes compensation cost for restricted stock and stock option grants with only service conditions that have a graded vesting schedule on a straight-line basis over the requisite service period for each separately vesting portion of the award as if the award was, in-substance, multiple awards. We incorporate an estimate of future forfeitures ( 6.5 percent assumption used for grants made in 2017, 2016, and 2015) in determining compensation cost for both grants of restricted stock and stock options. Chubb generally grants restricted stock and restricted stock units with a 4 -year vesting period, which vest in equal annual installments over the respective vesting period. The restricted stock is granted at market close price on the day of grant. Each restricted stock unit represents our obligation to deliver to the holder one Common Share upon vesting. Under the 2016 LTIP, 19,500,000 Common Shares were authorized to be issued, in addition to any shares that have not been delivered pursuant to the 2004 LTIP and remain available for grant pursuant to the 2004 LTIP, including any shares covered by awards granted under the 2004 LTIP that are forfeited, expire or are canceled after the effective date of the 2016 LTIP without delivery of shares or which result in the forfeiture of the shares back to Chubb. At December 31, 2017, a total of 17,065,705 shares remain available for future issuance under the 2016 LTIP, which includes shares canceled or forfeited from the 2004 LTIP, in addition to common shares that were previously registered and authorized to be issued. In May 2017, our shareholders approved an increase of 2,000,000 shares authorized to be issued under the Employee Stock Purchase Plan (ESPP), bringing the total shares authorized to 6,500,000 shares. At December 31, 2017, a total of 2,452,058 shares remain available for issuance under the ESPP. Chubb generally issues Common Shares for the exercise of stock options, restricted stock, and purchases under the ESPP from un-issued reserved shares (conditional share capital) and Common Shares in treasury. The following table presents pre-tax and after-tax share-based compensation expense: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Stock options and shares issued under ESPP: Pre-tax $ 41 $ 33 $ 31 After-tax (1) $ 26 $ 20 $ 21 Restricted stock: Pre-tax $ 259 $ 268 $ 143 After-tax $ 151 $ 167 $ 84 (1) Excludes windfall tax benefit for share-based compensation recognized as a direct adjustment to Additional paid-in capital of $32 million and $26 million for the years ended December 31, 2016 and 2015, respectively. Due to the adoption of new accounting guidance, windfall tax benefits for share-based compensation beginning in 2017 are recognized through Net income rather than Additional paid-in capital. The excess tax benefit recorded to Income tax expense in the Consolidated statement of operations was $48 million for the year ended December 31, 2017. Unrecognized compensation expense related to the unvested portion of Chubb's employee share-based awards was $345 million at December 31, 2017 , and is expected to be recognized over a weighted-average period of approximately 1 year. Stock options Both incentive and non-qualified stock options are principally granted at an option price per share equal to the grant date fair value of Chubb's Common Shares. Stock options are generally granted with a 3 -year vesting period and a 10 -year term. Stock options vest in equal annual installments over the respective vesting period, which is also the requisite service period. Chubb's 2017 share-based compensation expense includes a portion of the cost related to the 2014 through 2017 stock option grants. Stock option fair value was estimated on the grant date using the Black-Scholes option-pricing model that uses the weighted-average assumptions noted below: Year Ended December 31 2017 2016 2015 Dividend yield 2.0 % 2.3 % 2.3 % Expected volatility 19.7 % 23.2 % 21.0 % Risk-free interest rate 2.0 % 1.3 % 1.7 % Expected life 5.8 years 5.6 years 5.8 years The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The expected life (estimated period of time from grant to exercise date) was estimated using the historical exercise behavior of employees. Expected volatility was calculated as a blend of (a) historical volatility based on daily closing prices over a period equal to the expected life assumption, (b) long-term historical volatility based on daily closing prices over the period from Chubb's initial public trading date through the most recent quarter, and (c) implied volatility derived from Chubb's publicly traded options. The following table presents a roll-forward of Chubb's stock options: (Intrinsic Value in millions of U.S. dollars) Number of Options Weighted-Average Exercise Price Weighted-Average Fair Value Total Intrinsic Value Options outstanding, December 31, 2014 9,623,986 $ 69.06 Granted 1,892,641 $ 114.78 $ 18.49 Exercised (1,457,580 ) $ 60.88 $ 72 Forfeited (205,551 ) $ 100.25 Options outstanding, December 31, 2015 9,853,496 $ 78.40 Assumed in Chubb Corp Acquisition 339,896 $ 77.83 $ 36.07 Granted 1,929,616 $ 118.39 $ 21.52 Exercised (1,728,949 ) $ 66.65 $ 99 Forfeited (213,339 ) $ 110.01 Options outstanding, December 31, 2016 10,180,720 $ 87.29 Granted 2,079,522 $ 139.00 $ 22.97 Exercised (1,632,629 ) $ 73.53 $ 111 Forfeited (194,297 ) $ 119.44 Options outstanding, December 31, 2017 10,433,316 $ 99.20 $ 490 Options exercisable, December 31, 2017 6,675,491 $ 82.59 $ 424 The weighted-average remaining contractual term was 6.2 years for stock options outstanding and 4.8 years for stock options exercisable at December 31, 2017 . Cash received from the exercise of stock options for the year ended December 31, 2017 was $133 million . Restricted stock and restricted stock units Grants of restricted stock and restricted stock units awarded under both the 2004 LTIP and 2016 LTIP typically have a 4-year vesting period, based on a graded vesting schedule. Chubb grants performance-based restricted stock to certain executives that vest based on tangible book value (shareholders' equity less goodwill and intangible assets, net of tax) per share growth compared to a defined group of peer companies. The performance-based stock awards comprise target awards which have four installments that vest annually based on the performance criteria, and premium awards, which are earned only if tangible book value per share growth over the cumulative 4-year period after the grant of the associated target awards exceeds a higher threshold compared to our peer group. Shares representing target awards are issued when the performance award is approved. They are subject to forfeiture if applicable performance criteria are not met. For awards granted prior to February 2014, shares representing premium awards were not issued at the time the target award was approved. Rather, they were subject to issuance following the 4-year performance period, if and to the extent the premium awards were earned. For awards granted in February 2014 and thereafter, premium awards have been issued subject to vesting if actually earned or forfeited if not earned at the end of the 4-year performance period. The terms of performance-based restricted stock awards granted beginning in January 2017 were updated to now include a 3-year cliff vesting provision in place of the 4-year graded vesting period. In addition, these awards now include an additional vesting criteria based on the P&C combined ratio compared to a defined group of peer companies as well as an additional vesting provision based on total shareholder return (TSR) compared to a defined group of peer companies. Chubb also grants restricted stock awards to non-management directors which vest at the following year's annual general meeting. The restricted stock is granted at market close price on the grant date. Each restricted stock unit represents our obligation to deliver to the holder one Common Share upon vesting. Chubb's 2017 share-based compensation expense includes a portion of the cost related to the restricted stock granted in the years 2013 through 2017. The following table presents a roll-forward of our restricted stock awards. Included in the roll-forward below are 22,013 restricted stock awards, 23,812 restricted stock awards, and 24,945 restricted stock awards that were granted to non-management directors during the years ended December 31, 2017 , 2016 , and 2015 , respectively: Service-based Restricted Stock Awards and Restricted Stock Units Performance-based Restricted Stock Awards and Restricted Stock Units Number of Shares Weighted-Average Grant-Date Fair Value Number of Shares Weighted-Average Grant-Date Fair Value Unvested restricted stock, December 31, 2014 3,837,097 $ 83.60 378,690 $ 90.87 Granted 1,417,965 $ 114.37 326,860 $ 113.29 Vested (1,341,358 ) $ 80.05 (110,340 ) $ 98.70 Forfeited (424,535 ) $ 87.36 — $ — Unvested restricted stock, December 31, 2015 3,489,169 $ 97.01 595,210 $ 101.73 Assumed in Chubb Corp Acquisition 3,706,639 $ 111.02 — $ — Granted 1,622,065 $ 118.70 517,507 $ 118.96 Vested (2,592,622 ) $ 100.87 (181,548 ) $ 102.43 Forfeited (420,125 ) $ 109.42 — $ — Unvested restricted stock, December 31, 2016 5,805,126 $ 109.39 931,169 $ 111.17 Granted 1,707,094 $ 139.18 267,282 $ 138.90 Vested (2,646,084 ) $ 107.73 (222,954 ) $ 113.30 Forfeited (156,694 ) $ 114.54 — $ — Unvested restricted stock, December 31, 2017 4,709,422 $ 121.16 975,497 $ 118.28 Prior to 2009, legacy ACE granted restricted stock units with a 1 -year vesting period to non-management directors. Delivery of Common Shares on account of these restricted stock units to non-management directors is deferred until after the date of the non-management directors' termination from the Board. Legacy Chubb Corp historically allowed directors and certain key employees of Chubb Corp and its subsidiaries to defer a portion of their compensation earned with respect to services performed in the form of deferred stock units. In addition, legacy Chubb Corp provides supplemental retirement benefits for certain employees through its Defined Contribution Excess Benefit Plan in the form of deferred shares of stock. The minimum vesting period under these legacy Chubb Corp deferred plans is 1-year and the maximum is 3-years. Employees and directors had the option to elect to receive their awards at a future specified date or upon their termination of service with Chubb. At December 31, 2017 , there were 279,986 deferred restricted stock units. ESPP The ESPP gives participating employees the right to purchase Common Shares through payroll deductions during consecutive subscription periods at a purchase price of 85 percent of the fair value of a Common Share on the exercise date (Purchase Price). Annual purchases by participants are limited to the number of whole shares that can be purchased by an amount equal to ten percent of the participant's compensation or $ 25,000 , whichever is less. The ESPP has two six-month subscription periods each year, the first of which runs between January 1 and June 30 and the second of which runs between July 1 and December 31. Legacy Chubb Corp employees were eligible to participate in the ESPP beginning in the July 1 to December 31 subscription period of 2016. The amounts collected from participants during a subscription period are used on the exercise date to purchase full shares of Common Shares. An exercise date is generally the last trading day of a subscription period. The number of shares purchased is equal to the total amount, at the exercise date, collected from the participants through payroll deductions for that subscription period, divided by the Purchase Price, rounded down to the next full share. Participants may withdraw from an offering before the exercise date and obtain a refund of amounts withheld through payroll deductions. Pursuant to the provisions of the ESPP, during the years ended December 31, 2017 , 2016 , and 2015 , employees paid $34 million , $ 24 million, and $ 18 million to purchase 271,185 shares, 211,492 shares, and 197,442 shares, respectively.

Postretirement benefits

Postretirement benefits	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Postretirement benefits	Postretirement benefits Chubb provides postretirement benefits to eligible employees and their dependents through various defined contribution plans and defined benefit plans sponsored by Chubb. With the acquisition, Chubb assumed the outstanding pension and other postretirement benefit plan obligations of Chubb Corp, which consisted of several non-contributory defined benefit pension plans covering substantially all its employees, and several other postretirement benefit plans to retired employees. After the acquisition, Chubb also sponsors the defined contribution plans covering Chubb Corp employees. Defined benefit pension plans We maintain non-contributory defined benefit pension plans that cover certain employees located in the U.S., U.K., Canada, and various other statutorily required countries. We account for pension benefits using the accrual method. Benefits under these plans are based on employees' years of service and compensation during final years of service. All underlying plans are subject to periodic actuarial valuations by qualified actuarial firms using actuarial models to calculate the expense and liability for each plan. We use December 31 as the measurement date for our defined benefit pension plans. Under the Chubb Corp plans, prior to 2001, benefits were generally based on an employee’s years of service and average compensation during the last five years of employment. Effective January 1, 2001, the formula for providing pension benefits was changed from the final average pay formula to a cash balance formula. Under the cash balance formula, a notional account is established for each employee, which is credited semi-annually with an amount equal to a percentage of eligible compensation based on age and years of service plus interest based on the account balance. Chubb Corp employees hired prior to 2001 will generally be eligible to receive vested benefits based on the higher of the final average pay or cash balance formulas. Other postretirement benefit plans We also assumed Chubb Corp other postretirement benefit plans, principally healthcare and life insurance, to retired employees, their beneficiaries, and covered dependents. Healthcare coverage is contributory. Retiree contributions vary based upon retiree’s age, type of coverage, and years of service requirements. Life insurance coverage is non-contributory. Chubb funds a portion of the healthcare benefits obligation where such funding can be accomplished on a tax-effective basis. Benefits are paid as covered expenses are incurred. Amendments to U.S. Qualified and Excess Pension Plans and U.S. Retiree Healthcare Plan On October 31, 2016, we harmonized and amended several of our U.S. retirement programs to create a unified retirement savings program. In 2020, we will transition from a traditional defined benefit pension program that had been in effect for certain employees to a defined contribution program. Additionally, after 2025, we plan to eliminate a subsidized U.S. retiree healthcare and life insurance plan that had been in place for certain employees. Both amendments required a remeasurement of the plan assets and benefit obligations with updated assumptions, including discount rates and the expected return on assets. The plan amendments and related remeasurement of the obligation at October 31, 2016 resulted in a net decrease to the benefit obligations of $496 million as follows: • The amendment of the pension plan and excess pension plan resulted in a pre-tax curtailment gain of $113 million immediately recognized in income during the fourth quarter of 2016 as it reduced expected years of future service of active plan participants. • The amendment of the retiree healthcare plan resulted in a reduction in the obligation of $383 million , of which $410 million will be amortized as a reduction to expense over the next 4.5 years as it relates to benefits already accrued. During the fourth quarter of 2016 and for the year ended 2017, $ 15 million and $89 million , respectively, was amortized as a reduction to expense. Additionally, during 2017, the number of involuntary departures due to the Chubb integration met our established threshold for recognition in income. As a result, we recognized $39 million of accelerated amortization. At December 31, 2017, the remaining curtailment benefit balance was $267 million which will be amortized as a reduction to expense over the next 3.5 years. Obligations and funded status The funded status of the pension and other postretirement benefit plans as well as the amounts recognized in Accumulated other comprehensive income at December 31, 2017 and 2016 was as follows: Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 U.S. Plans Non-U.S. Plans U.S. Plans Non-U.S. Plans (in millions of U.S. dollars) Benefit obligation, beginning of year $ 3,035 $ 1,025 $ 10 $ 559 $ 165 $ 16 Acquisition of Chubb Corp — — 3,153 372 — 506 Service cost 63 17 75 18 2 10 Interest cost 105 27 103 30 4 17 Actuarial loss (gain) 232 (4 ) 131 204 (2 ) 36 Benefits paid (132 ) (28 ) (79 ) (22 ) (14 ) (11 ) Amendments — — — (9 ) (23 ) (410 ) Curtailments — (32 ) (259 ) (7 ) 2 — Settlements (18 ) (8 ) (99 ) (7 ) — — Foreign currency revaluation and other — 80 — (113 ) 3 1 Benefit obligation, end of year $ 3,285 $ 1,077 $ 3,035 $ 1,025 $ 137 $ 165 Plan assets at fair value, beginning of year $ 2,765 $ 962 $ 9 $ 564 $ 159 $ — Acquisition of Chubb Corp — — 2,473 315 — 138 Actual return on plan assets 441 100 359 168 6 29 Employer contributions 53 63 98 67 6 3 Benefits paid (132 ) (28 ) (79 ) (22 ) (14 ) (11 ) Settlements (18 ) (8 ) (95 ) (7 ) — — Foreign currency revaluation and other — 83 — (123 ) — — Plan assets at fair value, end of year $ 3,109 $ 1,172 $ 2,765 $ 962 $ 157 $ 159 Funded status at end of year $ (176 ) $ 95 $ (270 ) $ (63 ) $ 20 $ (6 ) Amounts recognized in Accumulated other comprehensive income, not yet recognized in net periodic cost (benefit): Net actuarial loss (gain) $ (227 ) $ 82 $ (207 ) $ 156 $ 12 $ 17 Prior service cost (benefit) — 6 — (2 ) (288 ) (395 ) Total $ (227 ) $ 88 $ (207 ) $ 154 $ (276 ) $ (378 ) The accumulated benefit obligation for the pension benefit plans was $ 4.3 billion and $ 3.8 billion at December 31, 2017 and 2016 , respectively. The accumulated benefit obligation is the present value of pension benefits earned as of the measurement date based on employee service and compensation prior to that date. It differs from the pension benefit obligation in the table above in that the accumulated benefit obligation includes no assumptions regarding future compensation levels. The net components of the funded status of the pension and other postretirement benefit plans are included in Accounts payable, accrued expenses, and other liabilities in the consolidated balance sheets. Chubb’s funding policy is to contribute amounts that meet regulatory requirements plus additional amounts determined based on actuarial valuations, market conditions and other factors. All benefit plans satisfy minimum funding requirements of the Employee Retirement Income Security Act of 1974 (ERISA). At December 31, 2017, we estimate that we will contribute $ 28 million to the pension plans and $2 million to the other postretirement benefits plan in 2018. The estimate is subject to change due to contribution decisions that are affected by various factors including our liquidity, market performance and management discretion. The weighted-average assumptions used to determine the projected benefit obligation were as follows: Pension Benefits U.S. Plans Non-U.S. Plans Other Postretirement Benefits December 31, 2017 Discount rate 3.59 % 2.76 % 2.77 % Rate of compensation increase 4.00 % 3.46 % N/A December 31, 2016 Discount rate 4.14 % 2.83 % 2.97 % Rate of compensation increase 4.00 % 3.57 % N/A The components of net pension and other postretirement benefit costs reflected in Net income and other changes in plan assets and benefit obligations recognized in other comprehensive income were as follows: Pension Benefits Other Postretirement Benefits U.S. Plans Non-U.S. Plans Year Ended December 31 2017 2016 2015 2017 2016 2015 2017 2016 2015 (in millions of U.S. dollars) Costs reflected in Net income: Service cost $ 63 $ 75 $ — $ 17 $ 18 $ 6 $ 2 $ 10 $ 1 Interest cost 105 103 — 27 30 21 4 17 — Expected return on plan assets (189 ) (165 ) — (42 ) (39 ) (29 ) (5 ) (8 ) — Amortization of net actuarial loss (gain) — — — 3 2 2 — (1 ) (1 ) Amortization of prior service cost — — — — (1 ) — (89 ) (15 ) — Curtailments — (117 ) — (27 ) — — (37 ) — — Settlements — (2 ) — — 1 1 — — — Net periodic (benefit) cost $ (21 ) $ (106 ) $ — $ (22 ) $ 11 $ 1 $ (125 ) $ 3 $ — Changes in plan assets and benefit obligations recognized in other comprehensive income Net actuarial loss (gain) $ (21 ) $ (326 ) $ — $ (57 ) $ 49 $ (16 ) $ (3 ) $ 17 $ — Prior service cost (benefit) — — — — (8 ) 1 (23 ) (395 ) — Amortization of net actuarial loss — — — (3 ) — — — — — Amortization of prior service cost — — — — — — 89 — — Curtailments — 117 — (6 ) — — 39 — — Settlements 1 2 — — (1 ) — — — — Total (increase) decrease in other comprehensive income $ (20 ) $ (207 ) $ — $ (66 ) $ 40 $ (15 ) $ 102 $ (378 ) $ — The estimated net actuarial loss that will be amortized from AOCI into net periodic benefit costs in Net income for Non-U.S. pension plans during 2018 is $1 million . The estimated net prior service credit that will be amortized from AOCI into net periodic benefit cost in Net income during 2018 for U.S. other postretirement benefit plans is $ 80 million . The weighted-average assumptions used to determine the net periodic pension and other postretirement benefit costs were as follows: Pension Benefits U.S. Plans Non-U.S. Plans Other Postretirement Benefits Year Ended December 31 2017 Discount rate in effect for determining service cost 4.20 % 3.55 % 2.84 % Discount rate in effect for determining interest cost 3.53 % 2.61 % 2.44 % Rate of compensation increase 4.00 % 3.57 % N/A Expected long-term rate of return on plan assets 7.00 % 4.23 % 3.00 % 2016 Discount rate in effect for determining service cost 4.38 % 3.85 % 4.32 % Discount rate in effect for determining interest cost 3.59 % 3.44 % 4.02 % Rate of compensation increase 4.00 % 3.33 % N/A Expected long-term rate of return on plan assets 7.00 % 4.79 % 6.34 % 2015 Discount rate NM 3.51 % NM Rate of compensation increase NM 3.09 % NM Expected long-term rate of return on plan assets NM 4.81 % NM NM – not meaningful The weighted-average healthcare cost trend rate assumptions used to measure the expected cost of healthcare benefits were as follows: U.S. Plans Non-U.S. Plans 2017 2016 2015 2017 2016 Healthcare cost trend rate 7.01 % 7.28 % 6.50 % 6.61 % 6.61 % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50 % 4.50 % 4.50 % 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate 2038 2038 2026 2029 2029 The healthcare cost trend rate assumption has a significant effect on the amount of the accumulated other postretirement benefit obligation and the net other postretirement benefit cost reported. To illustrate, a one percent increase in the trend rate for each year would increase the accumulated other postretirement benefit obligation at December 31, 2017 by approximately $ 8 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2017 by approximately $ 1 million . A one percent decrease in the trend rate for each year would decrease the accumulated other postretirement benefit obligation at December 31, 2017 by approximately $ 7 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2017 by approximately $ 1 million . Plan Assets The long term objective of the pension plan is to provide sufficient funding to cover expected benefit obligations, while assuming a prudent level of portfolio risk. The assets of the pension plan are invested, either directly or through pooled funds, in a diversified portfolio of predominately equity securities and fixed maturities. We seek to obtain a rate of return that over time equals or exceeds the returns of the broad markets in which the plan assets are invested. The target allocation of plan assets is 55 percent to 65 percent invested in equity securities (including certain other investments measured using NAV), with the remainder primarily invested in fixed maturities. We rebalance our pension assets to the target allocation as market conditions permit. We determined the expected long term rate of return assumption for each asset class based on an analysis of the historical returns and the expectations for future returns. The expected long term rate of return for the portfolio is a weighted aggregation of the expected returns for each asset class. In order to minimize risk, the Plan maintains a listing of permissible and prohibited investments. In addition, the Plan has certain concentration limits and investment quality requirements imposed on permissible investments options. Investment risk is measured and monitored on an ongoing basis. The following table presents the fair values of the pension plan assets, by valuation hierarchy. For additional information on how we classify these assets within the valuation hierarchy, refer to Note 4 to the Consolidated financial statements. December 31, 2017 Pension Benefits (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total U.S. Plans: Short-term investments $ 9 $ 52 $ — $ 61 U.S. Treasury and agency 446 79 — 525 Foreign and corporate bonds — 692 — 692 Equity securities 1,154 — — 1,154 Total U.S. Plan assets (1) $ 1,609 $ 823 $ — $ 2,432 Non-U.S. Plans: Short-term investments $ 5 $ — $ — $ 5 Foreign and corporate bonds — 456 — 456 Equity securities 122 492 — 614 Total Non-U.S. Plan assets (1) $ 127 $ 948 $ — $ 1,075 (1) Excluded from the table above are $ 677 million and $95 million of other investments measured using NAV as a practical expedient related to the U.S. Plans and non-U.S. Plans respectively. December 31, 2016 Pension Benefits (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total U.S. Plans: Short-term investments $ — $ 43 $ — $ 43 U.S. Treasury and agency 206 112 — 318 Foreign and corporate bonds — 482 5 487 Equity securities 728 — — 728 Derivative instruments 3 — — 3 Total U.S. Plan assets (1) $ 937 $ 637 $ 5 $ 1,579 Non-U.S. Plans: Short-term investments $ 2 $ — $ — $ 2 Foreign and corporate bonds — 435 — 435 Equity securities 100 412 — 512 Total Non-U.S. Plan assets (1) $ 102 $ 847 $ — $ 949 (1) Excluded from the table above are $ 1.2 billion and $ 13 million of other investments measured using NAV as a practical expedient related to the U.S. Plans and Non-U.S. Plans, respectively. We had other postretirement benefit plan assets of $157 million and $159 million at December 31, 2017 and 2016, respectively, all of which are held in equity securities and categorized as Level 1. Assets classified within Level 3 were nil and $5 million at December 31, 2017 and 2016, respectively, and the change in the balance during the years ended December 31, 2017 and 2016 was insignificant. Benefit payments were $200 million and $213 million for the years ended December 31, 2017 and 2016 , respectively. Expected future payments are as follows: Pension For the years ending December 31 U.S. Plans Non-U.S. Plans Other Postretirement Benefits (in millions of U.S. dollars) 2018 $ 129 $ 23 $ 17 2019 141 25 19 2020 148 29 20 2021 155 28 23 2022 163 27 25 2023-2027 881 159 44 Defined contribution plans (including 401(k)) Under these plans, employees' contributions may be supplemented by Chubb matching contributions based on the level of employee contribution. These contributions are invested at the election of each employee in one or more of several investment portfolios offered by a third-party investment advisor. Expenses for these plans totaled $166 million , $150 million , and $117 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.

Other (income) expense

Other (income) expense	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Other (income) expense	14 . Other (income) expense Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Equity in net (income) loss of partially-owned entities $ (418 ) $ (264 ) $ (113 ) (Gains) losses from fair value changes in separate account assets (1) (97 ) (11 ) 19 One-time contribution to the Chubb Charitable Foundation 50 — — Federal excise and capital taxes 35 19 19 Other 30 34 24 Other (income) expense $ (400 ) $ (222 ) $ (51 ) (1) Related to (gains) losses from fair value changes in separate account assets that do not qualify for separate account reporting under GAAP. Other (income) expense includes equity in net (income) loss of partially-owned entities, which includes our share of net (income) loss related to partially-owned investment companies (private equity) and partially-owned insurance companies. Also included in Other (income) expense are (Gains) losses from fair value changes in separate account assets that do not qualify for separate account reporting under GAAP. The offsetting movement in the separate account liabilities is included in Policy benefits in the Consolidated statements of operations. Certain federal excise and capital taxes incurred as a result of capital management initiatives are included in Other (income) expense as these are considered capital transactions and are excluded from underwriting results.

Segment information

Segment information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment information	Segment information Chubb operates through six business segments: North America Commercial P&C Insurance, North America Personal P&C Insurance, North America Agricultural Insurance, Overseas General Insurance, Global Reinsurance, and Life Insurance. These segments distribute their products through various forms of brokers, agencies, and direct marketing programs. All business segments have established relationships with reinsurance intermediaries. • The North America Commercial P&C Insurance segment includes the business written by Chubb divisions that provide property and casualty (P&C) insurance and services to large, middle market and small commercial businesses in the U.S., Canada, and Bermuda. This segment includes our retail divisions: Major Accounts, Commercial Insurance, including Small Commercial Insurance; and our wholesale and specialty divisions: Westchester and Chubb Bermuda. These divisions write a variety of coverages, including traditional commercial property, marine, general casualty, workers’ compensation, package policies, and risk management; specialty categories such as professional lines, marine, construction, environmental, medical, cyber risk, and excess casualty; as well as group accident and health (A&H) insurance. • The North America Personal P&C Insurance segment includes the business written by Chubb Personal Risk Services division, which comprises Chubb high net worth personal lines business and ACE Private Risk Services, with operations in the U.S. and Canada. This segment provides affluent and high net worth individuals and families with homeowners, automobile and collector cars, valuable articles (including fine arts), personal and excess liability, travel insurance, and recreational marine insurance and services. • The North America Agricultural Insurance segment includes the business written by Rain and Hail Insurance Service, Inc. which provides comprehensive multiple peril crop insurance (MPCI) and crop-hail insurance, and Chubb Agribusiness, which offers farm and ranch property as well as specialty P&C coverages, including commercial agriculture products. • The Overseas General Insurance segment includes the business written by two Chubb divisions that provide P&C insurance and services in the 51 countries and territories outside of North America where the company operates. Chubb International provides commercial P&C, A&H and traditional and specialty personal lines for large corporations, middle markets and small customers through retail brokers, agents and other channels locally around the world. Chubb Global Markets (CGM) provides commercial P&C excess and surplus lines and A&H through wholesale brokers in the London market and through Lloyd’s. These divisions write a variety of coverages, including traditional commercial P&C, specialty categories such as financial lines, marine, energy, aviation, political risk and construction risk, as well as group A&H and traditional and specialty personal lines. • The Global Reinsurance segment primarily includes the reinsurance business written by Chubb Tempest Re. Chubb Tempest Re provides a broad range of traditional and specialty reinsurance coverages to a diverse array of primary P&C companies. • The Life Insurance segment includes Chubb's international life operations written by Chubb Life, Chubb Tempest Life Re and the North American supplemental A&H and life business of Combined Insurance. Corporate primarily includes the results of all run-off asbestos and environmental (A&E) exposures, our run-off Brandywine business, and our Westchester specialty operations for 1996 and prior years, and certain other run-off exposures. In addition, Corporate includes the results of our non-insurance companies including Chubb Limited, Chubb Group Management and Holdings Ltd., and Chubb INA Holdings Inc. Our exposure to A&E claims principally arises out of liabilities acquired when we purchased Westchester Specialty in 1998, CIGNA’s P&C business in 1999, and the Chubb Corp run-off business in 2016. In addition, revenue and expenses managed at the corporate level, including realized gains and losses, interest expense, the non-operating income of our partially-owned entities, and income taxes are reported within Corporate. Chubb integration expenses and other merger-related expenses (both included in Chubb integration expenses in the Consolidated statements of operations), and the one-time benefit recorded in 2016 related to the harmonization of our U.S. pension plans, are also reported within Corporate. Chubb integration expenses are one-time costs that are directly attributable to the achievement of the annualized savings, including employee severance, third-party consulting fees, and systems integration expenses. Other merger-related expenses are one-time costs directly attributable to the merger, including rebranding, employee retention costs and other professional and legal fees related to the Chubb Corp acquisition. These items will not be allocated to the segment level as they are one-time in nature and are not related to the ongoing business activities of the segment. The Chief Executive Officer does not manage segment results or allocate resources to segments when considering these costs and they are therefore excluded from our definition of segment income. Therefore, segment income will only include underwriting income, net investment income, and other operating income and expense items such as each segment's share of the operating income (loss) related to partially-owned entities and miscellaneous income and expense items for which the segments are held accountable. Segment income also includes amortization of purchased intangibles related to business combination intangible assets acquired by the segment and other purchase accounting related intangible assets, including agency relationships, renewal rights, and client lists. The amortization of intangible assets purchased as part of the Chubb Corp acquisition is considered a Corporate cost as these are incurred by the overall company. We determined that this definition of segment income is appropriate and aligns with how the business is managed. As we progress through the integration and refine our processes as our business continues to evolve, we will evaluate and may further refine our segments and segment income measures. For segment reporting purposes, certain items are presented in a different manner below than in the consolidated financial statements. Management uses underwriting income as the main measures of segment performance. Chubb calculates underwriting income by subtracting Losses and loss expenses, Policy benefits, Policy acquisition costs, and Administrative expenses from Net premiums earned. To calculate segment income, include Net investment income, Other (income) expense, and Amortization of purchased intangibles. For the North America Agricultural Insurance segment, management includes gains and losses on crop derivatives as a component of underwriting income. For example, for the year ended December 31, 2017, underwriting income in our North America Agricultural Insurance segment was $ 392 million . This amount includes $ 7 million of realized losses related to crop derivatives which are reported in Net realized gains (losses) in the Corporate column below. For the Life Insurance segment, management includes Net investment income and (Gains) losses from fair value changes in separate account assets that do not qualify for separate account reporting under GAAP as components of Life Insurance underwriting income. For example, for the year ended December 31, 2017, Life Insurance underwriting income of $ 263 million includes Net investment income of $ 313 million and gains from fair value changes in separate account assets of $ 97 million . The gains from fair value changes in separate account assets are reported in Other (income) expense in the table below. The following tables present the Statement of Operations by segment: For the Year Ended December 31, 2017 (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Reinsurance Life Insurance Corporate Chubb Consolidated Net premiums written $ 12,028 $ 4,533 $ 1,516 $ 8,341 $ 685 $ 2,141 $ — $ 29,244 Net premiums earned 12,191 4,399 1,508 8,131 704 2,101 — 29,034 Losses and loss expenses 8,287 3,265 1,036 4,281 561 739 285 18,454 Policy benefits — — — — — 676 — 676 Policy acquisition costs 1,873 899 81 2,221 177 530 — 5,781 Administrative expenses 981 264 (8 ) 982 44 303 267 2,833 Underwriting income (loss) 1,050 (29 ) 399 647 (78 ) (147 ) (552 ) 1,290 Net investment income 1,961 226 25 610 273 313 (283 ) 3,125 Other (income) expense 1 4 2 (4 ) (1 ) (84 ) (318 ) (400 ) Amortization expense of purchased intangibles — 16 29 45 — 2 168 260 Segment income (loss) 3,010 177 393 1,216 196 248 (685 ) 4,555 Net realized gains (losses) including OTTI 84 84 Interest expense 607 607 Chubb integration expenses 310 310 Income tax benefit (139 ) (139 ) Net income (loss) $ (1,379 ) $ 3,861 For the Year Ended December 31, 2016 (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Life Insurance Corporate Chubb Net premiums written $ 11,740 $ 4,153 $ 1,328 $ 8,124 $ 676 $ 2,124 $ — $ 28,145 Net premiums earned 12,217 4,319 1,316 8,132 710 2,055 — 28,749 Losses and loss expenses 7,439 2,558 893 4,005 325 663 169 16,052 Policy benefits — — — — — 588 — 588 Policy acquisition costs 2,023 966 83 2,136 187 509 — 5,904 Administrative expenses 1,125 363 (6 ) 1,057 52 307 183 3,081 Underwriting income (loss) 1,630 432 346 934 146 (12 ) (352 ) 3,124 Net investment income 1,860 207 20 600 263 283 (368 ) 2,865 Other (income) expense (2 ) 6 1 (11 ) (4 ) 5 (217 ) (222 ) Amortization expense (benefit) of purchased intangibles — 19 29 48 — 3 (80 ) 19 Segment income (loss) 3,492 614 336 1,497 413 263 (423 ) 6,192 Net realized gains (losses) including OTTI (145 ) (145 ) Interest expense 605 605 Chubb integration expense 492 492 Income tax expense 815 815 Net income (loss) $ (2,480 ) $ 4,135 For the Year Ended December 31, 2015 (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Reinsurance Life Insurance Corporate Chubb Consolidated Net premiums written $ 5,715 $ 1,192 $ 1,346 $ 6,634 $ 828 $ 1,998 $ — $ 17,713 Net premiums earned 5,634 948 1,364 6,471 849 1,947 — 17,213 Losses and loss expenses 3,661 590 1,088 3,052 290 601 202 9,484 Policy benefits — — — — — 543 — 543 Policy acquisition costs 531 69 69 1,581 214 476 1 2,941 Administrative expenses 621 123 1 997 49 291 188 2,270 Underwriting income (loss) 821 166 206 841 296 36 (391 ) 1,975 Net investment income 1,032 25 23 534 300 265 15 2,194 Other (income) expense (7 ) 2 1 (17 ) (6 ) 23 (47 ) (51 ) Amortization expense of purchased intangibles — 78 30 61 — 2 — 171 Segment income (loss) 1,860 111 198 1,331 602 276 (329 ) 4,049 Net realized gains (losses) including OTTI (420 ) (420 ) Interest expense 300 300 Chubb Integration Expense 33 33 Income tax expense 462 462 Net income (loss) $ (1,544 ) $ 2,834 Underwriting assets are reviewed in total by management for purposes of decision-making. Other than Unpaid losses and loss expenses, Reinsurance recoverables, Goodwill and Other intangible assets, Chubb does not allocate assets to its segments. The following table presents net premiums earned for each segment by line of business: For the Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 North America Commercial P&C Insurance Property & other short-tail lines $ 1,899 $ 1,963 $ 1,040 Casualty & all other 9,554 9,552 4,175 A&H 738 702 419 Total North America Commercial P&C Insurance 12,191 12,217 5,634 North America Personal P&C Insurance Personal automobile 742 699 186 Personal homeowners 3,014 3,007 579 Personal other 643 613 183 Total North America Personal P&C Insurance 4,399 4,319 948 North America Agricultural Insurance 1,508 1,316 1,364 Overseas General Insurance Property & other short-tail lines 2,076 2,133 1,833 Casualty & all other 2,266 2,177 1,361 Personal lines 1,609 1,626 1,211 A&H 2,180 2,196 2,066 Total Overseas General Insurance 8,131 8,132 6,471 Global Reinsurance Property & other short-tail lines 132 118 155 Property catastrophe 198 185 219 Casualty & all other 374 407 475 Total Global Reinsurance 704 710 849 Life Insurance Life 980 1,002 931 A&H 1,121 1,053 1,016 Total Life Insurance 2,101 2,055 1,947 Total net premiums earned $ 29,034 $ 28,749 $ 17,213 The following table presents net premiums earned by geographic region. Allocations have been made on the basis of location of risk: North America Europe (1) Asia Pacific / Far East Latin America 2017 70 % 11 % 12 % 7 % 2016 70 % 12 % 11 % 7 % 2015 60 % 15 % 15 % 10 % (1) Europe includes Eurasia and Africa region.

Earnings per share

Earnings per share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings per share	Earnings per share Year Ended December 31 (in millions of U.S. dollars, except share and per share data) 2017 2016 2015 Numerator: Net income $ 3,861 $ 4,135 $ 2,834 Denominator: Denominator for basic earnings per share: Weighted-average shares outstanding 467,145,716 462,519,789 325,589,361 Denominator for diluted earnings per share: Share-based compensation plans 4,051,185 3,429,610 3,246,017 Weighted-average shares outstanding and assumed conversions 471,196,901 465,949,399 328,835,378 Basic earnings per share $ 8.26 $ 8.94 $ 8.71 Diluted earnings per share $ 8.19 $ 8.87 $ 8.62 Potential anti-dilutive share conversions 1,776,025 1,206,828 1,601,668 Excluded from weighted-average shares outstanding and assumed conversions is the impact of securities that would have been anti-dilutive during the respective years.

Related party transaction

Related party transaction	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related party transactions	Related party transactions Starr Indemnity & Liability Company and its affiliates (collectively, Starr) We have a number of agency and reinsurance agreements with Starr, the Chairman of which is related to a member of our senior management team. A number of these agreements pre-dated our acquisition of Chubb Corp; however, in connection with our acquisition of Chubb Corp on January 14, 2016, we obtained Chubb Corp’s pre-existing business with Starr, which included agency agreements and agreements in which Chubb Corp was a reinsurer to Starr. Our Board has reviewed and approved our arrangements with Starr. We have agency, claims services and underwriting services agreements with various Starr subsidiaries. Under the agency agreements, we secure the ability to sell our insurance policies through Starr as one of our non-exclusive agents for writing policies, contracts, binders, or agreements of insurance or reinsurance. Under the claims services agreements, Starr adjusts the claims under policies and arranges for third party treaty and facultative agreements covering such policies. Under the underwriting services agreements, Starr underwrites insurance policies on our behalf and we agree to reinsure such policies to Starr under one or more quota reinsurance agreements. Transactions generated under these agreements were as follows: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Gross premiums written $ 464 $ 658 $ 305 Ceded premiums written $ 175 $ 208 $ 78 Commissions paid $ 101 $ 145 $ 60 Commissions received $ 37 $ 56 $ 19 Losses and loss expenses incurred $ 438 $ 313 $ 137 Certain agency agreements also contain a profit-sharing arrangement based on loss ratios, triggered if Starr underwrites a minimum of $20 million of annual program business net written premiums on our behalf. No profit share commission has been payable yet under this arrangement. Another agency agreement contains a profit-sharing arrangement based on the earned premiums for the business underwritten by Starr (excluding workers’ compensation) and the reinsurance recoveries associated with excess of loss reinsurance agreements placed by Starr for the business underwritten. No profit share commission under this arrangement has been payable yet. Reinsurance recoverable on losses and loss expenses due from Starr was $557 million and $412 million as of December 31, 2017 and 2016, respectively, and the amount of ceded reinsurance premium payable included in Insurance and reinsurance balances payable in the consolidated balance sheet was $44 million and $72 million , respectively. ABR Re We own 11.3 percent of the common equity of ABR Reinsurance Capital Holdings Ltd. and warrants to acquire 0.5 percent of additional equity. ABR Reinsurance Capital Holdings Ltd., is the parent company of ABR Reinsurance Ltd. (ABR Re), an independent reinsurance company. Through long-term arrangements, Chubb will be the sole source of reinsurance risks ceded to ABR Re, and BlackRock, Inc. will be ABR Re’s exclusive investment management service provider. As an investor, Chubb is expected to benefit from underwriting profit generated by ABR Re’s reinsuring a wide range of Chubb’s primary insurance business and the income and capital appreciation BlackRock, Inc. seeks to deliver through its investment management services. In addition, Chubb has entered into an arrangement with BlackRock, Inc. under which both Chubb and BlackRock, Inc. will be entitled to an equal share of the aggregate amount of certain fees, including underwriting and investment management performance related fees, in connection with their respective reinsurance and investment management arrangements with ABR Re. ABR Re is a variable interest entity; however, Chubb is not the primary beneficiary and does not consolidate ABR Re because Chubb does not have the power to control and direct ABR Re’s most significant activities, including investing and underwriting. Our minority ownership interest is accounted for under the equity method of accounting. Chubb cedes premiums to ABR Re and recognizes the associated commissio ns. At December 31, 2017 and 2016, Chubb ceded reinsurance premiums of $ 342 million and $ 288 million , respectively, and recognized ceded commissions of $ 94 million and $ 66 million , respectively. At December 31, 2017 and 2016, the amount of Reinsurance recoverable on losses and loss expenses was $ 365 million and $ 148 million , respectively, and the amount of ceded reinsurance premium payable included in Insurance and reinsurance balances payable in our Consolidated balance sheets was $ 51 million and $ 53 million , respectively.

Statutory Financial Information

Statutory Financial Information	12 Months Ended
	Dec. 31, 2017
Statutory Financial Information [Abstract]
Statutory financial information	Statutory financial information Our subsidiaries file financial statements prepared in accordance with statutory accounting practices prescribed or permitted by insurance regulators. Statutory accounting differs from GAAP in the reporting of certain reinsurance contracts, investments, subsidiaries, acquisition expenses, fixed assets, deferred income taxes, and certain other items. Some jurisdictions impose complex regulatory requirements on insurance companies while other jurisdictions impose fewer requirements. In some jurisdictions, we must obtain licenses issued by governmental authorities to conduct local insurance business. These licenses may be subject to reserves and minimum capital and solvency tests. Jurisdictions may impose fines, censure, and/or criminal sanctions for violation of regulatory requirements. The 2017 amounts below are based on estimates. Chubb's insurance and reinsurance subsidiaries are subject to insurance laws and regulations in the jurisdictions in which they operate. These regulations include restrictions that limit the amount of dividends or other distributions, such as loans or cash advances, available to shareholders without prior approval of the local insurance regulatory authorities. The amount of dividends available to be paid in 2018 without prior approval totals $5.8 billion . The statutory capital and surplus of our insurance subsidiaries met regulatory requirements for 2017 , 2016 , and 2015 . The minimum amounts of statutory capital and surplus necessary to satisfy regulatory requirements was $23.9 billion and $ 22.2 billion for December 31, 2017 and 2016 , respectively. These minimum regulatory capital requirements were significantly lower than the corresponding amounts required by the rating agencies which review Chubb’s insurance and reinsurance subsidiaries. The following tables present the combined statutory capital and surplus and statutory net income (loss) of our Property and casualty and Life subsidiaries: December 31 (in millions of U.S. dollars) 2017 2016 Statutory capital and surplus Property and casualty $ 40,498 $ 38,734 Life $ 1,507 $ 1,225 Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Statutory net income (loss) Property and casualty $ 8,123 $ 6,903 $ 2,712 Life $ 74 $ 55 $ (148 ) Several insurance subsidiaries follow accounting practices prescribed or permitted by the jurisdiction of domicile that differ from the applicable local statutory practice. The application of prescribed or permitted accounting practices does not have a material impact on Chubb's statutory surplus and income. As prescribed by the Restructuring discussed previously in Note 7 , certain of our U.S. subsidiaries discount certain A&E liabilities, which increased statutory capital and surplus by approximately $ 169 million and $155 million at December 31, 2017 and 2016 , respectively. Federal Insurance Company (Federal), a direct subsidiary of Chubb INA Holdings Inc., has a permitted practice granted by the Indiana Department of Insurance that relates to its investments in foreign subsidiaries and affiliates. Under Statement of Statutory Accounting Principles No. 97, Investments in Subsidiary, Controlled and Affiliated Entities, A Replacement of SSAP No. 88, in order for a reporting entity to admit its investments in foreign subsidiaries and affiliates, audited financial statements of the subsidiary or affiliate must be obtained to support the carrying value. Such financial statements must be prepared in accordance with U.S. GAAP, or alternatively, in accordance with the local statutory requirements in the subsidiary’s or affiliate’s country of domicile, with an audited footnote reconciliation of net income and shareholder’s equity as reported to a U.S. GAAP basis. With the explicit permission of the Indiana Department of Insurance, Federal obtains audited financial statements for its admitted foreign subsidiaries and affiliates, which had an aggregate carrying value of $ 156 million and $308 million at December 31, 2017 and 2016, respectively, prepared in accordance with their respective local statutory requirements and supplemented with a separate unaudited reconciliation of shareholder’s equity as reported to a U.S. GAAP basis.

