Chubb (CHB) Inactive 10-K26 Feb 152014 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2014	Feb. 13, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Entity Registrant Name	CHUBB CORP
Entity Central Index Key	20171
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		230,856,872
Entity Public Float			$22,076,309,172

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Premiums Earned	$12,328	$12,066	$11,838
Investment Income	1,394	1,465	1,556
Other Revenues	7	14	8
Realized Investment Gains (Losses), Net
Total Other-Than-Temporary Impairment Losses on Investments	-7	-11	-40
Other-Than-Temporary Impairment Losses on Investments Recognized in Other Comprehensive Income			-5
Other Realized Investment Gains, Net	376	413	238
Total Realized Investment Gains, Net	369	402	193
TOTAL REVENUES	14,098	13,947	13,595
Losses and Expenses
Losses and Loss Expenses	6,985	6,520	7,507
Amortization of Deferred Policy Acquisition Costs	2,548	2,454	2,411
Other Insurance Operating Costs and Expenses	1,397	1,411	1,362
Investment Expenses	42	49	38
Other Expenses	16	22	11
Corporate Expenses	249	254	270
TOTAL LOSSES AND EXPENSES	11,237	10,710	11,599
INCOME BEFORE FEDERAL AND FOREIGN INCOME TAX	2,861	3,237	1,996
Federal and Foreign Income Tax	761	892	451
NET INCOME	$2,100	$2,345	$1,545
Net Income Per Share
Basic	$8.65	$9.08	$5.73
Diluted	$8.62	$9.04	$5.69

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net Income	$2,100	$2,345	$1,545
Other Comprehensive Income (Loss), Net of Tax
Change in Unrealized Appreciation of Investments	528	-788	275
Change in Unrealized Other-Than-Temporary Impairment Losses on Investments			2
Change in Postretirement Benefit Costs Not Yet Recognized in Net Income	-336	464	-30
Foreign Currency Translation Losses	-117	-72	-11
Total Other Comprehensive Income (Loss) Net of Tax	75	-396	236
COMPREHENSIVE INCOME	$2,175	$1,949	$1,781

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets
Short Term Investments	$1,318	$2,114
Fixed Maturities (cost $36,958 and $35,959)	38,780	37,091
Equity Securities (cost $1,089 and $1,057)	1,964	1,810
Other Invested Assets	1,423	1,598
TOTAL INVESTED ASSETS	43,485	42,613
Cash	47	52
Accrued Investment Income	410	418
Premiums Receivable	2,560	2,284
Reinsurance Recoverable on Unpaid Losses and Loss Expenses	1,639	1,802
Prepaid Reinsurance Premiums	256	290
Deferred Policy Acquisition Costs	1,284	1,255
Deferred Income Tax		47
Goodwill	467	467
Other Assets	1,138	1,205
TOTAL ASSETS	51,286	50,433
Liabilities
Unpaid Losses and Loss Expenses	22,678	23,146
Unearned Premiums	6,581	6,423
Long Term Debt	3,300	3,300
Dividend Payable to Shareholders	117	110
Deferred Income Tax	15
Accrued Expenses and Other Liabilities	2,299	1,357
TOTAL LIABILITIES	34,990	34,336
Commitments and Contingent Liabilities (Notes 5 and 12)
Shareholders' Equity
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372
Paid-In Surplus	171	171
Retained Earnings	23,520	21,902
Accumulated Other Comprehensive Income	1,110	1,035
Treasury Stock, at Cost - 139,551,071 and 123,673,969 Shares	-8,877	-7,383
TOTAL SHAREHOLDERS' EQUITY	16,296	16,097
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$51,286	$50,433

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Fixed Maturities, cost	$36,958	$35,959
Equity Securities, cost	$1,089	$1,057
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Par Value	$1	$1
Preferred Stock, Shares Issued	0	0
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Common Stock, Par Value	$1	$1
Common Stock, Shares Issued	371,980,460	371,980,460
Treasury Stock, Shares	139,551,071	123,673,969	110,217,445	99,519,509