Information provided in connect

Information provided in connection with outstanding debt of subsidiaries	12 Months Ended
	Dec. 31, 2017
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Abstract]
Information provided in connection with outstanding debt of subsidiaries	Information provided in connection with outstanding debt of subsidiaries The following tables present condensed consolidating financial information at December 31, 2017 and December 31, 2016 , and for the years ended December 31, 2017 , 2016 , and 2015 for Chubb Limited (Parent Guarantor) and Chubb INA Holdings Inc. (Subsidiary Issuer). The Subsidiary Issuer is an indirect 100 percent-owned subsidiary of the Parent Guarantor. The Parent Guarantor fully and unconditionally guarantees certain of the debt of the Subsidiary Issuer. Condensed consolidating financial information of the Parent Guarantor and Subsidiary Issuer are presented on the equity method of accounting. The revenues and expenses and cash flows of the subsidiaries of the Subsidiary Issuer are presented in the Other Chubb Limited Subsidiaries column on a combined basis. Condensed Consolidating Balance Sheet at December 31, 2017 (in millions of U.S. dollars) Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated Assets Investments $ — $ 168 $ 102,276 $ — $ 102,444 Cash (1) 3 1 839 (115 ) 728 Insurance and reinsurance balances receivable — — 10,820 (1,486 ) 9,334 Reinsurance recoverable on losses and loss expenses — — 27,514 (12,480 ) 15,034 Reinsurance recoverable on policy benefits — — 1,194 (1,010 ) 184 Value of business acquired — — 326 — 326 Goodwill and other intangible assets — — 22,054 — 22,054 Investments in subsidiaries 41,909 51,165 — (93,074 ) — Due from subsidiaries and affiliates, net 9,639 — — (9,639 ) — Other assets 3 287 20,701 (4,073 ) 16,918 Total assets $ 51,554 $ 51,621 $ 185,724 $ (121,877 ) $ 167,022 Liabilities Unpaid losses and loss expenses $ — $ — $ 74,767 $ (11,588 ) $ 63,179 Unearned premiums — — 18,875 (3,659 ) 15,216 Future policy benefits — — 6,331 (1,010 ) 5,321 Due to subsidiaries and affiliates, net — 9,432 207 (9,639 ) — Affiliated notional cash pooling programs (1) — 115 — (115 ) — Repurchase agreements — — 1,408 — 1,408 Short-term debt — 1,013 — — 1,013 Long-term debt — 11,546 10 — 11,556 Trust preferred securities — 308 — — 308 Other liabilities 382 1,411 18,848 (2,792 ) 17,849 Total liabilities 382 23,825 120,446 (28,803 ) 115,850 Total shareholders’ equity 51,172 27,796 65,278 (93,074 ) 51,172 Total liabilities and shareholders’ equity $ 51,554 $ 51,621 $ 185,724 $ (121,877 ) $ 167,022 (1) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Balance Sheet at December 31, 2016 (in millions of U.S. dollars) Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated Assets Investments $ 27 $ 485 $ 98,582 $ — $ 99,094 Cash (1) 1 1 1,965 (982 ) 985 Insurance and reinsurance balances receivable — — 10,498 (1,528 ) 8,970 Reinsurance recoverable on losses and loss expenses — — 24,496 (10,919 ) 13,577 Reinsurance recoverable on policy benefits — — 1,153 (971 ) 182 Value of business acquired — — 355 — 355 Goodwill and other intangible assets — — 22,095 — 22,095 Investments in subsidiaries 38,408 49,509 — (87,917 ) — Due from subsidiaries and affiliates, net 10,482 — — (10,482 ) — Other assets 3 436 18,442 (4,353 ) 14,528 Total assets $ 48,921 $ 50,431 $ 177,586 $ (117,152 ) $ 159,786 Liabilities Unpaid losses and loss expenses $ — $ — $ 70,683 $ (10,143 ) $ 60,540 Unearned premiums — — 18,538 (3,759 ) 14,779 Future policy benefits — — 6,007 (971 ) 5,036 Due to subsidiaries and affiliates, net — 10,209 273 (10,482 ) — Affiliated notional cash pooling programs (1) 363 619 — (982 ) — Repurchase agreements — — 1,403 — 1,403 Short-term debt — 500 — — 500 Long-term debt — 12,599 11 — 12,610 Trust preferred securities — 308 — — 308 Other liabilities 283 1,582 17,368 (2,898 ) 16,335 Total liabilities 646 25,817 114,283 (29,235 ) 111,511 Total shareholders’ equity 48,275 24,614 63,303 (87,917 ) 48,275 Total liabilities and shareholders’ equity $ 48,921 $ 50,431 $ 177,586 $ (117,152 ) $ 159,786 (1) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Statements of Operations and Comprehensive Income For the Year Ended December 31, 2017 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net premiums written $ — $ — $ 29,244 $ — $ 29,244 Net premiums earned — — 29,034 — 29,034 Net investment income 4 14 3,107 — 3,125 Equity in earnings of subsidiaries 3,640 2,424 — (6,064 ) — Net realized gains (losses) including OTTI — (25 ) 109 — 84 Losses and loss expenses — — 18,454 — 18,454 Policy benefits — — 676 — 676 Policy acquisition costs and administrative expenses 75 40 8,499 — 8,614 Interest (income) expense (332 ) 847 92 — 607 Other (income) expense (12 ) 93 (481 ) — (400 ) Amortization of purchased intangibles — — 260 — 260 Chubb integration expenses 32 69 209 — 310 Income tax expense (benefit) 20 (742 ) 583 — (139 ) Net income $ 3,861 $ 2,106 $ 3,958 $ (6,064 ) $ 3,861 Comprehensive income $ 4,718 $ 3,075 $ 4,430 $ (7,505 ) $ 4,718 Condensed Consolidating Statements of Operations and Comprehensive Income For the Year Ended December 31, 2016 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net premiums written $ — $ — $ 28,145 $ — $ 28,145 Net premiums earned — — 28,749 — 28,749 Net investment income 3 11 2,851 — 2,865 Equity in earnings of subsidiaries 3,901 2,555 — (6,456 ) — Net realized gains (losses) including OTTI — 3 (148 ) — (145 ) Losses and loss expenses — — 16,052 — 16,052 Policy benefits — — 588 — 588 Policy acquisition costs and administrative expenses 64 82 8,839 — 8,985 Interest (income) expense (353 ) 908 50 — 605 Other (income) expense (25 ) 35 (232 ) — (222 ) Amortization of purchased intangibles — — 19 — 19 Chubb integration expenses 62 126 304 — 492 Income tax expense (benefit) 21 (416 ) 1,210 — 815 Net income $ 4,135 $ 1,834 $ 4,622 $ (6,456 ) $ 4,135 Comprehensive income $ 4,556 $ 2,001 $ 5,045 $ (7,046 ) $ 4,556 Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) For the Year Ended December 31, 2015 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net premiums written $ — $ — $ 17,713 $ — $ 17,713 Net premiums earned — — 17,213 — 17,213 Net investment income 3 4 2,187 — 2,194 Equity in earnings of subsidiaries 2,673 1,038 — (3,711 ) — Net realized gains (losses) including OTTI — (9 ) (411 ) — (420 ) Losses and loss expenses — — 9,484 — 9,484 Policy benefits — — 543 — 543 Policy acquisition costs and administrative expenses 63 28 5,120 — 5,211 Interest (income) expense (32 ) 302 30 — 300 Other (income) expense (208 ) (4 ) 161 — (51 ) Amortization of purchased intangibles — — 171 — 171 Chubb Integration Expense 3 29 1 — 33 Income tax expense (benefit) 16 (349 ) 795 — 462 Net income $ 2,834 $ 1,027 $ 2,684 $ (3,711 ) $ 2,834 Comprehensive income (loss) $ 908 $ (192 ) $ 757 $ (565 ) $ 908 Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2017 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net cash flows from operating activities $ 781 $ 1,648 $ 4,598 $ (2,524 ) $ 4,503 Cash flows from investing activities Purchases of fixed maturities available for sale — (9 ) (25,738 ) — (25,747 ) Purchases of fixed maturities held to maturity — — (352 ) — (352 ) Purchases of equity securities — — (173 ) — (173 ) Sales of fixed maturities available for sale — 99 13,156 — 13,255 Sales of equity securities — — 187 — 187 Maturities and redemptions of fixed maturities available for sale — 29 10,396 — 10,425 Maturities and redemptions of fixed maturities held to maturity — — 879 — 879 Net change in short-term investments — 189 (726 ) — (537 ) Net derivative instruments settlements — (15 ) (250 ) — (265 ) Other — (10 ) (104 ) — (114 ) Net cash flows (used for) from investing activities — 283 (2,725 ) — (2,442 ) Cash flows from financing activities Dividends paid on Common Shares (1,308 ) — — — (1,308 ) Common Shares repurchased — — (801 ) — (801 ) Proceeds from issuance of repurchase agreements — — 2,353 — 2,353 Repayment of long-term debt — (500 ) (1 ) — (501 ) Repayment of repurchase agreements — — (2,348 ) — (2,348 ) Proceeds from share-based compensation plans — — 151 — 151 Advances (to) from affiliates 892 (927 ) 35 — — Dividends to parent company — — (2,524 ) 2,524 — Net payments to affiliated notional cash pooling programs (1) (363 ) (504 ) — 867 — Policyholder contract deposits — — 442 — 442 Policyholder contract withdrawals — — (307 ) — (307 ) Net cash flows used for financing activities (779 ) (1,931 ) (3,000 ) 3,391 (2,319 ) Effect of foreign currency rate changes on cash and cash equivalents — — 1 — 1 Net increase (decrease) in cash 2 — (1,126 ) 867 (257 ) Cash – beginning of year (1) 1 1 1,965 (982 ) 985 Cash – end of year (1) $ 3 $ 1 $ 839 $ (115 ) $ 728 (1) Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2016 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net cash flows from operating activities $ 3,618 $ 4,305 $ 5,536 $ (8,167 ) $ 5,292 Cash flows from investing activities Purchases of fixed maturities available for sale — (156 ) (30,659 ) — (30,815 ) Purchases of fixed maturities held to maturity — — (282 ) — (282 ) Purchases of equity securities — — (146 ) — (146 ) Sales of fixed maturities available for sale — 66 16,611 — 16,677 Sales of equity securities — — 1,000 — 1,000 Maturities and redemptions of fixed maturities available for sale — 66 9,283 — 9,349 Maturities and redemptions of fixed maturities held to maturity — — 958 — 958 Net change in short-term investments — 7,943 4,407 — 12,350 Net derivative instruments settlements — (9 ) (159 ) — (168 ) Acquisition of subsidiaries (net of cash acquired of $71) — (14,282 ) 34 — (14,248 ) Capital contribution (2,330 ) (215 ) (2,330 ) 4,875 — Other — (3 ) 13 — 10 Net cash flows used for investing activities (2,330 ) (6,590 ) (1,270 ) 4,875 (5,315 ) Cash flows from financing activities Dividends paid on Common Shares (1,173 ) — — — (1,173 ) Proceeds from issuance of repurchase agreements — — 2,310 — 2,310 Repayment of repurchase agreements — — (2,311 ) — (2,311 ) Proceeds from share-based compensation plans — — 167 — 167 Advances (to) from affiliates 404 (572 ) 168 — — Dividends to parent company — — (8,167 ) 8,167 — Capital contribution — 2,330 2,545 (4,875 ) — Net proceeds from (payments to) affiliated notional cash pooling programs (1) (519 ) 530 — (11 ) — Policyholder contract deposits — — 522 — 522 Policyholder contract withdrawals — — (253 ) — (253 ) Other — (4 ) — — (4 ) Net cash flows (used for) from financing activities (1,288 ) 2,284 (5,019 ) 3,281 (742 ) Effect of foreign currency rate changes on cash and cash equivalents — — (25 ) — (25 ) Net decrease in cash — (1 ) (778 ) (11 ) (790 ) Cash – beginning of year (1) 1 2 2,743 (971 ) 1,775 Cash – end of year (1) $ 1 $ 1 $ 1,965 $ (982 ) $ 985 (1) Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2015 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net cash flows from operating activities $ 3,125 $ 682 $ 3,836 $ (3,779 ) $ 3,864 Cash flows from investing activities Purchases of fixed maturities available for sale — — (16,053 ) (18 ) (16,071 ) Purchases of fixed maturities held to maturity — — (62 ) — (62 ) Purchases of equity securities — — (158 ) — (158 ) Sales of fixed maturities available for sale — — 10,814 — 10,814 Sales of equity securities — — 183 — 183 Maturities and redemptions of fixed maturities available for sale — — 6,567 — 6,567 Maturities and redemptions of fixed maturities held to maturity — — 669 — 669 Net change in short-term investments — (7,588 ) (628 ) — (8,216 ) Net derivative instruments settlements — (9 ) (12 ) — (21 ) Acquisition of subsidiaries (net of cash acquired of $629) — — 264 — 264 Capital contribution (2,670 ) (625 ) (2,791 ) 6,086 — Other — (25 ) (256 ) 18 (263 ) Net cash flows used for investing activities (2,670 ) (8,247 ) (1,463 ) 6,086 (6,294 ) Cash flows from financing activities Dividends paid on Common Shares (862 ) — — — (862 ) Common Shares repurchased — — (758 ) — (758 ) Proceeds from issuance of long-term debt — 6,090 — — 6,090 Proceeds from issuance of repurchase agreements — — 2,029 — 2,029 Repayment of long-term debt — (1,150 ) — — (1,150 ) Repayment of repurchase agreements — — (2,027 ) — (2,027 ) Proceeds from share-based compensation plans — — 131 — 131 Advances (to) from affiliates (228 ) 95 133 — — Dividends to parent company — — (3,779 ) 3,779 — Capital contribution — 2,791 3,295 (6,086 ) — Net proceeds from (payments to) affiliated notional cash pooling programs (1) 636 (220 ) — (416 ) — Policyholder contract deposits — — 503 — 503 Policyholder contract withdrawals — — (221 ) — (221 ) Other — (40 ) — — (40 ) Net cash flows (used for) from financing activities (454 ) 7,566 (694 ) (2,723 ) 3,695 Effect of foreign currency rate changes on cash and cash equivalents — — (145 ) — (145 ) Net increase in cash 1 1 1,534 (416 ) 1,120 Cash – beginning of year (1) — 1 1,209 (555 ) 655 Cash – end of year (1) $ 1 $ 2 $ 2,743 $ (971 ) $ 1,775 (1) Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Condensed Unaudited Quarterly F

Condensed Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Condensed unaudited quarterly financial data	Condensed unaudited quarterly financial data Three Months Ended March 31 June 30 September 30 December 31 (in millions of U.S. dollars, except per share data) 2017 2017 2017 2017 Net premiums earned $ 6,772 $ 7,237 $ 7,807 $ 7,218 Net investment income 745 770 813 797 Net realized gains (losses) including OTTI (7 ) 101 (10 ) — Total revenues $ 7,510 $ 8,108 $ 8,610 $ 8,015 Losses and loss expenses $ 3,789 $ 4,146 $ 6,247 $ 4,272 Policy benefits $ 168 $ 163 $ 169 $ 176 Net income (loss) $ 1,093 $ 1,305 $ (70 ) $ 1,533 Basic earnings (loss) per share $ 2.33 $ 2.79 $ (0.15 ) $ 3.29 Diluted earnings (loss) per share $ 2.31 $ 2.77 $ (0.15 ) $ 3.27 Net income for the three months ended September 30, 2017 included after-tax catastrophe losses of $1.5 billion . Net income for the three months ended December 31, 2017 included a one-time income tax transition benefit of $450 million related to the 2017 Tax Act. Refer to Note 8 for additional information. Three Months Ended March 31 June 30 September 30 December 31 (in millions of U.S. dollars, except per share data) 2016 2016 2016 2016 Net premiums earned $ 6,597 $ 7,405 $ 7,688 $ 7,059 Net investment income 674 708 739 744 Net realized gains (losses) including OTTI (394 ) (216 ) 100 365 Total revenues $ 6,877 $ 7,897 $ 8,527 $ 8,168 Losses and loss expenses $ 3,674 $ 4,254 $ 4,269 $ 3,855 Policy benefits $ 126 $ 146 $ 155 $ 161 Net income $ 439 $ 726 $ 1,360 $ 1,610 Basic earnings per share $ 0.98 $ 1.55 $ 2.90 $ 3.44 Diluted earnings per share $ 0.97 $ 1.54 $ 2.88 $ 3.41

Schedule I

Schedule I	12 Months Ended
	Dec. 31, 2017
Summary of Investments, Other than Investments in Related Parties [Abstract]
Schedule I: SUMMARY OF INVESTEMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES	SUMMARY OF INVESTMENTS – OTHER THAN INVESTMENTS IN RELATED PARTIES December 31, 2017 (in millions of U.S. dollars) Cost or Amortized Cost Fair Value Amount at Which Shown in the Balance Sheet Fixed maturities available for sale U.S. Treasury and agency $ 3,701 $ 3,698 $ 3,698 Foreign 20,514 21,030 21,030 Corporate securities 23,453 23,996 23,996 Mortgage-backed securities 15,279 15,290 15,290 States, municipalities, and political subdivisions 14,888 14,925 14,925 Total fixed maturities available for sale 77,835 78,939 78,939 Fixed maturities held to maturity U.S. Treasury and agency 908 915 908 Foreign 1,738 1,757 1,738 Corporate securities 3,159 3,219 3,159 Mortgage-backed securities 2,724 2,742 2,724 States, municipalities, and political subdivisions 5,806 5,841 5,806 Total fixed maturities held to maturity 14,335 14,474 14,335 Equity securities Industrial, miscellaneous, and all other 737 937 937 Short-term investments 3,561 3,561 3,561 Other investments (1) 4,331 4,586 4,586 Total investments - other than investments in related parties $ 100,799 $ 102,497 $ 102,358 (1) Excludes $86 million of related party investments.

Schedule II

Schedule II	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT	CONDENSED FINANCIAL INFORMATION OF REGISTRANT BALANCE SHEETS (Parent Company Only) December 31 December 31 (in millions of U.S. dollars) 2017 2016 Assets Investments in subsidiaries and affiliates on equity basis $ 41,909 $ 38,408 Short-term investments — 2 Other investments, at cost — 25 Total investments 41,909 38,435 Cash 3 1 Due from subsidiaries and affiliates, net 9,639 10,482 Other assets 3 3 Total assets $ 51,554 $ 48,921 Liabilities Affiliated notional cash pooling programs (1) $ — $ 363 Accounts payable, accrued expenses, and other liabilities 382 283 Total liabilities 382 646 Shareholders' equity Common Shares 11,121 11,121 Common Shares in treasury (1,944 ) (1,480 ) Additional paid-in capital 13,978 15,335 Retained earnings 27,474 23,613 Accumulated other comprehensive income (loss) 543 (314 ) Total shareholders' equity 51,172 48,275 Total liabilities and shareholders' equity $ 51,554 $ 48,921 (1) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. The condensed financial information should be read in conjunction with the consolidated financial statements and notes thereto. CONDENSED FINANCIAL INFORMATION OF REGISTRANT STATEMENTS OF OPERATIONS (Parent Company Only) Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Revenues Investment income, including interest income $ 336 $ 356 $ 35 Equity in net income of subsidiaries and affiliates 3,640 3,901 2,673 3,976 4,257 2,708 Expenses Administrative and other (income) expense 63 39 (145 ) Chubb integration expenses 32 62 3 Income tax expense 20 21 16 115 122 (126 ) Net income $ 3,861 $ 4,135 $ 2,834 Comprehensive income $ 4,718 $ 4,556 $ 908 The condensed financial information should be read in conjunction with the consolidated financial statements and notes thereto. CONDENSED FINANCIAL INFORMATION OF REGISTRANT STATEMENTS OF CASH FLOWS (Parent Company Only) Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Net cash flows from operating activities (1) $ 781 $ 3,618 $ 3,125 Cash flows from investing activities Capital contribution — (2,330 ) (2,670 ) Net cash flows used for investing activities — (2,330 ) (2,670 ) Cash flows from financing activities Dividends paid on Common Shares (1,308 ) (1,173 ) (862 ) Advances (to) from affiliates 892 404 (228 ) Net proceeds from (payments to) affiliated notional cash pooling programs (2) (363 ) (519 ) 636 Net cash flows used for financing activities (779 ) (1,288 ) (454 ) Net increase in cash 2 — 1 Cash – beginning of year 1 1 — Cash – end of year $ 3 $ 1 $ 1 (1) Includes cash dividends received from subsidiaries of $450 million , $3.4 billion , and $2.9 billion in 2017, 2016, and 2015, respectively. (2) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. The condensed financial information should be read in conjunction with the consolidated financial statements and notes thereto.

Schedule IV

Schedule IV	12 Months Ended
	Dec. 31, 2017
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]
SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE	SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE Premiums Earned For the years ended December 31, 2017, 2016, and 2015 (in millions of U.S. dollars, except for percentages) Direct Amount Ceded To Other Companies Assumed From Other Companies Net Amount Percentage of Amount Assumed to Net 2017 Property and Casualty $ 27,774 $ 6,650 $ 2,891 $ 24,015 12 % Accident and Health 4,167 349 221 4,039 5 % Life 841 81 220 980 22 % Total $ 32,782 $ 7,080 $ 3,332 $ 29,034 11 % 2016 Property and Casualty $ 26,919 $ 6,407 $ 3,284 $ 23,796 14 % Accident and Health 4,047 315 219 3,951 6 % Life 845 84 241 1,002 24 % Total $ 31,811 $ 6,806 $ 3,744 $ 28,749 13 % 2015 Property and Casualty $ 14,895 $ 5,373 $ 3,259 $ 12,781 25 % Accident and Health 3,684 351 168 3,501 5 % Life 776 94 249 931 27 % Total $ 19,355 $ 5,818 $ 3,676 $ 17,213 21 %

Schedule VI

Schedule VI	12 Months Ended
	Dec. 31, 2017
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
SUPPLEMENTARY INFORMATION CONCERNING PROPERTY AND CASUALTY OPERATIONS	SUPPLEMENTARY INFORMATION CONCERNING PROPERTY AND CASUALTY OPERATIONS As of and for the years ended December 31, 2017, 2016, and 2015 (in millions of U.S. dollars) Deferred Policy Acquisition Costs Net Reserves for Unpaid Losses and Loss Expenses Unearned Premiums Net Premiums Earned Net Investment Income Net Losses and Loss Expenses Incurred Related to Amortization of Deferred Policy Acquisition Costs Net Paid Losses and Loss Expenses Net Premiums Written Current Year Prior Year 2017 $ 3,805 $ 49,165 $ 15,216 $ 28,054 $ 2,890 $ 19,391 $ (937 ) $ 5,519 $ 17,448 $ 28,225 2016 $ 3,537 $ 47,832 $ 14,779 $ 27,747 $ 2,656 $ 17,256 $ (1,204 ) $ 5,654 $ 15,715 $ 27,074 2015 $ 2,219 $ 26,562 $ 8,439 $ 16,282 $ 2,007 $ 10,030 $ (546 ) $ 2,692 $ 9,665 $ 16,734

Summary of significant accoun34

Summary of significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Basis of presentation	Basis of presentation Chubb Limited is a holding company incorporated in Zurich, Switzerland. Chubb Limited, through its subsidiaries, provides a broad range of insurance and reinsurance products to insureds worldwide. Our results are reported through the following business segments: North America Commercial P&C Insurance, North America Personal P&C Insurance, North America Agricultural Insurance, Overseas General Insurance, Global Reinsurance, and Life Insurance. Refer to Note 15 for additional information. The accompanying consolidated financial statements, which include the accounts of Chubb Limited and its subsidiaries (collectively, Chubb, we, us, or our), have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and, in the opinion of management, reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of the results and financial position for such periods. All significant intercompany accounts and transactions, including internal reinsurance transactions, have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Amounts included in the Consolidated financial statements reflect our best estimates and assumptions; actual amounts could differ materially from these estimates. Chubb's principal estimates include: • unpaid loss and loss expense reserves, including long-tail asbestos and environmental (A&E) reserves; • future policy benefits reserves; • the valuation of value of business acquired (VOBA) and amortization of deferred policy acquisition costs and VOBA; • reinsurance recoverable, including a provision for uncollectible reinsurance; • the assessment of risk transfer for certain structured insurance and reinsurance contracts; • the valuation of the investment portfolio and assessment of OTTI; • the valuation of deferred tax assets; • the valuation of derivative instruments related to guaranteed living benefits (GLB); • the valuation and amortization of purchased intangibles; and • the assessment of goodwill for impairment.
Premiums	Premiums Premiums are generally recorded as written upon inception of the policy. For multi-year policies for which premiums written are payable in annual installments, only the current annual premium is included as written at policy inception due to the ability of the insured/reinsured to commute or cancel coverage within the policy term. The remaining annual premiums are recorded as written at each successive anniversary date within the multi-year term. For P&C insurance and reinsurance products, premiums written are primarily earned on a pro-rata basis over the policy terms to which they relate. Unearned premiums represent the portion of premiums written applicable to the unexpired portion of the policies in force. For retrospectively-rated policies, written premiums are adjusted to reflect expected ultimate premiums consistent with changes to incurred losses, or other measures of exposure as stated in the policy, and earned over the policy coverage period. For retrospectively-rated multi-year policies, premiums recognized in the current period are computed using a with-and-without method as the difference between the ceding enterprise's total contract costs before and after the experience under the contract at the reporting date. Accordingly, for retrospectively-rated multi-year policies, additional premiums are generally written and earned when losses are incurred. Mandatory reinstatement premiums assessed on reinsurance policies are earned in the period of the loss event that gave rise to the reinstatement premiums. All remaining unearned premiums are recognized over the remaining coverage period. Premiums from long-duration contracts such as certain traditional term life, whole life, endowment, and long-duration personal accident and health (A&H) policies are generally recognized as revenue when due from policyholders. Traditional life policies include those contracts with fixed and guaranteed premiums and benefits. Benefits and expenses are matched with income to result in the recognition of profit over the life of the contracts. Retroactive loss portfolio transfer (LPT) contracts in which the insured loss events occurred prior to contract inception are evaluated to determine whether they meet criteria for reinsurance accounting. If reinsurance accounting is appropriate, written premiums are fully earned and corresponding losses and loss expenses recognized at contract inception. These contracts can cause significant variances in gross premiums written, net premiums written, net premiums earned, and net incurred losses in the years in which they are written. Reinsurance contracts sold not meeting criteria for reinsurance accounting are recorded using the deposit method as described below in Note 1 k). Reinsurance premiums assumed are based on information provided by ceding companies supplemented by our own estimates of premium when we have not received ceding company reports. Estimates are reviewed and adjustments are recorded in the period in which they are determined. Premiums are earned over the coverage terms of the related reinsurance contracts and range from one to three years.
Deferred policy acquisition costs and value of business acquired	Deferred policy acquisition costs and value of business acquired Policy acquisition costs consist of commissions (direct and ceded), premium taxes, and certain underwriting costs related directly to the successful acquisition of new or renewal insurance contracts. A VOBA intangible asset is established upon the acquisition of blocks of long-duration contracts in a business combination and represents the present value of estimated net cash flows for the contracts in force at the acquisition date. Acquisition costs and VOBA, collectively policy acquisition costs, are deferred and amortized. Amortization is recorded in Policy acquisition costs in the Consolidated statements of operations. Policy acquisition costs on P&C contracts are generally amortized ratably over the period in which premiums are earned. Policy acquisition costs on traditional long-duration contracts are amortized over the estimated life of the contracts, generally in proportion to premium revenue recognized based upon the same assumptions used in estimating the liability for future policy benefits. For non-traditional long-duration contracts, we amortize policy acquisition costs over the expected life of the contracts in proportion to expected gross profits. The effect of changes in estimates of expected gross profits is reflected in the period the estimates are revised. Policy acquisition costs are reviewed to determine if they are recoverable from future income, including investment income. Unrecoverable policy acquisition costs are expensed in the period identified. Advertising costs are expensed as incurred except for direct-response campaigns that qualify for cost deferral, principally related to long-duration A&H business produced by the Overseas General Insurance segment, which are deferred and recognized as a component of Policy acquisition costs . For individual direct-response marketing campaigns that we can demonstrate have specifically resulted in incremental sales to customers and such sales have probable future economic benefits, incremental costs directly related to the marketing campaigns are capitalized as Deferred policy acquisition costs. Deferred policy acquisition costs, including deferred marketing costs, are reviewed regularly for recoverability from future income, including investment income, and amortized in proportion to premium revenue recognized, primarily over a ten -year period, the expected economic future benefit period based upon the same assumptions used in estimating the liability for future policy benefits. The expected future benefit period is evaluated periodically based on historical results and adjusted prospectively. The amount of deferred marketing costs reported in Deferred policy acquisition costs in the Consolidated balance sheets was $ 271 million and $ 256 million at December 31, 2017 and 2016 , respectively. Amortization expense for deferred marketing costs was $ 116 million, $ 92 million, and $ 78 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.
Reinsurance	Reinsurance Chubb assumes and cedes reinsurance with other insurance companies to provide greater diversification of business and minimize the net loss potential arising from large risks. Ceded reinsurance contracts do not relieve Chubb of its primary obligation to policyholders. For both ceded and assumed reinsurance, risk transfer requirements must be met in order to account for a contract as reinsurance, principally resulting in the recognition of cash flows under the contract as premiums and losses. To meet risk transfer requirements, a reinsurance contract must include insurance risk, consisting of both underwriting and timing risk, and a reasonable possibility of a significant loss for the assuming entity. To assess risk transfer for certain contracts, Chubb generally develops expected discounted cash flow analyses at contract inception. Deposit accounting is used for contracts that do not meet risk transfer requirements. Deposit accounting requires that consideration received or paid be recorded in the balance sheet as opposed to recording premiums written or losses incurred in the statement of operations. Non-refundable fees on deposit contracts are earned based on the terms of the contract described below in Note 1 k). Reinsurance recoverable includes balances due from reinsurance companies for paid and unpaid losses and loss expenses and future policy benefits that will be recovered from reinsurers, based on contracts in force. The method for determining the reinsurance recoverable on unpaid losses and loss expenses incurred but not reported (IBNR) involves actuarial estimates consistent with those used to establish the associated liability for unpaid losses and loss expenses as well as a determination of Chubb's ability to cede unpaid losses and loss expenses under the terms of the reinsurance agreement. Reinsurance recoverable is presented net of a provision for uncollectible reinsurance determined based upon a review of the financial condition of reinsurers and other factors. The provision for uncollectible reinsurance is based on an estimate of the reinsurance recoverable balance that will ultimately be unrecoverable due to reinsurer insolvency, a contractual dispute, or any other reason. The valuation of this provision includes several judgments including certain aspects of the allocation of reinsurance recoverable on IBNR claims by reinsurer and a default analysis to estimate uncollectible reinsurance. The primary components of the default analysis are reinsurance recoverable balances by reinsurer, net of collateral, and default factors used to determine the portion of a reinsurer's balance deemed uncollectible. The definition of collateral for this purpose requires some judgment and is generally limited to assets held in a Chubb-only beneficiary trust, letters of credit, and liabilities held with the same legal entity for which Chubb believes there is a contractual right of offset. The determination of the default factor is principally based on the financial strength rating of the reinsurer. Default factors require considerable judgment and are determined using the current financial strength rating, or rating equivalent, of each reinsurer as well as other key considerations and assumptions. The more significant considerations include, but are not necessarily limited to, the following: • For reinsurers that maintain a financial strength rating from a major rating agency, and for which recoverable balances are considered representative of the larger population (i.e., default probabilities are consistent with similarly rated reinsurers and payment durations conform to averages), the financial rating is based on a published source and the default factor is based on published default statistics of a major rating agency applicable to the reinsurer's particular rating class. When a recoverable is expected to be paid in a brief period of time by a highly rated reinsurer, such as certain property catastrophe claims, a default factor may not be applied; • For balances recoverable from reinsurers that are both unrated by a major rating agency and for which management is unable to determine a credible rating equivalent based on a parent, affiliate, or peer company, we determine a rating equivalent based on an analysis of the reinsurer that considers an assessment of the creditworthiness of the particular entity, industry benchmarks, or other factors as considered appropriate. We then apply the applicable default factor for that rating class. For balances recoverable from unrated reinsurers for which the ceded reserve is below a certain threshold, we generally apply a default factor of 34 percent, consistent with published statistics of a major rating agency; • For balances recoverable from reinsurers that are either insolvent or under regulatory supervision, we establish a default factor and resulting provision for uncollectible reinsurance based on reinsurer-specific facts and circumstances. Upon initial notification of an insolvency, we generally recognize an expense for a substantial portion of all balances outstanding, net of collateral, through a combination of write-offs of recoverable balances and increases to the provision for uncollectible reinsurance. When regulatory action is taken on a reinsurer, we generally recognize a default factor by estimating an expected recovery on all balances outstanding, net of collateral. When sufficient credible information becomes available, we adjust the provision for uncollectible reinsurance by establishing a default factor pursuant to information received; and • For other recoverables, management determines the provision for uncollectible reinsurance based on the specific facts and circumstances. The methods used to determine the reinsurance recoverable balance and related provision for uncollectible reinsurance are regularly reviewed and updated, and any resulting adjustments are reflected in earnings in the period identified. Prepaid reinsurance premiums represent the portion of premiums ceded to reinsurers applicable to the unexpired coverage terms of the reinsurance contracts in-force. The value of reinsurance business assumed of $ 18 million and $ 20 million at December 31, 2017 and 2016 , respectively, included in Other assets in the accompanying Consolidated balance sheets, represents the excess of estimated ultimate value of the liabilities assumed under retroactive reinsurance contracts over consideration received. The value of reinsurance business assumed is amortized and recorded to Losses and loss expenses based on the payment pattern of the losses assumed and ranges between 9 and 40 years. The unamortized value is reviewed regularly to determine if it is recoverable based upon the terms of the contract, estimated losses and loss expenses, and anticipated investment income. Unrecoverable amounts are expensed in the period identified.
Investments	Investments Fixed maturities are classified as either available for sale or held to maturity. The available for sale portfolio is reported at fair value. The held to maturity portfolio includes securities for which we have the ability and intent to hold to maturity or redemption and is reported at amortized cost. Equity securities are classified as available for sale and are recorded at fair value. Short-term investments comprise securities due to mature within one year of the date of purchase and are recorded at fair value which typically approximates cost. Short-term investments include certain cash and cash equivalents, which are part of investment portfolios under the management of external investment managers. Other investments principally comprise life insurance policies, policy loans, trading securities, other direct equity investments, investment funds, and limited partnerships. • Life insurance policies are carried at policy cash surrender value and income is recorded in Other income (expense). • Policy loans are carried at outstanding balance and interest income is recorded to Net investment income. • Trading securities are recorded on a trade date basis and carried at fair value. Unrealized gains and losses on trading securities are reflected in Other (income) expense. • Other investments over which Chubb can exercise significant influence are accounted for using the equity method and income is recorded in Other (income) expense. • All other investments over which Chubb cannot exercise significant influence are carried at fair value with changes in fair value recognized through OCI. For these investments, investment income is recognized in Net investment income and realized gains are recognized as related distributions are received. • Partially-owned investment companies comprise entities in which we hold an ownership interest in excess of three percent. These investments as well as Chubb's investments in investment funds where our ownership interest is in excess of three percent are accounted for under the equity method because Chubb exerts significant influence. These investments apply investment company accounting to determine operating results, and Chubb retains the investment company accounting in applying the equity method. This means that investment income, realized gains or losses, and unrealized gains or losses are included in the portion of equity earnings reflected in Other (income) expense. As a result of the timing of the receipt of valuation data from the investment managers, these investments are generally reported on a three month lag. Investments in partially-owned insurance companies primarily represent direct investments in which Chubb has significant influence and, as such, meet the requirements for equity accounting. We report our share of the net income or loss of the partially-owned insurance companies in Other (income) expense. Realized gains or losses on sales of investments are determined on a first-in, first-out basis. Unrealized appreciation (depreciation) on investments is included as a separate component of AOCI in Shareholders' equity. We regularly review our investments for OTTI. Refer to Note 3 for additional information. With respect to securities where the decline in value is determined to be temporary and the security's value is not written down, a subsequent decision may be made to sell that security and realize a loss. Subsequent decisions on security sales are the result of changing or unforeseen facts and circumstances (i.e., arising from a large insured loss such as a catastrophe), deterioration of the creditworthiness of the issuer or its industry, or changes in regulatory requirements. We believe that subsequent decisions to sell such securities are consistent with the classification of the majority of the portfolio as available for sale. We use derivative instruments including futures, options, swaps, and foreign currency forward contracts for the purpose of managing certain investment portfolio risks and exposures. Refer to Note 10 for additional information. Derivatives are reported at fair value and are recorded in the accompanying Consolidated balance sheets in either Accounts payable, accrued expenses, and other liabilities or Other assets with changes in fair value included in Net realized gains (losses) in the Consolidated statements of operations. Collateral held by brokers equal to a percentage of the total value of open futures contracts is included in the investment portfolio. Net investment income includes interest and dividend income and amortization of fixed maturity market premiums and discounts and is net of investment management and custody fees. In addition, net investment income includes the amortization of the fair value adjustment related to the acquired invested assets of Chubb Corp. An adjustment of $1,652 million related to the fair value of Chubb Corp’s fixed maturities securities was recorded (fair value adjustment) at the date of acquisition. At December 31, 2017, the remaining balance of this fair value adjustment was $858 million which is expected to amortize over the next four years; however, the estimate could vary materially based on current market conditions, bond calls, and the duration of the acquired investment portfolio. In addition, sales of these acquired fixed maturities would also reduce the fair value adjustment balance. For mortgage-backed securities, and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any adjustments required due to the resultant change in effective yields and maturities are recognized prospectively. Prepayment fees or call premiums that are only payable when a security is called prior to its maturity are earned when received and reflected in Net investment income. Chubb participates in a securities lending program operated by a third-party banking institution whereby certain assets are loaned to qualified borrowers and from which we earn an incremental return. Borrowers provide collateral, in the form of either cash or approved securities, of 102 percent of the fair value of the loaned securities. Each security loan is deemed to be an overnight transaction. Cash collateral is invested in a collateral pool which is managed by the banking institution. The collateral pool is subject to written investment guidelines with key objectives which include the safeguard of principal and adequate liquidity to meet anticipated redemptions. The fair value of the loaned securities is monitored on a daily basis, with additional collateral obtained or refunded as the fair value of the loaned securities changes. The collateral is held by the third-party banking institution, and the collateral can only be accessed in the event that the institution borrowing the securities is in default under the lending agreement. As a result of these restrictions, we consider our securities lending activities to be non-cash investing and financing activities. An indemnification agreement with the lending agent protects us in the event a borrower becomes insolvent or fails to return any of the securities on loan. The fair value of the securities on loan is included in fixed maturities and equity securities. The securities lending collateral is reported as a separate line in the Consolidated balance sheets with a related liability reflecting our obligation to return the collateral plus interest. Similar to securities lending arrangements, securities sold under repurchase agreements, whereby Chubb sells securities and repurchases them at a future date for a predetermined price, are accounted for as collateralized investments and borrowings and are recorded at the contractual repurchase amounts plus accrued interest. Assets to be repurchased are the same, or substantially the same, as the assets transferred and the transferor, through right of substitution, maintains the right and ability to redeem the collateral on short notice. The fair value of the underlying securities is included in fixed maturities and equity securities. In contrast to securities lending programs, the use of cash received is not restricted. We report the obligation to return the cash as Repurchase agreements in the Consolidated balance sheets. Refer to Note 4 for a discussion on the determination of fair value for Chubb's various investment securities.
Cash	Cash Cash includes cash on hand and deposits with an original maturity of three months or less at time of purchase. Cash held by external money managers is included in Short-term investments. We have agreements with a third-party bank provider which implemented two international multi-currency notional cash pooling programs. In each program, participating Chubb entities establish deposit accounts in different currencies with the bank provider and each day the credit or debit balances in every account are notionally translated into a single currency (U.S. dollars) and then notionally pooled. The bank extends overdraft credit to any participating Chubb entity as needed, provided that the overall notionally-pooled balance of all accounts in each pool at the end of each day is at least zero. Actual cash balances are not physically converted and are not commingled between legal entities. Any overdraft balances incurred under this program by a Chubb entity would be guaranteed by Chubb Limited (up to $ 300 million in the aggregate). Our syndicated letter of credit facility allows for same day drawings to fund a net pool overdraft should participating Chubb entities overdraw contributed funds from the pool.
Goodwill and other intangible assets	Goodwill and Other intangible assets Goodwill represents the excess of the cost of acquisitions over the fair value of net assets acquired and is not amortized. Goodwill is assigned at acquisition to the applicable reporting unit of the acquired entities giving rise to the goodwill. Goodwill impairment tests are performed annually or more frequently if circumstances indicate a possible impairment. For goodwill impairment testing, we use a qualitative assessment to determine whether it is more likely than not (i.e., more than a 50 percent probability) that the fair value of a reporting unit is greater than its carrying amount. If our assessment indicates less than a 50 percent probability that fair value exceeds carrying value, we quantitatively estimate a reporting unit's fair value. Goodwill recorded in connection with investments in partially-owned insurance companies is recorded in Investments in partially-owned insurance companies and is also measured for impairment annually. Indefinite lived intangible assets are not subject to amortization. Finite lived intangible assets are amortized over their useful lives, generally ranging from 1 to 30 years. Intangible assets are regularly reviewed for indicators of impairment. Impairment is recognized if the carrying amount is not recoverable from its undiscounted cash flows and is measured as the difference between the carrying amount and fair value.
Unpaid losses and loss expenses	Unpaid losses and loss expenses A liability is established for the estimated unpaid losses and loss expenses under the terms of, and with respect to, Chubb's policies and agreements. Similar to premiums that are recognized as revenues over the coverage period of the policy, a liability for unpaid losses and loss expenses is recognized as expense when insured events occur over the coverage period of the policy. This liability includes a provision for both reported claims (case reserves) and incurred but not reported claims (IBNR reserves). IBNR reserve estimates are generally calculated by first projecting the ultimate cost of all losses that have occurred (expected losses), and then subtracting paid losses, case reserves, and loss expenses. The methods of determining such estimates and establishing the resulting liability are reviewed regularly and any adjustments are reflected in operations in the period in which they become known. Future developments may result in losses and loss expenses materially greater or less than recorded amounts. Except for net loss and loss expense reserves of $ 36 million net of discount, held at December 31, 2017 , representing certain structured settlements for which the timing and amount of future claim payments are reliably determinable and $ 41 million, net of discount, of certain reserves for unsettled claims that are discounted in statutory filings, Chubb does not discount its P&C loss reserves. This compares with reserves of $ 38 million for certain structured settlements and $ 50 million of certain reserves for unsettled claims at December 31, 2016 . Structured settlements represent contracts purchased from life insurance companies primarily to settle workers' compensation claims, where payments to the claimant by the life insurance company are expected to be made in the form of an annuity. Chubb retains the liability to the claimant in the event that the life insurance company fails to pay. At December 31, 2017 , the liability due to claimants was $ 586 million, net of discount, and reinsurance recoverables due from the life insurance companies was $ 550 million, net of discount. For structured settlement contracts where payments are guaranteed regardless of claimant life expectancy, the amounts recoverable from the life insurance companies at December 31, 2017 are included in Other assets in the Consolidated balance sheets, as they do not meet the requirements for reinsurance accounting. Included in Unpaid losses and loss expenses are liabilities for asbestos and environmental (A&E) claims and expenses. These unpaid losses and loss expenses are principally related to claims arising from remediation costs associated with hazardous waste sites and bodily-injury claims related to asbestos products and environmental hazards. The estimation of these liabilities is particularly sensitive to changes in the legal environment including specific settlements that may be used as precedents to settle future claims. However, Chubb does not anticipate future changes in laws and regulations in setting its A&E reserve levels. Also included in Unpaid losses and loss expenses is a fair value adjustment of $ 309 million at December 31, 2017 related to Chubb Corp’s historical unpaid losses and loss expenses. The estimated fair value consists of the present value of the expected net unpaid loss and loss adjustment expense payments adjusted for an estimated risk margin. The estimated cash flows are discounted at a risk free rate. The estimated risk margin varies based on the inherent risks associated with each type of reserve. The fair value is amortized through Amortization of purchased intangibles on the consolidated statements of operations over a range of 5 to 17 years, based on the estimated payout patterns of unpaid loss and loss expenses at the acquisition date. Prior period development arises from changes to loss estimates recognized in the current year that relate to loss reserves first reported in previous calendar years and excludes the effect of losses from the development of earned premiums from previous accident years. For purposes of analysis and disclosure, management views prior period development to be changes in the nominal value of loss estimates from period to period, net of premium and profit commission adjustments on loss sensitive contracts. Prior period development generally excludes changes in loss estimates that do not arise from the emergence of claims, such as those related to uncollectible reinsurance, interest, unallocated loss adjustment expenses, or foreign currency. Accordingly, specific items excluded from prior period development include the following: gains/losses related to foreign currency remeasurement; losses recognized from the early termination or commutation of reinsurance agreements that principally relate to the time value of money; changes in the value of reinsurance business assumed reflected in losses incurred but principally related to the time value of money; and losses that arise from changes in estimates of earned premiums from prior accident years. Except for foreign currency remeasurement, which is included in Net realized gains (losses), these items are included in current year losses.
Future policy benefits	Future policy benefits The valuation of long-duration contract reserves requires management to make estimates and assumptions regarding expenses, mortality, persistency, and investment yields. Estimates are primarily based on historical experience and information provided by ceding companies and include a margin for adverse deviation. Interest rates used in calculating reserves range from less than 1.0 percent to 8.0 percent at both December 31, 2017 and 2016 . Actual results could differ materially from these estimates. Management monitors actual experience and where circumstances warrant, will revise assumptions and the related reserve estimates. Revisions are recorded in the period they are determined. Certain of our long-duration contracts are supported by assets that do not qualify for separate account reporting under GAAP. These assets are classified as trading securities and reported in Other investments and the offsetting liabilities are reported in Future policy benefits in the Consolidated balance sheets. Changes in the fair value of separate account assets that do not qualify for separate account reporting under GAAP are reported in Other income (expense) and the offsetting movements in the liabilities are included in Policy benefits in the Consolidated statements of operations.
Assumed reinsurance programs involving minimum benefit guarantees under annuity contracts	Assumed reinsurance programs involving minimum benefit guarantees under variable annuity contracts Chubb reinsures various death and living benefit guarantees associated with variable annuities issued primarily in the United States and Japan. We generally receive a monthly premium during the accumulation phase of the covered annuities (in-force) based on a percentage of either the underlying accumulated account values or the underlying accumulated guaranteed values. Depending on an annuitant's age, the accumulation phase can last many years. To limit our exposure under these programs, all reinsurance treaties include annual or aggregate claim limits and many include an aggregate deductible. The guarantees which are payable on death, referred to as guaranteed minimum death benefits (GMDB), principally cover shortfalls between accumulated account value at the time of an annuitant's death and either i) an annuitant's total deposits; ii) an annuitant's total deposits plus a minimum annual return; or iii) the highest accumulated account value attained at any policy anniversary date. In addition, a death benefit may be based on a formula specified in the variable annuity contract that uses a percentage of the growth of the underlying contract value. Liabilities for GMDBs are based on cumulative assessments or premiums to date multiplied by a benefit ratio that is determined by estimating the present value of benefit payments and related adjustment expenses divided by the present value of cumulative assessment or expected premiums during the contract period. Under reinsurance programs covering GLBs, we assume the risk of guaranteed minimum income benefits (GMIB) and guaranteed minimum accumulation benefits (GMAB) associated with variable annuity contracts. The GMIB risk is triggered if, at the time the contract holder elects to convert the accumulated account value to a periodic payment stream (annuitize), the accumulated account value is not sufficient to provide a guaranteed minimum level of monthly income. The GMAB risk is triggered if, at contract maturity, the contract holder's account value is less than a guaranteed minimum value. Our GLB reinsurance products meet the definition of a derivative for accounting purposes and are carried at fair value with changes in fair value recognized in income. Refer to Notes 5 c ) and 10 a) for additional information.
Deposit assets and liabilities	Deposit assets and liabilities Deposit assets arise from ceded reinsurance contracts purchased that do not transfer significant underwriting or timing risk. Deposit liabilities include reinsurance deposit liabilities and contract holder deposit funds. The reinsurance deposit liabilities arise from contracts sold for which there is not a significant transfer of risk. Contract holder deposit funds represent a liability for investment contracts sold that do not meet the definition of an insurance contract, and certain of these contracts are sold with a guaranteed rate of return. Under deposit accounting, consideration received or paid is recorded as a deposit asset or liability in the balance sheet as opposed to recording premiums and losses in the statement of operations. Interest income on deposit assets, representing the consideration received or to be received in excess of cash payments related to the deposit contract, is earned based on an effective yield calculation. The calculation of the effective yield is based on the amount and timing of actual cash flows at the balance sheet date and the estimated amount and timing of future cash flows. The effective yield is recalculated periodically to reflect revised estimates of cash flows. When a change in the actual or estimated cash flows occurs, the resulting change to the carrying amount of the deposit asset is reported as income or expense. Deposit assets of $ 89 million and $ 93 million at December 31, 2017 and 2016 , respectively, are reflected in Other assets in the Consolidated balance sheets and the accretion of deposit assets related to interest pursuant to the effective yield calculation is reflected in Net investment income in the Consolidated statements of operations. Deposit liabilities include reinsurance deposit liabilities of $ 100 million and $ 108 million and contract holder deposit funds of $ 1.8 billion and $ 1.5 billion at December 31, 2017 and 2016 , respectively. Deposit liabilities are reflected in Accounts payable, accrued expenses, and other liabilities in the Consolidated balance sheets. At contract inception, the deposit liability equals net cash received. An accretion rate is established based on actuarial estimates whereby the deposit liability is increased to the estimated amount payable over the contract term. The deposit accretion rate is the rate of return required to fund expected future payment obligations. We periodically reassess the estimated ultimate liability and related expected rate of return. Changes to the deposit liability are generally reflected through Interest expense to reflect the cumulative effect of the period the contract has been in force, and by an adjustment to the future accretion rate of the liability over the remaining estimated contract term. The liability for contract holder deposit funds equals accumulated policy account values, which consist of the deposit payments plus credited interest less withdrawals and amounts assessed through the end of the period.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment Property and equipment used in operations, including certain costs incurred to develop or obtain computer software for internal use, are capitalized and carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. Property and equipment are included in Other assets in the Consolidated balance sheets and totaled $ 1.3 billion and $ 1.2 billion at December 31, 2017 and 2016, respectively.
Foreign currency remeasurement and translation	Foreign currency remeasurement and translation The functional currency for each of our foreign operations is generally the currency of the local operating environment. Transactions in currencies other than a foreign operation's functional currency are remeasured into the functional currency and the resulting foreign exchange gains and losses are reflected in Net realized gains (losses) in the Consolidated statements of operations. Functional currency assets and liabilities are translated into the reporting currency, U.S. dollars, using period end exchange rates and the related translation adjustments are recorded as a separate component of AOCI. Functional statement of operations amounts expressed in functional currencies are translated using average exchange rates.
Administrative expenses	Administrative expenses Administrative expenses generally include all operating costs other than policy acquisition costs. The North America Commercial P&C Insurance segment manages and uses an in-house third-party claims administrator, ESIS Inc. (ESIS). ESIS performs claims management and risk control services for domestic and international organizations that self-insure P&C exposures as well as internal P&C exposures. The net operating results of ESIS are included within Administrative expenses in the Consolidated statements of operations and were $ 38 million, $ 32 million, and $ 30 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.
Income taxes	Income taxes Income taxes have been recorded related to those operations subject to income taxes. Deferred tax assets and liabilities result from temporary differences between the amounts recorded in the Consolidated financial statements and the tax basis of our assets and liabilities. The effect on deferred tax assets and liabilities of a change in tax law or rates is recognized in income in the period that includes the enactment date. For example, we recorded a net reduction in our deferred tax balances reflecting the impact of the Tax Cuts and Jobs Act (2017 Tax Act) in the fourth quarter of 2017, the period when the legislation was enacted. Refer to Note 8 for additional information. A valuation allowance against deferred tax assets is recorded if it is more likely than not that all, or some portion, of the benefits related to deferred tax assets will not be realized. The valuation allowance assessment considers tax planning strategies, where applicable. We recognize uncertain tax positions deemed more likely than not of being sustained upon examination. Recognized income tax positions are measured at the largest amount that has a greater than 50 percent likelihood of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs.
Earnings per share	Earnings per share Basic earnings per share is calculated using the weighted-average shares outstanding including participating securities with non-forfeitable rights to dividends such as unvested restricted stock. All potentially dilutive securities including stock options are excluded from the basic earnings per share calculation. In calculating diluted earnings per share, the weighted-average shares outstanding is increased to include all potentially dilutive securities. Basic and diluted earnings per share are calculated by dividing net income by the applicable weighted-average number of shares outstanding during the year.
Cash flow information	Cash flow information Premiums received and losses paid associated with the GLB reinsurance products, which as discussed previously meet the definition of a derivative instrument for accounting purposes, are included within Cash flows from operating activities. Cash flows, such as settlements and collateral requirements, associated with GLB and all other derivative instruments are included on a net basis within Cash flows from investing activities. Purchases, sales, and maturities of short-term investments are recorded on a net basis within Cash flows from investing activities.
Derivatives	Derivatives Chubb recognizes all derivatives at fair value in the Consolidated balance sheets and participates in derivative instruments in two principal ways: (i) To sell protection to customers as an insurance or reinsurance contract that meets the definition of a derivative for accounting purposes . For 2017 and 2016 , the reinsurance of GLBs was our primary product falling into this category; and (ii) To mitigate financial risks, principally arising from investment holdings, products sold, or assets and liabilities held in foreign currencies. For these instruments, changes in assets or liabilities measured at fair value are recorded as realized gains or losses in the Consolidated statements of operations. We did not designate any derivatives as accounting hedges during 2017 , 2016 , or 2015 .
Share-based compensation	Share-based compensation Chubb measures and records compensation cost for all share-based payment awards at grant-date fair value. Compensation costs are recognized for share-based payment awards with only service conditions that have graded vesting schedules on a straight-line basis over the requisite service period for each separately vesting portion of the award as if the award were, in substance, multiple awards. Refer to Note 12 for additional information.
Chubb integration expenses	Chubb integration expenses Direct costs related to the Chubb Corp acquisition were expensed as incurred. Chubb integration expenses were $ 310 million and $ 492 million for the years ended December 31, 2017 and 2016, respectively, and include all internal and external costs directly related to the integration activities of the Chubb Corp acquisition, consisting primarily of personnel-related expenses, including severance and employee retention and relocation; lease termination costs; and consulting fees. Chubb integration expenses were $ 33 million for the year ended December 31, 2015, consisting primarily of personnel-related expenses; consulting fees; and advisor fees.
New accounting pronouncements	Adopted in 2017 Stock Compensation Effective January 2017, we prospectively adopted new guidance on stock compensation which requires recognition of the excess tax benefits or deficiencies of share-based compensation awards to employees through net income rather than through additional paid in capital. The calculation of the excess tax benefits or deficiencies is based on the difference between the market value of a stock award at the date of vesting, or at the time of exercise for a stock option, compared to the grant date fair value recognized as compensation expense in the Consolidated statements of operations. For the year ended December 31, 2017, the excess tax benefit recorded to Income tax expense in the Consolidated statement of operations was $ 48 million . Additionally, the guidance allowed for an election to account for forfeitures related to share-based payments either as they occur or through an estimation method. We elected to retain our current accounting for compensation expense using a forfeiture estimation process. Income Tax Accounting Implications of the Tax Cuts and Jobs Act The Tax Cuts and Jobs Act (2017 Tax Act) was signed into legislation in December 2017. Among other things, the 2017 Tax Act reduces the U.S. federal income tax rate to 21 percent from 35 percent effective in 2018, institutes a dividends received deduction for foreign earnings with a related tax for the deemed repatriation of unremitted foreign earnings and creates a new base erosion anti-abuse tax (BEAT) which is a new U.S. minimum tax. The Securities and Exchange Commission issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, which provides guidance for the application of the 2017 Tax Act. The income tax guidance allows for the transition impact of the 2017 Tax Act to be recorded as 1) complete with all accounting implications identified, 2) provisional based on a reasonable estimate, or 3) not recorded as no reasonable estimate was determinable. We recorded a $450 million income tax transition benefit in the fourth quarter of 2017 on a provisional basis. This income tax benefit principally reflects our best estimate of the impact of the reduced U.S. corporate tax rate and other provisions of the 2017 Tax Act. Refer to Note 8 for additional information. Adopted in 2018 Revenue from Contracts with Customers In May 2014, the FASB issued an accounting standard that supersedes most existing revenue recognition guidance. The standard excludes from its scope the accounting for insurance contracts, leases, financial instruments, and certain other agreements that are governed under other GAAP guidance, but could affect the revenue recognition for certain of our claims management and risk control services. 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. This guidance was effective for us on January 1, 2018. The adoption of this guidance did not have a material impact on our financial condition or results of operations given that the majority of our business is outside the scope of this guidance. Financial Instruments – Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued guidance that affects the recognition, measurement, presentation, and disclosure of financial instruments. The guidance requires equity investments to be measured at fair value with changes in fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The standard was effective for us in the first quarter of 2018 and required recognition of a cumulative effect adjustment at adoption to beginning retained earnings. As a result, in the first quarter of 2018, we reduced other comprehensive income by $ 455 million , representing the unrealized appreciation on our equity investments, other than those accounted for under the equity method, with an offsetting increase in retained earnings. All subsequent changes in fair value will be recognized within realized gains (losses) on the consolidated statement of operations. Statement of Cash Flows In August 2016, the FASB issued guidance clarifying the classification of certain cash receipts and cash payments within the statement of cash flows, including distributions received from equity method investments. The guidance requires entities to make an accounting policy election to present cash flows received either in operating cash flows or investing cash flows based on cumulative equity-method earnings or on the nature of the distributions. We adopted this guidance effective January 1, 2018 and elected to retain our current presentation of cash receipts and cash payments based on the nature of the distributions. Goodwill Impairment In January 2017, the FASB issued updated guidance on goodwill impairment testing that eliminates Step 2 of the goodwill impairment test requiring entities to calculate the implied fair value of goodwill through a hypothetical purchase price allocation. Under the updated guidance, impairment will now be recognized as the amount by which a reporting unit’s carrying value exceeds its fair value. Although the standard would have been effective for us in the first quarter of 2020 on a prospective basis, we adopted this guidance early effective January 1, 2018, as permitted. The adoption of this guidance did not have an impact on our financial condition or results of operations.
Accounting guidance not yet adopted	ccounting guidance not yet adopted Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued guidance that allows the reclassification from accumulated other comprehensive loss to retained earnings for stranded tax effects resulting from the newly enacted corporate tax rate. Because the adjustment of deferred taxes due to the reduction of the corporate tax rate is required to be included in net income, the tax effects of items within accumulated other comprehensive income (referred to as stranded tax effects) do not reflect the appropriate tax rates. The amount of the reclassification will be the difference between the 35 percent historical U.S. corporate tax rate and the newly enacted 21 percent U.S. corporate tax rate. This guidance is effective for us in the first quarter of 2019 with early adoption permitted. Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued guidance on the amortization period for purchased callable debt securities held at a premium. The guidance requires the premium to be amortized to the earliest call date. Under current guidance, premiums generally are amortized over the contracted life of the security. This guidance is effective for us in the first quarter of 2019 on a modified retrospective basis through a cumulative effect adjustment to beginning retained earnings. Early adoption is permitted. Securities held at a discount do not require an accounting change. Based on our best estimate at the time of this filing, the cumulative effect adjustment at the time of adoption would be approximately $ 30 million pre-tax. Lease Accounting In February 2016, the FASB issued accounting guidance requiring leases with lease terms of more than 12 months to recognize a right of use asset and a corresponding lease liability on the balance sheets. This accounting guidance is effective for us in the first quarter of 2019 on a modified retrospective basis with early adoption permitted. In January 2018, the FASB issued a proposed update that provides an alternative transition method of adoption, permitting the recognition of a cumulative-effect adjustment to retained earnings on the date of adoption. The adoption of the guidance is not expected to have a material impact on our financial condition or results of operations. We expect that the most significant impact will be the recognition of a right of use asset and a corresponding lease liability for our real estate leases. Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued guidance on the accounting for credit losses of financial instruments that are measured at amortized cost, including held to maturity securities and reinsurance recoverables, by applying an approach based on the current expected credit losses (CECL). The estimate of expected credit losses should consider historical information, current information, as well as reasonable and supportable forecasts, including estimates of prepayments. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset in order to present the net carrying value at the amount expected to be collected on the financial asset on the Consolidated balance sheet. The guidance also amends the current debt security other-than-temporary impairment model by requiring an estimate of the expected credit loss (ECL) only when the fair value is below the amortized cost of the asset. The length of time the fair value of an AFS debt security has been below the amortized cost will no longer impact the determination of whether a potential credit loss exists. The AFS debt security model will also require the use of a valuation allowance as compared to the current practice of writing down the asset. The standard is effective for us in the first quarter of 2020 with early adoption permitted in the first quarter of 2019. We will be able to assess the effect of adopting this guidance on our financial condition and results of operations closer to the date of adoption.