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders' Equity (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Paid-In Surplus [Member]	Retained Earnings [Member]	Unrealized Appreciation of Investments Including Unrealized Other-Than-Temporary Impairment Losses [Member]	Postretirement Benefit Costs Not Yet Recognized in Net Income [Member]	Foreign Currency Translation Gains [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock, at Cost [Member]
In Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Paid-In Surplus [Member]	Retained Earnings [Member]			Foreign Currency Translation Gains [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock, at Cost [Member]
Balance, Beginning of Year at Dec. 31, 2011			$372	$190	$18,903	$1,736	($687)	$146		($5,359)
Net Income	1,545				1,545
Repurchase of Shares										-935
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $17, $28 and $27)				-12
Change During Year, Net of Tax	236					277	-30	-11
Dividends Declared (per share $2.00, $1.76 and $1.64)					-439
Shares Issued Under Stock-Based Employee Compensation Plans										131
Balance, End of Year at Dec. 31, 2012	15,827		372	178	20,009	2,013	-717	135	1,431	-6,163
Net Income	2,345				2,345
Repurchase of Shares										-1,300
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $17, $28 and $27)				-7
Change During Year, Net of Tax	-396					-788	464	-72
Dividends Declared (per share $2.00, $1.76 and $1.64)					-452
Shares Issued Under Stock-Based Employee Compensation Plans										80
Balance, End of Year at Dec. 31, 2013	16,097		372	171	21,902	1,225	-253	63	1,035	-7,383
Net Income	2,100				2,100
Repurchase of Shares										-1,555
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $17, $28 and $27)
Change During Year, Net of Tax	75					528	-336	-117
Dividends Declared (per share $2.00, $1.76 and $1.64)					-482
Shares Issued Under Stock-Based Employee Compensation Plans										61
Balance, End of Year at Dec. 31, 2014	$16,296		$372	$171	$23,520	$1,753	($589)	($54)	$1,110	($8,877)

Consolidated_Statements_of_Sha1

Consolidated Statements of Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Paid-In Surplus [Member]
Tax benefit, Stock-Based Employee Compensation	$17	$28	$27
Retained Earnings [Member]
Dividends Declared Per Share	$2	$1.76	$1.64

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows from Operating Activities
Net Income	$2,100	$2,345	$1,545
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Increase (Decrease) in Unpaid Losses and Loss Expenses, Net	-45	-582	691
Increase in Unearned Premiums, Net	264	158	32
Amortization of Premiums and Discounts on Fixed Maturities	196	183	163
Depreciation	54	55	54
Realized Investment Gains, Net	-369	-402	-193
Other, Net	-47	-26	7
NET CASH PROVIDED BY OPERATING ACTIVITIES	2,153	1,731	2,299
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	4,229	2,449	2,271
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	4,231	4,909	4,290
Proceeds from Sales of Equity Securities	213	545	160
Purchases of Fixed Maturities	-9,987	-8,275	-7,247
Purchases of Equity Securities	-110	-113	-112
Investments in Other Invested Assets, Net	315	498	293
Decrease (Increase) in Short Term Investments, Net	780	383	-629
Change in Receivable or Payable from Security Transactions not Settled, Net	222	-86	45
Purchases of Property and Equipment, Net	-49	-52	-43
Other, Net		-6
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	-156	252	-972
Cash Flows from Financing Activities
Repayment of Long Term Debt		-275
Decrease in Funds Held under Deposit Contracts	-2	-6	-12
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	22	38	74
Repurchase of Shares	-1,547	-1,288	-959
Dividends Paid to Shareholders	-475	-450	-438
NET CASH USED IN FINANCING ACTIVITIES	-2,002	-1,981	-1,335
Net Increase (Decrease) in Cash	-5	2	-8
Cash at Beginning of Year	52	50	58
CASH AT END OF YEAR	$47	$52	$50

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	(1) Summary of Significant Accounting Policies

	(a)	Basis of Presentation
	The Chubb Corporation (Chubb) is a holding company with subsidiaries principally engaged in the property and casualty insurance business. The property and casualty insurance subsidiaries (the P&C Group) underwrite most lines of property and casualty insurance in the United States, Canada, Europe, Australia and parts of Latin America and Asia. The geographic distribution of property and casualty business in the United States is broad with a particularly strong market presence in the Northeast.
	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include the accounts of Chubb and its subsidiaries (collectively, the Corporation). Significant intercompany transactions have been eliminated in consolidation. The results of our operations in Australia, Brazil and other smaller foreign locations are recorded on a three month lag in our consolidated financial statements. Specific events having significant financial impact that occur during the lag period are included in the current period results.
	The consolidated financial statements include amounts based on informed estimates and judgments of management for transactions that are not yet complete. Such estimates and judgments affect the reported amounts of assets and liabilities and 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. Actual results could differ from those estimates.
	Certain amounts in the consolidated financial statements for prior years have been reclassified to conform with the 2014 presentation.