Acquisitions Acquisitions (Tabl

Acquisitions Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	The purchase price allocation to intangible assets recorded in connection with the Chubb Corp acquisition and their related useful lives are as follows: (in millions of U.S. dollars) Purchase price Allocation at January 14, 2016 Estimated useful life Definite life Unearned premium reserves (UPR) intangible asset $ 1,550 1 year Agency distribution relationships and renewal rights 3,150 24 years Internally developed technology 95 3 years Indefinite life Trademarks 2,800 Indefinite Licenses 50 Indefinite Syndicate capacity 10 Indefinite Total identified intangible assets $ 7,655
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	(in millions of U.S. dollars, except per share data) Purchase consideration Chubb Limited common shares Chubb Corp common shares outstanding 228 Per share exchange ratio 0.6019 Common shares issued by Chubb Limited 137 Common share price of Chubb Limited at January 14, 2016 $ 111.02 Fair value of common shares issued by Chubb Limited to common shareholders of Chubb Corp $ 15,204 Cash consideration Chubb Corp common shares outstanding 228 Agreed cash price per share paid to common shareholders of Chubb Corp $ 62.93 Cash consideration paid by Chubb Limited to common shareholders of Chubb Corp $ 14,319 Stock-based awards Fair value of equity awards issued (1) $ 323 Fair value of purchase consideration $ 29,846 Assets acquired and (liabilities) assumed Cash $ 71 Investments 42,967 Accrued investment income 359 Insurance and reinsurance balances receivable 3,095 Reinsurance recoverable on losses and loss expenses 1,676 Indefinite lived intangible assets 2,860 Finite lived intangible assets 4,795 Prepaid reinsurance premiums 280 Other assets 853 Unpaid losses and loss expenses (22,923 ) Unearned premiums (7,011 ) Insurance and reinsurance balances payable (603 ) Accounts payable, accrued expenses, and other liabilities (2,030 ) Deferred tax liabilities (1,292 ) Long-term debt (3,765 ) Total identifiable net assets acquired 19,332 Goodwill 10,514 Purchase price $ 29,846 (1) The fair value of the replacement equity awards was $525 million , of which $323 million was attributed to service periods prior to the acquisition and was included in the purchase consideration. Refer to Note 12 for further information on these replacement equity awards.
Results of Operations From Date of Business Combination [Table Text Block]	The following table summarizes the results of the acquired Chubb Corp operations since the acquisition date that have been included within our Consolidated statement of operations: (in millions of U.S. dollars) January 14, 2016 to December 31, 2016 Total revenues $ 12,376 Net income $ 1,756
Business Acquisition, Pro Forma Information [Table Text Block]	Year Ended December 31 (in millions of U.S. dollars, except per share data) 2016 2015 Total revenues $ 31,937 $ 32,622 Net income $ 4,183 $ 4,478 Earnings per share Basic earnings per share $ 8.95 $ 9.61 Diluted earnings per share $ 8.88 $ 9.52

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule Of Amortized Cost and Fair Value of Available-for-sale Securities and Related OTTI Recognized in AOCI	December 31, 2017 Amortized Cost Gross Unrealized Appreciation Gross Unrealized Depreciation Fair Value OTTI Recognized in AOCI (in millions of U.S. dollars) Available for sale U.S. Treasury and agency $ 3,701 $ 32 $ (35 ) $ 3,698 $ — Foreign 20,514 622 (106 ) 21,030 (1 ) Corporate securities 23,453 638 (95 ) 23,996 (4 ) Mortgage-backed securities 15,279 111 (100 ) 15,290 (1 ) States, municipalities, and political subdivisions 14,888 125 (88 ) 14,925 — $ 77,835 $ 1,528 $ (424 ) $ 78,939 $ (6 ) Held to maturity U.S. Treasury and agency $ 908 $ 12 $ (5 ) $ 915 $ — Foreign 1,738 27 (8 ) 1,757 — Corporate securities 3,159 67 (7 ) 3,219 — Mortgage-backed securities 2,724 23 (5 ) 2,742 — States, municipalities, and political subdivisions 5,806 50 (15 ) 5,841 — $ 14,335 $ 179 $ (40 ) $ 14,474 $ — December 31, 2016 Amortized Gross Gross Fair OTTI Recognized (in millions of U.S. dollars) Available for sale U.S. Treasury and agency $ 2,883 $ 32 $ (45 ) $ 2,870 $ — Foreign 20,929 636 (125 ) 21,440 (5 ) Corporate securities 23,736 580 (167 ) 24,149 (8 ) Mortgage-backed securities 14,066 135 (194 ) 14,007 (1 ) States, municipalities, and political subdivisions 17,922 72 (345 ) 17,649 — $ 79,536 $ 1,455 $ (876 ) $ 80,115 $ (14 ) Held to maturity U.S. Treasury and agency $ 655 $ 9 $ (3 ) $ 661 $ — Foreign 640 28 (1 ) 667 — Corporate securities 2,771 50 (26 ) 2,795 — Mortgage-backed securities 1,393 35 — 1,428 — States, municipalities, and political subdivisions 5,185 26 (92 ) 5,119 — $ 10,644 $ 148 $ (122 ) $ 10,670 $ — December 31 December 31 (in millions of U.S. dollars) 2017 2016 Cost $ 737 $ 706 Gross unrealized appreciation 212 129 Gross unrealized depreciation (12 ) (21 ) Fair value $ 937 $ 814
Schedule Of Amortized Cost And Fair Value Of Held_to_Maturity And Related OTTI Recognized In AOCI	December 31, 2017 Amortized Cost Gross Unrealized Appreciation Gross Unrealized Depreciation Fair Value OTTI Recognized in AOCI (in millions of U.S. dollars) Available for sale U.S. Treasury and agency $ 3,701 $ 32 $ (35 ) $ 3,698 $ — Foreign 20,514 622 (106 ) 21,030 (1 ) Corporate securities 23,453 638 (95 ) 23,996 (4 ) Mortgage-backed securities 15,279 111 (100 ) 15,290 (1 ) States, municipalities, and political subdivisions 14,888 125 (88 ) 14,925 — $ 77,835 $ 1,528 $ (424 ) $ 78,939 $ (6 ) Held to maturity U.S. Treasury and agency $ 908 $ 12 $ (5 ) $ 915 $ — Foreign 1,738 27 (8 ) 1,757 — Corporate securities 3,159 67 (7 ) 3,219 — Mortgage-backed securities 2,724 23 (5 ) 2,742 — States, municipalities, and political subdivisions 5,806 50 (15 ) 5,841 — $ 14,335 $ 179 $ (40 ) $ 14,474 $ — December 31, 2016 Amortized Gross Gross Fair OTTI Recognized (in millions of U.S. dollars) Available for sale U.S. Treasury and agency $ 2,883 $ 32 $ (45 ) $ 2,870 $ — Foreign 20,929 636 (125 ) 21,440 (5 ) Corporate securities 23,736 580 (167 ) 24,149 (8 ) Mortgage-backed securities 14,066 135 (194 ) 14,007 (1 ) States, municipalities, and political subdivisions 17,922 72 (345 ) 17,649 — $ 79,536 $ 1,455 $ (876 ) $ 80,115 $ (14 ) Held to maturity U.S. Treasury and agency $ 655 $ 9 $ (3 ) $ 661 $ — Foreign 640 28 (1 ) 667 — Corporate securities 2,771 50 (26 ) 2,795 — Mortgage-backed securities 1,393 35 — 1,428 — States, municipalities, and political subdivisions 5,185 26 (92 ) 5,119 — $ 10,644 $ 148 $ (122 ) $ 10,670 $ —
Schedule Of Fixed Maturities By Contractual Maturity	The following table presents fixed maturities by contractual maturity: December 31 December 31 2017 2016 (in millions of U.S. dollars) Amortized Cost Fair Value Amortized Cost Fair Value Available for sale Due in 1 year or less $ 3,164 $ 3,182 $ 3,892 $ 3,913 Due after 1 year through 5 years 24,749 25,068 24,027 24,429 Due after 5 years through 10 years 25,388 25,704 27,262 27,379 Due after 10 years 9,255 9,695 10,289 10,387 62,556 63,649 65,470 66,108 Mortgage-backed securities 15,279 15,290 14,066 14,007 $ 77,835 $ 78,939 $ 79,536 $ 80,115 Held to maturity Due in 1 year or less $ 743 $ 746 $ 430 $ 435 Due after 1 year through 5 years 2,669 2,688 2,646 2,691 Due after 5 years through 10 years 4,744 4,756 2,969 2,944 Due after 10 years 3,455 3,542 3,206 3,172 11,611 11,732 9,251 9,242 Mortgage-backed securities 2,724 2,742 1,393 1,428 $ 14,335 $ 14,474 $ 10,644 $ 10,670
Schedule Of Default Assumptions By Moody's Rating Category	The following table presents default assumptions by Moody's rating category (historical mean default rate provided for comparison): Moody's Rating Category 1-in-100 Year Default Rate Historical Mean Default Rate Investment Grade: Aaa-Baa 0.0-1.3% 0.0-0.3% Below Investment Grade: Ba 4.8 % 1.0 % B 12.1 % 3.2 % Caa-C 36.8 % 10.5 %
Schedule Of Net Realized Gains (Losses) And The Losses Included In Net Realized Gains (Losses) And OCI	The following table presents the Net realized gains (losses) and the losses included in Net realized gains (losses) and OCI as a result of conditions which caused us to conclude the decline in fair value of certain investments was “other-than-temporary” and the change in net unrealized appreciation (depreciation) of investments: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Fixed maturities: OTTI on fixed maturities, gross $ (24 ) $ (89 ) $ (142 ) OTTI on fixed maturities recognized in OCI (pre-tax) 1 8 39 OTTI on fixed maturities, net (23 ) (81 ) (103 ) Gross realized gains excluding OTTI 149 183 158 Gross realized losses excluding OTTI (157 ) (265 ) (235 ) Total fixed maturities (31 ) (163 ) (180 ) Equity securities: OTTI on equity securities (10 ) (8 ) (7 ) Gross realized gains excluding OTTI 28 65 47 Gross realized losses excluding OTTI (2 ) (13 ) (11 ) Total equity securities 16 44 29 OTTI on other investments (12 ) (14 ) (2 ) Foreign exchange gains (losses) 36 118 (80 ) Investment and embedded derivative instruments (11 ) (33 ) 32 Fair value adjustments on insurance derivative 364 53 (203 ) S&P put options and futures (261 ) (136 ) (10 ) Other derivative instruments (5 ) (10 ) (12 ) Other (12 ) (4 ) 6 Net realized gains (losses) 84 (145 ) (420 ) Change in net unrealized appreciation (depreciation) on investments: Fixed maturities available for sale 519 142 (1,119 ) Fixed maturities held to maturity 18 (59 ) 43 Equity securities 88 52 (17 ) Other 8 (51 ) (36 ) Income tax (expense) benefit (241 ) 100 152 Change in net unrealized appreciation (depreciation) on investments 392 184 (977 ) Total net realized gains (losses) and change in net unrealized appreciation (depreciation) on investments $ 476 $ 39 $ (1,397 )
Schedule Of Roll-Forward Of Pre-Tax Credit Losses Related To Fixed Maturities For Which A Portion Of OTTI Was Recognized In OCI	The following table presents a roll-forward of pre-tax credit losses related to fixed maturities for which a portion of OTTI was recognized in OCI: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Balance of credit losses related to securities still held – beginning of year $ 35 $ 53 $ 28 Additions where no OTTI was previously recorded 4 17 41 Additions where an OTTI was previously recorded 2 14 9 Reductions for securities sold during the period (19 ) (49 ) (25 ) Balance of credit losses related to securities still held – end of year $ 22 $ 35 $ 53
Schedule Of Other Investments	December 31 December 31 2017 2016 (in millions of U.S. dollars) Fair Value Cost Fair Value Cost Investment funds $ 270 $ 123 $ 251 $ 126 Limited partnerships 549 441 730 607 Partially-owned investment companies 2,803 2,803 2,645 2,645 Life insurance policies 305 305 248 248 Policy loans 244 244 209 209 Trading securities 333 333 296 295 Other 168 168 140 140 Total $ 4,672 $ 4,417 $ 4,519 $ 4,270
Schedule Of Partially Owned Insurance Companies	December 31, 2017 December 31, 2016 (in millions of U.S. dollars, except for percentages) Carrying Value Issued Share Capital Ownership Percentage Carrying Value Issued Share Capital Ownership Percentage Domicile Huatai Group $ 438 $ 616 20 % $ 447 $ 624 20 % China Huatai Life Insurance Company 105 495 20 % 99 428 20 % China Freisenbruch-Meyer 9 — 40 % 8 5 40 % Bermuda Chubb Arabia Cooperative Insurance Company 15 27 30 % 13 27 30 % Saudi Arabia Russian Reinsurance Company 2 4 23 % 2 4 23 % Russia ABR Reinsurance Ltd. 93 800 11 % 97 800 11 % Bermuda Total $ 662 $ 1,942 $ 666 $ 1,888
Schedule Of Aggregate Fair Value And Gross Unrealized Loss By Length Of Time The Security Has Continuously Been In An Unrealized Loss Position	The following tables present, for all securities in an unrealized loss position (including securities on loan), the aggregate fair value and gross unrealized loss by length of time the security has continuously been in an unrealized loss position: 0 – 12 Months Over 12 Months Total December 31, 2017 Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss (in millions of U.S. dollars) U.S. Treasury and agency $ 2,172 $ (14 ) $ 1,249 $ (26 ) $ 3,421 $ (40 ) Foreign 5,657 (65 ) 1,693 (49 ) 7,350 (114 ) Corporate securities 5,210 (56 ) 1,332 (46 ) 6,542 (102 ) Mortgage-backed securities 6,194 (31 ) 3,209 (74 ) 9,403 (105 ) States, municipalities, and political subdivisions 9,259 (71 ) 1,402 (32 ) 10,661 (103 ) Total fixed maturities 28,492 (237 ) 8,885 (227 ) 37,377 (464 ) Equity securities 115 (12 ) — — 115 (12 ) Other investments 78 (8 ) — — 78 (8 ) Total $ 28,685 $ (257 ) $ 8,885 $ (227 ) $ 37,570 $ (484 ) 0 – 12 Months Over 12 Months Total December 31, 2016 Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss Fair Value Gross Unrealized Loss (in millions of U.S. dollars) U.S. Treasury and agency $ 2,216 $ (48 ) $ — $ — $ 2,216 $ (48 ) Foreign 5,918 (99 ) 386 (27 ) 6,304 (126 ) Corporate securities 7,021 (149 ) 641 (44 ) 7,662 (193 ) Mortgage-backed securities 8,638 (189 ) 234 (5 ) 8,872 (194 ) States, municipalities, and political subdivisions 19,448 (435 ) 49 (2 ) 19,497 (437 ) Total fixed maturities 43,241 (920 ) 1,310 (78 ) 44,551 (998 ) Equity securities 199 (21 ) — — 199 (21 ) Other investments 201 (18 ) — — 201 (18 ) Total $ 43,641 $ (959 ) $ 1,310 $ (78 ) $ 44,951 $ (1,037 )
Schedule Of Sources Of Net Investment Income	Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Fixed maturities $ 2,987 $ 2,779 $ 2,157 Short-term investments 131 93 49 Equity securities 38 36 16 Other investments 133 98 86 Gross investment income (1) 3,289 3,006 2,308 Investment expenses (164 ) (141 ) (114 ) Net investment income (1) $ 3,125 $ 2,865 $ 2,194 (1) Includes amortization expense related to fair value adjustment of acquired invested assets related to the Chubb Corp acquisition $ (332 ) $ (393 ) $ —
Schedule Of Components Of Restricted Assets	The following table presents the components of restricted assets: December 31 December 31 (in millions of U.S. dollars) 2017 2016 Trust funds $ 17,011 $ 13,880 Deposits with U.S. regulatory authorities 2,345 2,203 Deposits with non-U.S. regulatory authorities 2,250 2,191 Assets pledged under repurchase agreements 1,434 1,461 Other pledged assets 414 435 $ 23,454 $ 20,170

Fair value measurements (Tables

Fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
GMIB Annuitization Experience [Table Text Block]	% of total GMIB guaranteed value Year of GMIB eligibility Maximum annuitization rate(s) (per year) Maximum annuitization rates based on 67% First year 2% - 52% Actual Experience Subsequent years 1% - 100% 3% First year N/A N/A (1) Subsequent years 12%, 100% Weighted average (2) 30% First year 25%, 56% Weighted average (2) Subsequent years 12%, 36% (1) Because all policies in this bracket are past the first year of eligibility, first year annuitization assumptions are no longer modeled. (2) Weighted average of two different annuitization rates
Financial Instruments Measured At Fair Value On A Recurring Basis	Financial instruments measured at fair value on a recurring basis, by valuation hierarchy December 31, 2017 Level 1 Level 2 Level 3 Total (in millions of U.S. dollars) Assets: Fixed maturities available for sale U.S. Treasury and agency $ 3,129 $ 569 $ — $ 3,698 Foreign — 20,937 93 21,030 Corporate securities — 22,959 1,037 23,996 Mortgage-backed securities — 15,212 78 15,290 States, municipalities, and political subdivisions — 14,925 — 14,925 3,129 74,602 1,208 78,939 Equity securities 893 — 44 937 Short-term investments 2,309 1,252 — 3,561 Other investments (1) 466 305 263 1,034 Securities lending collateral — 1,737 — 1,737 Investment derivative instruments 18 — — 18 Other derivative instruments 1 — — 1 Separate account assets 2,635 99 — 2,734 Total assets measured at fair value (1) $ 9,451 $ 77,995 $ 1,515 $ 88,961 Liabilities: Investment derivative instruments $ 30 $ — $ — $ 30 Other derivative instruments 21 — 2 23 GLB (2) — — 204 204 Total liabilities measured at fair value $ 51 $ — $ 206 $ 257 (1) Excluded from the table above are partially-owned investments, investment funds, and limited partnerships of $3,623 million and other investments of $15 million at December 31, 2017 measured using NAV as a practical expedient. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information. December 31, 2016 Level 1 Level 2 Level 3 Total (in millions of U.S. dollars) Assets: Fixed maturities available for sale U.S. Treasury and agency $ 2,175 $ 695 $ — $ 2,870 Foreign — 21,366 74 21,440 Corporate securities — 23,468 681 24,149 Mortgage-backed securities — 13,962 45 14,007 States, municipalities, and political subdivisions — 17,649 — 17,649 2,175 77,140 800 80,115 Equity securities 773 — 41 814 Short-term investments 1,757 1,220 25 3,002 Other investments (1) 384 259 225 868 Securities lending collateral — 1,092 — 1,092 Investment derivative instruments 31 — — 31 Other derivative instruments 3 — — 3 Separate account assets 1,784 95 — 1,879 Total assets measured at fair value (1) $ 6,907 $ 79,806 $ 1,091 $ 87,804 Liabilities: Investment derivative instruments $ 54 $ — $ — $ 54 Other derivative instruments — — 13 13 GLB (2) — — 559 559 Total liabilities measured at fair value $ 54 $ — $ 572 $ 626 (1) Excluded from the table above are partially-owned investments, investment funds, and limited partnerships of $3,626 million and other investments of $25 million at December 31, 2016 measured using NAV as a practical expedient. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information.
Fair Value And Maximum Future Funding Commitments Related To Investments	The following table presents, by investment category, the expected liquidation period, fair value, and maximum future funding commitments of alternative investments: December 31 December 31 2017 2016 (in millions of U.S. dollars) Expected Liquidation Period of Underlying Assets Fair Value Maximum Future Funding Commitments Fair Value Maximum Future Funding Commitments Financial 5 to 9 Years $ 540 $ 330 $ 548 $ 428 Real Assets 3 to 7 Years 651 114 536 230 Distressed 3 to 7 Years 289 141 485 179 Private Credit 3 to 7 Years 187 327 236 259 Traditional 3 to 15 Years 1,656 3,149 1,550 930 Vintage 1 to 2 Years 30 — 21 14 Investment funds Not Applicable 270 — 251 — $ 3,623 $ 4,061 $ 3,627 $ 2,040
Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations	The following table presents the significant unobservable inputs used in the Level 3 liability valuations. Excluded from the table below are inputs used to determine the fair value of Level 3 assets which are based on single broker quotes and contain no quantitative unobservable inputs developed by management. (in millions of U.S. dollars, except for percentages) Fair Value at December 31, 2017 Valuation Technique Significant Unobservable Inputs Ranges GLB (1) $ 204 Actuarial model Lapse rate 3% – 33% Annuitization rate 0% – 100% (1) Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables present a reconciliation of the beginning and ending balances of financial instruments measured at fair value using significant unobservable inputs (Level 3): Assets Liabilities Available-for-Sale Debt Securities Equity securities Short-term investments Other investments Other derivative instruments GLB (2) Year Ended December 31, 2017 Foreign Corporate securities (1) MBS (in millions of U.S. dollars) Balance, beginning of year $ 74 $ 681 $ 45 $ 41 $ 25 $ 225 $ 13 $ 559 Transfers into Level 3 — 231 50 — — — — 9 Transfers out of Level 3 (3 ) (93 ) — — — — (9 ) — Change in Net Unrealized Gains (Losses) included in OCI 3 (12 ) — (1 ) — 6 — — Net Realized Gains/Losses — — — 2 — — (2 ) (364 ) Purchases 84 521 8 24 16 56 — — Sales (59 ) (111 ) (1 ) (22 ) — — — — Settlements (6 ) (180 ) (24 ) — (41 ) (24 ) — — Balance, end of year $ 93 $ 1,037 $ 78 $ 44 $ — $ 263 $ 2 $ 204 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (1 ) $ (2 ) $ — $ (1 ) $ — $ — $ (2 ) $ (364 ) (1) Transfers into and Purchases in Level 3 primarily consist of privately-placed fixed income securities. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information. Liabilities Available-for-Sale Debt Securities Equity securities Short-term investments Other Other derivative instruments GLB (1) Year Ended December 31, 2016 Foreign Corporate securities MBS (in millions of U.S. dollars) Balance, beginning of year $ 57 $ 174 $ 53 $ 16 $ — $ 212 — $ 6 $ 609 Transfers into Level 3 9 53 — — — — — — — Transfers out of Level 3 (24 ) (10 ) — — (50 ) — — — Change in Net Unrealized Gains (Losses) included in OCI 1 15 (1 ) 2 — (2 ) — — Net Realized Gains/Losses (6 ) (13 ) — 1 — 1 5 (50 ) Purchases (2) 70 566 1 27 75 33 2 — Sales (17 ) (59 ) (8 ) (5 ) — — — — Settlements (16 ) (45 ) — — — (19 ) — — Balance, end of year $ 74 $ 681 $ 45 $ 41 $ 25 $ 225 $ 13 $ 559 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (5 ) $ (11 ) $ — $ — $ — $ 1 $ 5 $ (50 ) (1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015 , which includes a fair value derivative adjustment of $559 million and $609 million , respectively. (2) Includes acquired invested assets as a result of the Chubb Corp acquisition. Assets Liabilities Available-for-Sale Debt Securities Other derivative instruments GLB (1) Year Ended December 31, 2015 Foreign Corporate securities MBS Equity securities Other investments (in millions of U.S. dollars) Balance, beginning of year $ 22 $ 187 $ 15 $ 2 $ 204 $ 4 $ 406 Transfers into Level 3 34 16 — — — — — Transfers out of Level 3 — — — — — — — Change in Net Unrealized Gains (Losses) included in OCI (2 ) (1 ) — 3 (6 ) — — Net Realized Gains/Losses (1 ) (4 ) — (2 ) — 2 203 Purchases 15 52 41 13 33 — — Sales (3 ) (28 ) (2 ) — — — — Settlements (8 ) (48 ) (1 ) (19 ) — Balance, end of year $ 57 $ 174 $ 53 $ 16 $ 212 $ 6 $ 609 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (1 ) $ (2 ) $ — $ (2 ) $ — $ 2 $ 203 (1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $ 406 million , respectively.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Assets Liabilities Available-for-Sale Debt Securities Equity securities Short-term investments Other investments Other derivative instruments GLB (2) Year Ended December 31, 2017 Foreign Corporate securities (1) MBS (in millions of U.S. dollars) Balance, beginning of year $ 74 $ 681 $ 45 $ 41 $ 25 $ 225 $ 13 $ 559 Transfers into Level 3 — 231 50 — — — — 9 Transfers out of Level 3 (3 ) (93 ) — — — — (9 ) — Change in Net Unrealized Gains (Losses) included in OCI 3 (12 ) — (1 ) — 6 — — Net Realized Gains/Losses — — — 2 — — (2 ) (364 ) Purchases 84 521 8 24 16 56 — — Sales (59 ) (111 ) (1 ) (22 ) — — — — Settlements (6 ) (180 ) (24 ) — (41 ) (24 ) — — Balance, end of year $ 93 $ 1,037 $ 78 $ 44 $ — $ 263 $ 2 $ 204 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (1 ) $ (2 ) $ — $ (1 ) $ — $ — $ (2 ) $ (364 ) (1) Transfers into and Purchases in Level 3 primarily consist of privately-placed fixed income securities. (2) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c ) for additional information. Liabilities Available-for-Sale Debt Securities Equity securities Short-term investments Other Other derivative instruments GLB (1) Year Ended December 31, 2016 Foreign Corporate securities MBS (in millions of U.S. dollars) Balance, beginning of year $ 57 $ 174 $ 53 $ 16 $ — $ 212 — $ 6 $ 609 Transfers into Level 3 9 53 — — — — — — — Transfers out of Level 3 (24 ) (10 ) — — (50 ) — — — Change in Net Unrealized Gains (Losses) included in OCI 1 15 (1 ) 2 — (2 ) — — Net Realized Gains/Losses (6 ) (13 ) — 1 — 1 5 (50 ) Purchases (2) 70 566 1 27 75 33 2 — Sales (17 ) (59 ) (8 ) (5 ) — — — — Settlements (16 ) (45 ) — — — (19 ) — — Balance, end of year $ 74 $ 681 $ 45 $ 41 $ 25 $ 225 $ 13 $ 559 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (5 ) $ (11 ) $ — $ — $ — $ 1 $ 5 $ (50 ) (1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015 , which includes a fair value derivative adjustment of $559 million and $609 million , respectively. (2) Includes acquired invested assets as a result of the Chubb Corp acquisition. Assets Liabilities Available-for-Sale Debt Securities Other derivative instruments GLB (1) Year Ended December 31, 2015 Foreign Corporate securities MBS Equity securities Other investments (in millions of U.S. dollars) Balance, beginning of year $ 22 $ 187 $ 15 $ 2 $ 204 $ 4 $ 406 Transfers into Level 3 34 16 — — — — — Transfers out of Level 3 — — — — — — — Change in Net Unrealized Gains (Losses) included in OCI (2 ) (1 ) — 3 (6 ) — — Net Realized Gains/Losses (1 ) (4 ) — (2 ) — 2 203 Purchases 15 52 41 13 33 — — Sales (3 ) (28 ) (2 ) — — — — Settlements (8 ) (48 ) (1 ) (19 ) — Balance, end of year $ 57 $ 174 $ 53 $ 16 $ 212 $ 6 $ 609 Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date $ (1 ) $ (2 ) $ — $ (2 ) $ — $ 2 $ 203 (1) Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $ 406 million , respectively.
Carrying Values And Fair Values Of Financial Instruments Not Measured At Fair Value	December 31, 2017 Fair Value Carrying Value (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total Assets: Fixed maturities held to maturity U.S. Treasury and agency $ 857 $ 58 $ — $ 915 $ 908 Foreign — 1,757 — 1,757 1,738 Corporate securities — 3,184 35 3,219 3,159 Mortgage-backed securities — 2,742 — 2,742 2,724 States, municipalities, and political subdivisions — 5,841 — 5,841 5,806 Total assets $ 857 $ 13,582 $ 35 $ 14,474 $ 14,335 Liabilities: Repurchase agreements $ — $ 1,408 $ — $ 1,408 $ 1,408 Short-term debt — 1,013 — 1,013 1,013 Long-term debt — 12,332 — 12,332 11,556 Trust preferred securities — 468 — 468 308 Total liabilities $ — $ 15,221 $ — $ 15,221 $ 14,285 December 31, 2016 Fair Value Carrying Value (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total Assets: Fixed maturities held to maturity U.S. Treasury and agency $ 555 $ 106 $ — $ 661 $ 655 Foreign — 667 — 667 640 Corporate securities — 2,782 13 2,795 2,771 Mortgage-backed securities — 1,428 — 1,428 1,393 States, municipalities, and political subdivisions — 5,119 — 5,119 5,185 Total assets $ 555 $ 10,102 $ 13 $ 10,670 $ 10,644 Liabilities: Repurchase agreements $ — $ 1,403 $ — $ 1,403 $ 1,403 Short-term debt — 503 — 503 500 Long-term debt — 12,998 — 12,998 12,610 Trust preferred securities — 456 — 456 308 Total liabilities $ — $ 15,360 $ — $ 15,360 $ 14,821

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2017
Reinsurance Disclosures [Abstract]
Schedule of direct, assumed and ceded premiums	The following table presents direct, assumed, and ceded premiums: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Premiums written Direct $ 33,137 $ 31,543 $ 19,879 Assumed 3,239 3,440 3,932 Ceded (7,132 ) (6,838 ) (6,098 ) Net $ 29,244 $ 28,145 $ 17,713 Premiums earned Direct $ 32,782 $ 31,811 $ 19,355 Assumed 3,332 3,744 3,676 Ceded (7,080 ) (6,806 ) (5,818 ) Net $ 29,034 $ 28,749 $ 17,213
Schedule of Reinsurance Recoverable On Paid Losses And Loss Expenses [Table Text Block]	b) Reinsurance recoverable on ceded reinsurance December 31 December 31 (in millions of U.S. dollars) 2017 2016 Reinsurance recoverable on unpaid losses and loss expenses (1) $ 14,014 $ 12,708 Reinsurance recoverable on paid losses and loss expenses (1) 1,020 869 Reinsurance recoverable on losses and loss expenses (1) $ 15,034 $ 13,577 Reinsurance recoverable on policy benefits (1) $ 184 $ 182 (1) Net of a provision for uncollectible reinsurance.
Schedule of reinsurance recoverable and provision by category of reinsurer	December 31, 2017 Gross Reinsurance Recoverable on Loss and Loss Expenses Provision for Uncollectible Reinsurance % of Gross Reinsurance Recoverable (in millions of U.S. dollars, except for percentages) Categories Largest reinsurers $ 5,190 $ 59 1.1 % Other reinsurers rated A- or better 5,898 58 1.0 % Other reinsurers with ratings lower than A- or not rated 681 75 11.0 % Pools 577 15 2.6 % Structured settlements 550 16 2.9 % Captives 2,199 18 0.8 % Other 260 80 30.8 % Total $ 15,355 $ 321 2.1 %
Schedule of income and expenses relating to GMDB and GLB reinsurance	The following table presents income and expenses relating to GMDB and GLB reinsurance. GLBs include GMIBs as well as some GMABs originating in Japan. Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 GMDB Net premiums earned $ 49 $ 55 $ 61 Policy benefits and other reserve adjustments $ 40 $ 45 $ 34 GLB Net premiums earned $ 110 $ 118 $ 121 Policy benefits and other reserve adjustments 105 52 45 Net realized gains (losses) 363 48 (203 ) Gain (loss) recognized in Net income $ 368 $ 114 $ (127 ) Net cash received and other 65 79 98 Net decrease (increase) in liability $ 303 $ 35 $ (225 )
Schedule of Net Amount of Risk and 100 Percent Mortality [Table Text Block]	(in millions of U.S. dollars, except for percentages) Net amount at risk Reinsurance covering December 31, 2017 December 31, 2016 2017 Future claims discount rate Other assumptions Total claims at 100% mortality at December 31, 2017 (1) GMDB Risk Only $ 279 $ 341 4.00% - 4.50% No lapses or withdrawals $ 189 Mortality according to 100% of the Annuity 2000 mortality table GLB Risk Only $ 691 $ 800 4.25% - 4.75% No deaths, lapses or withdrawals N/A Annuitization at a frequency most disadvantageous to Chubb (2) Claim calculated using interest rates in line with rates used to calculate reserve Both Risks: (3) GMDB $ 81 $ 88 4.25% - 4.75% No lapses or withdrawals $ 18 Mortality according to 100% of the Annuity 2000 mortality table GLB $ 392 $ 464 4.25% - 4.75% Annuitization at a frequency most disadvantageous to Chubb (2) N/A Claim calculated using interest rates in line with rates used to calculate reserve (1) Takes into account all applicable reinsurance treaty claim limits. (2) Annuitization at a level that maximizes claims taking into account the treaty limits. (3) Covering both the GMDB and GLB risks on the same underlying policyholders.

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill roll-forward by business segment	The following table presents a roll-forward of Goodwill by segment: (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Reinsurance Life Insurance Chubb Consolidated Balance at December 31, 2015 $ 1,203 $ 196 $ 134 $ 2,078 $ 365 $ 820 $ 4,796 Acquisition of Chubb Corp 5,714 2,025 — 2,775 — — 10,514 Foreign exchange revaluation and other 44 14 — (36 ) — — 22 Balance at December 31, 2016 $ 6,961 $ 2,235 $ 134 $ 4,817 $ 365 $ 820 $ 15,332 Foreign exchange revaluation and other 15 5 — 187 — 2 209 Balance at December 31, 2017 $ 6,976 $ 2,240 $ 134 $ 5,004 $ 365 $ 822 $ 15,541
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Associated with the Chubb Corp Acquisition For the Year Ending December 31 (in millions of U.S. dollars) Agency distribution relationships and renewal rights Internally developed technology Fair value adjustment on Unpaid losses and loss expense (1) Total Other intangible assets Total Amortization of purchased intangibles 2018 $ 325 $ 32 $ (102 ) $ 255 $ 83 $ 338 2019 282 — (63 ) 219 75 294 2020 241 — (36 ) 205 67 272 2021 218 — (20 ) 198 61 259 2022 198 — (14 ) 184 57 241 Total $ 1,264 $ 32 $ (235 ) $ 1,061 $ 343 $ 1,404 (1) In connection with the Chubb Corp acquisition, we recorded an increase to Unpaid losses and loss expenses acquired to adjust the carrying value of Chubb Corp's historical unpaid losses and loss expenses to fair value as of the acquisition date. This fair value adjustment amortizes through Amortization of purchased intangibles on the Consolidated statements of operations over a range of 5 to 17 years. The balance of the fair value adjustment on Unpaid losses and loss expense at December 31, 2017 was $309 million . Refer to Note 1(h) for additional information.
VOBA	The following table presents a roll-forward of VOBA: (in millions of U.S. dollars) 2017 2016 2015 Balance, beginning of year $ 355 $ 395 $ 466 Amortization of VOBA (1) (35 ) (41 ) (42 ) Foreign exchange revaluation 6 1 (29 ) Balance, end of year $ 326 $ 355 $ 395 (1) Recognized in Policy acquisition costs in the Consolidated statements of operations. The following table presents, as of December 31, 2017, the expected estimated pre-tax amortization expense related to VOBA for the next five years: For the Year Ending December 31 VOBA (in millions of U.S. dollars) 2018 $ 32 2019 27 2020 25 2021 22 2022 20 Total $ 126