	(b)	Invested Assets
	Short term investments, which have an original maturity of one year or less, are carried at amortized cost, which approximates fair value.
	Fixed maturities, which include taxable and tax exempt bonds, are classified as available-for-sale and carried at fair value as of the balance sheet date. Taxable bonds include U.S. government and government agency and authority obligations, including taxable bonds issued by states, municipalities and political subdivisions within the United States, and foreign government and government agency obligations, corporate bonds and mortgage-backed securities. Corporate bonds include redeemable preferred stocks. Tax exempt bonds consist of bonds issued by states, municipalities and political subdivisions within the United States. Fixed maturities are purchased to support the investment strategies of the Corporation. These strategies are developed based on many factors including rate of return, maturity, credit risk, tax considerations and regulatory requirements. Fixed maturities may be sold prior to maturity to support the investment strategies of the Corporation.
	Premiums and discounts arising from the purchase of fixed maturities are amortized using the interest method over the estimated remaining term of the securities. For mortgage-backed securities, prepayment assumptions are reviewed periodically and revised as necessary.
	Equity securities, which include common stocks and non-redeemable preferred stocks, are carried at fair value as of the balance sheet date.
	Unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of fixed maturities and equity securities carried at fair value is excluded from net income and is included, net of applicable deferred income tax, in other comprehensive income.

	Other invested assets primarily include private equity limited partnerships, which are carried at the Corporation’s equity in the net assets of the partnerships based on valuations provided by the manager of each partnership. 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. Changes in the Corporation’s equity in the net assets of the partnerships are included in net income as realized investment gains or losses. Other invested assets also include warrants, which are carried at fair value as of the balance sheet date. Changes in the fair value of warrants are included in net income as realized investment gains or losses.
	Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold and are included in net income.
	When the fair value of an investment is lower than its cost, an assessment is made to determine whether the decline is temporary or other than temporary. The assessment of other-than-temporary impairment of fixed maturities and equity securities is based on both quantitative criteria and qualitative information. A number of factors are considered including, but not limited to, the length of time and the extent to which the fair value has been less than the cost, the financial condition and near term prospects of the issuer, whether the issuer is current on contractually obligated interest and principal payments, general market conditions and industry or sector specific factors.
	In determining whether fixed maturities are other than temporarily impaired, the Corporation is required to recognize an other-than-temporary impairment loss when it concludes it has the intent to sell or it is more likely than not it will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value or it is likely it will not recover the entire amortized cost value of an impaired security. If the Corporation has the intent to sell or it is more likely than not that the Corporation will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value, the security is written down to fair value and the entire amount of the writedown is included in net income as a realized investment loss. For all other impaired fixed maturities, when the impairment is determined to be other than temporary, the impairment loss is separated into the amount representing the credit loss and the amount representing the loss related to all other factors. The amount of the impairment loss that represents the credit loss is included in net income as a realized investment loss and the amount of the impairment loss that relates to all other factors is included in other comprehensive income.
	For fixed maturities, the split between the amount of other-than-temporary impairment losses that represents credit losses and the amount that relates to all other factors is principally based on assumptions regarding the amount and timing of projected cash flows. For fixed maturities other than mortgage-backed securities, cash flow estimates are based on assumptions regarding the probability of default and estimates regarding the timing and amount of recoveries associated with a default. For mortgage-backed securities, cash flow estimates are based on assumptions regarding future prepayment rates, default rates, loss severity and timing of recoveries. The Corporation has developed the estimates of projected cash flows using information based on historical market data, industry analyst reports and forecasts and other data relevant to the collectibility of a security.
	In determining whether equity securities are other than temporarily impaired, the Corporation considers its intent and ability to hold a security for a period of time sufficient to allow for the recovery of cost. If the decline in the fair value of an equity security is deemed to be other than temporary, the security is written down to fair value and the amount of the writedown is included in net income as a realized investment loss.

	(c)	Premium Revenues and Related Expenses
	Insurance premiums are earned on a monthly pro rata basis over the terms of the policies and include estimates of audit premiums and premiums on retrospectively rated policies. Assumed reinsurance premiums are earned over the terms of the reinsurance contracts. Unearned premiums represent the portion of direct and assumed premiums written applicable to the unexpired terms of the insurance policies and reinsurance contracts in force.
	Ceded reinsurance premiums are reflected in operating results over the terms of the reinsurance contracts. Prepaid reinsurance premiums represent the portion of premiums ceded to reinsurers applicable to the unexpired terms of the reinsurance contracts in force.
	Reinsurance reinstatement premiums are recognized in the same period as the loss event that gave rise to the reinstatement premiums.
	Acquisition costs that are directly related to the successful acquisition of new or renewal insurance contracts are deferred and amortized over the period in which the related premiums are earned. Such costs include commissions, premium taxes and certain other underwriting and policy issuance costs. Commissions received related to reinsurance premiums ceded are considered in determining net acquisition costs eligible for deferral. Deferred policy acquisition costs are reviewed to determine whether they are recoverable from future income. If such costs are deemed to be unrecoverable, they are expensed. Anticipated investment income is considered in the determination of the recoverability of deferred policy acquisition costs.

	(d)	Unpaid Losses and Loss Expenses
	Unpaid losses and loss expenses (also referred to as loss reserves) include the accumulation of individual case estimates for claims that have been reported and estimates of claims that have been incurred but not reported as well as estimates of the expenses associated with processing and settling all reported and unreported claims, less estimates of anticipated salvage and subrogation recoveries. Estimates are based upon past loss experience modified for current trends as well as prevailing economic, legal and social conditions. Loss reserves are not discounted to present value.
	Loss reserves are regularly reviewed using a variety of actuarial techniques. Reserve estimates are updated as historical loss experience develops, additional claims are reported and/or settled and new information becomes available. Any changes in estimates are reflected in operating results in the period in which the estimates are changed.
	Reinsurance recoverable on unpaid losses and loss expenses represents an estimate of the portion of gross loss reserves that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated using assumptions that are consistent with those used in estimating the gross losses associated with the reinsured policies. A provision for estimated uncollectible reinsurance is recorded based on periodic evaluations of balances due from reinsurers, the financial condition of the reinsurers, coverage disputes and other relevant factors.

	(e)	Financial Products
	Derivatives are carried at fair value as of the balance sheet date. Changes in fair value are recognized in net income in the period of the change and are included in other revenues.
	Assets and liabilities related to these derivatives are included in other assets and other liabilities.

	(f)	Goodwill
	Goodwill represents the excess of the cost of an acquired entity over the fair value of net assets acquired. Goodwill is tested for impairment at least annually.

	(g)	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.

	(h)	Real Estate
	Real estate properties are carried at cost less accumulated depreciation and any writedowns for impairment. Real estate properties are reviewed for impairment whenever events or circumstances indicate that the carrying value of such properties may not be recoverable. Measurement of such impairment is based on the fair value of the property. Real estate properties are included in other assets.

	(i)	Income Taxes
	Deferred income tax assets and liabilities are recognized for the expected future tax effects attributable to temporary differences between the financial reporting and tax bases of assets and liabilities, based on enacted tax rates and other provisions of tax law. The effect on deferred tax assets and liabilities of a change in tax laws or rates is recognized in net income in the period in which such change is enacted. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized.
	The Corporation does not consider the earnings of its foreign subsidiaries to be permanently reinvested. Accordingly, provision has been made for the expected U.S. federal income tax liabilities applicable to undistributed earnings of foreign subsidiaries.

	(j)	Stock-Based Employee Compensation
	The fair value method of accounting is used for stock-based employee compensation plans. Under the fair value method, compensation cost is measured based on the fair value of the award at the grant date and recognized over the requisite service period.

	(k)	Foreign Exchange
	Assets and liabilities relating to foreign operations are translated into U.S. dollars using current exchange rates as of the balance sheet date. Revenues and expenses are translated into U.S. dollars using the average exchange rates during the year.
	The functional currency of foreign operations is generally the currency of the local operating environment since business is primarily transacted in such local currency. Translation gains and losses, net of applicable income tax, are excluded from net income and are credited or charged directly to other comprehensive income.

	(l)	Cash Flow Information
	In the statement of cash flows, short term investments are not considered to be cash equivalents. The effect of changes in foreign exchange rates on cash balances was insignificant.
	In 2013, the Corporation exchanged its holdings of common stock and warrants of Alterra Capital Holdings Limited, with a cost basis of $177 million and a carrying value of $63 million, respectively, for common stock of Markel Corporation, valued at $226 million, and cash of $98 million, as a result of a business combination. The noncash portions of the transaction have been excluded from the statement of cash flows.