Unpaid losses and loss expens40

Unpaid losses and loss expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Abstract]
Schedule Of Unpaid Losses And Loss Expenses Roll Forward	The following table presents a reconciliation of Unpaid losses and loss expenses: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Gross unpaid losses and loss expenses, beginning of year $ 60,540 $ 37,303 $ 38,315 Reinsurance recoverable on unpaid losses (1) (12,708 ) (10,741 ) (11,307 ) Net unpaid losses and loss expenses, beginning of year 47,832 26,562 27,008 Acquisition of subsidiaries — 21,402 417 Total 47,832 47,964 27,425 Net losses and loss expenses incurred in respect of losses occurring in: Current year 19,391 17,256 10,030 Prior years (2) (937 ) (1,204 ) (546 ) Total 18,454 16,052 9,484 Net losses and loss expenses paid in respect of losses occurring in: Current year 6,575 5,899 4,053 Prior years 10,873 9,816 5,612 Total 17,448 15,715 9,665 Foreign currency revaluation and other 327 (469 ) (682 ) Net unpaid losses and loss expenses, end of year 49,165 47,832 26,562 Reinsurance recoverable on unpaid losses (1) 14,014 12,708 10,741 Gross unpaid losses and loss expenses, end of year $ 63,179 $ 60,540 $ 37,303 (1) Net of provision for uncollectible reinsurance. (2) Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments, and earned premiums totaling $108 million , $69 million , and nil, for 2017, 2016, and 2015, respectively.
Reconciliation of Claims Development to Liability [Table Text Block]	The following table presents a reconciliation of the loss development tables to the liability for unpaid losses and loss expenses in the consolidated balance sheet: Reconciliation of Reserve Balances to Liability for Unpaid Loss and Loss Expenses (in millions of U.S. dollars) December 31, 2017 Presented in the loss development tables: North America Commercial P&C Insurance — Workers' Compensation $ 8,873 North America Commercial P&C Insurance — Liability 16,631 North America Commercial P&C Insurance — Other Casualty 1,789 North America Commercial P&C Insurance — Non-Casualty 2,398 North America Personal P&C Insurance 2,421 Overseas General Insurance — Casualty 6,026 Overseas General Insurance — Non-Casualty 2,549 Global Reinsurance — Casualty 1,340 Global Reinsurance — Non-Casualty 371 Excluded from the loss development tables: Other 4,302 Net unpaid loss and allocated loss adjustment expense 46,700 Ceded unpaid loss and allocated loss adjustment expense: North America Commercial P&C Insurance — Workers' Compensation $ 1,737 North America Commercial P&C Insurance — Liability 4,133 North America Commercial P&C Insurance — Other Casualty 813 North America Commercial P&C Insurance — Non-Casualty 1,336 North America Personal P&C Insurance 503 Overseas General Insurance — Casualty 2,550 Overseas General Insurance — Non-Casualty 1,269 Global Reinsurance — Casualty 76 Global Reinsurance — Non-Casualty 142 Other 1,628 Ceded unpaid loss and allocated loss adjustment expense 14,187 Unpaid loss and loss expense on other than short-duration contracts (1) 810 Unpaid unallocated loss adjustment expenses 1,482 Unpaid losses and loss expenses $ 63,179 (1) Primarily includes the claims reserve of our international A&H business and Life Insurance segment reserves.
Claims Development tables [Table Text Block]	This product line has a substantial geographic spread and a broad mix across industries. Types of coverage include risk management business predominantly with high deductible policies, loss sensitive business (i.e., retrospectively-rated policies), business fronted for captives, as well as excess and primary guaranteed cost coverages. The triangle below shows all loss and allocated expense development for the workers' compensation product line. In our prior period development disclosure, we exclude any loss development where there is a directly related premium adjustment. For workers' compensation, changes in the exposure base due to payroll audits will drive changes in ultimate losses. In addition, we record involuntary pool assumptions (premiums and losses) on a lagged basis. Both of these items will influence the development in the triangle, particularly the first prior accident year, and are included in the reconciliation table presented on page F-65. North America Commercial P&C Insurance — Workers' Compensation — Long-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 1,084 $ 1,042 $ 1,043 $ 1,037 $ 1,036 $ 1,010 $ 1,009 $ 1,004 $ 986 $ 993 $ 214 2009 1,029 998 997 990 980 977 966 972 965 233 2010 1,049 1,037 1,050 1,065 1,064 1,052 1,028 1,020 262 2011 1,037 1,030 1,046 1,049 1,053 1,022 1,012 294 2012 1,050 1,011 1,030 1,040 1,011 989 326 2013 1,109 1,108 1,122 1,127 1,085 368 2014 1,207 1,201 1,217 1,214 553 2015 1,282 1,259 1,271 631 2016 1,367 1,367 806 2017 1,411 1,080 Total $ 11,327 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 124 $ 275 $ 371 $ 439 $ 503 $ 546 $ 578 $ 607 $ 632 $ 651 333 2009 107 258 348 416 475 519 550 597 617 282 2010 123 300 411 493 551 592 617 641 304 2011 119 294 411 484 533 567 595 287 2012 111 271 365 436 486 532 288 2013 107 286 422 506 553 300 2014 113 295 410 484 337 2015 116 301 418 339 2016 122 326 310 2017 120 307 Total $ 4,937 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 2,483 All Accident years $ 8,873 This product line is comprised of D&O liability, E&O liability, financial institutions (including crime/fidelity coverages), and non-U.S. general liability as well as aviation and political risk. Exposures are located around the world, including Europe, Latin America, and Asia. Approximately 40 percent of Chubb International’s business is generated by European accounts. There is some U.S. exposure in Casualty from multinational accounts. The financial lines coverages are typically written on a claims-made form, while general liability coverages are typically on an occurrence basis and comprised of a mix of primary and excess businesses. Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 1,220 $ 1,334 $ 1,423 $ 1,444 $ 1,453 $ 1,408 $ 1,336 $ 1,315 $ 1,330 $ 1,281 $ 81 2009 1,284 1,425 1,474 1,485 1,482 1,365 1,257 1,256 1,202 76 2010 1,231 1,311 1,358 1,430 1,365 1,312 1,183 1,178 97 2011 1,272 1,277 1,270 1,262 1,176 1,109 1,094 157 2012 1,311 1,281 1,348 1,367 1,363 1,345 279 2013 1,289 1,284 1,284 1,330 1,270 314 2014 1,295 1,366 1,377 1,388 506 2015 1,223 1,324 1,353 542 2016 1,227 1,333 749 2017 1,229 968 Total $ 12,673 Overseas General Insurance — Casualty — Long-tail (continued) Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 121 $ 306 $ 472 $ 642 $ 790 $ 895 $ 971 $ 1,029 $ 1,083 $ 1,116 39 2009 123 341 524 667 763 824 896 993 1,020 39 2010 109 277 481 629 740 831 883 938 41 2011 91 250 400 534 638 719 795 42 2012 77 254 443 598 714 856 42 2013 90 272 432 584 727 42 2014 117 299 481 614 43 2015 92 296 504 45 2016 127 328 45 2017 99 34 Total $ 6,997 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 350 All Accident years $ 6,026 This line consists of primary and excess liability exposures, including medical liability, and professional lines, including directors and officers (D&O) liability, errors and omissions (E&O) liability, employment practices liability (EPL), fidelity bonds, and fiduciary liability. The primary and excess liability business represents the largest part of these exposures. The former includes both monoline and commercial package liability. The latter includes a substantial proportion of commercial umbrella, excess and high excess business, where loss activity can produce significant volatility in the loss triangles at later ages within an accident year (and sometimes across years) due to the size of the limits afforded and the complex nature of the underlying losses. This line includes management and professional liability products provided to a wide variety of clients, from national accounts to small firms along with private and not-for-profit organizations, distributed through brokers, agents, wholesalers and MGAs. Many of these coverages, particularly D&O and E&O, are typically written on a claims-made form. While most of the coverages are underwritten on a primary basis, there are significant amounts of excess exposure with large policy limits. Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 3,792 $ 3,823 $ 3,812 $ 3,791 $ 3,652 $ 3,412 $ 3,352 $ 3,278 $ 3,174 $ 3,157 $ 245 2009 3,798 3,783 3,770 3,743 3,642 3,392 3,316 3,244 3,103 250 2010 3,578 3,583 3,601 3,559 3,419 3,250 3,128 3,107 423 2011 3,500 3,585 3,629 3,664 3,593 3,498 3,383 589 2012 3,552 3,628 3,613 3,564 3,524 3,426 856 2013 3,546 3,541 3,542 3,532 3,430 1,090 2014 3,535 3,585 3,674 3,717 1,526 2015 3,559 3,708 3,818 1,941 2016 3,533 3,594 2,381 2017 3,386 2,994 Total $ 34,121 North America Commercial P&C Insurance — Liability — Long-tail (continued) Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 147 $ 580 $ 1,110 $ 1,643 $ 1,992 $ 2,323 $ 2,558 $ 2,657 $ 2,753 $ 2,836 21 2009 135 587 1,160 1,672 2,019 2,357 2,545 2,678 2,730 21 2010 126 611 1,108 1,559 1,893 2,259 2,426 2,527 20 2011 160 652 1,209 1,805 2,214 2,476 2,659 20 2012 166 656 1,172 1,680 2,092 2,326 20 2013 130 548 1,192 1,597 2,007 20 2014 164 679 1,250 1,804 21 2015 138 605 1,206 23 2016 171 663 24 2017 161 19 Total $ 18,919 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 1,429 All Accident years $ 16,631 North America Personal P&C Insurance — Short-tail Chubb provides personal lines coverages for high-net-worth individuals and families in North America including homeowners, automobile, valuable articles (including fine art), umbrella liability, and recreational marine insurance offered through independent regional agents and brokers. A portfolio acquired from Fireman’s Fund is presented on a prospective basis beginning in May of accident year 2015 . Reserves associated with prior accident periods were acquired through a loss portfolio transfer, which does not allow for a retrospective presentation. During this ten-year period, this segment was also impacted by natural catastrophes, mainly in 2008, 2012, and 2017 accident years. North America Personal P&C Insurance — Short-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 1,779 $ 1,779 $ 1,749 $ 1,724 $ 1,695 $ 1,677 $ 1,670 $ 1,661 $ 1,661 $ 1,659 $ 5 2009 1,611 1,598 1,568 1,554 1,545 1,538 1,538 1,534 1,533 7 2010 1,870 1,878 1,855 1,838 1,834 1,830 1,825 1,822 9 2011 2,208 2,210 2,185 2,173 2,164 2,160 2,159 13 2012 2,185 2,183 2,183 2,191 2,185 2,186 9 2013 1,860 1,888 1,896 1,899 1,924 41 2014 2,205 2,206 2,192 2,145 29 2015 2,494 2,549 2,560 126 2016 2,439 2,542 248 2017 3,034 725 Total $ 21,564 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 975 $ 1,409 $ 1,521 $ 1,586 $ 1,622 $ 1,638 $ 1,644 $ 1,647 $ 1,651 $ 1,651 139 2009 887 1,236 1,347 1,439 1,486 1,503 1,513 1,521 1,523 125 2010 1,153 1,522 1,670 1,729 1,772 1,793 1,805 1,811 149 2011 1,360 1,835 1,971 2,051 2,105 2,129 2,138 168 2012 1,176 1,806 1,957 2,063 2,117 2,149 173 2013 1,043 1,504 1,687 1,786 1,843 126 2014 1,310 1,764 1,925 2,034 135 2015 1,499 2,083 2,270 139 2016 1,453 2,051 140 2017 1,698 123 Total $ 19,168 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 25 All Accident years $ 2,421 This product line represents first party commercial product lines that are short-tailed in nature, such as property, inland marine, ocean marine, surety and A&H. There is a wide diversity of products, primary and excess coverages, and policy sizes. During this ten-year period, this product line was also impacted by natural catastrophes mainly in the 2008, 2012, and 2017 accident years. Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 1,999 $ 1,941 $ 1,916 $ 1,901 $ 1,890 $ 1,881 $ 1,877 $ 1,865 $ 1,863 $ 1,859 $ 5 2009 1,310 1,307 1,251 1,222 1,205 1,198 1,198 1,195 1,194 9 2010 1,507 1,543 1,466 1,430 1,428 1,420 1,416 1,410 9 2011 1,963 1,938 1,881 1,859 1,839 1,843 1,838 15 2012 2,034 1,918 1,884 1,866 1,861 1,848 11 2013 1,434 1,424 1,337 1,360 1,340 18 2014 1,647 1,663 1,581 1,561 29 2015 1,737 1,746 1,650 83 2016 1,911 1,888 168 2017 2,641 1,089 Total $ 17,229 North America Commercial P&C Insurance — Non-Casualty — Short-tail (continued) Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 965 $ 1,622 $ 1,744 $ 1,794 $ 1,823 $ 1,832 $ 1,838 $ 1,847 $ 1,848 $ 1,851 999 2009 620 1,035 1,125 1,149 1,163 1,171 1,179 1,181 1,181 1,125 2010 724 1,223 1,323 1,359 1,384 1,393 1,396 1,397 1,059 2011 939 1,573 1,718 1,777 1,787 1,811 1,816 1,053 2012 715 1,577 1,698 1,766 1,795 1,822 1,037 2013 651 1,138 1,237 1,285 1,311 1,074 2014 820 1,373 1,484 1,505 1,102 2015 726 1,343 1,488 1,173 2016 846 1,504 1,293 2017 979 1,175 Total $ 14,854 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 23 All Accident years $ 2,398 This product line includes proportional and excess coverages in general, automobile liability, professional liability, medical malpractice, workers' compensation and aviation, with exposures located around the world. In general, reinsurance exhibits less stable development patterns than primary business. In particular general casualty reinsurance and excess coverages are long-tailed and can be very volatile. Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 399 $ 420 $ 439 $ 431 $ 428 $ 407 $ 408 $ 404 $ 401 $ 399 $ 48 2009 319 351 363 370 366 347 331 320 316 24 2010 401 421 432 443 432 426 416 402 55 2011 409 416 431 434 429 419 415 45 2012 387 383 391 394 379 372 23 2013 321 327 330 330 331 41 2014 333 334 340 343 46 2015 285 289 300 47 2016 224 228 63 2017 214 121 Total $ 3,320 Global Reinsurance — Casualty — Long-tail (continued) Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 33 $ 77 $ 131 $ 176 $ 220 $ 253 $ 277 $ 295 $ 305 $ 315 1.209 2009 34 79 116 154 187 209 227 241 256 0.868 2010 56 125 179 221 249 274 292 307 0.795 2011 70 146 195 236 267 291 311 0.660 2012 77 167 222 261 292 308 0.472 2013 65 143 186 222 242 0.337 2014 92 185 218 249 0.400 2015 90 159 191 0.304 2016 57 113 0.258 2017 47 0.088 Total $ 2,339 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 359 All Accident years $ 1,340 This product line consists of the remaining commercial casualty coverages such as automobile liability and aviation. There is also a small portion of commercial multi-peril (CMP) business in accident years 2014 and prior . The paid and reported data are impacted by some catastrophe loss activity primarily on the CMP exposures just noted. North America Commercial P&C Insurance — Other-Casualty — Long-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 693 $ 733 $ 700 $ 661 $ 644 $ 647 $ 643 $ 646 $ 641 $ 637 $ 13 2009 594 584 550 531 488 454 447 445 441 2 2010 610 604 598 543 503 475 477 489 33 2011 577 586 578 545 530 521 513 33 2012 632 604 575 559 518 517 27 2013 526 530 522 515 468 60 2014 592 581 579 594 147 2015 486 469 501 191 2016 503 494 249 2017 531 387 Total $ 5,185 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 144 $ 342 $ 446 $ 520 $ 566 $ 591 $ 602 $ 610 $ 618 $ 617 20 2009 70 206 287 337 374 402 414 423 428 15 2010 97 236 322 364 392 434 444 449 15 2011 86 235 341 400 437 461 466 16 2012 69 223 319 386 435 470 16 2013 69 197 271 348 385 18 2014 80 220 317 391 17 2015 47 137 215 15 2016 52 146 15 2017 66 13 Total $ 3,633 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 237 All Accident years $ 1,789 This product line includes property, property catastrophe, marine, credit/surety, A&H and energy. This product line is impacted by natural catastrophes, particularly in the 2008, 2011 and 2017 years. Of the non-catastrophe book, the mixture of business varies by year with approximately 72 percent of loss on proportional treaties in Treaty Year 2008 and after . This percentage has increased over time with the proportion being approximately 60 percent from 2008 to 2012 growing to an average of 84 percent from 2013 to 2017, with the remainder being written on an excess of loss basis. Global Reinsurance — Non-Casualty — Short-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 316 $ 310 $ 301 $ 292 $ 286 $ 286 $ 287 $ 284 $ 285 $ 286 $ 2 2009 141 172 152 150 144 141 139 139 139 3 2010 200 235 224 218 222 224 225 225 5 2011 274 275 272 262 263 264 264 1 2012 232 210 200 191 189 187 2 2013 163 160 149 143 144 5 2014 163 179 179 182 9 2015 146 154 161 8 2016 182 188 17 2017 396 82 Total $ 2,172 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 79 $ 177 $ 228 $ 260 $ 274 $ 276 $ 278 $ 280 $ 280 $ 280 0.179 2009 52 106 122 129 132 134 134 134 134 0.114 2010 56 162 188 200 205 216 214 217 0.101 2011 85 176 207 232 251 255 258 0.128 2012 44 129 156 166 172 177 0.113 2013 46 103 121 131 133 0.119 2014 65 128 151 162 0.100 2015 56 103 132 0.110 2016 57 132 0.168 2017 191 0.205 Total $ 1,816 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 15 All Accident years $ 371 This product line is comprised of commercial fire, marine (predominantly cargo), surety, personal automobile (in Latin America, Asia Pacific and Japan), personal cell phones, personal residential (including high net worth), energy and construction. Latin America and Europe each make up about 35 percent of the Chubb International non-casualty book. In general, these lines have relatively stable payment and reporting patterns although they are impacted by natural catastrophes mainly in the 2008 , 2010 , 2011 , and 2017 accident years. Overseas General Insurance — Non-Casualty — Short-tail (continued) Net Incurred Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Net IBNR Reserves Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 1,609 $ 1,608 $ 1,563 $ 1,547 $ 1,553 $ 1,527 $ 1,524 $ 1,519 $ 1,508 $ 1,504 $ 25 2009 1,564 1,534 1,446 1,415 1,395 1,377 1,377 1,366 1,366 3 2010 1,713 1,734 1,705 1,693 1,687 1,673 1,660 1,643 13 2011 1,950 2,035 1,978 1,939 1,920 1,908 1,901 7 2012 1,775 1,764 1,723 1,667 1,661 1,650 34 2013 1,868 1,859 1,787 1,739 1,730 62 2014 1,975 2,048 1,985 1,959 72 2015 2,111 2,243 2,195 157 2016 2,164 2,148 19 2017 2,349 307 Total $ 18,445 Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses Years Ended December 31 December 31 2017 (in millions of U.S. dollars) Unaudited Reported Claims (in thousands) Accident Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2017 2008 $ 646 $ 1,218 $ 1,360 $ 1,428 $ 1,451 $ 1,461 $ 1,469 $ 1,477 $ 1,477 $ 1,484 539 2009 602 1,095 1,233 1,300 1,324 1,335 1,341 1,344 1,343 518 2010 698 1,276 1,480 1,543 1,583 1,596 1,603 1,604 561 2011 793 1,520 1,728 1,786 1,817 1,832 1,841 579 2012 716 1,284 1,479 1,539 1,562 1,572 600 2013 738 1,340 1,541 1,574 1,612 622 2014 800 1,497 1,715 1,782 594 2015 901 1,638 1,873 627 2016 1,083 1,752 637 2017 1,098 616 Total $ 15,961 Net Liabilities for Loss and Allocated Loss Adjustment Expenses (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 65 All Accident years $ 2,549 Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (3 ) All Accident years $ (141 )
Supplementary PPD [Table Text Block]	Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ — All Accident years $ 16 Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ — All Accident years $ (188 ) Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ 14 All Accident years $ — Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (35 ) All Accident years $ (108 ) Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (10 ) All Accident years $ 76 Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (13 ) All Accident years $ (68 ) Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (3 ) All Accident years $ (141 ) Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (154 ) All Accident years $ (434 ) Supplementary Information: (Favorable)/ Adverse Prior Period Development (in millions of U.S. dollars) December 31, 2017 Accident years prior to 2008 $ (60 ) All Accident years $ (72 )
Schedule of Historical Claims [Table Text Block]	Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 34 % 38 % 14 % 7 % 4 % 2 % — % 1 % — % — % North America Personal P&C Insurance — Short-tail (continued) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 58 % 24 % 7 % 5 % 3 % 1 % 1 % — % — % — % Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 8 % 15 % 14 % 12 % 10 % 8 % 6 % 6 % 3 % 3 % Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 19 % 20 % 12 % 11 % 8 % 6 % 5 % 4 % 4 % 3 % North America Commercial P&C Insurance — Other-Casualty — Long-tail (continued) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 15 % 26 % 17 % 12 % 8 % 6 % 2 % 1 % 1 % — % Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 4 % 14 % 17 % 15 % 12 % 9 % 6 % 4 % 2 % 3 % Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 46 % 37 % 7 % 3 % 1 % 1 % — % — % — % — % Overseas General Insurance — Non-Casualty — Short-tail (continued) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 44 % 35 % 11 % 4 % 2 % 1 % — % — % — % — % North America Commercial P&C Insurance — Workers' Compensation — Long-tail (continued) Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2017 Age in Years 1 2 3 4 5 6 7 8 9 10 Percentage 10 % 16 % 10 % 7 % 5 % 4 % 3 % 3 % 2 % 2 %
Supplementary PPD Reconciliation [Table Text Block]	The following table presents a reconciliation of the loss development triangles above to prior period development: Components of PPD Year Ended December 31, 2017 (in millions of U.S. dollars) 2008 - 2016 accident years (implied PPD per loss triangles) Accident years prior to 2008 Other (1) PPD on loss reserves RIPs, Expense adjustments, and earned premiums Total (favorable)/unfavorable North America Commercial P&C Insurance Long-tail $ (367 ) $ (175 ) $ (76 ) $ (618 ) $ 56 $ (562 ) Short-tail (188 ) — 3 (185 ) 1 (184 ) (555 ) (175 ) (73 ) (2) (803 ) 57 (746 ) North America Personal P&C Insurance (Short-tail) 86 (10 ) (7 ) 69 — 69 Overseas General Insurance Long-tail (55 ) (13 ) (3 ) (71 ) — (71 ) Short-tail (138 ) (3 ) (40 ) (181 ) — (181 ) (193 ) (16 ) (43 ) (3) (252 ) — (252 ) Global Reinsurance Long-tail (12 ) (60 ) 1 (71 ) 3 (68 ) Short-tail 16 — — 16 (7 ) 9 4 (60 ) 1 (55 ) (4 ) (59 ) Subtotal $ (658 ) $ (261 ) $ (122 ) $ (1,041 ) $ 53 $ (988 ) North America Agricultural Insurance (Short-tail) $ (174 ) $ 55 $ (119 ) Corporate (Long-tail) 278 — 278 Consolidated PPD $ (937 ) $ 108 $ (829 ) (1) Other includes the impact of foreign exchange. (2) Includes favorable development of $55 million related to our Alternative Risk Solutions business; the remaining difference relates to a number of other items, none of which are individually material. (3) Includes favorable development of $35 million related to International A&H business, the remaining difference relates to a number of other items, none of which are individually material.
Prior Period Development, by Segment [Table Text Block]	The following table summarizes (favorable) and adverse prior period development (PPD) by segment. Long-tail lines include lines such as workers' compensation, general liability, and professional liability; while short-tail lines include lines such as most property lines, energy, personal accident, and agriculture. In 2017, we determined that the loss development classification for certain businesses, previously grouped within the short-tail column in the table below, would be more appropriately grouped within the long-tail column to better align with the classification of these businesses within our loss development triangles. We also determined that the loss development for certain other businesses should be reclassified from long-tail to short-tail. We updated our 2016 and 2015 amounts below to conform to the current year presentation and reclassified $101 million and $46 million , respectively, of net favorable development into long-tail from short-tail. These changes to the previously disclosed amounts have no impact to our financial condition and results of operations. Years Ended December 31 (in millions of U.S. dollars, except for percentages) Long-tail Short-tail Total % of beginning net unpaid reserves (1) 2017 North America Commercial P&C Insurance $ (562 ) $ (184 ) $ (746 ) 1.6 % North America Personal P&C Insurance — 69 69 0.1 % North America Agricultural Insurance — (119 ) (119 ) 0.2 % Overseas General Insurance (71 ) (181 ) (252 ) 0.5 % Global Reinsurance (68 ) 9 (59 ) 0.1 % Corporate 278 — 278 0.6 % Total $ (423 ) $ (406 ) $ (829 ) 1.7 % 2016 North America Commercial P&C Insurance $ (693 ) $ (85 ) $ (778 ) 1.6 % North America Personal P&C Insurance — 27 27 0.1 % North America Agricultural Insurance — (72 ) (72 ) 0.2 % Overseas General Insurance (236 ) (187 ) (423 ) 0.9 % Global Reinsurance (77 ) (1 ) (78 ) 0.2 % Corporate 189 — 189 0.4 % Total $ (817 ) $ (318 ) $ (1,135 ) 2.4 % 2015 North America Commercial P&C Insurance $ (162 ) $ (102 ) $ (264 ) 1.0 % North America Personal P&C Insurance — 25 25 0.1 % North America Agricultural Insurance — (45 ) (45 ) 0.1 % Overseas General Insurance (192 ) (151 ) (343 ) 1.3 % Global Reinsurance (109 ) (10 ) (119 ) 0.4 % Corporate 200 — 200 0.7 % Total $ (263 ) $ (283 ) $ (546 ) 2.0 % (1) Calculated based on the beginning of period consolidated net unpaid losses and loss expenses. For 2016, the percent of beginning net unpaid reserves is calculated inclusive of the net unpaid losses and loss expenses acquired in the Chubb Corp acquisition of $21.4 billion .
Schedule Of Asbestos Environmental Loss Roll Forward and by segment	The following table presents a roll-forward of consolidated A&E loss reserves including allocated loss expense reserves for A&E exposures, and the provision for uncollectible paid and unpaid reinsurance recoverables: Asbestos Environmental Total (in millions of U.S. dollars) Gross Net Gross Net Gross Net Balance at December 31, 2016 $ 1,726 $ 1,119 $ 577 $ 490 $ 2,303 $ 1,609 Incurred activity 228 104 199 113 427 217 (1) Paid activity (333 ) (172 ) (169 ) (127 ) (502 ) (299 ) Balance at December 31, 2017 $ 1,621 $ 1,051 $ 607 $ 476 $ 2,228 $ 1,527 (1) Excludes unallocated loss expenses and the net activity reflects third-party reinsurance other than the aggregate excess of loss reinsurance provided by National Indemnity Company (NICO) to Westchester Specialty (see Westchester Specialty section below). The A&E net loss reserves including allocated loss expense reserves and provision for uncollectible reinsurance at December 31, 2017 and 2016 shown in the table above is comprised of: December 31 (in millions of U.S. dollars) 2017 2016 Brandywine operations $ 849 $ 760 Westchester Specialty 113 112 Chubb Corp 486 657 Other, mainly Overseas General Insurance 79 80 Total $ 1,527 $ 1,609

Taxation (Tables)

Taxation (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of components of income tax provision	The following table presents pre-tax income and the related provision for income taxes: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Pre-tax income: Switzerland $ 527 $ 766 $ 469 Outside Switzerland 3,195 4,184 2,827 Total pre-tax income $ 3,722 $ 4,950 $ 3,296 Provision for income taxes Current tax expense: Switzerland $ 46 $ 97 $ 38 Outside Switzerland 313 727 266 Total current tax expense 359 824 304 Deferred tax expense (benefit): Switzerland 2 (27 ) 4 Outside Switzerland (500 ) 18 154 Total deferred tax expense (benefit) (498 ) (9 ) 158 Provision for income taxes $ (139 ) $ 815 $ 462
Reconciliation schedule of the difference between the provision for income taxes and the expected tax provision at the Swiss statutory income tax rate	The following table presents a reconciliation of the difference between the provision for income taxes and the expected tax provision at the Swiss statutory income tax rate: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Expected tax provision at Swiss statutory tax rate $ 291 $ 388 $ 258 Permanent differences: Taxes on earnings subject to rate other than Swiss statutory rate 263 582 193 Tax-exempt interest and dividends received deduction, net of proration (199 ) (200 ) (32 ) Net withholding taxes 30 20 35 Excess tax benefit on share-based compensation (48 ) — — Impact of 2017 Tax Act (450 ) — — Corporate owned life insurance (37 ) — — Other 11 25 8 Total provision for income taxes $ (139 ) $ 815 $ 462
Schedule of the components of net deferred tax assets	The following table presents the components of net deferred tax assets and liabilities: December 31 December 31 (in millions of U.S. dollars) 2017 2016 Deferred tax assets: Loss reserve discount $ 715 $ 1,269 Unearned premiums reserve 231 498 Foreign tax credits 340 2,115 Provision for uncollectible balances 45 72 Loss carry-forwards 90 92 Debt related amounts 77 219 Compensation related amounts 260 449 Cumulative translation adjustments 30 59 Other, net 70 69 Total deferred tax assets 1,858 4,842 Deferred tax liabilities: Deferred policy acquisition costs 635 842 Other intangible assets, including VOBA 1,437 2,352 Un-remitted foreign earnings 66 2,001 Investments 53 406 Unrealized appreciation on investments 184 60 Depreciation 83 91 Total deferred tax liabilities 2,458 5,752 Valuation allowance 99 78 Net deferred tax assets (liabilities) $ (699 ) $ (988 )
Reconciliation schedule of unrecognized tax benefits	The following table presents a reconciliation of the beginning and ending amount of gross unrecognized tax benefits: December 31 December 31 (in millions of U.S. dollars) 2017 2016 Balance, beginning of year $ 17 $ 16 Additions based on tax positions related to the current year 3 3 Additions based on tax positions related to prior years (1) — 2 Reductions for tax positions of prior years (4 ) (4 ) Reductions for the lapse of the applicable statutes of limitations (3 ) — Balance, end of year $ 13 $ 17 (1) Assumed in connection with the Chubb Corp acquisition in 2016.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of debt outstanding	December 31 December 31 (in millions of U.S. dollars) 2017 2016 Early Redemption Option Repurchase agreements (weighted average interest rate of 1.5% in 2017 and 0.8% in 2016) $ 1,408 $ 1,403 None Short-term debt Chubb INA senior notes: $500 million 5.7% due February 2017 $ — $ 500 Make-whole premium plus 0.20% $300 million 5.8% due March 2018 300 — Make-whole premium plus 0.35% $600 million 5.75% due May 2018 610 — Make-whole premium plus 0.30% $100 million 6.6% due August 2018 103 — None Total short-term debt $ 1,013 $ 500 Long-term debt Chubb INA senior notes: $300 million 5.8% due March 2018 $ — $ 300 Make-whole premium plus 0.35% $600 million 5.75% due May 2018 — 635 Make-whole premium plus 0.30% $100 million 6.6% due August 2018 — 107 None $500 million 5.9% due June 2019 499 498 Make-whole premium plus 0.40% $1,300 million 2.3% due November 2020 1,296 1,294 Make-whole premium plus 0.15% $1,000 million 2.875% due November 2022 995 994 Make-whole premium plus 0.20% $475 million 2.7% due March 2023 472 471 Make-whole premium plus 0.10% $700 million 3.35% due May 2024 695 695 Make-whole premium plus 0.15% $800 million 3.15% due March 2025 795 794 Make-whole premium plus 0.15% $1,500 million 3.35% due May 2026 1,489 1,488 Make-whole premium plus 0.20% $100 million 8.875% due August 2029 100 100 None $200 million 6.8% due November 2031 254 257 Make-whole premium plus 0.25% $300 million 6.7% due May 2036 297 297 Make-whole premium plus 0.20% $800 million 6.0% due May 2037 971 980 Make-whole premium plus 0.20% $600 million 6.5% due May 2038 768 776 Make-whole premium plus 0.30% $475 million 4.15% due March 2043 469 469 Make-whole premium plus 0.15% $1,500 million 4.35% due November 2045 1,482 1,482 Make-whole premium plus 0.25% Chubb INA $1,000 million 6.375% capital securities due March 2067 (1) 964 962 Make-whole premium plus 0.25%-0.50% Other long-term debt (2.75% to 7.1% due December 2019 to September 2020) 10 11 None Total long-term debt $ 11,556 $ 12,610 Trust preferred securities Chubb INA capital securities due April 2030 $ 308 $ 308 Redemption prices (2)

Commitments, contingencies, a43

Commitments, contingencies, and guarantees (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Balance Sheet Locations, Fair Values In An Asset Or (Liability) Position, And Notional Values/Payment Provisions Of Derivative Instruments	The following table presents the balance sheet locations, fair values of derivative instruments in an asset or (liability) position, and notional values/payment provisions of our derivative instruments: December 31, 2017 December 31, 2016 Consolidated Fair Value Notional Fair Value Notional Derivative Asset Derivative (Liability) Derivative Asset Derivative (Liability) (in millions of U.S. dollars) Investment and embedded derivative instruments: Foreign currency forward contracts OA / (AP) $ 14 $ (27 ) $ 2,064 $ 25 $ (50 ) $ 2,220 Cross-currency swaps OA / (AP) — — 45 — — 95 Options/Futures contracts on notes and bonds OA / (AP) 4 (3 ) 1,007 6 (4 ) 2,344 Convertible securities (1) FM AFS/ES 5 — 6 2 — 7 $ 23 $ (30 ) $ 3,122 $ 33 $ (54 ) $ 4,666 Other derivative instruments: Futures contracts on equities (2) OA / (AP) $ — $ (21 ) $ 1,553 $ 1 $ — $ 1,316 Other OA / (AP) 1 (2 ) 75 2 (13 ) 214 $ 1 $ (23 ) $ 1,628 $ 3 $ (13 ) $ 1,530 GLB (3) (AP) / (FPB) $ — $ (550 ) $ 1,083 $ — $ (853 ) $ 1,264 (1) Includes fair value of embedded derivatives. (2) Related to GMDB and GLB blocks of business. (3) Includes both future policy benefits reserves and fair value derivative adjustment. Refer to Note 5 c ) for additional information. Note that the payment provision related to GLB is the net amount at risk. The concept of a notional value does not apply to the GLB reinsurance contracts.
Secured Borrowings Securities Lending Table	The following table presents the carrying value of collateral held under securities lending agreements by investment category and remaining contractual maturity of the underlying agreements: Remaining contractual maturity December 31 2017 December 31 2016 (in millions of U.S. dollars) Overnight and Continuous Collateral held under securities lending agreements: Cash $ 828 $ 423 U.S. Treasury and agency 36 54 Foreign 712 578 Corporate securities — 37 Mortgage-backed securities 74 — Equity securities 87 — $ 1,737 $ 1,092 Gross amount of recognized liability for securities lending payable $ 1,737 $ 1,093 Difference (1) $ — $ (1 ) (1) The carrying value of the securities lending collateral held is $1 million lower than the securities lending payable at December 31, 2016 due to accrued interest recorded in the securities lending payable. At December 31, 2017 and 2016 , our repurchase agreement obligations of $1,408 million and $ 1,403 million , respectively, were fully collateralized. In contrast to securities lending programs, the use of cash received is not restricted for the repurchase obligations. The fair value of the underlying securities sold remains in Fixed maturities available for sale, and the repurchase agreement obligation is recorded in Repurchase agreements in the Consolidated balance sheets. The following table presents the carrying value of collateral pledged under repurchase agreements by investment category and remaining contractual maturity of the underlying agreements: Remaining contractual maturity December 31, 2017 December 31, 2016 Up to 30 Days Greater than 90 Days Up to 30 Days Greater than 90 Days Total (in millions of U.S. dollars) Total Collateral pledged under repurchase agreements: Cash $ — $ — $ — $ — $ 1 $ 1 U.S. Treasury and agency 9 230 239 230 10 240 Mortgage-backed securities 369 826 1,195 339 881 1,220 $ 378 $ 1,056 $ 1,434 $ 569 $ 892 $ 1,461 Gross amount of recognized liabilities for repurchase agreements $ 1,408 $ 1,403 Difference (1) $ 26 $ 58 (1) Per the repurchase agreements, the amount of collateral posted is required to exceed the amount of gross liability.
Derivative Instruments, Gain (Loss) [Table Text Block]	The following table presents net realized gains (losses) related to derivative instrument activity in the Consolidated statements of operations: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Investment and embedded derivative instruments: Foreign currency forward contracts $ 9 $ (31 ) $ 31 All other futures contracts and options (21 ) (10 ) 9 Convertible securities (1) 1 8 (8 ) Total investment and embedded derivative instruments $ (11 ) $ (33 ) $ 32 GLB and other derivative instruments: GLB (2) $ 364 $ 53 $ (203 ) Futures contracts on equities (3) (261 ) (136 ) (8 ) Other (5 ) (10 ) (14 ) Total GLB and other derivative instruments $ 98 $ (93 ) $ (225 ) $ 87 $ (126 ) $ (193 ) (1) Includes embedded derivatives. (2)
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum lease payments under the leases are expected to be as follows: For the years ending December 31 (in millions of U.S. dollars) 2018 $ 181 2019 153 2020 133 2021 114 2022 89 Thereafter 230 Total minimum future lease commitments $ 900

Shareholders' equity (Tables)

Shareholders' equity (Tables)	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Dividends Declared [Table Text Block]	The following table presents dividend distributions per Common Share in Swiss francs (CHF) and U.S. dollars (USD): Year Ended December 31 2017 2016 2015 CHF USD CHF USD CHF USD Dividends - par value reduction — $ — — $ — 0.62 $ 0.65 Dividends - distributed from capital contribution reserves 2.76 2.82 2.70 2.74 1.94 2.01 Total dividend distributions per common share 2.76 $ 2.82 2.70 $ 2.74 2.56 $ 2.66
Schedule of changes in Common Shares issued and outstanding	Year Ended December 31 2017 2016 2015 Shares issued, beginning of year 479,783,864 342,832,412 342,832,412 Shares issued for Chubb Corp acquisition — 136,951,452 — Shares issued, end of year 479,783,864 479,783,864 342,832,412 Common Shares in treasury, end of year (at cost) (15,950,685 ) (13,815,148 ) (18,268,971 ) Shares issued and outstanding, end of year 463,833,179 465,968,716 324,563,441
Share Repurchase Program [Table Text Block]	The following table presents repurchases of Chubb's Common Shares conducted in a series of open market transactions under the Board authorizations: Year Ended December 31 (in millions of U.S. dollars, except share data) 2017 2016 2015 Number of shares repurchased 5,866,612 — 6,677,663 Cost of shares repurchased $ 830 $ — $ 734

Share-based compensation (Table

Share-based compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of pre-tax and after-tax share-based compensation expense	The following table presents pre-tax and after-tax share-based compensation expense: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Stock options and shares issued under ESPP: Pre-tax $ 41 $ 33 $ 31 After-tax (1) $ 26 $ 20 $ 21 Restricted stock: Pre-tax $ 259 $ 268 $ 143 After-tax $ 151 $ 167 $ 84 (1) Excludes windfall tax benefit for share-based compensation recognized as a direct adjustment to Additional paid-in capital of $32 million and $26 million for the years ended December 31, 2016 and 2015, respectively. Due to the adoption of new accounting guidance, windfall tax benefits for share-based compensation beginning in 2017 are recognized through Net income rather than Additional paid-in capital. The excess tax benefit recorded to Income tax expense in the Consolidated statement of operations was $48 million for the year ended December 31, 2017.
Schedule of the weighted-average model valuation assumptions	Year Ended December 31 2017 2016 2015 Dividend yield 2.0 % 2.3 % 2.3 % Expected volatility 19.7 % 23.2 % 21.0 % Risk-free interest rate 2.0 % 1.3 % 1.7 % Expected life 5.8 years 5.6 years 5.8 years
Rollforward of the company's stock options	The following table presents a roll-forward of Chubb's stock options: (Intrinsic Value in millions of U.S. dollars) Number of Options Weighted-Average Exercise Price Weighted-Average Fair Value Total Intrinsic Value Options outstanding, December 31, 2014 9,623,986 $ 69.06 Granted 1,892,641 $ 114.78 $ 18.49 Exercised (1,457,580 ) $ 60.88 $ 72 Forfeited (205,551 ) $ 100.25 Options outstanding, December 31, 2015 9,853,496 $ 78.40 Assumed in Chubb Corp Acquisition 339,896 $ 77.83 $ 36.07 Granted 1,929,616 $ 118.39 $ 21.52 Exercised (1,728,949 ) $ 66.65 $ 99 Forfeited (213,339 ) $ 110.01 Options outstanding, December 31, 2016 10,180,720 $ 87.29 Granted 2,079,522 $ 139.00 $ 22.97 Exercised (1,632,629 ) $ 73.53 $ 111 Forfeited (194,297 ) $ 119.44 Options outstanding, December 31, 2017 10,433,316 $ 99.20 $ 490 Options exercisable, December 31, 2017 6,675,491 $ 82.59 $ 424
Rollforward of the company's restricted stock	The following table presents a roll-forward of our restricted stock awards. Included in the roll-forward below are 22,013 restricted stock awards, 23,812 restricted stock awards, and 24,945 restricted stock awards that were granted to non-management directors during the years ended December 31, 2017 , 2016 , and 2015 , respectively: Service-based Restricted Stock Awards and Restricted Stock Units Performance-based Restricted Stock Awards and Restricted Stock Units Number of Shares Weighted-Average Grant-Date Fair Value Number of Shares Weighted-Average Grant-Date Fair Value Unvested restricted stock, December 31, 2014 3,837,097 $ 83.60 378,690 $ 90.87 Granted 1,417,965 $ 114.37 326,860 $ 113.29 Vested (1,341,358 ) $ 80.05 (110,340 ) $ 98.70 Forfeited (424,535 ) $ 87.36 — $ — Unvested restricted stock, December 31, 2015 3,489,169 $ 97.01 595,210 $ 101.73 Assumed in Chubb Corp Acquisition 3,706,639 $ 111.02 — $ — Granted 1,622,065 $ 118.70 517,507 $ 118.96 Vested (2,592,622 ) $ 100.87 (181,548 ) $ 102.43 Forfeited (420,125 ) $ 109.42 — $ — Unvested restricted stock, December 31, 2016 5,805,126 $ 109.39 931,169 $ 111.17 Granted 1,707,094 $ 139.18 267,282 $ 138.90 Vested (2,646,084 ) $ 107.73 (222,954 ) $ 113.30 Forfeited (156,694 ) $ 114.54 — $ — Unvested restricted stock, December 31, 2017 4,709,422 $ 121.16 975,497 $ 118.28

Postretirement benefits (Tables

Postretirement benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of Net Funded Status [Table Text Block]	Obligations and funded status The funded status of the pension and other postretirement benefit plans as well as the amounts recognized in Accumulated other comprehensive income at December 31, 2017 and 2016 was as follows: Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 U.S. Plans Non-U.S. Plans U.S. Plans Non-U.S. Plans (in millions of U.S. dollars) Benefit obligation, beginning of year $ 3,035 $ 1,025 $ 10 $ 559 $ 165 $ 16 Acquisition of Chubb Corp — — 3,153 372 — 506 Service cost 63 17 75 18 2 10 Interest cost 105 27 103 30 4 17 Actuarial loss (gain) 232 (4 ) 131 204 (2 ) 36 Benefits paid (132 ) (28 ) (79 ) (22 ) (14 ) (11 ) Amendments — — — (9 ) (23 ) (410 ) Curtailments — (32 ) (259 ) (7 ) 2 — Settlements (18 ) (8 ) (99 ) (7 ) — — Foreign currency revaluation and other — 80 — (113 ) 3 1 Benefit obligation, end of year $ 3,285 $ 1,077 $ 3,035 $ 1,025 $ 137 $ 165 Plan assets at fair value, beginning of year $ 2,765 $ 962 $ 9 $ 564 $ 159 $ — Acquisition of Chubb Corp — — 2,473 315 — 138 Actual return on plan assets 441 100 359 168 6 29 Employer contributions 53 63 98 67 6 3 Benefits paid (132 ) (28 ) (79 ) (22 ) (14 ) (11 ) Settlements (18 ) (8 ) (95 ) (7 ) — — Foreign currency revaluation and other — 83 — (123 ) — — Plan assets at fair value, end of year $ 3,109 $ 1,172 $ 2,765 $ 962 $ 157 $ 159 Funded status at end of year $ (176 ) $ 95 $ (270 ) $ (63 ) $ 20 $ (6 ) Amounts recognized in Accumulated other comprehensive income, not yet recognized in net periodic cost (benefit): Net actuarial loss (gain) $ (227 ) $ 82 $ (207 ) $ 156 $ 12 $ 17 Prior service cost (benefit) — 6 — (2 ) (288 ) (395 ) Total $ (227 ) $ 88 $ (207 ) $ 154 $ (276 ) $ (378 )
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]
Schedule of Assumptions Used [Table Text Block]	The weighted-average assumptions used to determine the projected benefit obligation were as follows: Pension Benefits U.S. Plans Non-U.S. Plans Other Postretirement Benefits December 31, 2017 Discount rate 3.59 % 2.76 % 2.77 % Rate of compensation increase 4.00 % 3.46 % N/A December 31, 2016 Discount rate 4.14 % 2.83 % 2.97 % Rate of compensation increase 4.00 % 3.57 % N/A The components of net pension and other postretirement benefit costs reflected in Net income and other changes in plan assets and benefit obligations recognized in other comprehensive income were as follows: Pension Benefits Other Postretirement Benefits U.S. Plans Non-U.S. Plans Year Ended December 31 2017 2016 2015 2017 2016 2015 2017 2016 2015 (in millions of U.S. dollars) Costs reflected in Net income: Service cost $ 63 $ 75 $ — $ 17 $ 18 $ 6 $ 2 $ 10 $ 1 Interest cost 105 103 — 27 30 21 4 17 — Expected return on plan assets (189 ) (165 ) — (42 ) (39 ) (29 ) (5 ) (8 ) — Amortization of net actuarial loss (gain) — — — 3 2 2 — (1 ) (1 ) Amortization of prior service cost — — — — (1 ) — (89 ) (15 ) — Curtailments — (117 ) — (27 ) — — (37 ) — — Settlements — (2 ) — — 1 1 — — — Net periodic (benefit) cost $ (21 ) $ (106 ) $ — $ (22 ) $ 11 $ 1 $ (125 ) $ 3 $ — Changes in plan assets and benefit obligations recognized in other comprehensive income Net actuarial loss (gain) $ (21 ) $ (326 ) $ — $ (57 ) $ 49 $ (16 ) $ (3 ) $ 17 $ — Prior service cost (benefit) — — — — (8 ) 1 (23 ) (395 ) — Amortization of net actuarial loss — — — (3 ) — — — — — Amortization of prior service cost — — — — — — 89 — — Curtailments — 117 — (6 ) — — 39 — — Settlements 1 2 — — (1 ) — — — — Total (increase) decrease in other comprehensive income $ (20 ) $ (207 ) $ — $ (66 ) $ 40 $ (15 ) $ 102 $ (378 ) $ — The estimated net actuarial loss that will be amortized from AOCI into net periodic benefit costs in Net income for Non-U.S. pension plans during 2018 is $1 million . The estimated net prior service credit that will be amortized from AOCI into net periodic benefit cost in Net income during 2018 for U.S. other postretirement benefit plans is $ 80 million . The weighted-average assumptions used to determine the net periodic pension and other postretirement benefit costs were as follows: Pension Benefits U.S. Plans Non-U.S. Plans Other Postretirement Benefits Year Ended December 31 2017 Discount rate in effect for determining service cost 4.20 % 3.55 % 2.84 % Discount rate in effect for determining interest cost 3.53 % 2.61 % 2.44 % Rate of compensation increase 4.00 % 3.57 % N/A Expected long-term rate of return on plan assets 7.00 % 4.23 % 3.00 % 2016 Discount rate in effect for determining service cost 4.38 % 3.85 % 4.32 % Discount rate in effect for determining interest cost 3.59 % 3.44 % 4.02 % Rate of compensation increase 4.00 % 3.33 % N/A Expected long-term rate of return on plan assets 7.00 % 4.79 % 6.34 % 2015 Discount rate NM 3.51 % NM Rate of compensation increase NM 3.09 % NM Expected long-term rate of return on plan assets NM 4.81 % NM NM – not meaningful
Schedule of Net Benefit Costs [Table Text Block]	The components of net pension and other postretirement benefit costs reflected in Net income and other changes in plan assets and benefit obligations recognized in other comprehensive income were as follows: Pension Benefits Other Postretirement Benefits U.S. Plans Non-U.S. Plans Year Ended December 31 2017 2016 2015 2017 2016 2015 2017 2016 2015 (in millions of U.S. dollars) Costs reflected in Net income: Service cost $ 63 $ 75 $ — $ 17 $ 18 $ 6 $ 2 $ 10 $ 1 Interest cost 105 103 — 27 30 21 4 17 — Expected return on plan assets (189 ) (165 ) — (42 ) (39 ) (29 ) (5 ) (8 ) — Amortization of net actuarial loss (gain) — — — 3 2 2 — (1 ) (1 ) Amortization of prior service cost — — — — (1 ) — (89 ) (15 ) — Curtailments — (117 ) — (27 ) — — (37 ) — — Settlements — (2 ) — — 1 1 — — — Net periodic (benefit) cost $ (21 ) $ (106 ) $ — $ (22 ) $ 11 $ 1 $ (125 ) $ 3 $ — Changes in plan assets and benefit obligations recognized in other comprehensive income Net actuarial loss (gain) $ (21 ) $ (326 ) $ — $ (57 ) $ 49 $ (16 ) $ (3 ) $ 17 $ — Prior service cost (benefit) — — — — (8 ) 1 (23 ) (395 ) — Amortization of net actuarial loss — — — (3 ) — — — — — Amortization of prior service cost — — — — — — 89 — — Curtailments — 117 — (6 ) — — 39 — — Settlements 1 2 — — (1 ) — — — — Total (increase) decrease in other comprehensive income $ (20 ) $ (207 ) $ — $ (66 ) $ 40 $ (15 ) $ 102 $ (378 ) $ —
Schedule of Health Care Cost Trend Rates [Table Text Block]	The weighted-average healthcare cost trend rate assumptions used to measure the expected cost of healthcare benefits were as follows: U.S. Plans Non-U.S. Plans 2017 2016 2015 2017 2016 Healthcare cost trend rate 7.01 % 7.28 % 6.50 % 6.61 % 6.61 % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50 % 4.50 % 4.50 % 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate 2038 2038 2026 2029 2029
Schedule of Allocation of Plan Assets [Table Text Block]	The following table presents the fair values of the pension plan assets, by valuation hierarchy. For additional information on how we classify these assets within the valuation hierarchy, refer to Note 4 to the Consolidated financial statements. December 31, 2017 Pension Benefits (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total U.S. Plans: Short-term investments $ 9 $ 52 $ — $ 61 U.S. Treasury and agency 446 79 — 525 Foreign and corporate bonds — 692 — 692 Equity securities 1,154 — — 1,154 Total U.S. Plan assets (1) $ 1,609 $ 823 $ — $ 2,432 Non-U.S. Plans: Short-term investments $ 5 $ — $ — $ 5 Foreign and corporate bonds — 456 — 456 Equity securities 122 492 — 614 Total Non-U.S. Plan assets (1) $ 127 $ 948 $ — $ 1,075 (1) Excluded from the table above are $ 677 million and $95 million of other investments measured using NAV as a practical expedient related to the U.S. Plans and non-U.S. Plans respectively. December 31, 2016 Pension Benefits (in millions of U.S. dollars) Level 1 Level 2 Level 3 Total U.S. Plans: Short-term investments $ — $ 43 $ — $ 43 U.S. Treasury and agency 206 112 — 318 Foreign and corporate bonds — 482 5 487 Equity securities 728 — — 728 Derivative instruments 3 — — 3 Total U.S. Plan assets (1) $ 937 $ 637 $ 5 $ 1,579 Non-U.S. Plans: Short-term investments $ 2 $ — $ — $ 2 Foreign and corporate bonds — 435 — 435 Equity securities 100 412 — 512 Total Non-U.S. Plan assets (1) $ 102 $ 847 $ — $ 949 (1) Excluded from the table above are $ 1.2 billion and $ 13 million of other investments measured using NAV as a practical expedient related to the U.S. Plans and Non-U.S. Plans, re
Schedule of expected future benefit payments	Expected future payments are as follows: Pension For the years ending December 31 U.S. Plans Non-U.S. Plans Other Postretirement Benefits (in millions of U.S. dollars) 2018 $ 129 $ 23 $ 17 2019 141 25 19 2020 148 29 20 2021 155 28 23 2022 163 27 25 2023-2027 881 159 44

Other (income) expense (Tables)

Other (income) expense (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Schedule of the components of Other (income) expense	Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Equity in net (income) loss of partially-owned entities $ (418 ) $ (264 ) $ (113 ) (Gains) losses from fair value changes in separate account assets (1) (97 ) (11 ) 19 One-time contribution to the Chubb Charitable Foundation 50 — — Federal excise and capital taxes 35 19 19 Other 30 34 24 Other (income) expense $ (400 ) $ (222 ) $ (51 ) (1) Related to (gains) losses from fair value changes in separate account assets that do not qualify for separate account reporting under GAAP.