Invested_Assets_and_Related_In

Invested Assets and Related Income	12 Months Ended
Invested Assets and Related Income	Dec. 31, 2014
Text Block [Abstract]
Invested Assets and Related Income	(2) Invested Assets and Related Income
	(a) The amortized cost and fair value of fixed maturities and equity securities were as follows:


			December 31, 2014
			Amortized			Gross			Gross			Fair
			Cost			Unrealized			Unrealized			Value
						Appreciation			Depreciation
			(in millions)
	Fixed maturities
	Tax exempt		$	18,614		$	1,174		$	16		$	19,772

	Taxable
	U.S. government and government agency and			1,962			46			1			2,007
	authority obligations			1,962			46			1			2,007
	Corporate bonds			8,741			327			40			9,028
	Foreign government and government agency obligations			6,380			295			3			6,672
	Residential mortgage-backed securities			192			20			1			211
	Commercial mortgage-backed securities			1,069			22			1			1,090

				18,344			710			46			19,008

	Total fixed maturities		$	36,958		$	1,884		$	62		$	38,780

	Equity securities		$	1,089		$	894		$	19		$	1,964



			December 31, 2013
			Amortized			Gross			Gross			Fair
			Cost			Unrealized			Unrealized			Value
						Appreciation			Depreciation
			(in millions)
	Fixed maturities
	Tax exempt		$	17,808		$	802		$	189		$	18,421

	Taxable
	U.S. government and government agency and authority obligations			784			27			9			802
	Corporate bonds			9,032			370			88			9,314
	Foreign government and government agency obligations			6,719			206			35			6,890
	Residential mortgage-backed securities			277			23			1			299
	Commercial mortgage-backed securities			1,339			29			3			1,365

				18,151			655			136			18,670

	Total fixed maturities		$	35,959		$	1,457		$	325		$	37,091

	Equity securities		$	1,057		$	756		$	3		$	1,810

	The following table summarizes the fair value of the tax exempt fixed maturities at December 31, 2014 and 2013:


			2014			2013
			(in millions)
	Special revenue bonds		$	12,936		$	11,717
	State general obligation bonds			2,415			2,292
	Municipal and political subdivision general obligation bonds			2,378			2,220
	Pre-refunded bonds			2,043			2,192

			$	19,772		$	18,421


	Special revenue bonds are supported by income streams generated in a broad range of sectors, primarily highways, water and sewer utilities, hospitals, electric utilities, airports, universities and housing, as well as specifically pledged tax revenues. The special revenue bond holdings are well-diversified and spread relatively evenly over these sectors. An irrevocable trust containing U.S. government or government agency obligations has been established to fund the remaining principal and interest payments of the pre-refunded bonds.
	The following table summarizes the fair value and amortized cost of the tax exempt fixed maturities other than pre-refunded bonds held at December 31, 2014 and 2013, for the five states having the largest concentration of issuers within the tax exempt fixed maturity portfolio. The remainder of tax exempt fixed maturities were issued by a broad range of other states and municipalities and political subdivisions within those states. In the following table, “state” identifies the issuer or the location of the issuing municipality or political subdivision within a state.


		December 31, 2014
		Fair Value
State		Special			Municipal			State			Total			Amortized
		Revenue			and Political			General						Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
New York		$	2,046		$	173		$	43		$	2,262		$	2,135
Texas			883			852			211			1,946			1,829
California			1,098			153			256			1,507			1,422
Illinois			608			381			97			1,086			1,022
Florida			850			63			167			1,080			1,017


		December 31, 2013
		Fair Value
State		Special			Municipal			State			Total			Amortized
		Revenue			and Political			General						Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
Texas		$	930		$	830		$	230		$	1,990		$	1,904
New York			1,611			197			31			1,839			1,809
California			859			82			198			1,139			1,093
Illinois			577			483			56			1,116			1,094
Florida			757			38			108			903			877
At December 31, 2014 and 2013, foreign government and government agency fixed maturities consisted of high quality fixed maturities primarily issued by national governments and, to a lesser extent, government agencies, regional governments and supranational organizations.
The following table summarizes the fair value and amortized cost of the foreign government and government agency fixed maturities held at December 31, 2014 and 2013, for the five countries having the largest concentration of issuers within the foreign government and government agency fixed maturity portfolio. In the following table, “country” identifies the issuer or the location of the issuing government agency or regional government within a country.


		2014						2013
Country		Fair			Amortized			Fair			Amortized
Country		Value			Cost			Value			Cost
		(in millions)
Canada		$	1,893		$	1,823		$	1,993		$	1,953
United Kingdom			1,230			1,163			1,026			1,004
Germany			1,102			1,045			1,241			1,211
Australia			746			700			739			700
Brazil			232			231			270			270

At December 31, 2014 and 2013, the foreign government and government agency fixed maturities also included $469 million and $547 million, respectively, of fixed maturities issued by supranational organizations.
The fair value and amortized cost of fixed maturities at December 31, 2014 by contractual maturity were as follows:


		Fair			Amortized
		Value			Cost
		(in millions)
Due in one year or less		$	2,947		$	2,922
Due after one year through five years			12,906			12,406
Due after five years through ten years			12,814			12,041
Due after ten years			8,812			8,328

			37,479			35,697
Residential mortgage-backed securities			211			192
Commercial mortgage-backed securities			1,090			1,069

		$	38,780		$	36,958

Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay obligations.
The Corporation’s equity securities comprise a diversified portfolio of primarily U.S. publicly-traded common stocks.
The Corporation is involved in the normal course of business with variable interest entities (VIEs) primarily as a passive investor in residential mortgage-backed securities, commercial mortgage-backed securities and private equity limited partnerships issued by third party VIEs. The Corporation is not the primary beneficiary of these VIEs. The Corporation’s maximum exposure to loss with respect to these investments is limited to the investment carrying values included in the Corporation’s consolidated balance sheet and any unfunded partnership commitments.
(b) The components of unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of investments carried at fair value were as follows:


		December 31
		2014			2013
		(in millions)
Fixed maturities
Gross unrealized appreciation		$	1,884		$	1,457
Gross unrealized depreciation			62			325

			1,822			1,132

Equity securities
Gross unrealized appreciation			894			756
Gross unrealized depreciation			19			3

			875			753

			2,697			1,885
Deferred income tax liability			944			660

		$	1,753		$	1,225


The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2014, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.


		Less Than 12 Months						12 Months or More						Total
		Fair			Gross			Fair			Gross			Fair		Gross
		Value			Unrealized			Value			Unrealized			Value		Unrealized
					Depreciation						Depreciation					Depreciation
		(in millions)
Fixed maturities
Tax exempt		$	422		$	3		$	305		$	13		$	727	$	16

Taxable
U.S. government and government agency			936			1			36			—			972		1
and authority obligations			936			1			36			—			972		1
Corporate bonds			1,327			23			888			17			2,215		40
Foreign government and government			318			1			207			2			525		3
agency obligations			318			1			207			2			525		3
Residential mortgage-backed securities			—			—			7			1			7		1
Commercial mortgage-backed securities			106			—			67			1			173		1

			2,687			25			1,205			21			3,892		46

Total fixed maturities			3,109			28			1,510			34			4,619		62

Equity securities			67			11			11			8			78		19

		$	3,176		$	39		$	1,521		$	42		$	4,697	$	81

At December 31, 2014, approximately 735 individual fixed maturities and 15 individual equity securities were in an unrealized loss position. The Corporation does not have the intent to sell and it is not more likely than not that the Corporation will be required to sell these fixed maturities before the securities recover to their amortized cost value. In addition, the Corporation believes that none of the declines in the fair values of these fixed maturities relate to credit losses. The Corporation has the intent and ability to hold the equity securities in an unrealized loss position for a period of time sufficient to allow for the recovery of cost. The Corporation believes that none of the declines in the fair value of these fixed maturities and equity securities were other than temporary at December 31, 2014.
The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2013, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.


		Less Than 12 Months						12 Months or More						Total
		Fair			Gross			Fair			Gross			Fair		Gross
		Value			Unrealized			Value			Unrealized			Value		Unrealized
					Depreciation						Depreciation					Depreciation
		(in millions)
Fixed maturities
Tax exempt		$	3,417		$	144		$	307		$	45		$	3,724	$	189

Taxable
U.S. government and government agency and authority obligations			213			6			35			3			248		9
Corporate bonds			2,526			76			222			12			2,748		88
Foreign government and government agency obligations			1,735			32			75			3			1,810		35
Residential mortgage-backed securities			4			—			14			1			18		1
Commercial mortgage-backed securities			153			1			39			2			192		3

			4,631			115			385			21			5,016		136

Total fixed maturities			8,048			259			692			66			8,740		325

Equity securities			41			3			—			—			41		3

		$	8,089		$	262		$	692		$	66		$	8,781	$	328


The change in unrealized appreciation or depreciation of investments carried at fair value, including the change in unrealized other-than-temporary impairment losses, was as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
Change in unrealized appreciation of fixed maturities		$	690		$	(1,546	)	$	256
Change in unrealized appreciation of equity securities			122			334			171

			812			(1,212	)		427
Deferred income tax (credit)			284			(424	)		150

		$	528		$	(788	)	$	277

(c) The sources of net investment income were as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
Fixed maturities		$	1,314		$	1,380		$	1,465
Equity securities			41			38			40
Short term investments			18			16			18
Other			21			31			33