Segment information (Tables)

Segment information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Operations By Segment	For the Year Ended December 31, 2017 (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Reinsurance Life Insurance Corporate Chubb Consolidated Net premiums written $ 12,028 $ 4,533 $ 1,516 $ 8,341 $ 685 $ 2,141 $ — $ 29,244 Net premiums earned 12,191 4,399 1,508 8,131 704 2,101 — 29,034 Losses and loss expenses 8,287 3,265 1,036 4,281 561 739 285 18,454 Policy benefits — — — — — 676 — 676 Policy acquisition costs 1,873 899 81 2,221 177 530 — 5,781 Administrative expenses 981 264 (8 ) 982 44 303 267 2,833 Underwriting income (loss) 1,050 (29 ) 399 647 (78 ) (147 ) (552 ) 1,290 Net investment income 1,961 226 25 610 273 313 (283 ) 3,125 Other (income) expense 1 4 2 (4 ) (1 ) (84 ) (318 ) (400 ) Amortization expense of purchased intangibles — 16 29 45 — 2 168 260 Segment income (loss) 3,010 177 393 1,216 196 248 (685 ) 4,555 Net realized gains (losses) including OTTI 84 84 Interest expense 607 607 Chubb integration expenses 310 310 Income tax benefit (139 ) (139 ) Net income (loss) $ (1,379 ) $ 3,861 For the Year Ended December 31, 2016 (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Life Insurance Corporate Chubb Net premiums written $ 11,740 $ 4,153 $ 1,328 $ 8,124 $ 676 $ 2,124 $ — $ 28,145 Net premiums earned 12,217 4,319 1,316 8,132 710 2,055 — 28,749 Losses and loss expenses 7,439 2,558 893 4,005 325 663 169 16,052 Policy benefits — — — — — 588 — 588 Policy acquisition costs 2,023 966 83 2,136 187 509 — 5,904 Administrative expenses 1,125 363 (6 ) 1,057 52 307 183 3,081 Underwriting income (loss) 1,630 432 346 934 146 (12 ) (352 ) 3,124 Net investment income 1,860 207 20 600 263 283 (368 ) 2,865 Other (income) expense (2 ) 6 1 (11 ) (4 ) 5 (217 ) (222 ) Amortization expense (benefit) of purchased intangibles — 19 29 48 — 3 (80 ) 19 Segment income (loss) 3,492 614 336 1,497 413 263 (423 ) 6,192 Net realized gains (losses) including OTTI (145 ) (145 ) Interest expense 605 605 Chubb integration expense 492 492 Income tax expense 815 815 Net income (loss) $ (2,480 ) $ 4,135 For the Year Ended December 31, 2015 (in millions of U.S. dollars) North America Commercial P&C Insurance North America Personal P&C Insurance North America Agricultural Insurance Overseas General Insurance Global Reinsurance Life Insurance Corporate Chubb Consolidated Net premiums written $ 5,715 $ 1,192 $ 1,346 $ 6,634 $ 828 $ 1,998 $ — $ 17,713 Net premiums earned 5,634 948 1,364 6,471 849 1,947 — 17,213 Losses and loss expenses 3,661 590 1,088 3,052 290 601 202 9,484 Policy benefits — — — — — 543 — 543 Policy acquisition costs 531 69 69 1,581 214 476 1 2,941 Administrative expenses 621 123 1 997 49 291 188 2,270 Underwriting income (loss) 821 166 206 841 296 36 (391 ) 1,975 Net investment income 1,032 25 23 534 300 265 15 2,194 Other (income) expense (7 ) 2 1 (17 ) (6 ) 23 (47 ) (51 ) Amortization expense of purchased intangibles — 78 30 61 — 2 — 171 Segment income (loss) 1,860 111 198 1,331 602 276 (329 ) 4,049 Net realized gains (losses) including OTTI (420 ) (420 ) Interest expense 300 300 Chubb Integration Expense 33 33 Income tax expense 462 462 Net income (loss) $ (1,544 ) $ 2,834
Net Premiums Earned For Segment By Product	The following table presents net premiums earned for each segment by line of business: For the Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 North America Commercial P&C Insurance Property & other short-tail lines $ 1,899 $ 1,963 $ 1,040 Casualty & all other 9,554 9,552 4,175 A&H 738 702 419 Total North America Commercial P&C Insurance 12,191 12,217 5,634 North America Personal P&C Insurance Personal automobile 742 699 186 Personal homeowners 3,014 3,007 579 Personal other 643 613 183 Total North America Personal P&C Insurance 4,399 4,319 948 North America Agricultural Insurance 1,508 1,316 1,364 Overseas General Insurance Property & other short-tail lines 2,076 2,133 1,833 Casualty & all other 2,266 2,177 1,361 Personal lines 1,609 1,626 1,211 A&H 2,180 2,196 2,066 Total Overseas General Insurance 8,131 8,132 6,471 Global Reinsurance Property & other short-tail lines 132 118 155 Property catastrophe 198 185 219 Casualty & all other 374 407 475 Total Global Reinsurance 704 710 849 Life Insurance Life 980 1,002 931 A&H 1,121 1,053 1,016 Total Life Insurance 2,101 2,055 1,947 Total net premiums earned $ 29,034 $ 28,749 $ 17,213
Net Premiums Earned by Geographic Region	North America Europe (1) Asia Pacific / Far East Latin America 2017 70 % 11 % 12 % 7 % 2016 70 % 12 % 11 % 7 % 2015 60 % 15 % 15 % 10 %

Earnings per share (Tables)

Earnings per share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule Of Earnings Per Share, Basic And Diluted	Year Ended December 31 (in millions of U.S. dollars, except share and per share data) 2017 2016 2015 Numerator: Net income $ 3,861 $ 4,135 $ 2,834 Denominator: Denominator for basic earnings per share: Weighted-average shares outstanding 467,145,716 462,519,789 325,589,361 Denominator for diluted earnings per share: Share-based compensation plans 4,051,185 3,429,610 3,246,017 Weighted-average shares outstanding and assumed conversions 471,196,901 465,949,399 328,835,378 Basic earnings per share $ 8.26 $ 8.94 $ 8.71 Diluted earnings per share $ 8.19 $ 8.87 $ 8.62 Potential anti-dilutive share conversions 1,776,025 1,206,828 1,601,668

Related party transaction Relat

Related party transaction Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]	Transactions generated under these agreements were as follows: Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Gross premiums written $ 464 $ 658 $ 305 Ceded premiums written $ 175 $ 208 $ 78 Commissions paid $ 101 $ 145 $ 60 Commissions received $ 37 $ 56 $ 19 Losses and loss expenses incurred $ 438 $ 313 $ 137

Statutory Financial Informati51

Statutory Financial Information (Tables)	12 Months Ended
	Dec. 31, 2017
Statutory Financial Information [Abstract]
Schedule of combined statutory capital and surplus and statutory net income (loss)	December 31 (in millions of U.S. dollars) 2017 2016 Statutory capital and surplus Property and casualty $ 40,498 $ 38,734 Life $ 1,507 $ 1,225 Year Ended December 31 (in millions of U.S. dollars) 2017 2016 2015 Statutory net income (loss) Property and casualty $ 8,123 $ 6,903 $ 2,712 Life $ 74 $ 55 $ (148 )

Information provided in conne52

Information provided in connection with outstanding debt of subsidiaries (Tables)	12 Months Ended
	Dec. 31, 2017
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Abstract]
Condensed Consolidating Balance Sheet	ondensed Consolidating Balance Sheet at December 31, 2017 (in millions of U.S. dollars) Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated Assets Investments $ — $ 168 $ 102,276 $ — $ 102,444 Cash (1) 3 1 839 (115 ) 728 Insurance and reinsurance balances receivable — — 10,820 (1,486 ) 9,334 Reinsurance recoverable on losses and loss expenses — — 27,514 (12,480 ) 15,034 Reinsurance recoverable on policy benefits — — 1,194 (1,010 ) 184 Value of business acquired — — 326 — 326 Goodwill and other intangible assets — — 22,054 — 22,054 Investments in subsidiaries 41,909 51,165 — (93,074 ) — Due from subsidiaries and affiliates, net 9,639 — — (9,639 ) — Other assets 3 287 20,701 (4,073 ) 16,918 Total assets $ 51,554 $ 51,621 $ 185,724 $ (121,877 ) $ 167,022 Liabilities Unpaid losses and loss expenses $ — $ — $ 74,767 $ (11,588 ) $ 63,179 Unearned premiums — — 18,875 (3,659 ) 15,216 Future policy benefits — — 6,331 (1,010 ) 5,321 Due to subsidiaries and affiliates, net — 9,432 207 (9,639 ) — Affiliated notional cash pooling programs (1) — 115 — (115 ) — Repurchase agreements — — 1,408 — 1,408 Short-term debt — 1,013 — — 1,013 Long-term debt — 11,546 10 — 11,556 Trust preferred securities — 308 — — 308 Other liabilities 382 1,411 18,848 (2,792 ) 17,849 Total liabilities 382 23,825 120,446 (28,803 ) 115,850 Total shareholders’ equity 51,172 27,796 65,278 (93,074 ) 51,172 Total liabilities and shareholders’ equity $ 51,554 $ 51,621 $ 185,724 $ (121,877 ) $ 167,022 (1) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Balance Sheet at December 31, 2016 (in millions of U.S. dollars) Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated Assets Investments $ 27 $ 485 $ 98,582 $ — $ 99,094 Cash (1) 1 1 1,965 (982 ) 985 Insurance and reinsurance balances receivable — — 10,498 (1,528 ) 8,970 Reinsurance recoverable on losses and loss expenses — — 24,496 (10,919 ) 13,577 Reinsurance recoverable on policy benefits — — 1,153 (971 ) 182 Value of business acquired — — 355 — 355 Goodwill and other intangible assets — — 22,095 — 22,095 Investments in subsidiaries 38,408 49,509 — (87,917 ) — Due from subsidiaries and affiliates, net 10,482 — — (10,482 ) — Other assets 3 436 18,442 (4,353 ) 14,528 Total assets $ 48,921 $ 50,431 $ 177,586 $ (117,152 ) $ 159,786 Liabilities Unpaid losses and loss expenses $ — $ — $ 70,683 $ (10,143 ) $ 60,540 Unearned premiums — — 18,538 (3,759 ) 14,779 Future policy benefits — — 6,007 (971 ) 5,036 Due to subsidiaries and affiliates, net — 10,209 273 (10,482 ) — Affiliated notional cash pooling programs (1) 363 619 — (982 ) — Repurchase agreements — — 1,403 — 1,403 Short-term debt — 500 — — 500 Long-term debt — 12,599 11 — 12,610 Trust preferred securities — 308 — — 308 Other liabilities 283 1,582 17,368 (2,898 ) 16,335 Total liabilities 646 25,817 114,283 (29,235 ) 111,511 Total shareholders’ equity 48,275 24,614 63,303 (87,917 ) 48,275 Total liabilities and shareholders’ equity $ 48,921 $ 50,431 $ 177,586 $ (117,152 ) $ 159,786 (1) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
Condensed Consolidating Statement Of Operations and Comprehensive Income	Condensed Consolidating Statements of Operations and Comprehensive Income For the Year Ended December 31, 2017 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net premiums written $ — $ — $ 29,244 $ — $ 29,244 Net premiums earned — — 29,034 — 29,034 Net investment income 4 14 3,107 — 3,125 Equity in earnings of subsidiaries 3,640 2,424 — (6,064 ) — Net realized gains (losses) including OTTI — (25 ) 109 — 84 Losses and loss expenses — — 18,454 — 18,454 Policy benefits — — 676 — 676 Policy acquisition costs and administrative expenses 75 40 8,499 — 8,614 Interest (income) expense (332 ) 847 92 — 607 Other (income) expense (12 ) 93 (481 ) — (400 ) Amortization of purchased intangibles — — 260 — 260 Chubb integration expenses 32 69 209 — 310 Income tax expense (benefit) 20 (742 ) 583 — (139 ) Net income $ 3,861 $ 2,106 $ 3,958 $ (6,064 ) $ 3,861 Comprehensive income $ 4,718 $ 3,075 $ 4,430 $ (7,505 ) $ 4,718 Condensed Consolidating Statements of Operations and Comprehensive Income For the Year Ended December 31, 2016 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net premiums written $ — $ — $ 28,145 $ — $ 28,145 Net premiums earned — — 28,749 — 28,749 Net investment income 3 11 2,851 — 2,865 Equity in earnings of subsidiaries 3,901 2,555 — (6,456 ) — Net realized gains (losses) including OTTI — 3 (148 ) — (145 ) Losses and loss expenses — — 16,052 — 16,052 Policy benefits — — 588 — 588 Policy acquisition costs and administrative expenses 64 82 8,839 — 8,985 Interest (income) expense (353 ) 908 50 — 605 Other (income) expense (25 ) 35 (232 ) — (222 ) Amortization of purchased intangibles — — 19 — 19 Chubb integration expenses 62 126 304 — 492 Income tax expense (benefit) 21 (416 ) 1,210 — 815 Net income $ 4,135 $ 1,834 $ 4,622 $ (6,456 ) $ 4,135 Comprehensive income $ 4,556 $ 2,001 $ 5,045 $ (7,046 ) $ 4,556 Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) For the Year Ended December 31, 2015 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net premiums written $ — $ — $ 17,713 $ — $ 17,713 Net premiums earned — — 17,213 — 17,213 Net investment income 3 4 2,187 — 2,194 Equity in earnings of subsidiaries 2,673 1,038 — (3,711 ) — Net realized gains (losses) including OTTI — (9 ) (411 ) — (420 ) Losses and loss expenses — — 9,484 — 9,484 Policy benefits — — 543 — 543 Policy acquisition costs and administrative expenses 63 28 5,120 — 5,211 Interest (income) expense (32 ) 302 30 — 300 Other (income) expense (208 ) (4 ) 161 — (51 ) Amortization of purchased intangibles — — 171 — 171 Chubb Integration Expense 3 29 1 — 33 Income tax expense (benefit) 16 (349 ) 795 — 462 Net income $ 2,834 $ 1,027 $ 2,684 $ (3,711 ) $ 2,834 Comprehensive income (loss) $ 908 $ (192 ) $ 757 $ (565 ) $ 908
Condensed Consolidating Statement of Cash Flows	Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2017 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net cash flows from operating activities $ 781 $ 1,648 $ 4,598 $ (2,524 ) $ 4,503 Cash flows from investing activities Purchases of fixed maturities available for sale — (9 ) (25,738 ) — (25,747 ) Purchases of fixed maturities held to maturity — — (352 ) — (352 ) Purchases of equity securities — — (173 ) — (173 ) Sales of fixed maturities available for sale — 99 13,156 — 13,255 Sales of equity securities — — 187 — 187 Maturities and redemptions of fixed maturities available for sale — 29 10,396 — 10,425 Maturities and redemptions of fixed maturities held to maturity — — 879 — 879 Net change in short-term investments — 189 (726 ) — (537 ) Net derivative instruments settlements — (15 ) (250 ) — (265 ) Other — (10 ) (104 ) — (114 ) Net cash flows (used for) from investing activities — 283 (2,725 ) — (2,442 ) Cash flows from financing activities Dividends paid on Common Shares (1,308 ) — — — (1,308 ) Common Shares repurchased — — (801 ) — (801 ) Proceeds from issuance of repurchase agreements — — 2,353 — 2,353 Repayment of long-term debt — (500 ) (1 ) — (501 ) Repayment of repurchase agreements — — (2,348 ) — (2,348 ) Proceeds from share-based compensation plans — — 151 — 151 Advances (to) from affiliates 892 (927 ) 35 — — Dividends to parent company — — (2,524 ) 2,524 — Net payments to affiliated notional cash pooling programs (1) (363 ) (504 ) — 867 — Policyholder contract deposits — — 442 — 442 Policyholder contract withdrawals — — (307 ) — (307 ) Net cash flows used for financing activities (779 ) (1,931 ) (3,000 ) 3,391 (2,319 ) Effect of foreign currency rate changes on cash and cash equivalents — — 1 — 1 Net increase (decrease) in cash 2 — (1,126 ) 867 (257 ) Cash – beginning of year (1) 1 1 1,965 (982 ) 985 Cash – end of year (1) $ 3 $ 1 $ 839 $ (115 ) $ 728 (1) Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2016 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net cash flows from operating activities $ 3,618 $ 4,305 $ 5,536 $ (8,167 ) $ 5,292 Cash flows from investing activities Purchases of fixed maturities available for sale — (156 ) (30,659 ) — (30,815 ) Purchases of fixed maturities held to maturity — — (282 ) — (282 ) Purchases of equity securities — — (146 ) — (146 ) Sales of fixed maturities available for sale — 66 16,611 — 16,677 Sales of equity securities — — 1,000 — 1,000 Maturities and redemptions of fixed maturities available for sale — 66 9,283 — 9,349 Maturities and redemptions of fixed maturities held to maturity — — 958 — 958 Net change in short-term investments — 7,943 4,407 — 12,350 Net derivative instruments settlements — (9 ) (159 ) — (168 ) Acquisition of subsidiaries (net of cash acquired of $71) — (14,282 ) 34 — (14,248 ) Capital contribution (2,330 ) (215 ) (2,330 ) 4,875 — Other — (3 ) 13 — 10 Net cash flows used for investing activities (2,330 ) (6,590 ) (1,270 ) 4,875 (5,315 ) Cash flows from financing activities Dividends paid on Common Shares (1,173 ) — — — (1,173 ) Proceeds from issuance of repurchase agreements — — 2,310 — 2,310 Repayment of repurchase agreements — — (2,311 ) — (2,311 ) Proceeds from share-based compensation plans — — 167 — 167 Advances (to) from affiliates 404 (572 ) 168 — — Dividends to parent company — — (8,167 ) 8,167 — Capital contribution — 2,330 2,545 (4,875 ) — Net proceeds from (payments to) affiliated notional cash pooling programs (1) (519 ) 530 — (11 ) — Policyholder contract deposits — — 522 — 522 Policyholder contract withdrawals — — (253 ) — (253 ) Other — (4 ) — — (4 ) Net cash flows (used for) from financing activities (1,288 ) 2,284 (5,019 ) 3,281 (742 ) Effect of foreign currency rate changes on cash and cash equivalents — — (25 ) — (25 ) Net decrease in cash — (1 ) (778 ) (11 ) (790 ) Cash – beginning of year (1) 1 2 2,743 (971 ) 1,775 Cash – end of year (1) $ 1 $ 1 $ 1,965 $ (982 ) $ 985 (1) Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015 , the cash balance of one or more entities was negative; however, the overall Pool balances were positive. Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2015 Chubb Limited (Parent Guarantor) Chubb INA Holdings Inc. (Subsidiary Issuer) Other Chubb Limited Subsidiaries Consolidating Adjustments and Eliminations Chubb Limited Consolidated (in millions of U.S. dollars) Net cash flows from operating activities $ 3,125 $ 682 $ 3,836 $ (3,779 ) $ 3,864 Cash flows from investing activities Purchases of fixed maturities available for sale — — (16,053 ) (18 ) (16,071 ) Purchases of fixed maturities held to maturity — — (62 ) — (62 ) Purchases of equity securities — — (158 ) — (158 ) Sales of fixed maturities available for sale — — 10,814 — 10,814 Sales of equity securities — — 183 — 183 Maturities and redemptions of fixed maturities available for sale — — 6,567 — 6,567 Maturities and redemptions of fixed maturities held to maturity — — 669 — 669 Net change in short-term investments — (7,588 ) (628 ) — (8,216 ) Net derivative instruments settlements — (9 ) (12 ) — (21 ) Acquisition of subsidiaries (net of cash acquired of $629) — — 264 — 264 Capital contribution (2,670 ) (625 ) (2,791 ) 6,086 — Other — (25 ) (256 ) 18 (263 ) Net cash flows used for investing activities (2,670 ) (8,247 ) (1,463 ) 6,086 (6,294 ) Cash flows from financing activities Dividends paid on Common Shares (862 ) — — — (862 ) Common Shares repurchased — — (758 ) — (758 ) Proceeds from issuance of long-term debt — 6,090 — — 6,090 Proceeds from issuance of repurchase agreements — — 2,029 — 2,029 Repayment of long-term debt — (1,150 ) — — (1,150 ) Repayment of repurchase agreements — — (2,027 ) — (2,027 ) Proceeds from share-based compensation plans — — 131 — 131 Advances (to) from affiliates (228 ) 95 133 — — Dividends to parent company — — (3,779 ) 3,779 — Capital contribution — 2,791 3,295 (6,086 ) — Net proceeds from (payments to) affiliated notional cash pooling programs (1) 636 (220 ) — (416 ) — Policyholder contract deposits — — 503 — 503 Policyholder contract withdrawals — — (221 ) — (221 ) Other — (40 ) — — (40 ) Net cash flows (used for) from financing activities (454 ) 7,566 (694 ) (2,723 ) 3,695 Effect of foreign currency rate changes on cash and cash equivalents — — (145 ) — (145 ) Net increase in cash 1 1 1,534 (416 ) 1,120 Cash – beginning of year (1) — 1 1,209 (555 ) 655 Cash – end of year (1) $ 1 $ 2 $ 2,743 $ (971 ) $ 1,775 (1) Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Condensed Unaudited Quarterly53

Condensed Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	Three Months Ended March 31 June 30 September 30 December 31 (in millions of U.S. dollars, except per share data) 2017 2017 2017 2017 Net premiums earned $ 6,772 $ 7,237 $ 7,807 $ 7,218 Net investment income 745 770 813 797 Net realized gains (losses) including OTTI (7 ) 101 (10 ) — Total revenues $ 7,510 $ 8,108 $ 8,610 $ 8,015 Losses and loss expenses $ 3,789 $ 4,146 $ 6,247 $ 4,272 Policy benefits $ 168 $ 163 $ 169 $ 176 Net income (loss) $ 1,093 $ 1,305 $ (70 ) $ 1,533 Basic earnings (loss) per share $ 2.33 $ 2.79 $ (0.15 ) $ 3.29 Diluted earnings (loss) per share $ 2.31 $ 2.77 $ (0.15 ) $ 3.27 Net income for the three months ended September 30, 2017 included after-tax catastrophe losses of $1.5 billion . Net income for the three months ended December 31, 2017 included a one-time income tax transition benefit of $450 million related to the 2017 Tax Act. Refer to Note 8 for additional information. Three Months Ended March 31 June 30 September 30 December 31 (in millions of U.S. dollars, except per share data) 2016 2016 2016 2016 Net premiums earned $ 6,597 $ 7,405 $ 7,688 $ 7,059 Net investment income 674 708 739 744 Net realized gains (losses) including OTTI (394 ) (216 ) 100 365 Total revenues $ 6,877 $ 7,897 $ 8,527 $ 8,168 Losses and loss expenses $ 3,674 $ 4,254 $ 4,269 $ 3,855 Policy benefits $ 126 $ 146 $ 155 $ 161 Net income $ 439 $ 726 $ 1,360 $ 1,610 Basic earnings per share $ 0.98 $ 1.55 $ 2.90 $ 3.44 Diluted earnings per share $ 0.97 $ 1.54 $ 2.88 $ 3.41

Summary of significant accoun54

Summary of significant accounting policies (Narrative) (Detail) - USD ($) $ in Millions	Dec. 22, 2017	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2016		Dec. 31, 2015	Jan. 14, 2016	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Chubb integration expenses		$ 310	$ 492				$ 33
Affiliated notional cash pooling program		300	0	[1]	$ 0	[1]
Reinsurance business assumed		$ 18	20
Recoverable from unrated reinsurers, ceded reserve, default factor (percent)		34.00%
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense			455		455
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deposit assets reflected in Other assets		$ 89	93		93
Unpaid losses and loss expenses		63,179	60,540		60,540		37,303		$ 38,315
Deposit liabilities included in Deposit liabilities		100	108		108
Borrowings under Guaranteed Investment Agreements		1,800	1,500		1,500
Summary of significant accounting policies [Line Items]
Deferred Policy Acquisition Costs, Amortization Expense		5,781	5,904				2,941
Deferred Advertising Costs		$ 271	256		256
Deferred Marketing Costs, Amortization Period		10 years
Percentage of fair value of loaned securities		102.00%
Quality assessment threshold used in goodwill impairment testing		50.00%
Supplemental Information for Property, Casualty Insurance Underwriters, Reserves for Unpaid Claims and Claims Adjustment Expense		$ 49,165	47,832		47,832		26,562
Entity Well-known Seasoned Issuer		Yes
Net operating results of ESIS included within Administrative expenses		$ 38	32				30
Property, Plant and Equipment, Net		1,300	1,200		1,200
Finite-Lived Intangible Assets, Net		3,500	3,805		3,805
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		48
Income tax benefit related to 2017 Tax Act		(450)	0				0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ (450)
Tax Year 2018 [Member]
Summary of significant accounting policies [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Tax Year 2017 [Member]
Summary of significant accounting policies [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%
The Chubb Corporation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and loss expenses								$ 22,923
The Chubb Corporation [Member] | Debt Securities [Member]
Summary of significant accounting policies [Line Items]
Assets, Fair Value Adjustment		$ 858			1,652
Selling and Marketing Expense [Member]
Summary of significant accounting policies [Line Items]
Deferred Policy Acquisition Costs, Amortization Expense		116	$ 92				$ 78
Fair Value Adjustment to Acquired Loss Reserves [Member] | The Chubb Corporation [Member]
Summary of significant accounting policies [Line Items]
Increase Decrease on Acquired Unpaid Losses and Loss Expenses		$ 309
Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rates used in calculating future policy benefits		0.01	0.01
Summary of significant accounting policies [Line Items]
Reinsurance Premiums, Amortization Period		1 year
Amortization period for value of reinsurance business assumed		9 years
Finite-Lived Intangible Asset, Useful Life		1 year
Minimum | The Chubb Corporation [Member]
Summary of significant accounting policies [Line Items]
Amortization Period of Increase Decrease to Acquired Unpaid Losses and Loss Expenses		5 years
Minimum | Fair Value Adjustment to Acquired Loss Reserves [Member] | The Chubb Corporation [Member]
Summary of significant accounting policies [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years
Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rates used in calculating future policy benefits		0.08	0.080
Summary of significant accounting policies [Line Items]
Reinsurance Premiums, Amortization Period		3 years
Amortization period for value of reinsurance business assumed		40 years
Finite-Lived Intangible Asset, Useful Life		30 years
Maximum | The Chubb Corporation [Member]
Summary of significant accounting policies [Line Items]
Amortization Period of Increase Decrease to Acquired Unpaid Losses and Loss Expenses		17 years
Maximum | Fair Value Adjustment to Acquired Loss Reserves [Member] | The Chubb Corporation [Member]
Summary of significant accounting policies [Line Items]
Finite-Lived Intangible Asset, Useful Life		17 years
Structured settlements
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deposit assets reflected in Other assets		$ 36	$ 38		38
Unpaid losses and loss expenses		586
Reinsurance recoverables for amounts due from life insurance companies		550
Other Short-duration Insurance Product Line [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and loss expenses		41	$ 50		$ 50
Initial Application Period Cumulative Effect Transition [Domain] | purchased callable debt [Member]
Summary of significant accounting policies [Line Items]
Debt Instrument, Unamortized Premium		$ 30
[1]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Acquisitions (Detail)

Acquisitions (Detail) $ / shares in Units, $ in Millions		Jan. 14, 2016USD ($)$ / sharesshares	Dec. 31, 2017USD ($)shares		Dec. 31, 2016USD ($)$ / sharesshares		Dec. 31, 2016USD ($)		Dec. 31, 2015USD ($)$ / sharesshares		Apr. 01, 2015USD ($)	Dec. 31, 2014USD ($)
Business Acquisition [Line Items]
Weighted Average Number of Shares Outstanding, Basic | shares			467,145,716		462,519,789				325,589,361
Cash			$ 728	[1],[2]	$ 985	[1],[3],[4]	$ 985	[1],[3],[4]	$ 1,775	[1],[5]		$ 655	[5]
Investments			102,444		99,094		99,094
Accrued investment income			909		918		918
Insurance and reinsurance balances receivable			9,334		8,970		8,970
Reinsurance recoverable on paid losses and loss expenses	[6]		15,034		13,577		13,577
Prepaid reinsurance premiums			2,529		2,448		2,448
Other assets			6,358		5,090		5,090
Unpaid losses and loss expenses			(63,179)		(60,540)		(60,540)		(37,303)			$ (38,315)
Unearned premiums			(15,216)		(14,779)		(14,779)
Reinsurance Payable			(5,868)		(5,637)		(5,637)
Accounts Payable, Accrued Expenses and Other Liabilities			(9,545)		(8,617)		(8,617)
Deferred Tax Liabilities, Net			(699)		(988)		(988)
Long-term Debt			(11,556)		(12,610)		(12,610)
Intangible Assets, Net (Excluding Goodwill)			6,513		6,763		6,763
Goodwill			15,541		15,332		15,332		4,796
Common Shares (CHF 24.15 par value; 479,783,864 shares issued; 463,833,179 and 465,968,716 shares outstanding)			$ 11,121		11,121		11,121
Fireman's Fund high net worth personal lines [Member]
Business Acquisition [Line Items]
Business Acquisition, Financing Of Acquisition With Cash											$ 365
Cash											629
Insurance and reinsurance balances receivable											124
Unpaid losses and loss expenses											(417)
Unearned premiums											(428)
Fair Value of Assets Acquired											753
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities											863
Intangible Assets, Net (Excluding Goodwill)											278
Goodwill											$ 196
The Chubb Corporation [Member]
Business Acquisition [Line Items]
Total Value of Equity Awards Issued in Acquisition		$ 525
Purchase Price		29,500
Business Acquisition, Financing Of Acquisition With Cash		9,000
Senior notes issued to finance acquisition		$ 5,300
Weighted Average Number of Shares Outstanding, Basic | shares		228,000,000
Shares Conversion Ratio in Acquisition		0.6019
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares		137,000,000
Share Price | $ / shares		$ 111.02
Equity Issued in Business Combination, Fair Value Disclosure		$ 15,204
Business Acquisition, Share Price | $ / shares		$ 62.93
Payments to Acquire Businesses, Gross		$ 14,319
Attributed Value Equity Awards Assumed in Acquisition	[7]	323
Business Combination, Consideration Transferred		29,846
Cash		71
Investments		42,967
Accrued investment income		359
Insurance and reinsurance balances receivable		3,095
Reinsurance recoverable on paid losses and loss expenses		1,676
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets		2,860
Finite lived intangible assets		4,795
Prepaid reinsurance premiums		280
Other assets		853
Unpaid losses and loss expenses		(22,923)
Unearned premiums		(7,011)
Reinsurance Payable		(603)
Accounts Payable, Accrued Expenses and Other Liabilities		(2,030)
Deferred Tax Liabilities, Net		(1,292)
Long-term Debt		(3,765)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		19,332
Goodwill		10,514
Goodwill, Expected Tax Deductible Amount		$ 0
Chubb Corp, Revenue since acquisition date							12,376
Chubb Corp, Earnings since acquisition date							$ 1,756
Chubb Corp, Pro Forma Revenue					31,937				32,622
Chubb Corp, Pro Forma Net Income (Loss)					$ 4,183				$ 4,478
Chubb Corp, Pro Forma Earnings Per Share, Basic | $ / shares					$ 8.95				$ 9.61
Chubb Corp, Pro Forma Earnings Per Share, Diluted | $ / shares					$ 8.88				$ 9.52
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[6]	(1) Net of a provision for uncollectible reinsurance.
[7]	(1) The fair value of the replacement equity awards was $525 million, of which $323 million was attributed to service periods prior to the acquisition and was included in the purchase consideration. Refer to Note 12 for further information on these replacement equity awards.

Acquisitions Intangible Assets

Acquisitions Intangible Assets (Details) - USD ($) $ in Millions	Jan. 14, 2016	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets Acquired	$ 7,655
Developed Technology Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		3 years
Unearned premium reserves [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		1 year
Distribution Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		24 years
The Chubb Corporation [Member] | Developed Technology Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		$ 95
The Chubb Corporation [Member] | Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets Acquired		2,800
The Chubb Corporation [Member] | Unearned premium reserves [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		1,550
The Chubb Corporation [Member] | Distribution Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired		3,150
The Chubb Corporation [Member] | Licensing Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets Acquired		50
The Chubb Corporation [Member] | Syndicate capacity [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets Acquired		$ 10

Investments (Narrative) (Detail

Investments (Narrative) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)Securitypartnerships	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Investment [Line Items]
Held-to-maturity Securities, Transferred Security from Available-for-Sale	$ 4,300
Net unrealized appreciation (depreciation) included in OCI	(2)	$ 62
AOCI Portion Attributable to change of FV of investments with OTTI	7	10
Reinsurance recoverable on losses and loss expenses	15,034	13,577
Ceded Premiums Written	7,132	6,838	$ 6,098
Insurance and reinsurance balances payable	5,868	5,637
Carrying Value	662	666
Portion of gross unrealized loss represented by the United States Treasury and Agency obligations	$ 311
Moodys historical mean recovery rate	42.00%
Limited partnerships number | partnerships	138
Trading securities - mutual funds	$ 333	271
Trading securities - equity securities	0	14
Trading securities - fixed maturities	$ 0	11
Number of fixed maturities in an unrealized loss position | Security	9,828
Total number of fixed maturities | Security	30,932
Largest single unrealized loss in the fixed maturities	$ 7
Number of equity securities in an unrealized loss position | Security	82
Total number of equity securities | Security	328
Largest single unrealized loss in the equity securities	$ 3
Restricted assets in fixed maturities and short-term investments	$ 23,300	$ 20,100
Percentage of mortgage-backed securities represented by investments in US government agency bonds	83.00%	81.00%
Restricted assets in cash	$ 123	$ 103
ABR Reinsurance Capital Holdings Ltd. [Member]
Investment [Line Items]
Warrants & Rights Outstanding		0.50%
Corporate securities
Investment [Line Items]
Credit losses recognized in net income	$ 5	$ 30	50
Company assumed recovery rate	32.00%
Collateralized Mortgage Backed Securities [Member]
Investment [Line Items]
Credit losses recognized in net income	$ 0	$ 1	$ 0

Investments Investments (Schedu

Investments Investments (Schedule Of Amortized Cost and Fair Value of Available-for-sale Securities and Related OTTI Recognized in AOCI) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 77,835	$ 79,536
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,528	1,455
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(424)	(876)
Available for sale, Fair Value	78,939	80,115
Available for sale, OTTI recognized in AOCI	(6)	(14)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	3,701	2,883
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	32	32
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(35)	(45)
Available for sale, Fair Value	3,698	2,870
Available for sale, OTTI recognized in AOCI	0	0
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	20,514	20,929
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	622	636
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(106)	(125)
Available for sale, Fair Value	21,030	21,440
Available for sale, OTTI recognized in AOCI	(1)	(5)
Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	23,453	23,736
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	638	580
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(95)	(167)
Available for sale, Fair Value	23,996	24,149
Available for sale, OTTI recognized in AOCI	(4)	(8)
Collateralized Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	15,279	14,066
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	111	135
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(100)	(194)
Available for sale, Fair Value	15,290	14,007
Available for sale, OTTI recognized in AOCI	(1)	(1)
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	14,888	17,922
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	125	72
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(88)	(345)
Available for sale, Fair Value	14,925	17,649
Available for sale, OTTI recognized in AOCI	$ 0	$ 0

Investments (Schedule Of Amorti

Investments (Schedule Of Amortized Cost And Fair Value Of Held-to-Maturity And Related Other-Than-Temporary Impairment Recognized In Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	$ 14,335	$ 10,644
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	179	148
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(40)	(122)
Held to maturity, Fair Value	14,474	10,670
Held to maturity, OTTI recognized in AOCI		0
U.S. Treasury and agency
Schedule of Held-to-maturity Securities [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	908	655
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	12	9
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(5)	(3)
Held to maturity, Fair Value	915	661
Held to maturity, OTTI recognized in AOCI	0	0
Foreign
Schedule of Held-to-maturity Securities [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	1,738	640
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	27	28
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(8)	(1)
Held to maturity, Fair Value	1,757	667
Held to maturity, OTTI recognized in AOCI	0	0
Corporate securities
Schedule of Held-to-maturity Securities [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	3,159	2,771
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	67	50
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(7)	(26)
Held to maturity, Fair Value	3,219	2,795
Held to maturity, OTTI recognized in AOCI	0	0
Mortgage backed-securities
Schedule of Held-to-maturity Securities [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	2,724	1,393
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	23	35
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(5)	0
Held to maturity, Fair Value	2,742	1,428
Held to maturity, OTTI recognized in AOCI	0	0
States, municipalities, and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	5,806	5,185
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	50	26
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(15)	(92)
Held to maturity, Fair Value	5,841	5,119
Held to maturity, OTTI recognized in AOCI	$ 0	$ 0

Investments (Schedule Of Fixed

Investments (Schedule Of Fixed Maturities By Contractual Maturity) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Available for sale, Due in 1 year or less, Amortized Cost	$ 3,164	$ 3,892
Available for sale, Due after 1 year through 5 years, Amortized Cost	24,749	24,027
Available for sale, Due after 5 years though 10 years, Amortized Cost	25,388	27,262
Available for sale, Due after 10 years, Amortized Cost	9,255	10,289
Available for sale, Subtotal, Amortized Cost	62,556	65,470
Available for sale, Mortgage-backed securities, Amortized Cost	15,279	14,066
Available-for-sale Debt Securities, Amortized Cost Basis	77,835	79,536
Available for sale, Due in 1 year or less, Fair Value	3,182	3,913
Available for sale, Due after 1 year through 5 years, Fair Value	25,068	24,429
Available for sale, Due after 5 years through 10 years, Fair Value	25,704	27,379
Available for sale, Due after 10 years, Fair Value	9,695	10,387
Available for sale, Subtotal, Fair Value	63,649	66,108
Available for sale, Mortgage backed securities, Fair Value	15,290	14,007
Available for sale, Fair Value	78,939	80,115
Held to maturity, Due in 1 year or less, Amortized Cost	743	430
Held to maturity, Due after 1 year through 5 years, Amortized Cost	2,669	2,646
Held to maturity, Due after 5 years through 10 years, Amortized Cost	4,744	2,969
Held to maturity, Due after 10 years, Amortized Cost	3,455	3,206
Held to maturity, Subtotal, Amortized Cost	11,611	9,251
Held to maturity, Mortgage backed securities, Amortized Cost	2,724	1,393
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	14,335	10,644
Held to maturity, Due in 1 year or less, Fair Value	746	435
Held to maturity, Due after 1 year through 5, Fair Value	2,688	2,691
Held to maturity, Due after 5 years through 10 years, Fair Value	4,756	2,944
Held to maturity, Due after 10 years, Fair Value	3,542	3,172
Held to maturity, Subtotal, Fair Value	11,732	9,242
Held to maturity, Mortgage backed securities, Fair Value	2,742	1,428
Held to maturity, Fair Value	$ 14,474	$ 10,670

Investments (Schedule Of Cost A

Investments (Schedule Of Cost And Fair Value Of Equity Securities) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Equity securities, at cost	$ 737	$ 706
Gross unrealized appreciation	212	129
Gross unrealized depreciation	(12)	(21)
Equity securities, at fair value (cost – $737 and $706)	$ 937	$ 814

Investments (Schedule Of Defaul

Investments (Schedule Of Default Assumptions By Moody's Rating Categories) (Details)	12 Months Ended
	Dec. 31, 2017
Investment Grade | Aaa - Bbb | Minimum
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	0.00%
Historical Mean Default Rate	0.00%
Investment Grade | Aaa - Bbb | Maximum
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	1.30%
Historical Mean Default Rate	0.30%
Below Investment Grade | Ba
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	4.80%
Historical Mean Default Rate	1.00%
Below Investment Grade | B
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	12.10%
Historical Mean Default Rate	3.20%
Below Investment Grade | Caa - C
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	36.80%
Historical Mean Default Rate	10.50%

Investments (Net Realized Gains

Investments (Net Realized Gains (Losses) And Losses Included In Net Realized Gains (Losses) And Other Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment (OTTI) losses gross									$ (46)	$ (111)	$ (151)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, before Tax, Including Portion Attributable to Noncontrolling Interest									1	8	39
Foreign exchange gains( losses)									36	118	(80)
Fair Value adjustment on insurance derivative									364	53	(203)
Derivative, Gain (Loss) on Derivative, Net									87	(126)	(193)
Total Net realized gains (losses) including OTTI	$ 0	$ (10)	$ 101	$ (7)	$ 365	$ 100	$ (216)	$ (394)	84	(145)	(420)
Unrealized Gain (Loss) on Investments									392	184	(977)
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax									(241)	100	152
Total net realized gains (losses) and change in net unrealized appreciation (depreciation) on investments									476	39	(1,397)
Other derivative instruments
Gain (Loss) on Investments [Line Items]
Derivative, Gain (Loss) on Derivative, Net									(5)	(10)	(12)
Investment and embedded derivative instruments
Gain (Loss) on Investments [Line Items]
Derivative, Gain (Loss) on Derivative, Net									(11)	(33)	32
S&P Options and Futures
Gain (Loss) on Investments [Line Items]
Derivative, Gain (Loss) on Derivative, Net									(261)	(136)	(10)
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Cost-method Investments, Other than Temporary Impairment									(10)	(8)	(7)
Equity Securities - Gross Realized Gains Excluding OTTI									28	65	47
Equity Securities - Gross realized losses excluding OTTI									(2)	(13)	(11)
Total Equity Securities									16	44	29
Unrealized Gain (Loss) on Investments									88	52	(17)
Fixed maturities held to maturity
Gain (Loss) on Investments [Line Items]
Unrealized Gain (Loss) on Investments									18	(59)	43
Other Investments [Member]
Gain (Loss) on Investments [Line Items]
Cost-method Investments, Other than Temporary Impairment									(12)	(14)	(2)
Gain (Loss) on Sale of Other Investments									(12)	(4)	6
Unrealized Gain (Loss) on Investments									8	(51)	(36)
Available-for-sale Securities [Member]
Gain (Loss) on Investments [Line Items]
Unrealized Gain (Loss) on Investments									519	142	(1,119)
Debt Securities [Member]
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment (OTTI) losses gross									(24)	(89)	(142)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, before Tax, Including Portion Attributable to Noncontrolling Interest									1	8	39
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities									(23)	(81)	(103)
Available-for-sale Securities, Gross Realized Gains									149	183	158
Available-for-sale Securities, Gross Realized Losses									(157)	(265)	(235)
Available-for-sale Securities, Gross Realized Gain (Loss)									$ (31)	$ (163)	$ (180)

Investments (Roll-Forward Of Pr

Investments (Roll-Forward Of Pre-Tax Credit Losses Related To Fixed Maturities For Which Portion Of Other-Than-Temporary Impairment Was Recognized In Other Comprehensive Income) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Roll-Forward Of Pre-Tax Credit Losses Related To Fixed Maturities For Which Portion Of OTTI Was Recognized In OCI
Balance of credit losses related to securities still held-beginning of period	$ 35	$ 53	$ 28
Additions where no OTTI was previously recorded	4	17	41
Additions where an OTTI was previously recorded	2	14	9
Reductions for securities sold during the period	(19)	(49)	(25)
Balance of credit losses related to securities still held-end of period	$ 22	$ 35	$ 53

Investments (Schedule Of Other

Investments (Schedule Of Other Investments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Cost-method Investments [Line Items]
Other investments (cost – $4,417 and $4,270)	$ 4,672	$ 4,519
Other Investments and Securities, at Cost	4,417	4,270
Fair Value
Schedule of Cost-method Investments [Line Items]
Investment Funds	270	251
Limited Partnerships	549	730
Investment Funds Limited Partnerships Partially Owned Investment Companies Total	2,803	2,645
Life Settlement Contracts, Fair Value Method, Face Value	305	248
Policy Loans Investments	244	209
Trading Securities	333	296
Other Other Investments	168	140
Other investments (cost – $4,417 and $4,270)	4,672	4,519
Cost
Schedule of Cost-method Investments [Line Items]
Investment Funds	123	126
Limited Partnerships	441	607
Investment Funds Limited Partnerships Partially Owned Investment Companies Total	2,803	2,645
Life Settlement Contracts, Fair Value Method, Face Value	305	248
Policy Loans Investments	244	209
Trading Securities	333	295
Other Other Investments	168	140
Other Investments and Securities, at Cost	$ 4,417	$ 4,270

Investments (Schedule Of Invest

Investments (Schedule Of Investments In Partially-Owned Insurance Companies) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Carrying Value	$ 662	$ 666
Issued Share Capital	1,942	1,888
Huatai Group | CHINA
Investment [Line Items]
Carrying Value	438	447
Issued Share Capital	$ 616	$ 624
Ownership Percentage	20.00%	20.00%
Huatai Life Insurance Company | CHINA
Investment [Line Items]
Carrying Value	$ 105	$ 99
Issued Share Capital	$ 495	$ 428
Ownership Percentage	20.00%	20.00%
Freisenbruch-Meyer | Bermuda
Investment [Line Items]
Carrying Value	$ 9	$ 8
Issued Share Capital	$ 0	$ 5
Ownership Percentage	40.00%	40.00%
Russian Reinsurance Company | Russia
Investment [Line Items]
Carrying Value	$ 2	$ 2
Issued Share Capital	$ 4	$ 4
Ownership Percentage	23.00%	23.00%
ABR Reinsurance Capital Holdings Ltd. [Member] | Bermuda
Investment [Line Items]
Carrying Value	$ 93	$ 97
Issued Share Capital	$ 800	$ 800
Ownership Percentage	11.00%	11.00%
Chubb Arabia Cooperative Insurance Company [Member] | Saudi Arabia
Investment [Line Items]
Carrying Value	$ 15	$ 13
Issued Share Capital	$ 27	$ 27
Ownership Percentage	30.00%	30.00%

Investments (Aggregate Fair Val

Investments (Aggregate Fair Value And Gross Unrealized Loss By Length Of Time Security Has Continuously Been In Unrealized Loss Position) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	$ 28,685	$ 43,641
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(257)	(959)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	8,885	1,310
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(227)	(78)
Investment securities, Unrealized loss position, Total Fair Value	37,570	44,951
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(484)	(1,037)
U.S. Treasury and agency
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	2,172	2,216
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(14)	(48)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	1,249	0
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(26)	0
Investment securities, Unrealized loss position, Total Fair Value	3,421	2,216
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(40)	(48)
Foreign
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	5,657	5,918
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(65)	(99)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	1,693	386
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(49)	(27)
Investment securities, Unrealized loss position, Total Fair Value	7,350	6,304
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(114)	(126)
Corporate securities
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	5,210	7,021
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(56)	(149)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	1,332	641
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(46)	(44)
Investment securities, Unrealized loss position, Total Fair Value	6,542	7,662
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(102)	(193)
Mortgage backed-securities
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	6,194	8,638
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(31)	(189)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	3,209	234
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(74)	(5)
Investment securities, Unrealized loss position, Total Fair Value	9,403	8,872
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(105)	(194)
States, municipalities, and political subdivisions
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	9,259	19,448
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(71)	(435)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	1,402	49
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(32)	(2)
Investment securities, Unrealized loss position, Total Fair Value	10,661	19,497
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(103)	(437)
Total fixed maturities
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	28,492	43,241
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(237)	(920)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	8,885	1,310
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(227)	(78)
Investment securities, Unrealized loss position, Total Fair Value	37,377	44,551
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(464)	(998)
Equity securities
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	115	199
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(12)	(21)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	0	0
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	0	0
Investment securities, Unrealized loss position, Total Fair Value	115	199
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(12)	(21)
Other investments
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	78	201
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(8)	(18)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	0	0
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	0	0
Investment securities, Unrealized loss position, Total Fair Value	78	201
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	$ (8)	$ (18)

Investments (Schedule Of Source

Investments (Schedule Of Sources Of Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Investment Income [Line Items]
Gross investment income									$ 3,289	$ 3,006	$ 2,308
Investment expenses									(164)	(141)	(114)
Net investment income	$ 797	$ 813	$ 770	$ 745	$ 744	$ 739	$ 708	$ 674	3,125	2,865	2,194
Amortization of Debt Issuance Costs and Discounts									694	737	158
The Chubb Corporation [Member]
Net Investment Income [Line Items]
Amortization of Debt Issuance Costs and Discounts									(332)	(393)
Fixed Maturities [Member]
Net Investment Income [Line Items]
Gross investment income									2,987	2,779	2,157
Short-term investments
Net Investment Income [Line Items]
Gross investment income									131	93	49
Equity securities
Net Investment Income [Line Items]
Gross investment income									38	36	16
Other Investments [Member]
Net Investment Income [Line Items]
Gross investment income									$ 133	$ 98	$ 86

Investments (Schedule Of Compon

Investments (Schedule Of Components Of Restricted Assets) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Funds Held under Reinsurance Agreements, Asset	$ 17,011	$ 13,880
Deposits with non-U.S. regulatory authorities	2,250	2,191
Collateral pledged under repurchase agreements	1,434	1,461
Deposits with U.S. regulatory authorities	2,345	2,203
Other pledged assets	414	435
Total restricted assets	$ 23,454	$ 20,170

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Detail)		12 Months Ended
		Dec. 31, 2017USD ($)Year	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
GLB - Lapse rate - lower range		3.00%
GLB - Lapse rate - upper range		9.00%
GLB - Spike lapse rate - lower range		6.00%
GLB - Spike lapse rate - upper range		33.00%
GLB - Ultimate lapse rate		10.00%
GLB - Length of ultimate lapse rate period, years | Year		2
GLB - Adjustment factor for valuable guarantees - lower		15.00%
GLB - Adjustment factor for valuable guarantees - upper		75.00%
Realized Gain Losses As A Result of Change in Partial Withdrawal Assumption		$ 43,000,000
Realized Gain Losses As A Result of Change in Lapse Assumption (GLB)		9,000,000
Realized Gain Losses As A Result of Annuitization Changes (GLB)		117,000,000
Realized Gain Losses As A Result of Valuation Model Refinement (GLB)		94,000,000
Fair Value, Level 1 to Level 2 transfers, Amount		0	$ 0	$ 0
Assets measured using NAV		3,623,000,000	3,627,000,000
Other investments (cost – $4,417 and $4,270)		4,672,000,000	4,519,000,000
Derivative, Gain (Loss) on Derivative, Net		87,000,000	(126,000,000)	(193,000,000)
Guaranteed Minimum Income Benefit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Gain (Loss) on Derivative, Net	[1]	364,000,000	53,000,000	(203,000,000)
Guaranteed Minimum Income Benefit | Variable Annuity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Gain (Loss) on Derivative, Net	[1]	$ 25,000,000
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notice period for redemption for alternative investments investment funds, days		5 days
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notice period for redemption for alternative investments investment funds, days		120 days
Other Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments (cost – $4,417 and $4,270)		$ 15,000,000	25,000,000
Investment Funds Limited Partnerships Partially Owned Investment Companies Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments (cost – $4,417 and $4,270)		3,623,000,000	3,626,000,000
Guaranteed Minimum Income Benefit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
GLB liability		$ 550,000,000	$ 853,000,000	$ 888,000,000	$ 663,000,000
[1]	(2) Excludes foreign exchange gains (losses) related to GLB.