Gross investment income			1,394			1,465			1,556
Investment expenses			42			49			38

		$	1,352		$	1,416		$	1,518

(d) Realized investment gains and losses were as follows:


		Years Ended
		December 31
		2014			2013			2012
		(in millions)
Fixed maturities
Gross realized gains		$	126		$	62		$	124
Gross realized losses			(36	)		(42	)		(20	)
Other-than-temporary impairment losses			(5	)		(2	)		(5	)

			85			18			99

Equity securities
Gross realized gains			137			204			68
Gross realized losses			—			(1	)		—
Other-than-temporary impairment losses			(2	)		(9	)		(40	)

			135			194			28

Other invested assets			149			190			66

		$	369		$	402		$	193

(e) As of December 31, 2014 and 2013, fixed maturities still held by the Corporation for which a portion of their other-than-temporary impairment losses were recognized in other comprehensive income had cumulative credit-related losses of $18 million and $20 million, respectively, recognized in net income.

Deferred_Policy_Acquisition_Co

Deferred Policy Acquisition Costs	12 Months Ended
Deferred Policy Acquisition Costs	Dec. 31, 2014
Text Block [Abstract]
Deferred Policy Acquisition Costs	(3) Deferred Policy Acquisition Costs
	Policy acquisition costs deferred and the related amortization reflected in operating results were as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Balance, beginning of year	$	1,255		$	1,206		$	1,210

	Costs deferred during year
	Commissions and brokerage		2,073			1,979			1,919
	Premium taxes and assessments		258			263			247
	Underwriting and policy issuance costs		262			271			248

			2,593			2,513			2,414

	Foreign currency translation effect		(16	)		(10	)		-7

	Amortization during year		(2,548	)		(2,454	)		(2,411	)

	Balance, end of year	$	1,284		$	1,255		$	1,206

Property_and_Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	(4) Property and Equipment
	Property and equipment included in other assets were as follows:


		December 31
		2014		2013
		(in millions)
	Cost	$	488	$	501
	Accumulated depreciation		239		243

		$	249	$	258

	Depreciation expense related to property and equipment was $54 million, $55 million and $54 million for 2014, 2013, and 2012, respectively.

Unpaid_Losses_and_Loss_Expense

Unpaid Losses and Loss Expenses	12 Months Ended
Unpaid Losses and Loss Expenses	Dec. 31, 2014
Insurance [Abstract]
Unpaid Losses and Loss Expenses	(5) Unpaid Losses and Loss Expenses
	(a) The process of establishing loss reserves is complex and imprecise as it must take into consideration many variables that are subject to the outcome of future events. As a result, informed subjective estimates and judgments as to the P&C Group’s ultimate exposure to losses are an integral component of the loss reserving process. The loss reserve estimation process relies on the basic assumption that past experience, adjusted for the effects of current developments and likely trends, is an appropriate basis for predicting future outcomes.
	Most of the P&C Group’s loss reserves relate to long tail liability classes of business. For many liability claims significant periods of time, ranging up to several years or even decades, may elapse between the occurrence of the loss, the reporting of the loss and the settlement of the claim. The longer the time span between the incidence of a loss and the settlement of the claim, the more the ultimate settlement amount can vary.
	There are numerous factors that contribute to the inherent uncertainty in the process of establishing loss reserves. Among these factors are changes in the inflation rate for goods and services related to covered damages such as medical care and home repair costs; changes in the judicial interpretation of policy provisions relating to the determination of coverage; changes in the general attitude of juries in the determination of liability and damages; legislative actions; changes in the medical condition of claimants; changes in the estimates of the number and/or severity of claims that have been incurred but not reported as of the date of the financial statements; and changes in the P&C Group’s book of business, underwriting standards and/or claim handling procedures.
	In addition, the uncertain effects of emerging or potential claims and coverage issues that arise as legal, judicial, economic and social conditions change must be taken into consideration. These issues have had, and may continue to have, a negative effect on loss reserves by either extending coverage beyond the original underwriting intent or by increasing the number or size of claims. As a result of such issues, the uncertainties inherent in estimating ultimate claim costs on the basis of past experience have grown, further complicating the already complex loss reserving process.
	Management believes that the aggregate net loss reserves of the P&C Group at December 31, 2014 were adequate to cover claims for losses that had occurred as of that date, including both those known and those yet to be reported. In establishing such reserves, management considers facts currently known and the present state of the law and coverage litigation. However, given the significant uncertainties inherent in the loss reserving process, it is possible that management’s estimate of the ultimate liability for losses that had occurred as of December 31, 2014 may change, which could have a material effect on the Corporation’s results of operations and financial condition.