Fair value measurements Fair Va

Fair value measurements Fair Value Measurements (Annuitization Experience for GMIB Policies) (Details)	12 Months Ended
	Dec. 31, 2017
One Year Of Credible Experience [Member]
Annuitization Experience For GMIB Policies [Line Items]
Percent of GMIB guaranteed value that are represented by clients with several years of annuitization experience	67.00%
Several Years Of Credible Experience [Member]
Annuitization Experience For GMIB Policies [Line Items]
Percent of GMIB guaranteed value that are represented by clients with several years of annuitization experience	3.00%
Several Years Of Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	0.00%
No Credible Experience [Member]
Annuitization Experience For GMIB Policies [Line Items]
Percent of GMIB guaranteed value that are represented by clients with several years of annuitization experience	30.00%
No Credible Experience [Member] | First Year [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	0.00%
No Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	0.00%
Maximum
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	100.00%	[1]
Maximum | One Year Of Credible Experience [Member] | First Year [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	52.00%
Maximum | One Year Of Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	100.00%
Maximum | Several Years Of Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	100.00%
Maximum | No Credible Experience [Member] | First Year [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	56.00%
Maximum | No Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	36.00%
Minimum
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	0.00%	[1]
Minimum | One Year Of Credible Experience [Member] | First Year [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	2.00%
Minimum | One Year Of Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	1.00%
Minimum | Several Years Of Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	12.00%
Minimum | No Credible Experience [Member] | First Year [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	25.00%
Minimum | No Credible Experience [Member] | Subsequent years [Member]
Annuitization Experience For GMIB Policies [Line Items]
Annuitization rate	12.00%
[1]	Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.

Fair Value Measurements (Financ

Fair Value Measurements (Financial Instruments Measured At Fair Value On Recurring Basis) (Detail) - USD ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015	[2],[3]	Dec. 31, 2014	[3]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	$ 78,939		$ 80,115
Equity securities, at fair value (cost – $737 and $706)	937		814
Short-term investments	3,561		3,002
Other investments (cost – $4,417 and $4,270)	4,672		4,519
Securities lending collateral	1,737		1,092
Investment Funds Limited Partnerships Partially Owned Investment Companies Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other investments (cost – $4,417 and $4,270)	3,623		3,626
Other Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other investments (cost – $4,417 and $4,270)	15		25
Fair Value, Measurements, Recurring [Member] | Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	3,129		2,175
Equity securities, at fair value (cost – $737 and $706)	893		773
Short-term investments	2,309		1,757
Other investments (cost – $4,417 and $4,270)	466		384
Investment derivative instruments, assets	18		31
Other derivative instruments, assets	1		3
Separate Account Assets	2,635		1,784
Total assets measured at fair value	9,451		6,907
Investment derivative instruments, liability	30		54
Other derivative instruments, liability	21
Total liabilities measured at fair value	51		54
Fair Value, Measurements, Recurring [Member] | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	74,602		77,140
Short-term investments	1,252		1,220
Other investments (cost – $4,417 and $4,270)	305		259
Securities lending collateral	1,737		1,092
Separate Account Assets	99		95
Total assets measured at fair value	77,995		79,806
Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	1,208		800
Equity securities, at fair value (cost – $737 and $706)	44		41
Short-term investments			25
Other investments (cost – $4,417 and $4,270)	263		225
Total assets measured at fair value	1,515		1,091
Other derivative instruments, liability	2		13
Total liabilities measured at fair value	206		572
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	3,129		2,175
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	569		695
Fair Value, Measurements, Recurring [Member] | Foreign | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	20,937		21,366
Fair Value, Measurements, Recurring [Member] | Foreign | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	93		74
Fair Value, Measurements, Recurring [Member] | Corporate securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	22,959		23,468
Fair Value, Measurements, Recurring [Member] | Corporate securities | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	1,037		681
Fair Value, Measurements, Recurring [Member] | Mortgage backed-securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	15,212		13,962
Fair Value, Measurements, Recurring [Member] | Mortgage backed-securities | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	78		45
Fair Value, Measurements, Recurring [Member] | States, municipalities, and political subdivisions | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	14,925		17,649
Guaranteed Minimum Income Benefit
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	204	[1]	559	[1],[2]	$ 609		$ 406
Guaranteed Minimum Income Benefit | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	204	[4]	559
Guaranteed Minimum Income Benefit | Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross	$ 204		$ 559
[1]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c) for additional information.
[2]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015, which includes a fair value derivative adjustment of $559 million and $609 million, respectively.
[3]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $406 million, respectively.
[4]	Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value And Maximum Future Funding Commitments Related To Investments) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 3,623	$ 3,627
Maximum future funding commitment	4,061	2,040
Financial
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	540	548
Maximum future funding commitment	$ 330	$ 428
Financial | Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	5 years	5 years
Financial | Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	9 years	9 years
Real Assets
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 651	$ 536
Maximum future funding commitment	$ 114	$ 230
Real Assets | Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	3 years	3 years
Real Assets | Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	7 years	7 years
Distressed
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 289	$ 485
Maximum future funding commitment	$ 141	$ 179
Distressed | Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	3 years	3 years
Distressed | Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	7 years	7 years
Private Credit
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 187	$ 236
Maximum future funding commitment	$ 327	$ 259
Private Credit | Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	3 years	3 years
Private Credit | Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	7 years	7 years
Traditional
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 1,656	$ 1,550
Maximum future funding commitment	$ 3,149	$ 930
Traditional | Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	3 years	3 years
Traditional | Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	15 years	15 years
Vintage
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 30	$ 21
Maximum future funding commitment		$ 14
Vintage | Minimum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	1 year	1 year
Vintage | Maximum
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Expected liquidation period	2 years	2 years
Investment Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 270	$ 251

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	[1]	Actuarial model
Guaranteed Minimum Income Benefit
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases		$ 0	[2]	$ 0	[3]	$ 0	[4]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3				0	[3]	0	[4]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		204	[2]	559	[2],[3]	609	[3],[4]	$ 406	[4]
Level 3 | Guaranteed Minimum Income Benefit
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		$ 204	[1]	559
Minimum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate	[1]	3.00%
Annuitization rate	[1]	0.00%
Maximum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate	[1]	33.00%
Annuitization rate	[1]	100.00%
Short-term Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		$ 41		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				50
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0
Other Derivative Instruments Fair Value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases		0		2		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		9
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value		$ 2		$ 13		$ 6		$ 4
[1]	Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.
[2]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c) for additional information.
[3]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015, which includes a fair value derivative adjustment of $559 million and $609 million, respectively.
[4]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $406 million, respectively.

Fair value measurements Fair 75

Fair value measurements Fair Value Measurements (Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets		$ 0
Transfers into Level 3, assets		0
Balance- End of year, assets			$ 0
Other Long-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets	$ 225	212	204
Transfers into Level 3, assets	0
Change in Net Unrealized Gains (Losses) included in OCI, Assets	6	(2)	(6)
Net Realized Gains/Losses, Assets	0	1
Purchased, assets	56	33	33
Sales, assets	0
Settlements, assets	(24)	(19)	(19)
Balance- End of year, assets	263	225	212
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	0	1	0
Short-term investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets	25
Transfers into Level 3, assets	0	0
Transfers out of Level 3, assets		(50)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	0	0
Net Realized Gains/Losses, Assets	0	0
Purchased, assets	16	75
Sales, assets	0	0
Settlements, assets	(41)	0
Balance- End of year, assets		25
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	0	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets	41	16	2
Transfers into Level 3, assets	0
Change in Net Unrealized Gains (Losses) included in OCI, Assets	(1)	2	3
Net Realized Gains/Losses, Assets	2	1	(2)
Purchased, assets	24	27	13
Sales, assets	(22)	(5)
Settlements, assets	0
Balance- End of year, assets	44	41	16
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	(1)		(2)
Collateralized Mortgage Backed Securities [Member] | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets	45	53	15
Transfers into Level 3, assets	50	0
Change in Net Unrealized Gains (Losses) included in OCI, Assets	0	(1)
Net Realized Gains/Losses, Assets	0	0
Purchased, assets	8	1	41
Sales, assets	(1)	(8)	(2)
Settlements, assets	(24)		(1)
Balance- End of year, assets	78	45	53
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	0	0	0
Corporate securities | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets	681	174	187
Transfers into Level 3, assets	231	53	16
Transfers out of Level 3, assets	(93)	(10)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	(12)	15	(1)
Net Realized Gains/Losses, Assets	0	(13)	(4)
Purchased, assets	521	566	52
Sales, assets	(111)	(59)	(28)
Settlements, assets	(180)	(45)	(48)
Balance- End of year, assets	1,037	681	174
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	(2)	(11)	(2)
Foreign Government Debt Securities [Member] | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance- Beginning of year, assets	74	57	22
Transfers into Level 3, assets	0	9	34
Transfers out of Level 3, assets	(3)	(24)
Change in Net Unrealized Gains (Losses) included in OCI, Assets	3	1	(2)
Net Realized Gains/Losses, Assets	0	(6)	(1)
Purchased, assets	84	70	15
Sales, assets	(59)	(17)	(3)
Settlements, assets	(6)	(16)	(8)
Balance- End of year, assets	93	74	57
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Assets	$ (1)	$ (5)	$ (1)

Fair value measurements Fair 76

Fair value measurements Fair Value Measurements (Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Guaranteed Minimum Income Benefit
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance - Beginning of year, liabilities	$ 559	[1],[2]	$ 609	[2],[3]	$ 406	[3]
Transfers Into Level 3, liabilities	9	[1]	0	[2]	0	[3]
Transfers out of Level 3, liabilities			0	[2]	0	[3]
Change in Net Unrealized Gains (Losses) included in OCI, Liabilities	0	[1]	0	[2]
Net Realized Gains/Losses, Liabilities	(364)	[1]	(50)	[2]	203	[3]
Purchased, liabilities	0	[1]	0	[2]	0	[3]
Sales, liabilities	0	[1]	0	[2]	0	[3]
Settlements, liabilities	0	[1]	0	[2]		[3]
Balance - End of year, liabilities	204	[1]	559	[1],[2]	609	[2],[3]
GLB liability	550		853		888		$ 663
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Liabilities	(364)	[1]	(50)	[2]	203	[3]
Other Derivative Instruments Fair Value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance - Beginning of year, liabilities	13		6		4
Transfers Into Level 3, liabilities	0		0		0
Transfers out of Level 3, liabilities	(9)
Change in Net Unrealized Gains (Losses) included in OCI, Liabilities	0		0
Net Realized Gains/Losses, Liabilities	(2)		5		2
Purchased, liabilities	0		2		0
Sales, liabilities	0		0
Settlements, liabilities	0
Balance - End of year, liabilities	2		13		6
Net Realized Gains/Losses Attributable to Changes in Fair Value at the Balance Sheet Date, Liabilities	$ (2)		$ 5		$ 2
[1]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c) for additional information.
[2]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015, which includes a fair value derivative adjustment of $559 million and $609 million, respectively.
[3]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $406 million, respectively.

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Values And Fair Values Of Financial Instruments Not Measured At Fair Value) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	$ 14,474	$ 10,670
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	14,335	10,644
Repurchase agreements	1,408	1,403
Short-term debt	1,013	500
Long-term debt	11,556	12,610
Trust preferred securities	308	308
Total liabilities	115,850	111,511
US Treasury and Government [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	915	661
Foreign
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	1,757	667
Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	3,219	2,795
Mortgage backed-securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	2,742	1,428
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	5,841	5,119
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Repurchase agreements	1,408	1,403
Short-term debt, Fair Value	1,013	503
Long-term debt, Fair Value	12,332	12,998
Trust preferred securities	468	456
Total liabilities	15,221	15,360
Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	14,335	10,644
Repurchase agreements	1,408	1,403
Short-term debt	1,013	500
Long-term debt	11,556	12,610
Trust preferred securities	308	308
Total liabilities	14,285	14,821
Reported Value Measurement | US Treasury and Government [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	908	655
Reported Value Measurement | Foreign
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	1,738	640
Reported Value Measurement | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	3,159	2,771
Reported Value Measurement | Mortgage backed-securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	2,724	1,393
Reported Value Measurement | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities held to maturity, at amortized cost (fair value – $14,474 and $10,670)	5,806	5,185
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	857	555
Repurchase agreements	0	0
Short-term debt, Fair Value	0	0
Long-term debt, Fair Value	0	0
Trust preferred securities	0	0
Total liabilities	0	0
Level 1 | US Treasury and Government [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	857	555
Level 1 | Foreign
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Level 1 | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Level 1 | Mortgage backed-securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Level 1 | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	13,582	10,102
Repurchase agreements	1,408	1,403
Short-term debt, Fair Value	1,013	503
Long-term debt, Fair Value	12,332	12,998
Trust preferred securities	468	456
Total liabilities	15,221	15,360
Level 2 | US Treasury and Government [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	58	106
Level 2 | Foreign
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	1,757	667
Level 2 | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	3,184	2,782
Level 2 | Mortgage backed-securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	2,742	1,428
Level 2 | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	5,841	5,119
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	35	13
Repurchase agreements	0	0
Short-term debt, Fair Value	0	0
Long-term debt, Fair Value	0	0
Trust preferred securities	0	0
Total liabilities	0	0
Level 3 | US Treasury and Government [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Level 3 | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	35	13
Level 3 | Mortgage backed-securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	0	0
Level 3 | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity Securities, Fair Value	$ 0	$ 0

Reinsurance (Consolidated Reins

Reinsurance (Consolidated Reinsurance) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Premiums written [Abstract]
Direct									$ 33,137	$ 31,543	$ 19,879
Assumed									3,239	3,440	3,932
Ceded									(7,132)	(6,838)	(6,098)
Net									29,244	28,145	17,713
Premiums earned [Abstract]
Direct									32,782	31,811	19,355
Assumed									3,332	3,744	3,676
Ceded									(7,080)	(6,806)	(5,818)
Net premiums earned	$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	29,034	28,749	17,213
Reinsurance recoveries on losses and loss expenses incurred									$ 5,500	$ 4,100	$ 3,100

Reinsurance (Reinsurance Recove

Reinsurance (Reinsurance Recoverable on Ceded Reinsurance) (Details) - USD ($) $ in Millions		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Reinsurance Disclosures [Abstract]
Reinsurance recoverable on unpaid losses	[1]	$ 14,014	[2]	$ 12,708	[2]	$ 10,741	$ 11,307
Reinsurance recoverable on paid losses and loss expenses	[2]	1,020		869
Net reinsurance recoverable on losses and loss expenses	[2]	15,034		13,577
Reinsurance Recoverable Future Policy Benefits	[2]	$ 184		$ 182
[1]	(1) Net of provision for uncollectible reinsurance.
[2]	(1) Net of a provision for uncollectible reinsurance.

Reinsurance (Reinsurance Reco80

Reinsurance (Reinsurance Recoverable by Category and Listing of Largest Reinsurers) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 15,355
Provision	$ 321	$ 300
% of Gross	2.10%
Largest reinsurers
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 5,190
Provision	$ 59
% of Gross	1.10%
Other reinsurers balances rated A- or better
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 5,898
Provision	$ 58
% of Gross	1.00%
Other reinsurers balances with ratings lower than A- or not rated
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 681
Provision	$ 75
% of Gross	11.00%
Other pools and government agencies
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 577
Provision	$ 15
% of Gross	2.60%
Structured settlements
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 550
Provision	$ 16
% of Gross	2.90%
Other captives
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 2,199
Provision	$ 18
% of Gross	0.80%
Other
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross reinsurance recoverable	$ 260
Provision	$ 80
% of Gross	30.80%

Reinsurance Reinsurance (Assume

Reinsurance Reinsurance (Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts - Schedule Of Guaranteed Minimum Benefits Income And Expense) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	$ 29,034	$ 28,749	$ 17,213
Policy benefits and other reserve adjustments	176	169	163	168	161	155	146	126	676	588	543
Net realized gains (losses) including OTTI	$ 0	$ (10)	$ 101	$ (7)	$ 365	$ 100	$ (216)	$ (394)	84	(145)	(420)
Guaranteed Minimum Death Benefit
Guaranteed Minimum Benefits [Line Items]
Net premiums earned									49	55	61
Policy benefits and other reserve adjustments									40	45	34
Guaranteed Minimum Income Benefit
Guaranteed Minimum Benefits [Line Items]
Net premiums earned									110	118	121
Policy benefits and other reserve adjustments									105	52	45
Net realized gains (losses) including OTTI									363	48	(203)
Gain (loss) recognized in income									368	114	(127)
Net cash received									65	79	98
Net (increase) decrease in liability									$ 303	$ 35	$ (225)

Reinsurance (Assumed Life Reins

Reinsurance (Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts - Narrative) (Detail) - USD ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Guaranteed Minimum Death Benefit
Net Amount at Risk by Product and Guarantee [Line Items]
GLB liability	$ 129		$ 120
Guaranteed Minimum Income Benefit
Net Amount at Risk by Product and Guarantee [Line Items]
GLB liability	550		853		$ 888		$ 663
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	204	[1]	559	[1],[2]	$ 609	[2],[3]	$ 406	[3]
Level 3 | Guaranteed Minimum Income Benefit
Net Amount at Risk by Product and Guarantee [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 204	[4]	$ 559
[1]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. Refer to Note 5 c) for additional information.
[2]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $853 million at December 31, 2016 and $888 million at December 31, 2015, which includes a fair value derivative adjustment of $559 million and $609 million, respectively.
[3]	Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the Consolidated balance sheets. The liability for GLB reinsurance was $888 million at December 31, 2015 and $663 million at December 31, 2014, which includes a fair value derivative adjustment of $609 million and $406 million, respectively.
[4]	Discussion of the most significant inputs used in the fair value measurement of GLB and the sensitivity of those assumptions is included within Note 4 a) Guaranteed living benefits.

Reinsurance Reinsurance (Net Am

Reinsurance Reinsurance (Net Amount at Risk and 100 Percent Mortality) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Guaranteed Minimum Benefits [Line Items]
Average attained age of all policyholders under all benefits reinsured, years	70 years
GLB
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	$ 691	$ 800
GMDB
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	$ 279	341
Mortality percentage according to Annuity 2000 mortality table	100.00%
GMDB with Both Risk(GMDB and GLB) [Member]
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	$ 81	88
GLB with Both Risk(GLB and GMDB) [Member]
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	$ 392	$ 464
Minimum | GLB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.25%
Minimum | GMDB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.00%
Minimum | GLB with Both Risk(GLB and GMDB) [Member]
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.25%
Maximum | GLB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.75%
Maximum | GMDB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.50%
Maximum | GLB with Both Risk(GLB and GMDB) [Member]
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.75%

Intangible Assets (Narrative) (

Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 15,541	$ 15,332	$ 4,796
Other intangible assets	6,500	6,800
Intangible assets subject to amortization	3,500	3,805
Intangible assets not subject to amortization	3,000
Amortization of Purchased Intangibles	$ 260	$ 19	$ 171

Intangible Assets (Roll-forward

Intangible Assets (Roll-forward of Goodwill by Business Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at beginning of period	$ 15,332	$ 4,796
Foreign exchange revaluation and other	209	22
Balance at end of period	15,541	15,332
North America Commercial P&C Insurance
Goodwill [Roll Forward]
Balance at beginning of period	6,961	1,203
Foreign exchange revaluation and other	15	44
Balance at end of period	6,976	6,961
North American Personal P&C [Member]
Goodwill [Roll Forward]
Balance at beginning of period	2,235	196
Foreign exchange revaluation and other	5	14
Balance at end of period	2,240	2,235
North America Agricultural Insurance
Goodwill [Roll Forward]
Balance at beginning of period	134	134
Foreign exchange revaluation and other	0	0
Balance at end of period	134	134
Overseas General Insurance
Goodwill [Roll Forward]
Balance at beginning of period	4,817	2,078
Foreign exchange revaluation and other	187	(36)
Balance at end of period	5,004	4,817
Global Reinsurance
Goodwill [Roll Forward]
Balance at beginning of period	365	365
Foreign exchange revaluation and other	0	0
Balance at end of period	365	365
Life Insurance
Goodwill [Roll Forward]
Balance at beginning of period	820	820
Foreign exchange revaluation and other	2	0
Balance at end of period	$ 822	820
The Chubb Corporation [Member]
Goodwill [Roll Forward]
Acquisition		10,514
The Chubb Corporation [Member] | North America Commercial P&C Insurance
Goodwill [Roll Forward]
Acquisition		5,714
The Chubb Corporation [Member] | North American Personal P&C [Member]
Goodwill [Roll Forward]
Acquisition		2,025
The Chubb Corporation [Member] | North America Agricultural Insurance
Goodwill [Roll Forward]
Acquisition		0
The Chubb Corporation [Member] | Overseas General Insurance
Goodwill [Roll Forward]
Acquisition		2,775
The Chubb Corporation [Member] | Global Reinsurance
Goodwill [Roll Forward]
Acquisition		0
The Chubb Corporation [Member] | Life Insurance
Goodwill [Roll Forward]
Acquisition		$ 0

Intangible Assets (Estimated Am

Intangible Assets (Estimated Amortization Expense Over Next Five Years) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
2018, Other intangible assets	$ 338
2019, Other intangible assets	294
2020, Other intangible assets	272
2021, Other intangible assets	259
2022, Other intangible assets	241
Total, Other intangible assets	1,404
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		3 years
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
2018, Other intangible assets	83
2019, Other intangible assets	75
2020, Other intangible assets	67
2021, Other intangible assets	61
2022, Other intangible assets	57
Total, Other intangible assets	343
The Chubb Corporation [Member]
Finite-Lived Intangible Assets [Line Items]
2018, Other intangible assets	255
2019, Other intangible assets	219
2020, Other intangible assets	205
2021, Other intangible assets	198
2022, Other intangible assets	184
Total, Other intangible assets	1,061
The Chubb Corporation [Member] | Agency distribution relationships and renewal rights [Member]
Finite-Lived Intangible Assets [Line Items]
2018, Other intangible assets	325
2019, Other intangible assets	282
2020, Other intangible assets	241
2021, Other intangible assets	218
2022, Other intangible assets	198
Total, Other intangible assets	1,264
The Chubb Corporation [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
2018, Other intangible assets	32
2019, Other intangible assets	0
2020, Other intangible assets	0
2021, Other intangible assets	0
2022, Other intangible assets	0
Total, Other intangible assets	32
The Chubb Corporation [Member] | Fair Value Adjustment to Acquired Loss Reserves [Member]
Finite-Lived Intangible Assets [Line Items]
2018, Other intangible assets	(102)
2019, Other intangible assets	(63)
2020, Other intangible assets	(36)
2021, Other intangible assets	(20)
2022, Other intangible assets	(14)
Total, Other intangible assets	(235)
Increase Decrease on Acquired Unpaid Losses and Loss Expenses	$ 309
Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Minimum | The Chubb Corporation [Member] | Fair Value Adjustment to Acquired Loss Reserves [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	30 years
Maximum | The Chubb Corporation [Member] | Fair Value Adjustment to Acquired Loss Reserves [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	17 years

Intangible Assets (VOBA) (Detai

Intangible Assets (VOBA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
VOBA Roll Forward
VOBA balance, beginning of year	$ 355	$ 395	$ 466
Amortization of Value of Business Acquired (VOBA)	(35)	(41)	(42)
VOBA Foreign exchange revaluation	6	1	(29)
VOBA balance, end of year	326	$ 355	$ 395
Present Value of Future Insurance Profits, Amortization Expense, Next Five Years [Abstract]
2018, VOBA	32
2019, VOBA	27
2020, VOBA	25
2021, VOBA	22
2022, VOBA	20
Total, VOBA	$ 126

Unpaid losses and loss expens88

Unpaid losses and loss expenses (Unpaid Losses and Loss Expenses Rollforward) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015	Jan. 14, 2016	Apr. 01, 2015
Unpaid Losses and Loss Expenses [Roll Forward]
Gross unpaid losses and loss expenses, beginning of year		$ 60,540		$ 37,303		$ 38,315
Reinsurance recoverable on unpaid losses, beginning of year	[1]	(12,708)	[2]	(10,741)		(11,307)
Net unpaid losses and loss expenses, beginning of year		47,832		26,562		27,008
Acquistion of subsidiaries		0					$ 21,402	$ 417
Total		47,832		47,964		27,425
Net losses and loss expenses incurred in respect of losses incurring in Current Year		19,391		17,256		10,030
PPD, Gross	[3]	(937)		(1,204)		(546)
Total		18,454		16,052		9,484
Net losses and loss expenses incurred in respect of losses paid in Current Year		6,575		5,899		4,053
Net losses and loss expenses incurred in respect of losses paid in Prior Year		10,873		9,816		5,612
Total		17,448		15,715		9,665
Foreign currency revaluation and other		327		(469)		(682)
Net unpaid losses and loss expenses, end of year		49,165		47,832		26,562
Reinsurance recoverable on unpaid losses, end of year	[1]	14,014	[2]	12,708	[2]	10,741
Gross unpaid losses and loss expenses, end of year		63,179		60,540		37,303
prior period development, net adjustments		$ 108		$ 69		$ 0
[1]	(1) Net of provision for uncollectible reinsurance.
[2]	(1) Net of a provision for uncollectible reinsurance.
[3]	(2) Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments, and earned premiums totaling $108 million, $69 million, and nil, for 2017, 2016, and 2015, respectively.

Unpaid losses and loss expens89

Unpaid losses and loss expenses Unpaid losses and loss expenses (Reconciliation of reserve Balances to Liability for Unpaid Loss)(Details) (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		$ 46,700
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		14,187
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Aggregate Reconciling Items	[1]	810
Unpaid unallocated loss adjustment expenses		1,482
Unpaid losses and loss expenses		63,179	$ 60,540	$ 37,303	$ 38,315
North America Commercial P&C Insurance - Workers' Compensation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		8,873
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		1,737
North America Commercial P&C Insurance - Liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		16,631
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		4,133
North America Commercial P&C Insurance - Other Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		1,789
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		813
North America Commercial P&C Insurance - Non-Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		2,398
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		1,336
North America Personal P&C Insurance [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		2,421
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		503
Overseas General Insurance - Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		6,026
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		2,550
Overseas General Insurance - Non-Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		2,549
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		1,269
Global Reinsurance - Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		1,340
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		76
Global Reinsurance - Non-Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		371
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		142
Other Short-duration Insurance Product Line [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid Loss and Allocated Loss Adjustment Expenses, Net		4,302
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments		$ 1,628
[1]	(1) Primarily includes the claims reserve of our international A&H business and Life Insurance segment reserves.

Unpaid losses and loss expens90

Unpaid losses and loss expenses Unpaid Losses and loss expenses, claims development (Cumulative Net incurred Loss and Allocated Loss Adjustment Expense) (Details) number in Thousands, $ in Millions	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)	Dec. 31, 2009USD ($)	Dec. 31, 2008USD ($)
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	$ 46,700
North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	11,327
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	4,937
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	2,483
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	8,873
North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	34,121
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	18,919
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	1,429
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	16,631
North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	5,185
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	3,633
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	237
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	1,789
North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	17,229
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	14,854
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	23
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	2,398
North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	21,564
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	19,168
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	25
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	2,421
Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	12,673
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	6,997
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	350
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	6,026
Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	18,445
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	15,961
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	65
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	2,549
Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	3,320
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	2,339
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	359
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	1,340
Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	2,172
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,816
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	15
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	371
Short-duration Insurance Contracts, Accident Year 2008 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	993	$ 986	$ 1,004	$ 1,009	$ 1,010	$ 1,036	$ 1,037	$ 1,043	$ 1,042	$ 1,084
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	214
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 651	632	607	578	546	503	439	371	275	124
Short-duration Insurance Contracts, Number of Reported Claims	333
Short-duration Insurance Contracts, Accident Year 2008 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,157	3,174	3,278	3,352	3,412	3,652	3,791	3,812	3,823	3,792
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	245
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,836	2,753	2,657	2,558	2,323	1,992	1,643	1,110	580	147
Short-duration Insurance Contracts, Number of Reported Claims	21
Short-duration Insurance Contracts, Accident Year 2008 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 637	641	646	643	647	644	661	700	733	693
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	13
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 617	618	610	602	591	566	520	446	342	144
Short-duration Insurance Contracts, Number of Reported Claims	20
Short-duration Insurance Contracts, Accident Year 2008 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,859	1,863	1,865	1,877	1,881	1,890	1,901	1,916	1,941	1,999
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	5
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,851	1,848	1,847	1,838	1,832	1,823	1,794	1,744	1,622	965
Short-duration Insurance Contracts, Number of Reported Claims	999
Short-duration Insurance Contracts, Accident Year 2008 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,659	1,661	1,661	1,670	1,677	1,695	1,724	1,749	1,779	1,779
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	5
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,651	1,651	1,647	1,644	1,638	1,622	1,586	1,521	1,409	975
Short-duration Insurance Contracts, Number of Reported Claims	139
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,281	1,330	1,315	1,336	1,408	1,453	1,444	1,423	1,334	1,220
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	81
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,116	1,083	1,029	971	895	790	642	472	306	121
Short-duration Insurance Contracts, Number of Reported Claims	39
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,504	1,508	1,519	1,524	1,527	1,553	1,547	1,563	1,608	1,609
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	25
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,484	1,477	1,477	1,469	1,461	1,451	1,428	1,360	1,218	646
Short-duration Insurance Contracts, Number of Reported Claims	539
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 399	401	404	408	407	428	431	439	420	399
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	48
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 315	305	295	277	253	220	176	131	77	33
Short-duration Insurance Contracts, Number of Reported Claims	1
Short-duration Insurance Contracts, Accident Year 2008 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 286	285	284	287	286	286	292	301	310	316
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 280	280	280	278	276	274	260	228	177	$ 79
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2009 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 965	972	966	977	980	990	997	998	1,029
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	233
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 617	597	550	519	475	416	348	258	107
Short-duration Insurance Contracts, Number of Reported Claims	282
Short-duration Insurance Contracts, Accident Year 2009 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,103	3,244	3,316	3,392	3,642	3,743	3,770	3,783	3,798
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	250
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,730	2,678	2,545	2,357	2,019	1,672	1,160	587	135
Short-duration Insurance Contracts, Number of Reported Claims	21
Short-duration Insurance Contracts, Accident Year 2009 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 441	445	447	454	488	531	550	584	594
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 428	423	414	402	374	337	287	206	70
Short-duration Insurance Contracts, Number of Reported Claims	15
Short-duration Insurance Contracts, Accident Year 2009 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,194	1,195	1,198	1,198	1,205	1,222	1,251	1,307	1,310
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	9
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,181	1,181	1,179	1,171	1,163	1,149	1,125	1,035	620
Short-duration Insurance Contracts, Number of Reported Claims	1,125
Short-duration Insurance Contracts, Accident Year 2009 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,533	1,534	1,538	1,538	1,545	1,554	1,568	1,598	1,611
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	7
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,523	1,521	1,513	1,503	1,486	1,439	1,347	1,236	887
Short-duration Insurance Contracts, Number of Reported Claims	125
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,202	1,256	1,257	1,365	1,482	1,485	1,474	1,425	1,284
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	76
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,020	993	896	824	763	667	524	341	123
Short-duration Insurance Contracts, Number of Reported Claims	39
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,366	1,366	1,377	1,377	1,395	1,415	1,446	1,534	1,564
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	3
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,343	1,344	1,341	1,335	1,324	1,300	1,233	1,095	602
Short-duration Insurance Contracts, Number of Reported Claims	518
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 316	320	331	347	366	370	363	351	319
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	24
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 256	241	227	209	187	154	116	79	34
Short-duration Insurance Contracts, Number of Reported Claims	1
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 139	139	139	141	144	150	152	172	141
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	3
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 134	134	134	134	132	129	122	106	$ 52
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2010 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,020	1,028	1,052	1,064	1,065	1,050	1,037	1,049
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	262
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 641	617	592	551	493	411	300	123
Short-duration Insurance Contracts, Number of Reported Claims	304
Short-duration Insurance Contracts, Accident Year 2010 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,107	3,128	3,250	3,419	3,559	3,601	3,583	3,578
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	423
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,527	2,426	2,259	1,893	1,559	1,108	611	126
Short-duration Insurance Contracts, Number of Reported Claims	20
Short-duration Insurance Contracts, Accident Year 2010 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 489	477	475	503	543	598	604	610
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	33
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 449	444	434	392	364	322	236	97
Short-duration Insurance Contracts, Number of Reported Claims	15
Short-duration Insurance Contracts, Accident Year 2010 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,410	1,416	1,420	1,428	1,430	1,466	1,543	1,507
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	9
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,397	1,396	1,393	1,384	1,359	1,323	1,223	724
Short-duration Insurance Contracts, Number of Reported Claims	1,059
Short-duration Insurance Contracts, Accident Year 2010 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,822	1,825	1,830	1,834	1,838	1,855	1,878	1,870
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	9
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,811	1,805	1,793	1,772	1,729	1,670	1,522	1,153
Short-duration Insurance Contracts, Number of Reported Claims	149
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,178	1,183	1,312	1,365	1,430	1,358	1,311	1,231
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	97
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 938	883	831	740	629	481	277	109
Short-duration Insurance Contracts, Number of Reported Claims	41
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,643	1,660	1,673	1,687	1,693	1,705	1,734	1,713
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	13
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,604	1,603	1,596	1,583	1,543	1,480	1,276	698
Short-duration Insurance Contracts, Number of Reported Claims	561
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 402	416	426	432	443	432	421	401
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	55
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 307	292	274	249	221	179	125	56
Short-duration Insurance Contracts, Number of Reported Claims	1
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 225	225	224	222	218	224	235	200
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	5
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 217	214	216	205	200	188	162	$ 56
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2011 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,012	1,022	1,053	1,049	1,046	1,030	1,037
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	294
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 595	567	533	484	411	294	119
Short-duration Insurance Contracts, Number of Reported Claims	287
Short-duration Insurance Contracts, Accident Year 2011 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,383	3,498	3,593	3,664	3,629	3,585	3,500
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	589
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,659	2,476	2,214	1,805	1,209	652	160
Short-duration Insurance Contracts, Number of Reported Claims	20
Short-duration Insurance Contracts, Accident Year 2011 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 513	521	530	545	578	586	577
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	33
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 466	461	437	400	341	235	86
Short-duration Insurance Contracts, Number of Reported Claims	16
Short-duration Insurance Contracts, Accident Year 2011 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,838	1,843	1,839	1,859	1,881	1,938	1,963
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	15
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,816	1,811	1,787	1,777	1,718	1,573	939
Short-duration Insurance Contracts, Number of Reported Claims	1,053
Short-duration Insurance Contracts, Accident Year 2011 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,159	2,160	2,164	2,173	2,185	2,210	2,208
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	13
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,138	2,129	2,105	2,051	1,971	1,835	1,360
Short-duration Insurance Contracts, Number of Reported Claims	168
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,094	1,109	1,176	1,262	1,270	1,277	1,272
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	157
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 795	719	638	534	400	250	91
Short-duration Insurance Contracts, Number of Reported Claims	42
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,901	1,908	1,920	1,939	1,978	2,035	1,950
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	7
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,841	1,832	1,817	1,786	1,728	1,520	793
Short-duration Insurance Contracts, Number of Reported Claims	579
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 415	419	429	434	431	416	409
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	45
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 311	291	267	236	195	146	70
Short-duration Insurance Contracts, Number of Reported Claims	1
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 264	264	263	262	272	275	274
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 258	255	251	232	207	176	$ 85
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 989	1,011	1,040	1,030	1,011	1,050
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	326
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 532	486	436	365	271	111
Short-duration Insurance Contracts, Number of Reported Claims	288
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,426	3,524	3,564	3,613	3,628	3,552
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	856
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,326	2,092	1,680	1,172	656	166
Short-duration Insurance Contracts, Number of Reported Claims	20
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 517	518	559	575	604	632
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	27
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 470	435	386	319	223	69
Short-duration Insurance Contracts, Number of Reported Claims	16
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,848	1,861	1,866	1,884	1,918	2,034
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	11
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,822	1,795	1,766	1,698	1,577	715
Short-duration Insurance Contracts, Number of Reported Claims	1,037
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,186	2,185	2,191	2,183	2,183	2,185
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	9
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,149	2,117	2,063	1,957	1,806	1,176
Short-duration Insurance Contracts, Number of Reported Claims	173
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,345	1,363	1,367	1,348	1,281	1,311
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	279
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 856	714	598	443	254	77
Short-duration Insurance Contracts, Number of Reported Claims	42
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,650	1,661	1,667	1,723	1,764	1,775
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	34
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,572	1,562	1,539	1,479	1,284	716
Short-duration Insurance Contracts, Number of Reported Claims	600
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 372	379	394	391	383	387
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	23
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 308	292	261	222	167	77
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 187	189	191	200	210	232
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 177	172	166	156	129	$ 44
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,085	1,127	1,122	1,108	1,109
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	368
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 553	506	422	286	107
Short-duration Insurance Contracts, Number of Reported Claims	300
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,430	3,532	3,542	3,541	3,546
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,090
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,007	1,597	1,192	548	130
Short-duration Insurance Contracts, Number of Reported Claims	20
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 468	515	522	530	526
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	60
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 385	348	271	197	69
Short-duration Insurance Contracts, Number of Reported Claims	18
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,340	1,360	1,337	1,424	1,434
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	18
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,311	1,285	1,237	1,138	651
Short-duration Insurance Contracts, Number of Reported Claims	1,074
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,924	1,899	1,896	1,888	1,860
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	41
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,843	1,786	1,687	1,504	1,043
Short-duration Insurance Contracts, Number of Reported Claims	126
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,270	1,330	1,284	1,284	1,289
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	314
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 727	584	432	272	90
Short-duration Insurance Contracts, Number of Reported Claims	42
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,730	1,739	1,787	1,859	1,868
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	62
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,612	1,574	1,541	1,340	738
Short-duration Insurance Contracts, Number of Reported Claims	622
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 331	330	330	327	321
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	41
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 242	222	186	143	65
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 144	143	149	160	163
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	5
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 133	131	121	103	$ 46
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,214	1,217	1,201	1,207
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	553
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 484	410	295	113
Short-duration Insurance Contracts, Number of Reported Claims	337
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,717	3,674	3,585	3,535
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,526
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,804	1,250	679	164
Short-duration Insurance Contracts, Number of Reported Claims	21
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 594	579	581	592
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	147
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 391	317	220	80
Short-duration Insurance Contracts, Number of Reported Claims	17
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,561	1,581	1,663	1,647
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	29
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,505	1,484	1,373	820
Short-duration Insurance Contracts, Number of Reported Claims	1,102
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,145	2,192	2,206	2,205
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	29
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,034	1,925	1,764	1,310
Short-duration Insurance Contracts, Number of Reported Claims	135
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,388	1,377	1,366	1,295
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	506
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 614	481	299	117
Short-duration Insurance Contracts, Number of Reported Claims	43
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,959	1,985	2,048	1,975
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	72
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,782	1,715	1,497	800
Short-duration Insurance Contracts, Number of Reported Claims	594
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 343	340	334	333
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	46
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 249	218	185	92
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 182	179	179	163
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	9
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 162	151	128	$ 65
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,271	1,259	1,282
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	631
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 418	301	116
Short-duration Insurance Contracts, Number of Reported Claims	339
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,818	3,708	3,559
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,941
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,206	605	138
Short-duration Insurance Contracts, Number of Reported Claims	23
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 501	469	486
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	191
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 215	137	47
Short-duration Insurance Contracts, Number of Reported Claims	15
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,650	1,746	1,737
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	83
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,488	1,343	726
Short-duration Insurance Contracts, Number of Reported Claims	1,173
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,560	2,549	2,494
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	126
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,270	2,083	1,499
Short-duration Insurance Contracts, Number of Reported Claims	139
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,353	1,324	1,223
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	542
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 504	296	92
Short-duration Insurance Contracts, Number of Reported Claims	45
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,195	2,243	2,111
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	157
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,873	1,638	901
Short-duration Insurance Contracts, Number of Reported Claims	627
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 300	289	285
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	47
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 191	159	90
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 161	154	146
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	8
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 132	103	$ 56
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,367	1,367
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	806
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 326	122
Short-duration Insurance Contracts, Number of Reported Claims	310
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,594	3,533
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2,381
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 663	171
Short-duration Insurance Contracts, Number of Reported Claims	24
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 494	503
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	249
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 146	52
Short-duration Insurance Contracts, Number of Reported Claims	15
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,888	1,911
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	168
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,504	846
Short-duration Insurance Contracts, Number of Reported Claims	1,293
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,542	2,439
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	248
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,051	1,453
Short-duration Insurance Contracts, Number of Reported Claims	140
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,333	1,227
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	749
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 328	127
Short-duration Insurance Contracts, Number of Reported Claims	45
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,148	2,164
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	19
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,752	1,083
Short-duration Insurance Contracts, Number of Reported Claims	637
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 228	224
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	63
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 113	57
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 188	182
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	17
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 132	$ 57
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,411
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,080
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 120
Short-duration Insurance Contracts, Number of Reported Claims	307
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,386
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2,994
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 161
Short-duration Insurance Contracts, Number of Reported Claims	19
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 531
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	387
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 66
Short-duration Insurance Contracts, Number of Reported Claims	13
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,641
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,089
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 979
Short-duration Insurance Contracts, Number of Reported Claims	1,175
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,034
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	725
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,698
Short-duration Insurance Contracts, Number of Reported Claims	123
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,229
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	968
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 99
Short-duration Insurance Contracts, Number of Reported Claims	34
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,349
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	307
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,098
Short-duration Insurance Contracts, Number of Reported Claims	616
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 214
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	121
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 47
Short-duration Insurance Contracts, Number of Reported Claims	0
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 396
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	82
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 191
Short-duration Insurance Contracts, Number of Reported Claims	0

Unpaid losses and loss expens91

Unpaid losses and loss expenses Unpaid losses and loss expenses (Details) (Supplementary PPD) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
North America Commercial P&C Insurance - Workers' Compensation [Member]
Supplementary PPD [Line Items]
short-duration PPD	$ (108)
North America Commercial P&C Insurance - Workers' Compensation [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	(35)
North America Commercial P&C Insurance - Liability [Member]
Supplementary PPD [Line Items]
short-duration PPD	(434)
North America Commercial P&C Insurance - Liability [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	(154)
North America Commercial P&C Insurance - Other Casualty [Member]
Supplementary PPD [Line Items]
short-duration PPD	0
North America Commercial P&C Insurance - Other Casualty [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	14
North America Commercial P&C Insurance - Non-Casualty [Member]
Supplementary PPD [Line Items]
short-duration PPD	(188)
North America Commercial P&C Insurance - Non-Casualty [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	0
North America Personal P&C Insurance [Member]
Supplementary PPD [Line Items]
short-duration PPD	76
North America Personal P&C Insurance [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	(10)
Overseas General Insurance - Casualty [Member]
Supplementary PPD [Line Items]
short-duration PPD	(68)
Overseas General Insurance - Casualty [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	(13)
Overseas General Insurance - Non-Casualty [Member]
Supplementary PPD [Line Items]
short-duration PPD	(141)
Overseas General Insurance - Non-Casualty [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	(3)
Global Reinsurance - Casualty [Member]
Supplementary PPD [Line Items]
short-duration PPD	(72)
Global Reinsurance - Casualty [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	(60)
Global Reinsurance - Non-Casualty [Member]
Supplementary PPD [Line Items]
short-duration PPD	16
Global Reinsurance - Non-Casualty [Member] | prior to 2008 [Member]
Supplementary PPD [Line Items]
short-duration PPD	$ 0

Unpaid losses and loss expens92

Unpaid losses and loss expenses Unpaid losses and loss expenses (Average Annual Payout) (Details)	Dec. 31, 2017
North America Commercial P&C Insurance - Workers' Compensation [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	10.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	16.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	10.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	5.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	3.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	3.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	2.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	2.00%
North America Commercial P&C Insurance - Liability [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	14.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	17.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	15.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	12.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	9.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	6.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	2.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	3.00%
North America Commercial P&C Insurance - Other Casualty [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	15.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	26.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	17.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	12.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	8.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	6.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	2.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%
North America Commercial P&C Insurance - Non-Casualty [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	46.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	37.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	7.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	3.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%
North America Personal P&C Insurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	58.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	24.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	7.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	5.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	3.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%
Overseas General Insurance - Casualty [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	8.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	15.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	14.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	12.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	10.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	8.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	6.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	6.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	3.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	3.00%
Overseas General Insurance - Non-Casualty [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	44.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	35.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	11.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	2.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%
Global Reinsurance - Casualty [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	19.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	12.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	11.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	8.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	6.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	5.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	3.00%
Global Reinsurance - Non-Casualty [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	34.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	38.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	14.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	2.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.00%

Unpaid losses and loss expens93

Unpaid losses and loss expenses Unpaid losses and loss expenses (Details) (Supplementary PPD Reconciliation) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
supplementary PPD reconciliation [Line Items]
PPD, Gross	[1]	$ (937)	$ (1,204)	$ (546)
prior period development, net adjustments		108	69	0
Prior Year Claims and Claims Adjustment Expense		(829)	(1,135)	(546)
Long Tail [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		(423)	(817)	(263)
Short Tail [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		(406)	(318)	(283)
Segments included in loss triangles [Domain]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	(122)
PPD, Gross		(1,041)
prior period development, net adjustments		53
Prior Year Claims and Claims Adjustment Expense		(988)
Segments included in loss triangles [Domain] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(658)
Segments included in loss triangles [Domain] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(261)
North America Commercial P&C Insurance
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2],[3]	(73)
PPD, Gross		(803)
prior period development, net adjustments		57
Prior Year Claims and Claims Adjustment Expense		(746)	(778)	(264)
North America Commercial P&C Insurance | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(555)
North America Commercial P&C Insurance | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(175)
North America Commercial P&C Insurance | Long Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	(76)
PPD, Gross		(618)
prior period development, net adjustments		56
Prior Year Claims and Claims Adjustment Expense		(562)	(693)	(162)
North America Commercial P&C Insurance | Long Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(367)
North America Commercial P&C Insurance | Long Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(175)
North America Commercial P&C Insurance | Short Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	3
PPD, Gross		(185)
prior period development, net adjustments		1
Prior Year Claims and Claims Adjustment Expense		(184)	(85)	(102)
North America Commercial P&C Insurance | Short Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(188)
North America Commercial P&C Insurance | Short Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		0
North America Commercial P&C Insurance - Other Casualty [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		0
North America Commercial P&C Insurance - Other Casualty [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		14
North America Commercial P&C Insurance - Non-Casualty [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(188)
North America Commercial P&C Insurance - Non-Casualty [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		0
North America Personal P&C Insurance [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		76
Prior Year Claims and Claims Adjustment Expense		69	27	25
North America Personal P&C Insurance [Member] | Alternative Risk Solutions [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		(55)
North America Personal P&C Insurance [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(10)
North America Personal P&C Insurance [Member] | Long Tail [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		0	0	0
North America Personal P&C Insurance [Member] | Short Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	(7)
PPD, Gross		69
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		69	27	25
North America Personal P&C Insurance [Member] | Short Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		86
North America Personal P&C Insurance [Member] | Short Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(10)
Overseas General Insurance
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2],[4]	(43)
PPD, Gross		(252)
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		(252)	(423)	(343)
Overseas General Insurance | International A&H [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		(35)
Overseas General Insurance | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(193)
Overseas General Insurance | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(16)
Overseas General Insurance | Long Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	(3)
PPD, Gross		(71)
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		(71)	(236)	(192)
Overseas General Insurance | Long Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(55)
Overseas General Insurance | Long Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(13)
Overseas General Insurance | Short Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	(40)
PPD, Gross		(181)
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		(181)	(187)	(151)
Overseas General Insurance | Short Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(138)
Overseas General Insurance | Short Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(3)
Overseas General Insurance - Casualty [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(68)
Overseas General Insurance - Casualty [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(13)
Overseas General Insurance - Non-Casualty [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(141)
Overseas General Insurance - Non-Casualty [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(3)
Segment Global Reinsurance [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	1
PPD, Gross		(55)
prior period development, net adjustments		(4)
Prior Year Claims and Claims Adjustment Expense		(59)
Segment Global Reinsurance [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		4
Segment Global Reinsurance [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(60)
Segment Global Reinsurance [Member] | Long Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	1
PPD, Gross		(71)
prior period development, net adjustments		3
Prior Year Claims and Claims Adjustment Expense		(68)
Segment Global Reinsurance [Member] | Long Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(12)
Segment Global Reinsurance [Member] | Long Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(60)
Segment Global Reinsurance [Member] | Short Tail [Member]
supplementary PPD reconciliation [Line Items]
Other PPD adjustments	[2]	0
PPD, Gross		16
prior period development, net adjustments		(7)
Prior Year Claims and Claims Adjustment Expense		9
Segment Global Reinsurance [Member] | Short Tail [Member] | 2008 to 2016 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		16
Segment Global Reinsurance [Member] | Short Tail [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		0
Global Reinsurance - Casualty [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(72)
Global Reinsurance - Casualty [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		(60)
Global Reinsurance - Non-Casualty [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		16
Global Reinsurance - Non-Casualty [Member] | prior to 2008 [Member]
supplementary PPD reconciliation [Line Items]
short-duration PPD		0
North America Agricultural Insurance
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		(119)	(72)	(45)
North America Agricultural Insurance | Long Tail [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		0	0	0
North America Agricultural Insurance | Short Tail [Member]
supplementary PPD reconciliation [Line Items]
PPD, Gross		(174)
prior period development, net adjustments		55
Prior Year Claims and Claims Adjustment Expense		(119)	(72)	(45)
Corporate Segment [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		278	189	200
Corporate Segment [Member] | Long Tail [Member]
supplementary PPD reconciliation [Line Items]
PPD, Gross		278
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		278	189	200
Corporate Segment [Member] | Short Tail [Member]
supplementary PPD reconciliation [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 0	$ 0	$ 0
[1]	(2) Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments, and earned premiums totaling $108 million, $69 million, and nil, for 2017, 2016, and 2015, respectively.
[2]	(1) Other includes the impact of foreign exchange.
[3]	(2) Includes favorable development of $55 million related to our Alternative Risk Solutions business; the remaining difference relates to a number of other items, none of which are individually material.
[4]	(3) Includes favorable development of $35 million related to International A&H business, the remaining difference relates to a number of other items, none of which are individually material.

Unpaid losses and loss expens94

Unpaid losses and loss expenses Unpaid losses and loss expenses (PPD table) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 14, 2016	Dec. 31, 2014
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net		$ 49,165	$ 47,832	$ 26,562		$ 27,008
Prior Year Claims and Claims Adjustment Expense		$ (829)	$ (1,135)	$ (546)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	1.70%	2.40%	2.00%
Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (423)	$ (817)	$ (263)
Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(406)	(318)	(283)
North America Commercial P&C Insurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (746)	$ (778)	$ (264)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	1.60%	1.60%	1.00%
North America Commercial P&C Insurance | Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (562)	$ (693)	$ (162)
North America Commercial P&C Insurance | Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(184)	(85)	(102)
North America Personal P&C Insurance [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 69	$ 27	$ 25
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.10%	0.10%	0.10%
North America Personal P&C Insurance [Member] | Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 0	$ 0	$ 0
North America Personal P&C Insurance [Member] | Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		69	27	25
North America Agricultural Insurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (119)	$ (72)	$ (45)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.20%	0.20%	0.10%
North America Agricultural Insurance | Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 0	$ 0	$ 0
North America Agricultural Insurance | Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(119)	(72)	(45)
Overseas General Insurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (252)	$ (423)	$ (343)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.50%	0.90%	1.30%
Overseas General Insurance | Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (71)	$ (236)	$ (192)
Overseas General Insurance | Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(181)	(187)	(151)
Global Reinsurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (59)	$ (78)	$ (119)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.10%	0.20%	0.40%
Global Reinsurance | Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (68)	$ (77)	$ (109)
Global Reinsurance | Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		9	(1)	(10)
Corporate Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 278	$ 189	$ 200
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.60%	0.40%	0.70%
Corporate Segment [Member] | Long Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 278	$ 189	$ 200
Corporate Segment [Member] | Short Tail [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 0	$ 0	$ 0
The Chubb Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net					$ 21,400
[1]	(1) Calculated based on the beginning of period consolidated net unpaid losses and loss expenses. For 2016, the percent of beginning net unpaid reserves is calculated inclusive of the net unpaid losses and loss expenses acquired in the Chubb Corp acquisition of $21.4 billion.

Unpaid losses and loss expens95

Unpaid losses and loss expenses (A&E Loss Roll-forward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Liability for Catastrophe Claims [Line Items]
Unpaid losses and loss expenses	$ 63,179		$ 60,540	$ 37,303	$ 38,315
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (gross) at December 31, 2016	2,303
Balance (net) at December 31, 2016	1,609
Incurred activity, gross	427
Incurred activity, net	217	[1]	164
Paid activity, gross	(502)
Paid activity, net	(299)
Balance (gross) at December 31, 2017	2,228		2,303
Balance (net) at December 31, 2017	1,527		1,609
Brandywine [Member]
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (net) at December 31, 2016	760
Balance (net) at December 31, 2017	849		760
Westchester Specialty [Member]
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (net) at December 31, 2016	112
Balance (net) at December 31, 2017	113		112
Chubb Corp [Member]
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (net) at December 31, 2016	657
Balance (net) at December 31, 2017	486		657
Other Segments [Member]
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (net) at December 31, 2016	80
Balance (net) at December 31, 2017	79		80
Environmental
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (gross) at December 31, 2016	577
Balance (net) at December 31, 2016	490
Incurred activity, gross	199
Incurred activity, net	113
Paid activity, gross	(169)
Paid activity, net	(127)
Balance (gross) at December 31, 2017	607		577
Balance (net) at December 31, 2017	476		490
Asbestos
Liability For Asbestos And Environmental Claims Net Roll Forward
Balance (gross) at December 31, 2016	1,726
Balance (net) at December 31, 2016	1,119
Incurred activity, gross	228
Incurred activity, net	104
Paid activity, gross	(333)
Paid activity, net	(172)
Balance (gross) at December 31, 2017	1,621		1,726
Balance (net) at December 31, 2017	1,051		$ 1,119
Brandywine Run-off [Member]
Liability for Catastrophe Claims [Line Items]
Unpaid losses and loss expenses	$ 2,000
[1]	(1) Excludes unallocated loss expenses and the net activity reflects third-party reinsurance other than the aggregate excess of loss reinsurance provided by National Indemnity Company (NICO) to Westchester Specialty (see Westchester Specialty section below).

Unpaid losses and loss expens96

Unpaid losses and loss expenses (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2004
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		$ 108	$ 69	$ 0
Prior Year Claims and Claims Adjustment Expense		$ (829)	$ (1,135)	$ (546)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	1.70%	2.40%	2.00%
Incurred activity		$ 18,454	$ 16,052	$ 9,484
Liability for Claims and Claims Adjustment Expense		63,179	60,540	37,303	$ 38,315
Brandywine Run-off [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred activity		672
Reinsurance coverage to Century provided by ACE INA under XOL		800
Statutory capital and surplus		25
Dividend retention fund established by INA Financial Corporation		50
Required minimum balance under the dividend retention fund		50
Contributions to the dividend retention fund		49				$ 35	$ 15
Minimum contribution from the dividend retention fund to Century not required for XOL agreement		200
Aggregate reinsurance balances ceded by active ACE companies to Century		1,400	1,200
Liability for Claims and Claims Adjustment Expense		$ 2,000
Surplus note								$ 100
Westchester and Brandywine Run-off [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
NICO pro-rata share of reinsurance protection (percent)		75.00%
NICO retention for losses and loss expenses incurred on or before 12/31/1996		$ 721
NICO reinsurance protection on losses and loss expenses incurred on or before 12/31/1996, net of retenion		1,000
NICO reinsurance protection on losses and loss expenses		409
Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
PPD adjustments			(101)	(46)
Prior Year Claims and Claims Adjustment Expense		(423)	(817)	(263)
Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(406)	(318)	(283)
North America Commercial P&C Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		57
Prior Year Claims and Claims Adjustment Expense		$ (746)	$ (778)	$ (264)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	1.60%	1.60%	1.00%
North America Commercial P&C Insurance | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		$ 56
Prior Year Claims and Claims Adjustment Expense		(562)	$ (693)	$ (162)
North America Commercial P&C Insurance | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		1
Prior Year Claims and Claims Adjustment Expense		(184)	(85)	(102)
North America Commercial P&C Insurance | North America Commercial P&C Insurance - Workers' Compensation [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(123)	(141)
North America Commercial P&C Insurance | Commercial Excess and Umbrella [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(184)
North America Commercial P&C Insurance | Multi-Line [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		26
North America Commercial P&C Insurance | Management Liability [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(181)
North America Commercial P&C Insurance | 2011 and prior [Member] | Directors and Officers Liability Insurance [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(220)
North America Commercial P&C Insurance | Accident Year 2010 and Prior [Member] | Commercial Excess and Umbrella [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(264)
North America Commercial P&C Insurance | Accident year 2015 and 2016 [Member] | Accident and Health [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(20)
North America Commercial P&C Insurance | Accident year 2015 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(40)
North America Commercial P&C Insurance | Accident year 2015 [Member] | Surety [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(45)
North America Commercial P&C Insurance | Accident Year 2016 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(57)
North America Commercial P&C Insurance | Accident years 2012 and prior [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(92)
North America Commercial P&C Insurance | Accident years 2012 and prior [Member] | Professional Errors and Omissions Insurance [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(58)
North America Commercial P&C Insurance | Accident Year 2013 and prior [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(65)
North America Commercial P&C Insurance | Accident year 2012 and 2013 [Member] | Professional Errors and Omissions Insurance [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(32)
North America Commercial P&C Insurance | Accident year 2012 and 2013 [Member] | Multi-Line [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(28)
North America Commercial P&C Insurance | Accident year 2013 [Member] | Auto Liability Excess Lines [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		21
North America Commercial P&C Insurance | Accident year 2013 [Member] | Political [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(21)
North America Commercial P&C Insurance | Accident Years 2012 - 2016 [Member] | Property and Inland Marine [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(98)
North America Commercial P&C Insurance | Accident Year 2012 [Member] | Political [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(21)
North America Personal P&C Insurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 69	$ 27	$ 25
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.10%	0.10%	0.10%
North America Personal P&C Insurance [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 0	$ 0	$ 0
North America Personal P&C Insurance [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		69	27	25
North America Personal P&C Insurance [Member] | Accident Year 2014 [Member] | Personal Excess [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(58)
North America Personal P&C Insurance [Member] | Accident years 2013 and 2016 [Member] | Personal homeowner [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		105
North America Agricultural Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (119)	$ (72)	$ (45)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.20%	0.20%	0.10%
North America Agricultural Insurance | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 0	$ 0	$ 0
North America Agricultural Insurance | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		55
Prior Year Claims and Claims Adjustment Expense		(119)	(72)	(45)
Overseas General Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		$ (252)	$ (423)	$ (343)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.50%	0.90%	1.30%
Overseas General Insurance | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		$ 0
Prior Year Claims and Claims Adjustment Expense		(71)	$ (236)	$ (192)
Overseas General Insurance | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		0
Prior Year Claims and Claims Adjustment Expense		(181)	(187)	(151)
Overseas General Insurance | Financial [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(34)
Overseas General Insurance | Casualty [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(10)
Overseas General Insurance | Casualty and Financial [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(177)
Overseas General Insurance | Individual Legacy Liability [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(25)
Overseas General Insurance | Accident year 2015 and 2016 [Member] | Marine [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(42)
Overseas General Insurance | Accident years 2012 and prior [Member] | Casualty and Financial [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(266)
Overseas General Insurance | Accident years 2012 and prior [Member] | Aviation [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(28)
Overseas General Insurance | Accident year 2013 - 2015 [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			89
Overseas General Insurance | Accident year 2013 - 2015 [Member] | Property [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(25)
Overseas General Insurance | Accident year 2013 - 2015 [Member] | Accident and Health [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(28)
Overseas General Insurance | Accident year 2012 - 2014 [Member] | Property [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(97)
Overseas General Insurance | Accident year 2010 - 2014 [Member] | Energy [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(43)
Overseas General Insurance | Accident Year 2013 and prior [Member] | Financial [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(124)
Overseas General Insurance | Accident Year 2013 and prior [Member] | Casualty [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(69)
Overseas General Insurance | Accident years 2016 and prior [Member] | Casualty [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		32
Overseas General Insurance | Accident years 2014 - 2016 [Member] | Financial [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		90
Overseas General Insurance | Accident years 2014 - 2016 [Member] | Casualty [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		27
Overseas General Insurance | Accident years 2014 - 2016 [Member] | Energy and Technical Risk Property [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(43)
Overseas General Insurance | Accident years 2014 - 2016 [Member] | Accident and Health [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (48)
Overseas General Insurance - Non-Casualty [Member] | Latin America [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss by Geographic Percentage		35.00%
Global Reinsurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (59)	$ (78)	$ (119)
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.10%	0.20%	0.40%
Global Reinsurance | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ (68)	$ (77)	$ (109)
Global Reinsurance | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		9	(1)	(10)
Global Reinsurance | Auto Liability Excess Lines [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		10
Global Reinsurance | 2011 and prior [Member] | Casualty and Financial [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(42)
Global Reinsurance | 2011 and prior [Member] | Professional Liability [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense			(30)
Global Reinsurance | Accident Year 2013 and prior [Member] | Casualty [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		(67)
Global Reinsurance | Accident Year 2015 and prior [Member] | Auto Liability Excess Lines [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 9
Global Reinsurance | UNITED STATES | Accident year 2008 and after [Member] | Non-catastrophe [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss by Geographic Percentage		72.00%
Global Reinsurance | UNITED STATES | Accident years 2008 to 2012 [Member] | Non-catastrophe [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss by Geographic Percentage		60.00%
Global Reinsurance | UNITED STATES | Accident years 2013 - 2017 [Member] | Non-catastrophe [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Loss by Geographic Percentage		84.00%
Corporate Segment [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 278	$ 189	$ 200
Prior Period Development Percentage Opening Net Unpaid Reserves	[1]	0.60%	0.40%	0.70%
Corporate Segment [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
prior period development, net adjustments		$ 0
Prior Year Claims and Claims Adjustment Expense		278	$ 189	$ 200
Corporate Segment [Member] | Long Tail [Member] | Discontinued Operations [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		39	48
Corporate Segment [Member] | Short Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		0	0	$ 0
Corporate Segment [Member] | Asbestos & Environmental [Member] | Long Tail [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior Year Claims and Claims Adjustment Expense		$ 239	$ 141
[1]	(1) Calculated based on the beginning of period consolidated net unpaid losses and loss expenses. For 2016, the percent of beginning net unpaid reserves is calculated inclusive of the net unpaid losses and loss expenses acquired in the Chubb Corp acquisition of $21.4 billion.

Taxation (Narrative) (Details)

Taxation (Narrative) (Details) - USD ($) $ in Millions	Dec. 22, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Examination [Line Items]
Income tax benefit related to 2017 Tax Act		$ (450)	$ 0	$ 0
Unrecognized Tax Benefits		13	17	$ 16
Valuation allowance		99	78
Unrecognized tax benefits that would affect the effective tax rate			17
Tax-related interest and penalties reported in the consolidated statements of operations		1
Liabilities recorded for tax-related interest and penalties		3	$ 4
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		450
Impact on deferred tax liability [Member]
Income Tax Examination [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		743
Impact on Deferred Tax Asset [Member]
Income Tax Examination [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		(371)
Other impact [Member]
Income Tax Examination [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ 78
Tax Year 2017 [Member]
Income Tax Examination [Line Items]
Applicable income tax rates		35.00%
Tax Year 2018 [Member]
Income Tax Examination [Line Items]
Applicable income tax rates	21.00%	21.00%
Domestic Tax Authority [Member]
Income Tax Examination [Line Items]
Net operating loss carry-forwards		$ 329
Switzerland
Income Tax Examination [Line Items]
Applicable income tax rates		7.83%
Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Foreign tax credit carry-forward		$ 340
Bermuda
Income Tax Examination [Line Items]
Applicable income tax rates		0.00%
UNITED STATES
Income Tax Examination [Line Items]
Applicable income tax rates		35.00%
U.K.
Income Tax Examination [Line Items]
Applicable income tax rates		19.00%

Taxation (Provision For Income

Taxation (Provision For Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Examination [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ 527	$ 766	$ 469
Income (Loss) from Continuing Operations before Income Taxes, Foreign	3,195	4,184	2,827
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	3,722	4,950	3,296
Current tax expense	359	824	304
Deferred tax expense	(498)	(9)	158
Provision for income taxes	(139)	815	462
Domestic Tax Authority [Member]
Income Tax Examination [Line Items]
Current tax expense	46	97	38
Deferred tax expense	2	(27)	4
Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Current tax expense	313	727	266
Deferred tax expense	$ (500)	$ 18	$ 154

Taxation (Reconciliation Of The

Taxation (Reconciliation Of The Difference Between The Provision for Income Taxes and the Expected Tax Provision at Swiss Statutory Income Tax Rate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Expected tax provision at Swiss statutory rate	$ 291	$ 388	$ 258
Taxes on earnings subject to rates other that Swiss statutory rate	263	582	193
Tax exempt interest and dividends received deduction, net of proration	(199)	(200)	(32)
Net witholding taxes	30	20	35
Change in valuation allowance	(48)	0	0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(450)
Income tax benefit related to 2017 Tax Act	(450)	0	0
Income Tax Reconciliation, Non-taxable Acquisition Gain	(37)	0	0
Other	11	25	8
Provision for income taxes	$ (139)	$ 815	$ 462

Taxation (Components Of Net Def

Taxation (Components Of Net Deferred Tax Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Gross [Abstract]
Loss reserve discount	$ 715	$ 1,269
Unearned premium reserve	231	498
Foreign tax credits	340	2,115
Provision for uncollectible balances	45	72
Loss carry-forwards	90	92
Debt related amounts	77	219
Compensation related amounts	260	449
Cumulative translation adjustments	30	59
Other, net	70	69
Total deferred tax assets	1,858	4,842
Deferred Tax Liabilities, Gross [Abstract]
Deferred policy acquisition costs	635	842
VOBA and other intangible assets	1,437	2,352
Un-remitted foreign earnings	66	2,001
Investments	53	406
Unrealized appreciation on investments	184	60
Depreciation	83	91
Deferred Tax Liabilities, Gross	2,458	5,752
Valuation allowance	99	78
Deferred Tax Liabilities, Net	$ (699)	$ (988)

Taxation (Reconciliation of Unr

Taxation (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, beginning of year	$ 17	$ 16
Additions based on tax provisions related to the current year	3	3
Additions based on tax positions related to prior years	0	2
Reductions for tax positions of prior years	(4)	(4)
Reductions for the lapse of the applicable statutes of limitations	(3)	0
Unrecognized Tax Benefits, end of year	$ 13	$ 17

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($) $ in Millions	Jan. 14, 2016	Dec. 31, 2017	Apr. 14, 2017	Mar. 31, 2000
Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Debt issued		$ 1,000
Junior Subordinated Debt [Member] | Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Long-term debt stated interest rate		3.97%	6.375%
Debt issued		$ 1,000
Junior Subordinated Debt [Member] | Chubb INA Capital Securities Due 2067 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.25%
Senior Notes [Member] | INA Senior Notes Due February 2017 [Member]
Debt Instrument [Line Items]
Long-term debt stated interest rate		5.70%
Debt issued		$ 500
Trust Preferred Securities | INA capital securities due 2030
Debt Instrument [Line Items]
Long-term debt stated interest rate		9.70%		9.70%
Debt issued		$ 309		$ 300
ACE Capital Trust II common securities purchased				$ 9.2
The Chubb Corporation [Member]
Debt Instrument [Line Items]
Business Combination, Consideration Transferred, Liabilities Incurred	$ 5,300

Debt (Schedule of Debt Outstand

Debt (Schedule of Debt Outstanding) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Apr. 14, 2017	Dec. 31, 2016	Mar. 31, 2000
Debt Instrument [Line Items]
Repurchase agreements	$ 1,408		$ 1,403
Short-term debt	1,013		500
Long-term debt	11,556		12,610
Trust preferred securities	308		308
Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	1,000
Junior Subordinated Debt [Member] | Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Long-term debt	964		962
Debt Instrument, Face Amount	$ 1,000
Long-term debt stated interest rate	3.97%	6.375%
Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 11,556		12,610
Senior Notes | INA Senior Notes Due February 2017 [Member]
Debt Instrument [Line Items]
Short-term debt	0		500
Long-term debt	0		0
Debt Instrument, Face Amount	$ 500
Long-term debt stated interest rate	5.70%
Additional percentage on 'make-whole' premium	0.20%
Senior Notes | INA Senior Notes Due March 2018 [Member]
Debt Instrument [Line Items]
Short-term debt	$ 300		0
Long-term debt	0		300
Debt Instrument, Face Amount	$ 300
Long-term debt stated interest rate	5.80%
Additional percentage on 'make-whole' premium	0.35%
Senior Notes | INA Senior Notes Due May 2018 [Member]
Debt Instrument [Line Items]
Short-term debt	$ 610		0
Senior Notes | Chubb INA Senior Notes Due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	0		635
Debt Instrument, Face Amount	$ 600
Long-term debt stated interest rate	5.75%
Additional percentage on 'make-whole' premium	0.30%
Senior Notes | Chubb INA Senior Notes Due August 2018 [Member]
Debt Instrument [Line Items]
Short-term debt	$ 103		0
Senior Notes | INA Senior Notes Due June 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	499		498
Debt Instrument, Face Amount	$ 500
Long-term debt stated interest rate	5.90%
Additional percentage on 'make-whole' premium	0.40%
Senior Notes | INA Senior Notes Due November 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,296		1,294
Debt Instrument, Face Amount	$ 1,300
Long-term debt stated interest rate	2.30%
Additional percentage on 'make-whole' premium	0.15%
Senior Notes | INA Senior Notes Due November 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 995		994
Debt Instrument, Face Amount	$ 1,000
Long-term debt stated interest rate	2.875%
Additional percentage on 'make-whole' premium	0.20%
Senior Notes | INA Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 472		471
Debt Instrument, Face Amount	$ 475
Long-term debt stated interest rate	2.70%
Additional percentage on 'make-whole' premium	0.10%
Senior Notes | INA Senior Notes Due May 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 695		695
Debt Instrument, Face Amount	$ 700
Long-term debt stated interest rate	3.35%
Additional percentage on 'make-whole' premium	0.15%
Senior Notes | INA Senior Notes Due March 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 795		794
Debt Instrument, Face Amount	$ 800
Long-term debt stated interest rate	3.15%
Additional percentage on 'make-whole' premium	0.15%
Senior Notes | INA Senior Notes Due May 2026 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,489		1,488
Debt Instrument, Face Amount	$ 1,500
Long-term debt stated interest rate	3.35%
Additional percentage on 'make-whole' premium	0.20%
Senior Notes | INA Senior Notes Due May 2036 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 297		297
Debt Instrument, Face Amount	$ 300
Long-term debt stated interest rate	6.70%
Additional percentage on 'make-whole' premium	0.20%
Senior Notes | Chubb INA Senior Notes Due 2037 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 971		980
Debt Instrument, Face Amount	$ 800
Long-term debt stated interest rate	6.00%
Additional percentage on 'make-whole' premium	0.20%
Senior Notes | Chubb INA Senior Notes Due 2038 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 768		776
Debt Instrument, Face Amount	$ 600
Long-term debt stated interest rate	6.50%
Additional percentage on 'make-whole' premium	0.30%
Senior Notes | INA Senior Notes Due March 2043 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 469		469
Debt Instrument, Face Amount	$ 475
Long-term debt stated interest rate	4.15%
Additional percentage on 'make-whole' premium	0.15%
Senior Notes | INA Senior Notes Due November 2045 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,482		1,482
Debt Instrument, Face Amount	$ 1,500
Long-term debt stated interest rate	4.35%
Additional percentage on 'make-whole' premium	0.25%
Senior Notes | Other
Debt Instrument [Line Items]
Long-term debt	$ 10		11
Senior secured debentures | Chubb INA Senior Notes Due August 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	0		107
Debt Instrument, Face Amount	$ 100
Long-term debt stated interest rate	6.60%
Senior secured debentures | INA Senior Notes Due August 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 100		100
Debt Instrument, Face Amount	$ 100
Long-term debt stated interest rate	8.875%
Unsecured Debt [Member] | Chubb INA Senior Notes Due 2031 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 254		257
Debt Instrument, Face Amount	$ 200
Long-term debt stated interest rate	6.80%
Additional percentage on 'make-whole' premium	0.25%
Trust Preferred Securities | INA capital securities due 2030
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 309			$ 300
Trust preferred securities	$ 308		308
Long-term debt stated interest rate	9.70%			9.70%
Repurchase agreements
Debt Instrument [Line Items]
Short-term debt	$ 1,408		$ 1,403
Weighted average interest rate on short-term debt	1.50%		0.80%
Minimum | Junior Subordinated Debt [Member] | Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Additional percentage on 'make-whole' premium	0.25%
Minimum | Senior Notes | Other
Debt Instrument [Line Items]
Long-term debt stated interest rate	2.75%
Maximum | Junior Subordinated Debt [Member] | Chubb INA Capital Securities Due 2067 [Member]
Debt Instrument [Line Items]
Additional percentage on 'make-whole' premium	0.50%
Maximum | Senior Notes | Other
Debt Instrument [Line Items]
Long-term debt stated interest rate	7.10%

Commitments, contingencies, 104

Commitments, contingencies, and guarantees (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Derivative Liability, Fair Value, Amount Subject to a Master Netting Agreement	$ 24	$ 10
Securities lending collateral	1,737	1,092
Collateral held under securities lending agreements	1,737	1,093
Purchase Commitment, Remaining Minimum Amount Committed	1,020
Carrying value of limited partnerships and partially-owned investment companies included in other investments	3,400
Funding commitments relating to limited partnerships and partially-owned investment companies	4,100
Line of Credit Facility, Current Borrowing Capacity	1,000			$ 1,500
Line of Credit Facility, Maximum Borrowing Capacity	2,000
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases	1,000
Total rental expense related to operating leases	211	209	$ 126
Securities Sold under Agreements to Repurchase	$ 1,408	$ 1,403
Concentration Risk, Percentage	10.00%
Letter of Credit [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Line of Credit Facility, Amount Outstanding	$ 250

Commitments, contingencies, 105

Commitments, contingencies, and guarantees (Balance Sheet Locations, Fair Values In Asset Or (Liability) Position, And Notional Values/Payment Provisions Of Derivative Instruments) (Detail) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		$ 3,122	$ 4,666
Convertible Securities [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	[1]	6	7
Foreign currency forward contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		2,064	2,220
Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		45	95
Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		1,007	2,344
Futures contracts on equities
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	[2]	1,553	1,316
Other
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		75	214
Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		1,628	1,530
Guaranteed Minimum Income Benefit
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	[3]	1,083	1,264
Accounts Payable and Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability		(30)	(54)
Accounts Payable and Accrued Liabilities [Member] | Convertible Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability	[1]	0	0
Accounts Payable and Accrued Liabilities [Member] | Foreign currency forward contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability		(27)	(50)
Accounts Payable and Accrued Liabilities [Member] | Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability		0	0
Accounts Payable and Accrued Liabilities [Member] | Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability		(3)	(4)
Accounts Payable and Accrued Liabilities [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Derivative Liability	[2]	(21)	0
Accounts Payable and Accrued Liabilities [Member] | Other
Derivatives, Fair Value [Line Items]
Derivative Liability		(2)	(13)
Accounts Payable and Accrued Liabilities [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability		(23)	(13)
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		23	33
Other Assets [Member] | Foreign currency forward contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		14	25
Other Assets [Member] | Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		0	0
Other Assets [Member] | Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		4	6
Other Assets [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Derivative Asset	[2]	0	1
Other Assets [Member] | Other
Derivatives, Fair Value [Line Items]
Derivative Asset		1	2
Other Assets [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		1	3
Other Assets [Member] | Guaranteed Minimum Income Benefit
Derivatives, Fair Value [Line Items]
Derivative Asset	[3]	0	0
Accounts Payable Future Policy Benefits [Member] | Guaranteed Minimum Income Benefit
Derivatives, Fair Value [Line Items]
Derivative Liability	[3]	(550)	(853)
Available-for-sale Securities [Member] | Convertible Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	[1]	$ 5	$ 2
[1]	(1)Includes fair value of embedded derivatives.
[2]	(2) Related to GMDB and GLB blocks of business.
[3]	(3) Includes both future policy benefits reserves and fair value derivative adjustment. Refer to Note 5 c) for additional information. Note that the payment provision related to GLB is the net amount at risk. The concept of a notional value does not apply to the GLB reinsurance contracts.

Commitments, contingencies, 106

Commitments, contingencies, and guarantees Commitments, Contingencies, And Guarantees (Transactions accounted for as secured borrowings) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	$ 1,737	$ 1,092
Collateral held under securities lending agreements	1,737	1,093
Repurchase Agreements [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	26	58
Maturity Overnight [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	0	(1)
Maturity Overnight [Member] | Cash and Cash Equivalents [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	828	423
Maturity Overnight [Member] | U.S. Treasury and agency
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	36	54
Maturity Overnight [Member] | Foreign Government Debt [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	712	578
Maturity Overnight [Member] | Corporate securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	0	37
Maturity Overnight [Member] | Mortgage backed-securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	74	0
Maturity Overnight [Member] | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	$ 87	$ 0

Commitments, contingencies, 107

Commitments, contingencies, and guarantees Commitments, contingencies, and guarantees (Collateral pledged under repurchase agreements) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	$ 1,434	$ 1,461
Securities Sold under Agreements to Repurchase	1,408	1,403
Cash and Cash Equivalents [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	0	1
US Treasury and Government [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	239	240
Mortgage backed-securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	1,195	1,220
Repurchase Agreements [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	26	58
Maturity Greater than 90 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	1,056	892
Maturity Greater than 90 Days [Member] | Cash and Cash Equivalents [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	0	1
Maturity Greater than 90 Days [Member] | US Treasury and Government [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	230	10
Maturity Greater than 90 Days [Member] | Mortgage backed-securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	826	881
Maturity Less than 30 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	378	569
Maturity Less than 30 Days [Member] | Cash and Cash Equivalents [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	0	0
Maturity Less than 30 Days [Member] | US Treasury and Government [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	9	230
Maturity Less than 30 Days [Member] | Mortgage backed-securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements	$ 369	$ 339

Commitments, contingencies, 108

Commitments, contingencies, and guarantees (Net Realized Gains (Losses) Of Derivative Instrument Activity In Consolidated Statement Of Operations) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		$ 87	$ (126)	$ (193)
Foreign currency forward contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		9	(31)	31
All Other Futures Contracts And Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		(21)	(10)	9
Convertible Securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	[1]	1	8	(8)
Investment And Embedded Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		(11)	(33)	32
GLB
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	[2]	364	53	(203)
Single-Stock Future [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	[3]	(261)	(136)	(8)
Other Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		(5)	(10)	(14)
Guaranteed Living Benefit And Other Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		$ 98	$ (93)	$ (225)
[1]	1) Includes embedded derivatives.
[2]	(2) Excludes foreign exchange gains (losses) related to GLB.
[3]	(3) Related to GMDB and GLB blocks of business.

Commitments, contingencies, 109

Commitments, contingencies, and guarantees (Future Minimum Lease Payments) (Details) $ in Millions	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 181
2,019	153
2,020	133
2,021	114
2,022	89
Thereafter	230
Total minimum future lease commitments	$ 900

Shareholders' equity (Detail)

Shareholders' equity (Detail) $ / shares in Units, $ in Millions

12 Months Ended

Apr. 30, 2018$ / shares

Dec. 31, 2017USD ($)shares

Apr. 30, 2017$ / shares

Dec. 31, 2016USD ($)shares

Apr. 30, 2016$ / shares

Dec. 31, 2015USD ($)shares

Dec. 31, 2017SFr / shares

May 31, 2017$ / shares

Dec. 31, 2016SFr / shares

Nov. 30, 2016USD ($)

May 31, 2016$ / shares

May 31, 2015$ / shares

Nov. 30, 2014USD ($)

Stockholders' Equity Note [Abstract]

Dividend installments | $ / shares

$ 0.71

$ 0.69

$ 0.67

The number of votes associated with one Common Share

1

The maximum ownership percentage for voting allowed for any one shareholder

10.00%

Annual dividend per share approved by shareholders | $ / shares

$ 2.84

$ 2.76

$ 2.68

Authorized Share Capital [Line Items]

Stock repurchase program authorized amount | $

$ 1,000

$ 1,000

$ 1,500

Common Shares, par value | SFr / shares

SFr 24.15

SFr 24.15

General Purpose

Authorized Share Capital [Line Items]

Authorized share capital for future issuance

200,000,000

Issuance of Debt

Authorized Share Capital [Line Items]

Authorized share capital for future issuance

33,000,000

Employee Benefit Plans

Authorized Share Capital [Line Items]

Authorized share capital for future issuance

25,410,929

Nov 2016 Stock Repurchase Plan [Member]

Authorized Share Capital [Line Items]

Treasury Stock, Shares, Acquired

5,866,612

0

6,677,663

Treasury Stock, Value, Acquired, Cost Method | $

$ 830

$ 0

$ 734

Shareholders' equity Schedule o

Shareholders' equity Schedule of Dividends Declared (Details)	12 Months Ended
	Dec. 31, 2017$ / shares	Dec. 31, 2017SFr / shares	Dec. 31, 2016$ / shares	Dec. 31, 2016SFr / shares	Dec. 31, 2015$ / shares	Dec. 31, 2015SFr / shares
Switzerland, Francs
Dividends Declared [Line Items]
Dividends - par value reduction | SFr / shares		SFr 0		SFr 0		SFr 0.62
Dividends - distributed from capital contribution reserves | SFr / shares		2.76		2.70		1.94
Total dividend distributions per common share | SFr / shares		SFr 2.76		SFr 2.70		SFr 2.56
United States of America, Dollars
Dividends Declared [Line Items]
Dividends - par value reduction | $ / shares	$ 0		$ 0		$ 0.65
Dividends - distributed from capital contribution reserves | $ / shares	2.82		2.74		2.01
Total dividend distributions per common share | $ / shares	$ 2.82		$ 2.74		$ 2.66

Shareholders' equity (Rollforwa

Shareholders' equity (Rollforward Of Changes In Common Stock Shares Issued And Outstanding) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Shares issued, Beginning of year	479,783,864	479,783,864	342,832,412	342,832,412
Stock Issued During Period, Shares, New Issues	0	136,951,452	0
Common Shares in treasury, end of year	(15,950,685)	(13,815,148)	(18,268,971)
Shares issued and outstanding, end of year	463,833,179	465,968,716	324,563,441

Shareholders' equity Repurchase

Shareholders' equity Repurchase of Common Shares (Details) - Nov 2016 Stock Repurchase Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased	5,866,612	0	6,677,663
Common Shares repurchased	$ 830	$ 0	$ 734

Share-based compensation (Narra

Share-based compensation (Narrative) (Detail) - USD ($)		Jan. 14, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2017	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 48,000,000
Unrecognized compensation expense related to the unvested share-based awards			$ 345,000,000
Weighted-average expected recognition period for the unrecognized compensation expense			1 year
Weighted average remaining contractual term for stock options outstanding			6 years 2 months 15 days
Weighted-average remaining contractual term for stock options exercisable			4 years 10 months
Cash received from exercise of stock options			$ 133,000,000
Restricted stock awards granted to non-management directors			22,013	23,812	24,945
Amounts paid during period by employees for the purchase of shares under the ESPP			$ 34,000,000	$ 24,000,000	$ 18,000,000
Number of shares purchased during period by employees pursuant to the provisions of the ESPP			271,185	211,492	197,442
Discounted purchase price from market price for the ESPP			85.00%
Annual estimate of forfeitures for equity awards			6.50%	6.50%	6.50%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate for the ESPP			10.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan Authorized Amount			$ 25,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of award			3 years
Stock option term in years			10 years
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of unvested restricted stock outstanding			4,709,422	5,805,126	3,489,169		3,837,097
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of deferred restricted stock units			279,986
ACE Limited 2004 Long-Term Incentive Plan [Member] | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of award			4 years
Common shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares remaining as available for issuance under the 2016 LTIP			2,452,058
Employee Stock Ownership Plan (ESOP), Shares in ESOP			6,500,000			2,000,000
Common shares | Chubb Limited 2016 Long-Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares authorized for issuance under plan			19,500,000
Common shares remaining as available for issuance under the 2016 LTIP			17,065,705
The Chubb Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Value of Equity Awards Issued in Acquisition		$ 525,000,000
Attributed Value Equity Awards Assumed in Acquisition	[1]	$ 323,000,000
[1]	(1) The fair value of the replacement equity awards was $525 million, of which $323 million was attributed to service periods prior to the acquisition and was included in the purchase consideration. Refer to Note 12 for further information on these replacement equity awards.

Share-based compensation (Pre-t

Share-based compensation (Pre-tax and After-tax Share-based Compensation Expense) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, pre-tax		$ 259	$ 268	$ 143
Share-based compensation expense, after-tax		151	167	84
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, pre-tax		41	33	31
Share-based compensation expense, after-tax	[1]	$ 26	20	21
Additional Paid-in Capital
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Tax benefit on share-based compensation expense			$ 32	$ 26
[1]	(1) Excludes windfall tax benefit for share-based compensation recognized as a direct adjustment to Additional paid-in capital of $32 million and $26 million for the years ended December 31, 2016 and 2015, respectively.

Share-based compensation (Weigh

Share-based compensation (Weighted Average Assumptions for Option Grants) (Details) - Options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	2.00%	2.30%	2.30%
Expected volatility	19.70%	23.20%	21.00%
Risk-free interest rate	2.00%	1.30%	1.70%
Expected life	5 years 8 months 32 days	5 years 6 months 27 days	5 years 9 months 18 days

Share-based compensation (Rollf

Share-based compensation (Rollforward Of Company's Stock Options) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Options, Weighted-Average Fair Value and Total Intrinsic Value [Abstract]
Weighted-average fair value of stock options granted (US$ per share)	$ 22.97	$ 21.52	$ 18.49
Total intrinsic value of options exercised	$ 111	$ 99	$ 72
Total intrinsic value of options outstanding	490
Total intrinsic value of options exercisable, December 31, 2015	$ 424
Number of Options [Roll Forward]
Number of option outstanding, beginning of period	10,180,720	9,853,496	9,623,986
Number of options granted	2,079,522	1,929,616	1,892,641
Number of options exercised	(1,632,629)	(1,728,949)	(1,457,580)
Number of options forfeited	(194,297)	(213,339)	(205,551)
Number of option outstanding, end of period	10,433,316	10,180,720	9,853,496
Number of options exercisable, December 31, 2015	6,675,491
Weighted-Average Exercise Price [Roll Forward]
Weighted-average exercise price of options outstanding, beginning of period (US$ oer share)	$ 87.29	$ 78.40	$ 69.06
Weighted-average exercise price of options granted (US$ per share)	139	118.39	114.78
Weighted-average exercise price of options exercised (US$ per share)	73.53	66.65	60.88
Weighted average exercise price of options forfeited (US$ per share)	119.44	110.01	100.25
Weighted-average exercise price of options outstanding, end of period (US$ oer share	99.20	87.29	$ 78.40
Weighted average exercise price of options exercisable, December 31, 2015 (US$ per share)	$ 82.59
The Chubb Corporation [Member]
Options, Weighted-Average Fair Value and Total Intrinsic Value [Abstract]
Weighted-average fair value of stock options granted (US$ per share)		$ 36.07
Number of Options [Roll Forward]
Number of options granted		339,896
Weighted-Average Exercise Price [Roll Forward]
Weighted-average exercise price of options granted (US$ per share)		$ 77.83

Share-based compensation (Ro118

Share-based compensation (Rollforward Of Company's Restricted Stock) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted stock
Number of Restricted Stock [Roll Forward]
Number of unvested restricted stock, beginning of period	5,805,126	3,489,169	3,837,097
Number of restricted stock, granted	1,707,094	1,622,065	1,417,965
Number of restricted stock, vested and issued	(2,646,084)	(2,592,622)	(1,341,358)
Number of restricted stock, forfeited	(156,694)	(420,125)	(424,535)
Number of unvested restricted stock, end of period	4,709,422	5,805,126	3,489,169
Weighted-Average Grant-Day Fair Value [Roll Forward]
Weighted average grant-day fair value of unvested restricted stock outstanding, beginning of period (US$ per share)	$ 109.39	$ 97.01	$ 83.60
Weighted average grant-day fair value of restricted stock, granted (US$ per share)	139.18	118.70	114.37
Weighted average grant-day fair value of restricted stock, vested and issued (US$ per share)	107.73	100.87	80.05
Weighted average grant-day fair value of restricted stock, forfeited (US$ per share)	114.54	109.42	87.36
Weighted average grant-day fair value of unvested restricted stock outstanding, end of period (US$ per share)	$ 121.16	$ 109.39	$ 97.01
Performance Shares
Number of Restricted Stock [Roll Forward]
Number of unvested restricted stock, beginning of period	931,169	595,210	378,690
Number of restricted stock, granted	267,282	517,507	326,860
Number of restricted stock, vested and issued	(222,954)	(181,548)	(110,340)
Number of restricted stock, forfeited	0	0	0
Number of unvested restricted stock, end of period	975,497	931,169	595,210
Weighted-Average Grant-Day Fair Value [Roll Forward]
Weighted average grant-day fair value of unvested restricted stock outstanding, beginning of period (US$ per share)	$ 111.17	$ 101.73	$ 90.87
Weighted average grant-day fair value of restricted stock, granted (US$ per share)	138.90	118.96	113.29
Weighted average grant-day fair value of restricted stock, vested and issued (US$ per share)	113.30	102.43	98.70
Weighted average grant-day fair value of restricted stock, forfeited (US$ per share)	0	0	0
Weighted average grant-day fair value of unvested restricted stock outstanding, end of period (US$ per share)	$ 118.28	$ 111.17	$ 101.73
The Chubb Corporation [Member] | Restricted stock
Number of Restricted Stock [Roll Forward]
Number of restricted stock, granted		3,706,639
Weighted-Average Grant-Day Fair Value [Roll Forward]
Weighted average grant-day fair value of restricted stock, granted (US$ per share)		$ 111.02
The Chubb Corporation [Member] | Performance Shares
Number of Restricted Stock [Roll Forward]
Number of restricted stock, granted		0
Weighted-Average Grant-Day Fair Value [Roll Forward]
Weighted average grant-day fair value of restricted stock, granted (US$ per share)		$ 0

Postretirement benefits (Narrat

Postretirement benefits (Narrative) (Details) - USD ($) $ in Millions	Oct. 31, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Expenses recognized during period under the defined contributions plans			$ 166	$ 150	$ 117
Available for sale, Fair Value		$ 80,115	78,939	80,115
Defined benefit plan, benefits paid inclusive of settlements			200	213
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation			8
Effect of One Percentage Point Increase on Service and Interest Cost Components			1
Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation			7
Effect of One Percentage Point Decrease on Service and Interest Cost Components			$ 1
Minimum
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Defined Benefit Plan, Target Allocation Percentage			0.55
Maximum
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Defined Benefit Plan, Target Allocation Percentage			0.65
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation		3,800	$ 4,300	3,800
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year			28
Defined Benefit Plan, Plan Amendment [Abstract]
Defined Benefit Plan, Accumulated Benefit Obligation		3,800	4,300	3,800
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		159	157	159	0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year			2
Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		962	1,172	962	564
Future Amortization of (Gain) Loss			1
UNITED STATES
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation		496
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		2,765	3,109	2,765	$ 9
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation		113
UNITED STATES | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Future Amortization of Prior Service (Cost) Credit			80
UNITED STATES | Postretirement Health Coverage [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation	$ 383
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Remaining Balance of Change in Benefit Obligation For Plan Amendment			267
UNITED STATES | Postretirement Health Coverage [Member] | Subject to Amortization [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation	$ 410	15	89
UNITED STATES | Postretirement Health Coverage [Member] | Subject to Amortization [Member] | The Chubb Corporation [Member]
Defined Benefit Plan, Plan Amendment [Abstract]
Effect of Plan Amendment on Accumulated Benefit Obligation			39
Foreign Government Debt Securities [Member] | Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value		435	456	435
Foreign Government Debt Securities [Member] | UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value		487	692	487
Level 3 | Foreign Government Debt Securities [Member] | Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value		0	0	0
Level 3 | Foreign Government Debt Securities [Member] | UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value		$ 5	$ 0	$ 5

Postretirement benefits Schedul

Postretirement benefits Schedule of Net Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	$ 3,035	$ 10
Acquisition of Chubb Corp, Benefit obligation	0	3,153
Service Cost	63	75	$ 0
Interest Cost	105	103	0
Actuarial Loss	232	131
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(132)	(79)
Amendments	0	0
Curtailments	0	(259)
Settlements, Benefit obligations	(18)	(99)
Foreign currency revaluation, benefit obligations	0	0
Benefit Obligation, end of year	3,285	3,035	10
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	2,765	9
Acquisition of Chubb Corp, Plan Assets	0	2,473
Actual Return on Plan Assets	441	359
Employer Contributions	53	98
Benefits Paid	(132)	(79)
Settlements, Plan Assets	(18)	(95)
Foreign currency revaluation, Plan Assets	0	0
Plan assets at fair value, end of year	3,109	2,765	9
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(176)	(270)
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	1,025	559
Acquisition of Chubb Corp, Benefit obligation	0	372
Service Cost	17	18	6
Interest Cost	27	30	21
Actuarial Loss	(4)	204
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(28)	(22)
Amendments	0	(9)
Curtailments	(32)	(7)
Settlements, Benefit obligations	(8)	(7)
Foreign currency revaluation, benefit obligations	80	(113)
Benefit Obligation, end of year	1,077	1,025	559
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	962	564
Acquisition of Chubb Corp, Plan Assets	0	315
Actual Return on Plan Assets	100	168
Employer Contributions	63	67
Benefits Paid	(28)	(22)
Settlements, Plan Assets	(8)	(7)
Foreign currency revaluation, Plan Assets	83	(123)
Plan assets at fair value, end of year	1,172	962	564
Defined Benefit Plan, Funded (Unfunded) Status of Plan	95	(63)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	165	16
Acquisition of Chubb Corp, Benefit obligation	0	506
Service Cost	2	10	1
Interest Cost	4	17	0
Actuarial Loss	(2)	36
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(14)	(11)
Amendments	(23)	(410)
Curtailments	2	0
Settlements, Benefit obligations	0	0
Foreign currency revaluation, benefit obligations	3	1
Benefit Obligation, end of year	137	165	16
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	159	0
Acquisition of Chubb Corp, Plan Assets	0	138
Actual Return on Plan Assets	6	29
Employer Contributions	6	3
Benefits Paid	(14)	(11)
Settlements, Plan Assets	0	0
Foreign currency revaluation, Plan Assets	0	0
Plan assets at fair value, end of year	157	159	$ 0
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ 20	$ (6)

Postretirement benefits Sche121

Postretirement benefits Schedule of amounts recognized in AOCI on a pretax basis (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member] | UNITED STATES
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	$ (227)	$ (207)
Prior Service Cost	0	0
Total	(227)	(207)
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	82	156
Prior Service Cost	6	(2)
Total	88	154
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	12	17
Prior Service Cost	(288)	(395)
Total	$ (276)	$ (378)

Postretirement benefits Sche122

Postretirement benefits Schedule of assumptions used to determine benefit obligation (Details)	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	3.59%	4.14%
Benefit Obligation, Rate of Compensation Increase	4.00%	4.00%
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	2.76%	2.83%
Benefit Obligation, Rate of Compensation Increase	3.46%	3.57%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit Obligation, Discount Rate	2.77%	2.97%

Postretirement benefits Sche123

Postretirement benefits Schedule of net periodic benefit costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax [Abstract]
(Increase) decrease in other comprehensive income, curtailment			$ 0
(Increase) decrease in other comprehensive income, settlement			0
Total (increase) decrease in other comprehensive (Income) Loss	$ 16	$ (545)	(15)
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax [Abstract]
Service Cost	63	75	0
Interest Cost	105	103	0
Expected Return on Plan Assets	(189)	(165)	0
Amortization of (Gains) Losses	0	0	0
Amortization of Prior Service Cost (Credit)	0	0	0
Recognized Net (Gain) Loss Due to Curtailments	0	(117)	0
Recognized Net (Gain) Loss Due to Settlements	0	(2)	0
Net Periodic Benefit Cost	(21)	(106)	0
(Increase) decrease in Other Comprehensive Income (Loss), Net Actuarial (Gain) Loss)	(21)	(326)	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	0	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0	0	0
(Increase) decrease in other comprehensive income, curtailment	0	117
(Increase) decrease in other comprehensive income, settlement	1	2
Total (increase) decrease in other comprehensive (Income) Loss	(20)	(207)	0
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax [Abstract]
Service Cost	17	18	6
Interest Cost	27	30	21
Expected Return on Plan Assets	(42)	(39)	(29)
Amortization of (Gains) Losses	3	2	2
Amortization of Prior Service Cost (Credit)	0	(1)	0
Recognized Net (Gain) Loss Due to Curtailments	(27)	0	0
Recognized Net (Gain) Loss Due to Settlements	0	1	1
Net Periodic Benefit Cost	(22)	11	1
(Increase) decrease in Other Comprehensive Income (Loss), Net Actuarial (Gain) Loss)	(57)	49	(16)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	0	(8)	1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(3)	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0	0	0
(Increase) decrease in other comprehensive income, curtailment	(6)	0
(Increase) decrease in other comprehensive income, settlement	0	(1)
Total (increase) decrease in other comprehensive (Income) Loss	(66)	40	(15)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax [Abstract]
Service Cost	2	10	1
Interest Cost	4	17	0
Expected Return on Plan Assets	(5)	(8)	0
Amortization of (Gains) Losses	0	(1)	(1)
Amortization of Prior Service Cost (Credit)	(89)	(15)	0
Recognized Net (Gain) Loss Due to Curtailments	(37)	0	0
Recognized Net (Gain) Loss Due to Settlements	0	0	0
Net Periodic Benefit Cost	(125)	3	0
(Increase) decrease in Other Comprehensive Income (Loss), Net Actuarial (Gain) Loss)	(3)	17	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	(23)	(395)	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	0	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	89	0	0
(Increase) decrease in other comprehensive income, curtailment	39	0	0
(Increase) decrease in other comprehensive income, settlement	0	0	0
Total (increase) decrease in other comprehensive (Income) Loss	$ 102	$ (378)	$ 0

Postretirement benefits Sche124

Postretirement benefits Schedule of Assumptions Used to determine net periodic benefit costs(Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Rate of Compensation Increase	4.00%	4.00%
Expected Long-term Return on Assets	7.00%	7.00%
Pension Plan [Member] | UNITED STATES | Service Cost [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	4.20%	4.38%
Pension Plan [Member] | UNITED STATES | Interest Cost [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	3.53%	3.59%
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate			3.51%
Rate of Compensation Increase	3.57%	3.33%	3.09%
Expected Long-term Return on Assets	4.23%	4.79%	4.81%
Pension Plan [Member] | Non-US [Member] | Service Cost [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	3.55%	3.85%
Pension Plan [Member] | Non-US [Member] | Interest Cost [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	2.61%	3.44%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Expected Long-term Return on Assets	3.00%	6.34%
Other Postretirement Benefits Plan [Member] | Service Cost [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	2.84%	4.32%
Other Postretirement Benefits Plan [Member] | Interest Cost [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	2.44%	4.02%

Postretirement benefits Sche125

Postretirement benefits Schedule of Health Care Cost Trend Rates (Details) - Other Postretirement Benefits Plan [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
UNITED STATES
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rate	7.01%	7.28%	6.50%
Ultimate Health Care Cost Trend Rate	4.50%	4.50%	4.50%
Year that Rate Reaches Ultimate Trend Rate	2,038	2,038	2,026
Non-US [Member]
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rate	6.61%	6.61%
Ultimate Health Care Cost Trend Rate	4.50%	4.50%
Year that Rate Reaches Ultimate Trend Rate	2,029	2,029

Postretirement benefits Sche126

Postretirement benefits Schedule of Allocation of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	$ 3,561	$ 3,002
Available for sale, Fair Value	78,939	80,115
Equity securities	937	814
Other investments	4,672	4,519
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Other investments	15	25
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	61	43
Equity securities	1,154	728
Derivative Instruments Fair Value		3
Defined benefit plan, fair value of plan assets excluding measured using NAV	2,432	1,579
Pension Plan [Member] | UNITED STATES | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Other investments	677	1,200
Pension Plan [Member] | UNITED STATES | Level 1
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	9	0
Equity securities	1,154	728
Derivative Instruments Fair Value		3
Defined benefit plan, fair value of plan assets excluding measured using NAV	1,609	937
Pension Plan [Member] | UNITED STATES | Level 2
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	52	43
Equity securities	0	0
Derivative Instruments Fair Value		0
Defined benefit plan, fair value of plan assets excluding measured using NAV	823	637
Pension Plan [Member] | UNITED STATES | Level 3
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	0	0
Equity securities	0	0
Derivative Instruments Fair Value		0
Defined benefit plan, fair value of plan assets excluding measured using NAV	0	5
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	5	2
Equity securities	614	512
Defined benefit plan, fair value of plan assets excluding measured using NAV	1,075	949
Pension Plan [Member] | Non-US [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Other investments	95	13
Pension Plan [Member] | Non-US [Member] | Level 1
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	5	2
Equity securities	122	100
Defined benefit plan, fair value of plan assets excluding measured using NAV	127	102
Pension Plan [Member] | Non-US [Member] | Level 2
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	0	0
Equity securities	492	412
Defined benefit plan, fair value of plan assets excluding measured using NAV	948	847
Pension Plan [Member] | Non-US [Member] | Level 3
Defined Benefit Plan Disclosure [Line Items]
Short-term investments	0	0
Equity securities	0	0
Defined benefit plan, fair value of plan assets excluding measured using NAV		0
Pension Plan [Member] | US Treasury and Government [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	525	318
Pension Plan [Member] | US Treasury and Government [Member] | UNITED STATES | Level 1
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	446	206
Pension Plan [Member] | US Treasury and Government [Member] | UNITED STATES | Level 2
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	79	112
Pension Plan [Member] | US Treasury and Government [Member] | UNITED STATES | Level 3
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	0	0
Pension Plan [Member] | Foreign Government Debt Securities [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	692	487
Pension Plan [Member] | Foreign Government Debt Securities [Member] | UNITED STATES | Level 1
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	0	0
Pension Plan [Member] | Foreign Government Debt Securities [Member] | UNITED STATES | Level 2
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	692	482
Pension Plan [Member] | Foreign Government Debt Securities [Member] | UNITED STATES | Level 3
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	0	5
Pension Plan [Member] | Foreign Government Debt Securities [Member] | Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	456	435
Pension Plan [Member] | Foreign Government Debt Securities [Member] | Non-US [Member] | Level 1
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	0	0
Pension Plan [Member] | Foreign Government Debt Securities [Member] | Non-US [Member] | Level 2
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	456	435
Pension Plan [Member] | Foreign Government Debt Securities [Member] | Non-US [Member] | Level 3
Defined Benefit Plan Disclosure [Line Items]
Available for sale, Fair Value	$ 0	$ 0

Postretirement benefits (Schedu

Postretirement benefits (Schedule of Expected Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2017USD ($)
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
2,018	$ 129
2,019	141
2,020	148
2,021	155
2,022	163
2023-2027	881
Pension Plan [Member] | Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	23
2,019	25
2,020	29
2,021	28
2,022	27
2023-2027	159
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	17
2,019	19
2,020	20
2,021	23
2,022	25
2023-2027	$ 44

Other (income) expense (Details

Other (income) expense (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Income and Expenses [Abstract]
Equity in net (income) loss of partially-owned entities		$ (418)	$ (264)	$ (113)
(Gains) losses from fair value changes in separate account assets	[1]	(97)	(11)	19
One-time contribution to the Chubb Charitable Foundation		50	0	0
Federal excise and capital taxes		35	19	19
Other		30	34	24
Other (income) expense		$ (400)	$ (222)	$ (51)
[1]	(1) Related to (gains) losses from fair value changes in separate account assets that do not qualify for separate account reporting under GAAP.

Segment Information (Operations

Segment Information (Operations By Segment) (Detail) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Derivative, Gain (Loss) on Derivative, Net										$ 87	$ (126)	$ (193)
Net premiums written										29,244	28,145	17,713
Net premiums earned		$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	29,034	28,749	17,213
Losses and loss expenses		4,272	6,247	4,146	3,789	3,855	4,269	4,254	3,674	18,454	16,052	9,484
Policy benefits		176	169	163	168	161	155	146	126	676	588	543
Policy Acquisition Costs										5,781	5,904	2,941
Administrative expenses										2,833	3,081	2,270
Underwriting income (loss)										1,290	3,124	1,975
Net Investment Income		797	813	770	745	744	739	708	674	3,125	2,865	2,194
Other (Income) Expense										(400)	(222)	(51)
Segment Underwriting Income Loss and Net Investment Income Loss										4,555	6,192	4,049
Net realized gains (losses) including OTTI		0	(10)	101	(7)	365	100	(216)	(394)	84	(145)	(420)
Interest expense										607	605	300
Other (income) expense										(400)	(222)	(51)
Amortization of Purchased Intangibles										260	19	171
Chubb integration expenses										310	492	33
(Gains) losses from fair value changes in separate account assets	[1]									97	11	(19)
Income tax expense (benefit)										(139)	815	462
Net income		$ 1,533	$ (70)	$ 1,305	$ 1,093	$ 1,610	$ 1,360	$ 726	$ 439	3,861	4,135	2,834
North America Commercial P&C Insurance
Segment Reporting Information [Line Items]
Net premiums written										12,028	11,740	5,715
Net premiums earned										12,191	12,217	5,634
Losses and loss expenses										8,287	7,439	3,661
Policy benefits										0	0	0
Policy Acquisition Costs										1,873	2,023	531
Administrative expenses										981	1,125	621
Underwriting income (loss)										1,050	1,630	821
Net Investment Income										1,961	1,860	1,032
Other (Income) Expense										1	(2)	(7)
Segment Underwriting Income Loss and Net Investment Income Loss										3,010	3,492	1,860
Amortization of Purchased Intangibles										0	0	0
North American Personal P&C [Member]
Segment Reporting Information [Line Items]
Net premiums written										4,533	4,153	1,192
Net premiums earned										4,399	4,319	948
Losses and loss expenses										3,265	2,558	590
Policy benefits										0	0	0
Policy Acquisition Costs										899	966	69
Administrative expenses										264	363	123
Underwriting income (loss)										(29)	432	166
Net Investment Income										226	207	25
Other (Income) Expense										4	6	2
Segment Underwriting Income Loss and Net Investment Income Loss										177	614	111
Amortization of Purchased Intangibles										16	19	78
North America Agricultural Insurance
Segment Reporting Information [Line Items]
Segment Income Loss Including Gains Losses On Crop Derivatives										392
Derivative, Gain (Loss) on Derivative, Net										7
Net premiums written										1,516	1,328	1,346
Net premiums earned										1,508	1,316	1,364
Losses and loss expenses										1,036	893	1,088
Policy benefits										0	0	0
Policy Acquisition Costs										81	83	69
Administrative expenses										(8)	(6)	1
Underwriting income (loss)										399	346	206
Net Investment Income										25	20	23
Other (Income) Expense										2	1	1
Segment Underwriting Income Loss and Net Investment Income Loss										393	336	198
Amortization of Purchased Intangibles										29	29	30
Overseas General Insurance
Segment Reporting Information [Line Items]
Net premiums written										8,341	8,124	6,634
Net premiums earned										8,131	8,132	6,471
Losses and loss expenses										4,281	4,005	3,052
Policy benefits										0	0	0
Policy Acquisition Costs										2,221	2,136	1,581
Administrative expenses										982	1,057	997
Underwriting income (loss)										647	934	841
Net Investment Income										610	600	534
Other (Income) Expense										(4)	(11)	(17)
Segment Underwriting Income Loss and Net Investment Income Loss										1,216	1,497	1,331
Amortization of Purchased Intangibles										45	48	61
Global Reinsurance
Segment Reporting Information [Line Items]
Net premiums written										685	676	828
Net premiums earned										704	710	849
Losses and loss expenses										561	325	290
Policy benefits										0	0	0
Policy Acquisition Costs										177	187	214
Administrative expenses										44	52	49
Underwriting income (loss)										(78)	146	296
Net Investment Income										273	263	300
Other (Income) Expense										(1)	(4)	(6)
Segment Underwriting Income Loss and Net Investment Income Loss										196	413	602
Amortization of Purchased Intangibles										0	0	0
Life Insurance
Segment Reporting Information [Line Items]
Management underwriting income loss Insurance										263
Net premiums written										2,141	2,124	1,998
Net premiums earned										2,101	2,055	1,947
Losses and loss expenses										739	663	601
Policy benefits										676	588	543
Policy Acquisition Costs										530	509	476
Administrative expenses										303	307	291
Underwriting income (loss)										(147)	(12)	36
Net Investment Income										313	283	265
Other (Income) Expense										(84)	5	23
Segment Underwriting Income Loss and Net Investment Income Loss										248	263	276
Amortization of Purchased Intangibles										2	3	2
(Gains) losses from fair value changes in separate account assets										97
Corporate and Other
Segment Reporting Information [Line Items]
Net premiums written										0	0	0
Net premiums earned										0	0	0
Losses and loss expenses										285	169	202
Policy benefits										0	0	0
Policy Acquisition Costs										0	0	1
Administrative expenses										267	183	188
Underwriting income (loss)										(552)	(352)	(391)
Net Investment Income										(283)	(368)	15
Other (Income) Expense										(318)	(217)	(47)
Segment Underwriting Income Loss and Net Investment Income Loss										(685)	(423)	(329)
Net realized gains (losses) including OTTI										84	(145)	(420)
Interest expense										607	605	300
Amortization of Purchased Intangibles										168	(80)	0
Chubb integration expenses										310	492	33
Income tax expense (benefit)										(139)	815	462
Net income										$ (1,379)	$ (2,480)	$ (1,544)
[1]	(1) Related to (gains) losses from fair value changes in separate account assets that do not qualify for separate account reporting under GAAP.

Segment Information (Net Premiu

Segment Information (Net Premiums Earned For Segment By Product) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net premiums earned	$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	$ 29,034	$ 28,749	$ 17,213
North America Commercial P&C Insurance
Segment Reporting Information [Line Items]
Net premiums earned									12,191	12,217	5,634
North America Commercial P&C Insurance | Property and other short-tail [Member]
Segment Reporting Information [Line Items]
Net premiums earned									1,899	1,963	1,040
North America Commercial P&C Insurance | Casualty and all other [Member]
Segment Reporting Information [Line Items]
Net premiums earned									9,554	9,552	4,175
North America Commercial P&C Insurance | Accident and Health [Member]
Segment Reporting Information [Line Items]
Net premiums earned									738	702	419
North American Personal P&C [Member]
Segment Reporting Information [Line Items]
Net premiums earned									4,399	4,319	948
North American Personal P&C [Member] | Automobiles [Member]
Segment Reporting Information [Line Items]
Net premiums earned									742	699	186
North American Personal P&C [Member] | Personal homeowner [Member]
Segment Reporting Information [Line Items]
Net premiums earned									3,014	3,007	579
North American Personal P&C [Member] | Other Insurance Product Line [Member]
Segment Reporting Information [Line Items]
Net premiums earned									643	613	183
North America Agricultural Insurance
Segment Reporting Information [Line Items]
Net premiums earned									1,508	1,316	1,364
Overseas General Insurance
Segment Reporting Information [Line Items]
Net premiums earned									8,131	8,132	6,471
Overseas General Insurance | Property and other short-tail [Member]
Segment Reporting Information [Line Items]
Net premiums earned									2,076	2,133	1,833
Overseas General Insurance | Casualty and all other [Member]
Segment Reporting Information [Line Items]
Net premiums earned									2,266	2,177	1,361
Overseas General Insurance | Accident and Health [Member]
Segment Reporting Information [Line Items]
Net premiums earned									2,180	2,196	2,066
Overseas General Insurance | Personal lines [Member]
Segment Reporting Information [Line Items]
Net premiums earned									1,609	1,626	1,211
Global Reinsurance
Segment Reporting Information [Line Items]
Net premiums earned									704	710	849
Global Reinsurance | Property and other short-tail [Member]
Segment Reporting Information [Line Items]
Net premiums earned									132	118	155
Global Reinsurance | Casualty and all other [Member]
Segment Reporting Information [Line Items]
Net premiums earned									374	407	475
Global Reinsurance | Property catastrophe [Member]
Segment Reporting Information [Line Items]
Net premiums earned									198	185	219
Life Insurance
Segment Reporting Information [Line Items]
Net premiums earned									2,101	2,055	1,947
Life Insurance | Accident and Health [Member]
Segment Reporting Information [Line Items]
Net premiums earned									1,121	1,053	1,016
Life Insurance | Life Insurance Product Line [Member]
Segment Reporting Information [Line Items]
Net premiums earned									$ 980	$ 1,002	$ 931

Segment Information (Net Pre131

Segment Information (Net Premiums Earned By Geographic Region) (Details)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net Premiums Earned by Geographic Region		North America Europe (1) Asia Pacific / Far East Latin America 2017 70 % 11 % 12 % 7 % 2016 70 % 12 % 11 % 7 % 2015 60 % 15 % 15 % 10 %
North America [Member]
Segment Reporting Information [Line Items]
Percentage of net premiums earned by geographic region		70.00%	70.00%	60.00%
Europe [Member]
Segment Reporting Information [Line Items]
Percentage of net premiums earned by geographic region	[1]	11.00%	12.00%	15.00%
Asia Pacific and Far East [Member]
Segment Reporting Information [Line Items]
Percentage of net premiums earned by geographic region		12.00%	11.00%	15.00%
Latin America [Member]
Segment Reporting Information [Line Items]
Percentage of net premiums earned by geographic region		7.00%	7.00%	10.00%
[1]	(1) Europe includes Eurasia and Africa region.

Earnings Per Share (Detail)

Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Stock Issued During Period, Shares, New Issues									0	136,951,452	0
Net income	$ 1,533	$ (70)	$ 1,305	$ 1,093	$ 1,610	$ 1,360	$ 726	$ 439	$ 3,861	$ 4,135	$ 2,834
Weighted-average shares outstanding									467,145,716	462,519,789	325,589,361
Share-based compensation plans									4,051,185	3,429,610	3,246,017
Adjusted weighted-average shares outstanding and assumed conversions									471,196,901	465,949,399	328,835,378
Basic earnings per share	$ 3.29	$ (0.15)	$ 2.79	$ 2.33	$ 3.44	$ 2.90	$ 1.55	$ 0.98	$ 8.26	$ 8.94	$ 8.71
Diluted earnings per share	$ 3.27	$ (0.15)	$ 2.77	$ 2.31	$ 3.41	$ 2.88	$ 1.54	$ 0.97	$ 8.19	$ 8.87	$ 8.62
Potential anti-dilutive share conversions									1,776,025	1,206,828	1,601,668

Related party transaction (Deta

Related party transaction (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Other investments	$ 4,672				$ 4,519				$ 4,672	$ 4,519
Net premiums written									29,244	28,145	$ 17,713
Losses and loss expenses	4,272	$ 6,247	$ 4,146	$ 3,789	3,855	$ 4,269	$ 4,254	$ 3,674	18,454	16,052	9,484
Insurance and reinsurance balances payable	5,868				5,637				5,868	5,637
Reinsurance recoverable on losses and loss expenses	15,034				13,577				15,034	13,577
Ceded Premiums Written									7,132	6,838	6,098
All Related Party [Member]
Related Party Transaction [Line Items]
Other investments	86								86
Starr Technical Risk Agency and Affiliates [Member]
Related Party Transaction [Line Items]
Paid commissions									101	145	60
Losses and loss expenses									438	313	137
Insurance and reinsurance balances payable	44				72				44	72
Reinsurance recoverable on losses and loss expenses	557				412				557	412
Gross premiums written									464	658	305
Ceded Premiums Written									175	208	78
Minimum Amount of Program Business to be Written to Earn Profit Sharing									20
Ceded Commissions									37	56	$ 19
ABR Reinsurance Capital Holdings Ltd. [Member]
Related Party Transaction [Line Items]
Insurance and reinsurance balances payable	51				53				51	53
Reinsurance recoverable on losses and loss expenses	$ 365				$ 148				365	148
Ceded Premiums Written									342	288
Fees and Commissions, Other									$ 94	$ 66
Equity Method Investment, Ownership Percentage					11.30%					11.30%

Statutory Financial Informat134

Statutory Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statutory Accounting Practices [Line Items]
Dividends available to be paid	$ 5,800
Approximate increase in statutory capital and surplus resulting from discount of certain A&E liabilities	169	$ 155
Minimum statutory capital and surplus required to satisfy regulatory requirements	23,900	22,200
Statutory Accounting Practices, Permitted Practice, Amount	156	308
PropertyAndCasualtySubsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	40,498	38,734
Statutory net income	8,123	6,903	$ 2,712
LifeSubsidiaries [Member] [Member]
Statutory Accounting Practices [Line Items]
Statutory capital and surplus	1,507	1,225
Statutory net income	$ 74	$ 55	$ (148)

Information provided in conn135

Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions		Dec. 31, 2017		Dec. 31, 2016		Jan. 14, 2016	Dec. 31, 2015		Dec. 31, 2014
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		$ 102,444		$ 99,094
Cash		728	[1],[2]	985	[1],[3],[4]		$ 1,775	[1],[5]	$ 655	[5]
Insurance and reinsurance balances receivable		9,334		8,970
Reinsurance recoverable on losses and loss expenses		15,034		13,577
Reinsurance Recoverable Future Policy Benefits	[6]	184		182
Value of business acquired		326		355			395		466
Goodwill		22,054		22,095
Other assets		16,918		14,528
Total assets		167,022		159,786
Unpaid losses and loss expenses		63,179		60,540			37,303		38,315
Unearned premiums		15,216		14,779
Future policy benefits		5,321		5,036
Affiliated notional cash pooling program		300		0	[4]
Repurchase agreements		1,408		1,403
Short-term debt		1,013		500
Long-term debt		11,556		12,610
Trust preferred securities		308		308
Other liabilities		17,849		16,335
Total liabilities		115,850		111,511
Total shareholders' equity		51,172		48,275
Total liabilities and shareholders’ equity		167,022		159,786
Consolidating Adjustments
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Cash		(115)	[1],[2]	(982)	[1],[3],[4]		(971)	[1],[5]	(555)	[5]
Insurance and reinsurance balances receivable		(1,486)		(1,528)
Reinsurance recoverable on losses and loss expenses		(12,480)		(10,919)
Reinsurance Recoverable Future Policy Benefits		(1,010)		(971)
Investments in subsidiaries		(93,074)		(87,917)
Due from subsidiaries and affiliates, net		(9,639)		(10,482)
Other assets		(4,073)		(4,353)
Total assets		(121,877)		(117,152)
Unpaid losses and loss expenses		(11,588)		(10,143)
Unearned premiums		(3,659)		(3,759)
Future policy benefits		(1,010)		(971)
Due to subsidiaries and affiliates, net		(9,639)		(10,482)
Affiliated notional cash pooling program		(115)	[2]	(982)	[4]
Repurchase agreements		0		0
Other liabilities		(2,792)		(2,898)
Total liabilities		(28,803)		(29,235)
Total shareholders' equity		(93,074)		(87,917)
Total liabilities and shareholders’ equity		(121,877)		(117,152)
Chubb limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments				27
Cash		3	[1],[2]	1	[1],[3],[4]		1	[1],[5]	0	[5]
Investments in subsidiaries		41,909		38,408
Due from subsidiaries and affiliates, net		9,639		10,482
Other assets		3		3
Total assets		51,554		48,921
Affiliated notional cash pooling program		0		363	[4]
Repurchase agreements		0		0
Other liabilities		382		283
Total liabilities		382		646
Total shareholders' equity		51,172		48,275
Total liabilities and shareholders’ equity		51,554		48,921
Chubb INA Holdings Inc. (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		168		485
Cash		1	[1],[2]	1	[1],[3],[4]		2	[1],[5]	1	[5]
Investments in subsidiaries		51,165		49,509
Other assets		287		436
Total assets		51,621		50,431
Due to subsidiaries and affiliates, net		9,432		10,209
Affiliated notional cash pooling program		115	[2]	619	[4]
Repurchase agreements		0		0
Short-term debt		1,013		500
Long-term debt		11,546		12,599
Trust preferred securities		308		308
Other liabilities		1,411		1,582
Total liabilities		23,825		25,817
Total shareholders' equity		27,796		24,614
Total liabilities and shareholders’ equity		51,621		50,431
Other Chubb Limited Subsidiaries and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		102,276		98,582
Cash		839	[1],[2]	1,965	[1],[3],[4]		$ 2,743	[5]	$ 1,209	[5]
Insurance and reinsurance balances receivable		10,820		10,498
Reinsurance recoverable on losses and loss expenses		27,514		24,496
Reinsurance Recoverable Future Policy Benefits		1,194		1,153
Value of business acquired		326		355
Goodwill		22,054		22,095
Other assets		20,701		18,442
Total assets		185,724		177,586
Unpaid losses and loss expenses		74,767		70,683
Unearned premiums		18,875		18,538
Future policy benefits		6,331		6,007
Due to subsidiaries and affiliates, net		207		273
Repurchase agreements		1,408		1,403
Long-term debt		10		11
Other liabilities		18,848		17,368
Total liabilities		120,446		114,283
Total shareholders' equity		65,278		63,303
Total liabilities and shareholders’ equity		$ 185,724		$ 177,586
The Chubb Corporation [Member]
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments						$ 42,967
Cash						71
Insurance and reinsurance balances receivable						3,095
Unpaid losses and loss expenses						22,923
Unearned premiums						7,011
Long-term debt						$ 3,765
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[6]	(1) Net of a provision for uncollectible reinsurance.

Information provided in conn136

Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Statement Of Operations and Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written									$ 29,244	$ 28,145	$ 17,713
Net premiums earned	$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	29,034	28,749	17,213
Net Investment Income	797	813	770	745	744	739	708	674	3,125	2,865	2,194
Net realized gains (losses) including OTTI	0	(10)	101	(7)	365	100	(216)	(394)	84	(145)	(420)
Losses and loss expenses	4,272	6,247	4,146	3,789	3,855	4,269	4,254	3,674	18,454	16,052	9,484
Policy benefits	176	169	163	168	161	155	146	126	676	588	543
Policy acquisition costs and administrative expenses									8,614	8,985	5,211
Interest (income) expense									607	605	300
Other (Income) Expense									(400)	(222)	(51)
Amortization of Purchased Intangibles									260	19	171
Chubb integration expenses									310	492	33
Income tax expense									(139)	815	462
Net income	$ 1,533	$ (70)	$ 1,305	$ 1,093	$ 1,610	$ 1,360	$ 726	$ 439	3,861	4,135	2,834
Comprehensive income									4,718	4,556	908
Chubb limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written											0
Net premiums earned											0
Net Investment Income									4	3	3
Equity in earnings of subsidiaries									3,640	3,901	2,673
Net realized gains (losses) including OTTI									0	0	0
Losses and loss expenses											0
Policy benefits											0
Policy acquisition costs and administrative expenses									75	64	63
Interest (income) expense									(332)	(353)	(32)
Other (Income) Expense									(12)	(25)	(208)
Amortization of Purchased Intangibles									0	0	0
Chubb integration expenses									32	62	3
Income tax expense									20	21	16
Net income									3,861	4,135	2,834
Comprehensive income									4,718	4,556	908
Chubb INA Holdings Inc. (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written									0	0	0
Net premiums earned									0	0	0
Net Investment Income									14	11	4
Equity in earnings of subsidiaries									2,424	2,555	1,038
Net realized gains (losses) including OTTI									(25)	3	(9)
Losses and loss expenses									0	0	0
Policy benefits									0	0	0
Policy acquisition costs and administrative expenses									40	82	28
Interest (income) expense									847	908	302
Other (Income) Expense									93	35	(4)
Amortization of Purchased Intangibles									0	0	0
Chubb integration expenses									69	126	29
Income tax expense									(742)	(416)	(349)
Net income									2,106	1,834	1,027
Comprehensive income									3,075	2,001	(192)
Other Chubb Limited Subsidiaries and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written									29,244	28,145	17,713
Net premiums earned									29,034	28,749	17,213
Net Investment Income									3,107	2,851	2,187
Equity in earnings of subsidiaries											0
Net realized gains (losses) including OTTI									109	(148)	(411)
Losses and loss expenses									18,454	16,052	9,484
Policy benefits									676	588	543
Policy acquisition costs and administrative expenses									8,499	8,839	5,120
Interest (income) expense									92	50	30
Other (Income) Expense									(481)	(232)	161
Amortization of Purchased Intangibles									260	19	171
Chubb integration expenses									209	304	1
Income tax expense									583	1,210	795
Net income									3,958	4,622	2,684
Comprehensive income									4,430	5,045	757
Consolidating Adjustments
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written											0
Net premiums earned											0
Equity in earnings of subsidiaries									(6,064)	(6,456)	(3,711)
Net realized gains (losses) including OTTI									0	0	0
Losses and loss expenses											0
Policy benefits											0
Policy acquisition costs and administrative expenses											0
Interest (income) expense											0
Amortization of Purchased Intangibles									0	0	0
Chubb integration expenses									0	0
Income tax expense										0	0
Net income									(6,064)	(6,456)	(3,711)
Comprehensive income									$ (7,505)	$ (7,046)	$ (565)

Information provided in conn137

Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		$ 4,503		$ 5,292		$ 3,864
Purchases of fixed maturities available for sale		(25,747)		(30,815)		(16,071)
Purchases of fixed maturities held to maturity		(352)		(282)		(62)
Purchases of equity securities		(173)		(146)		(158)
Sales of fixed maturities available for sale		13,255		16,677		10,814
Sales of equity securities		187		1,000		183
Maturities and redemptions of fixed maturities available for sale		10,425		9,349		6,567
Maturities and redemptions of fixed maturities held to maturity		879		958		669
Net change in short-term investments		(537)		12,350		(8,216)
Net derivative instruments settlements		(265)		(168)		(21)
Acquisition of subsidiaries (net of cash acquired)				(14,248)		264
Capital contribution				0		0
Other		(114)		10		(263)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		(2,442)		(5,315)		(6,294)
Dividends paid on Common Shares		(1,308)		(1,173)		(862)
Common Shares repurchased		(801)				(758)
Proceeds from issuance of long-term debt						6,090
Proceeds from issuance of repurchase agreements		2,353		2,310		2,029
Repayments of Long-term Debt		(501)		0		(1,150)
Repayments of repurchase agreements		(2,348)		(2,311)		(2,027)
Proceeds from share-based compensation plans		151		167		131
Advances from (to) affiliates		0
Capital contribution				0		0
Policyholder contract deposits		442		522		503
Policyholder contract withdrawals		(307)		(253)		(221)
Other		0		(4)		(40)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(2,319)		(742)		3,695
Effect of foreign currency rate changes on cash and cash equivalents		1		(25)		(145)
Net increase (decrease) in cash		(257)		(790)		1,120
Cash – beginning of year		985	[1],[2],[3]	1,775	[2],[4]	655	[4]
Cash – end of year	[2]	728	[5]	985	[1],[3]	1,775	[4]
Parent Company Only
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		781		3,618		3,125
Purchases of fixed maturities available for sale						0
Purchases of fixed maturities held to maturity						0
Purchases of equity securities						0
Sales of fixed maturities available for sale						0
Sales of equity securities						0
Maturities and redemptions of fixed maturities available for sale						0
Maturities and redemptions of fixed maturities held to maturity						0
Net change in short-term investments		0		0		0
Net derivative instruments settlements		0		0		0
Acquisition of subsidiaries (net of cash acquired)						0
Capital contribution				(2,330)		(2,670)
Other						0
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		0		(2,330)		(2,670)
Dividends paid on Common Shares		(1,308)		(1,173)		(862)
Common Shares repurchased						0
Proceeds from issuance of long-term debt						0
Repayments of Long-term Debt		0				0
Repayments of repurchase agreements		0				0
Proceeds from share-based compensation plans		0		0		0
Advances from (to) affiliates		892		404		(228)
Dividends to parent company						0
Net proceeds from (Repayments to) affiliated notional cash pooling program		(363)		(519)		636
Policyholder contract deposits		0				0
Policyholder contract withdrawals		0				0
Other						0
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(779)		(1,288)		(454)
Effect of foreign currency rate changes on cash and cash equivalents				0		0
Net increase (decrease) in cash		2		0		1
Cash – beginning of year		1	[1],[2],[3]	1	[2],[4]	0	[4]
Cash – end of year	[2]	3	[5]	1	[1],[3]	1	[4]
Chubb INA Holdings Inc. (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		1,648		4,305		682
Purchases of fixed maturities available for sale		(9)		(156)		0
Purchases of fixed maturities held to maturity						0
Purchases of equity securities						0
Sales of fixed maturities available for sale		99		66		0
Sales of equity securities						0
Maturities and redemptions of fixed maturities available for sale		29		66		0
Maturities and redemptions of fixed maturities held to maturity						0
Net change in short-term investments		189		7,943		(7,588)
Net derivative instruments settlements		(15)		(9)		(9)
Acquisition of subsidiaries (net of cash acquired)				(14,282)		0
Capital contribution				(215)		(625)
Other		(10)		(3)		(25)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		283		(6,590)		(8,247)
Dividends paid on Common Shares						0
Common Shares repurchased						0
Proceeds from issuance of long-term debt						6,090
Proceeds from issuance of repurchase agreements						0
Repayments of Long-term Debt		(500)				(1,150)
Repayments of repurchase agreements		0				0
Proceeds from share-based compensation plans		0		0		0
Advances from (to) affiliates		(927)		(572)		95
Dividends to parent company						0
Capital contribution				2,330		2,791
Net proceeds from (Repayments to) affiliated notional cash pooling program		(504)		530		(220)
Policyholder contract deposits		0				0
Policyholder contract withdrawals		0				0
Other				(4)		(40)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(1,931)		2,284		7,566
Effect of foreign currency rate changes on cash and cash equivalents				0		0
Net increase (decrease) in cash				(1)		1
Cash – beginning of year		1	[1],[2],[3]	2	[2],[4]	1	[4]
Cash – end of year	[2]	1	[5]	1	[1],[3]	2	[4]
Other Chubb Limited Subsidiaries and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		4,598		5,536		3,836
Purchases of fixed maturities available for sale		(25,738)		(30,659)		(16,053)
Purchases of fixed maturities held to maturity		(352)		(282)		(62)
Purchases of equity securities		(173)		(146)		(158)
Sales of fixed maturities available for sale		13,156		16,611		10,814
Sales of equity securities		187		1,000		183
Maturities and redemptions of fixed maturities available for sale		10,396		9,283		6,567
Maturities and redemptions of fixed maturities held to maturity		879		958		669
Net change in short-term investments		(726)		4,407		(628)
Net derivative instruments settlements		(250)		(159)		(12)
Acquisition of subsidiaries (net of cash acquired)				34		264
Capital contribution				(2,330)		(2,791)
Other		(104)		13		(256)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		(2,725)		(1,270)		(1,463)
Dividends paid on Common Shares						0
Common Shares repurchased		(801)				(758)
Proceeds from issuance of long-term debt						0
Proceeds from issuance of repurchase agreements		2,353		2,310		2,029
Repayments of Long-term Debt		(1)				0
Repayments of repurchase agreements		(2,348)		(2,311)		(2,027)
Proceeds from share-based compensation plans		151		167		131
Advances from (to) affiliates		35		168		133
Dividends to parent company		(2,524)		(8,167)		(3,779)
Capital contribution				2,545		3,295
Net proceeds from (Repayments to) affiliated notional cash pooling program		0
Policyholder contract deposits		442		522		503
Policyholder contract withdrawals		(307)		(253)		(221)
Other						0
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		(3,000)		(5,019)		(694)
Effect of foreign currency rate changes on cash and cash equivalents		1		(25)		(145)
Net increase (decrease) in cash		(1,126)		(778)		1,534
Cash – beginning of year		1,965	[1],[2],[3]	2,743	[4]	1,209	[4]
Cash – end of year		839	[2],[5]	1,965	[1],[2],[3]	2,743	[4]
Consolidating Adjustments
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		(2,524)		(8,167)		(3,779)
Purchases of fixed maturities available for sale						(18)
Purchases of fixed maturities held to maturity						0
Purchases of equity securities						0
Sales of fixed maturities available for sale						0
Sales of equity securities						0
Maturities and redemptions of fixed maturities available for sale						0
Maturities and redemptions of fixed maturities held to maturity						0
Net change in short-term investments		0		0		0
Net derivative instruments settlements						0
Acquisition of subsidiaries (net of cash acquired)						0
Capital contribution				4,875		6,086
Other						18
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		0		4,875		6,086
Dividends paid on Common Shares						0
Common Shares repurchased						0
Proceeds from issuance of long-term debt						0
Proceeds from issuance of repurchase agreements						0
Repayments of Long-term Debt		0				0
Repayments of repurchase agreements		0				0
Proceeds from share-based compensation plans		0		0		0
Advances from (to) affiliates		0				0
Dividends to parent company		2,524		8,167		3,779
Capital contribution				(4,875)		(6,086)
Net proceeds from (Repayments to) affiliated notional cash pooling program		867		(11)	[1]	(416)
Policyholder contract deposits		0		0		0
Policyholder contract withdrawals		0		0		0
Other						0
Net Cash Provided by (Used in) Financing Activities, Continuing Operations		3,391		3,281		(2,723)
Effect of foreign currency rate changes on cash and cash equivalents				0		0
Net increase (decrease) in cash		867		(11)		(416)
Cash – beginning of year		(982)	[1],[2],[3]	(971)	[2],[4]	(555)	[4]
Cash – end of year	[2]	$ (115)	[5]	$ (982)	[1],[3]	$ (971)	[4]
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Condensed Unaudited Quarterl138

Condensed Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Income Statements, Captions [Line Items]
Income tax benefit related to 2017 Tax Act									$ (450)	$ 0	$ 0
Net premiums earned	$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	29,034	28,749	17,213
Net Investment Income	797	813	770	745	744	739	708	674	3,125	2,865	2,194
Net realized gains (losses) including OTTI	0	(10)	101	(7)	365	100	(216)	(394)	84	(145)	(420)
Total revenues	8,015	8,610	8,108	7,510	8,168	8,527	7,897	6,877	32,243	31,469	18,987
Losses and loss expenses	4,272	6,247	4,146	3,789	3,855	4,269	4,254	3,674	18,454	16,052	9,484
Policy benefits	176	169	163	168	161	155	146	126	676	588	543
Net income	$ 1,533	$ (70)	$ 1,305	$ 1,093	$ 1,610	$ 1,360	$ 726	$ 439	$ 3,861	$ 4,135	$ 2,834
Basic earnings per share	$ 3.29	$ (0.15)	$ 2.79	$ 2.33	$ 3.44	$ 2.90	$ 1.55	$ 0.98	$ 8.26	$ 8.94	$ 8.71
Diluted earnings per share	$ 3.27	$ (0.15)	$ 2.77	$ 2.31	$ 3.41	$ 2.88	$ 1.54	$ 0.97	$ 8.19	$ 8.87	$ 8.62
Loss from Catastrophes		$ 1,500

Schedule I (Details)

Schedule I (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Other investments (cost – $4,417 and $4,270)	$ 4,672	$ 4,519
Cost or Amortized Cost	100,799
Fair Value	102,497
Amount at Which Shown in the Balance Sheet	102,358
Fixed maturities available for sale
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	77,835
Fair Value	78,939
Amount at Which Shown in the Balance Sheet	78,939
Fixed maturities available for sale | U.S. Treasury and agency
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	3,701
Fair Value	3,698
Amount at Which Shown in the Balance Sheet	3,698
Fixed maturities available for sale | Foreign
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	20,514
Fair Value	21,030
Amount at Which Shown in the Balance Sheet	21,030
Fixed maturities available for sale | Corporate securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	23,453
Fair Value	23,996
Amount at Which Shown in the Balance Sheet	23,996
Fixed maturities available for sale | Mortgage backed-securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	15,279
Fair Value	15,290
Amount at Which Shown in the Balance Sheet	15,290
Fixed maturities available for sale | States, municipalities, and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	14,888
Fair Value	14,925
Amount at Which Shown in the Balance Sheet	14,925
Fixed maturities held to maturity
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	14,335
Fair Value	14,474
Amount at Which Shown in the Balance Sheet	14,335
Fixed maturities held to maturity | U.S. Treasury and agency
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	908
Fair Value	915
Amount at Which Shown in the Balance Sheet	908
Fixed maturities held to maturity | Foreign
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,738
Fair Value	1,757
Amount at Which Shown in the Balance Sheet	1,738
Fixed maturities held to maturity | Corporate securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	3,159
Fair Value	3,219
Amount at Which Shown in the Balance Sheet	3,159
Fixed maturities held to maturity | Mortgage backed-securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,724
Fair Value	2,742
Amount at Which Shown in the Balance Sheet	2,724
Fixed maturities held to maturity | States, municipalities, and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	5,806
Fair Value	5,841
Amount at Which Shown in the Balance Sheet	5,806
Industrial, miscellaneous, and all others
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	737
Fair Value	937
Amount at Which Shown in the Balance Sheet	937
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	3,561
Fair Value	3,561
Amount at Which Shown in the Balance Sheet	3,561
Other investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	4,331
Fair Value	4,586
Amount at Which Shown in the Balance Sheet	4,586
All Related Party [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Other investments (cost – $4,417 and $4,270)	$ 86

Schedule II (BALANCE SHEETS - P

Schedule II (BALANCE SHEETS - Parent Company Only) (Details) - USD ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014	[5]
Assets
Short-term investments	$ 3,561		$ 3,002
Other investments (cost – $4,417 and $4,270)	4,672		4,519
Cash	728	[1],[2]	985	[1],[3],[4]	$ 1,775	[1],[5]	$ 655
Other assets	6,358		5,090
Total assets	167,022		159,786
Liabilities
Accounts payable, accrued expenses, and other liabilities	9,545		8,617
Affiliated notional cash pooling program	300		0	[4]
Short-term debt	1,013		500
Total liabilities	115,850		111,511
Stockholders' Equity Attributable to Parent [Abstract]
Common Shares	11,121		11,121
Common Shares in treasury (15,950,685 and 13,815,148 shares)	(1,944)		(1,480)
Retained earnings	27,474		23,613
Accumulated other comprehensive income	543		(314)
Total shareholders' equity	51,172		48,275		29,135
Total liabilities and shareholders’ equity	167,022		159,786
Parent Company Only
Assets
Investments in subsidiaries and affiliates on equity basis	41,909		38,408
Short-term investments	0		2
Other investments (cost – $4,417 and $4,270)	0		25
Total investments	41,909		38,435
Cash	3	[1],[2]	1	[1],[3],[4]	$ 1	[1],[5]	$ 0
Due from subsidiaries and affiliates, net	9,639		10,482
Other assets	3		3
Total assets	51,554		48,921
Liabilities
Accounts payable, accrued expenses, and other liabilities	382		283
Affiliated notional cash pooling program	0		363	[4]
Total liabilities	382		646
Stockholders' Equity Attributable to Parent [Abstract]
Common Shares	11,121		11,121
Common Shares in treasury (15,950,685 and 13,815,148 shares)	(1,944)		(1,480)
Additional paid-in capital	13,978		15,335
Retained earnings	27,474		23,613
Accumulated other comprehensive income	543		(314)
Total shareholders' equity	51,172		48,275
Total liabilities and shareholders’ equity	$ 51,554		$ 48,921
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Schedule II Schedule II (STATEM

Schedule II Schedule II (STATEMENTS OF OPERATIONS - Parent Company Only) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Equity in net income of subsidiaries and affiliates									$ 418	$ 264	$ 113
Net realized gains (losses)	$ 0	$ (10)	$ 101	$ (7)	$ 365	$ 100	$ (216)	$ (394)	84	(145)	(420)
Total revenues	8,015	8,610	8,108	7,510	8,168	8,527	7,897	6,877	32,243	31,469	18,987
Administrative and other (income) expense									2,833	3,081	2,270
Business Combination, Integration Related Costs									310	492	33
Income tax expense (benefit)									(139)	815	462
Total expenses									28,521	26,519	15,691
Net income	$ 1,533	$ (70)	$ 1,305	$ 1,093	$ 1,610	$ 1,360	$ 726	$ 439	3,861	4,135	2,834
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									4,718	4,556	908
Chubb limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Investment income, including intercompany interest income									336	356	35
Equity in net income of subsidiaries and affiliates									3,640	3,901	2,673
Net realized gains (losses)									0	0	0
Total revenues									3,976	4,257	2,708
Administrative and other (income) expense									63	39	(145)
Business Combination, Integration Related Costs									32	62	3
Income tax expense (benefit)									20	21	16
Total expenses									115	122	(126)
Net income									3,861	4,135	2,834
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest									$ 4,718	$ 4,556	$ 908

Schedule II (STATEMENTS OF CASH

Schedule II (STATEMENTS OF CASH FLOWS - Parent Company Only) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Purchases of fixed maturities available for sale		$ (25,720)		$ (30,759)		$ (16,040)
Sales of fixed maturities available for sale		13,228		16,621		10,783
Net change in short-term investments		(537)		12,350		(8,216)
Net derivative instruments settlements		(265)		(168)		(21)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		(2,442)		(5,315)		(6,294)
Other		114		(10)		263
Dividends paid on Common Shares		(1,308)		(1,173)		(862)
Proceeds from issuance of repurchase agreements		2,353		2,310		2,029
Repayments of Short-term Debt		2,348		2,311		2,027
Proceeds from share-based compensation plans		151		167		131
Net increase (decrease) in cash		(257)		(790)		1,120
Cash – beginning of year		985	[1],[2],[3]	1,775	[2],[4]	655	[4]
Cash – end of year	[2]	728	[5]	985	[1],[3]	1,775	[4]
Chubb limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Payments To From Affiliates		892		404		(228)
Cash dividend paid by Affiliates		450		3,400		2,900
Net cash flows from operating activities		781		3,618		3,125
Net change in short-term investments		0		0		0
Net derivative instruments settlements		0		0		0
Capital contributions to subsidiaries		0		(2,330)		(2,670)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations		0		(2,330)		(2,670)
Other						0
Dividends paid on Common Shares		(1,308)		(1,173)		(862)
Repayments of Short-term Debt		0				0
Net proceeds from (payments to) affiliated notional cash pooling programs		(363)		(519)		636
Proceeds from share-based compensation plans		0		0		0
Net cash flows (used for) from financing activities		(779)		(1,288)		(454)
Net increase (decrease) in cash		2		0		1
Cash – beginning of year		1	[1],[2],[3]	1	[2],[4]	0	[4]
Cash – end of year	[2]	$ 3	[5]	$ 1	[1],[3]	$ 1	[4]
[1]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4]	Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5]	Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

Schedule IV (SUPPLEMENTAL INFOR

Schedule IV (SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									11.00%	13.00%	21.00%
Net Amount	$ 7,218	$ 7,807	$ 7,237	$ 6,772	$ 7,059	$ 7,688	$ 7,405	$ 6,597	$ 29,034	$ 28,749	$ 17,213
Assumed From Other Companies									3,332	3,744	3,676
Ceded To Other Companies									7,080	6,806	5,818
Direct Amount									$ 32,782	$ 31,811	$ 19,355
Property and Casualty [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									12.00%	14.00%	25.00%
Net Amount									$ 24,015	$ 23,796	$ 12,781
Assumed From Other Companies									2,891	3,284	3,259
Ceded To Other Companies									6,650	6,407	5,373
Direct Amount									$ 27,774	$ 26,919	$ 14,895
Accident and Health [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									5.00%	6.00%	5.00%
Net Amount									$ 4,039	$ 3,951	$ 3,501
Assumed From Other Companies									221	219	168
Ceded To Other Companies									349	315	351
Direct Amount									$ 4,167	$ 4,047	$ 3,684
Life [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Percentage of Amount Assumed to Net									22.00%	24.00%	27.00%
Net Amount									$ 980	$ 1,002	$ 931
Assumed From Other Companies									220	241	249
Ceded To Other Companies									81	84	94
Direct Amount									$ 841	$ 845	$ 776

Schedule VI (SUPPLEMENTARY INFO

Schedule VI (SUPPLEMENTARY INFORMATION CONCERNING PROPERTY AND CASUALTY OPERATIONS) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Deferred Policy Acquisition Costs		$ 3,805	$ 3,537	$ 2,219
Net Reserves for Unpaid Losses		49,165	47,832	26,562
Unearned Premiums		15,216	14,779	8,439
Net Premiums Earned		28,054	27,747	16,282
Net Investment Income		2,890	2,656	2,007
Net Losses and Loss Expenses Incurred Related to Current Year		19,391	17,256	10,030
PPD, Gross	[1]	(937)	(1,204)	(546)
Net Losses and Loss Expenses Incurred Related to Prior Year		(829)	(1,135)	(546)
Amortization of Deferred Policy Acquisition Costs		5,519	5,654	2,692
Net Paid Losses and Loss Expenses		17,448	15,715	9,665
Net Premiums Written		$ 28,225	$ 27,074	$ 16,734
[1]	(2) Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments, and earned premiums totaling $108 million, $69 million, and nil, for 2017, 2016, and 2015, respectively.

Uncategorized Items - cb-201712

Label	Element	Value
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Other Long-term Investments	us-gaap_OtherLongTermInvestments	$ 868,000,000
Other Long-term Investments	us-gaap_OtherLongTermInvestments	1,034,000,000
Available-for-sale Securities, Equity Securities	us-gaap_AvailableForSaleSecuritiesEquitySecurities	814,000,000
Available-for-sale Securities, Equity Securities	us-gaap_AvailableForSaleSecuritiesEquitySecurities	937,000,000
Investment Derivative Instruments Fair Value	cb_InvestmentDerivativeInstrumentsFairValue	31,000,000
Investment Derivative Instruments Fair Value	cb_InvestmentDerivativeInstrumentsFairValue	18,000,000
Liabilities, Fair Value Disclosure, Recurring	us-gaap_LiabilitiesFairValueDisclosureRecurring	626,000,000
Liabilities, Fair Value Disclosure, Recurring	us-gaap_LiabilitiesFairValueDisclosureRecurring	257,000,000
Assets, Fair Value Disclosure	us-gaap_AssetsFairValueDisclosure	87,804,000,000
Assets, Fair Value Disclosure	us-gaap_AssetsFairValueDisclosure	88,961,000,000
Other Derivative Instruments Fair Value	cb_OtherDerivativeInstrumentsFairValue	3,000,000
Other Derivative Instruments Fair Value	cb_OtherDerivativeInstrumentsFairValue	1,000,000
Securities Held as Collateral, at Fair Value	us-gaap_SecuritiesHeldAsCollateralAtFairValue	1,092,000,000
Securities Held as Collateral, at Fair Value	us-gaap_SecuritiesHeldAsCollateralAtFairValue	1,737,000,000
InvestmentDerivativeInstrumentsLiability	cb_InvestmentDerivativeInstrumentsLiability	54,000,000
InvestmentDerivativeInstrumentsLiability	cb_InvestmentDerivativeInstrumentsLiability	30,000,000
Other Derivative Instruments Fair Value Liability	cb_OtherDerivativeInstrumentsFairValueLiability	13,000,000
Other Derivative Instruments Fair Value Liability	cb_OtherDerivativeInstrumentsFairValueLiability	23,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	80,115,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	78,939,000,000
Separate Account Assets	us-gaap_SeparateAccountAssets	1,879,000,000
Separate Account Assets	us-gaap_SeparateAccountAssets	2,734,000,000
Other Short-term Investments	us-gaap_OtherShortTermInvestments	3,002,000,000
Other Short-term Investments	us-gaap_OtherShortTermInvestments	3,561,000,000
Corporate Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	24,149,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	23,996,000,000
Collateralized Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	14,007,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	15,290,000,000
US States and Political Subdivisions Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	17,649,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	14,925,000,000
Foreign Government Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	21,440,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	21,030,000,000
US Treasury and Government [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	2,870,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	3,698,000,000
Guaranteed Minimum Income Benefit [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross	us-gaap_LiabilitiesForGuaranteesOnLongDurationContractsGuaranteedBenefitLiabilityGross	559,000,000
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross	us-gaap_LiabilitiesForGuaranteesOnLongDurationContractsGuaranteedBenefitLiabilityGross	$ 204,000,000