	(b) A reconciliation of the beginning and ending liability for unpaid losses and loss expenses, net of reinsurance recoverable, and a reconciliation of the net liability to the corresponding liability on a gross basis is as follows:


		2014			2013			2012
		(in millions)
	Gross liability, beginning of year	$	23,146		$	23,963		$	23,068
	Reinsurance recoverable, beginning of year		1,802			1,941			1,739

	Net liability, beginning of year		21,344			22,022			21,329

	Net incurred losses and loss expenses related to
	Current year		7,621			7,232			8,121
	Prior years		(636	)		(712	)		(614	)

			6,985			6,520			7,507

	Net payments for losses and loss expenses related to
	Current year		2,496			2,150			2,323
	Prior years		4,534			4,952			4,493

			7,030			7,102			6,816


	Foreign currency translation effect		(260	)		(96	)		2


	Net liability, end of year		21,039			21,344			22,022
	Reinsurance recoverable, end of year		1,639			1,802			1,941

	Gross liability, end of year	$	22,678		$	23,146		$	23,963

	Changes in loss reserve estimates are unavoidable because such estimates are subject to the outcome of future events. Loss trends vary and time is required for changes in trends to be recognized and confirmed. During 2014, the P&C Group experienced overall favorable development of $636 million on net unpaid losses and loss expenses established as of the previous year end. This compares with favorable prior year development of $712 million in 2013 and $614 million in 2012. Such favorable development was reflected in operating results in these respective years.
	The net favorable development of $636 million in 2014 was due to various factors. Overall favorable development of about $320 million was experienced in the professional liability classes other than fidelity. This favorable development was driven mainly by the directors and officers liability and fiduciary liability classes. The reported loss activity for these classes was less than expected, mostly in terms of claim severity. The aggregate favorable emergence was driven by accident years 2010 and prior. Favorable development of about $205 million in the aggregate was experienced in the personal and commercial liability classes. The most significant favorable development occurred in the excess liability classes, particularly in accident years 2011 and prior. This was partially offset by adverse development experienced in other liability classes, most notably due to $100 million of incurred losses related to asbestos and toxic waste claims in older accident years. Overall, prior accident year claim activity for the personal and commercial liability classes was less severe than expected. Favorable development of about $60 million in the aggregate was experienced in the personal and commercial property classes, with the most significant amounts related to the 2013 and 2012 accident years. The severity of late developing property claims that emerged during 2014 was lower than expected. Favorable development of about $50 million was experienced in the workers’ compensation class, with favorable development occurring in most accident years. The severity of prior accident year claim activity for this class was lower than expected.

	The net favorable development of $712 million in 2013 was due to various factors. Favorable development of about $265 million in the aggregate, including $30 million related to catastrophes, was experienced in the personal and commercial property classes, mostly related to the 2012 and 2011 accident years. The severity and frequency of late developing property claims that emerged during 2013 were lower than expected, including those related to catastrophes, and the development of existing case reserves was more favorable than expected. Overall favorable development of about $260 million was experienced in the professional liability classes other than fidelity. This favorable development was driven by the directors and officers liability and fiduciary liability classes, partially offset by adverse development in the errors and omissions liability and employment practices liability classes. The reported loss activity was less than expected, with aggregate favorable emergence from accident years 2010 and prior. Favorable development of about $160 million in the aggregate was experienced in the personal and commercial liability classes. The most significant favorable development occurred in the excess liability classes, particularly in accident years 2010 and prior. There was some offsetting adverse development in other liability classes, most notably due to $106 million of incurred losses related to asbestos and toxic waste claims in older accident years. Overall, prior period liability claims were lower than expected, particularly the severity of such claims, and the effects of underwriting changes that affected these years have been more positive than expected. Unfavorable development of about $50 million was experienced in the fidelity class due to higher than expected reported loss emergence, related mostly to accident years subsequent to 2007. Favorable development of about $35 million was experienced in the personal automobile business due primarily to more favorable case reserve development and lower severity of prior period claims than expected. Favorable development of about $30 million was experienced in the surety business due to lower than expected loss emergence in recent accident years.
	The net favorable development of $614 million in 2012 was due to various factors. Favorable development of about $250 million in the aggregate was experienced in the personal and commercial liability classes. The most significant favorable development occurred in accident years 2006 to 2009, which more than offset adverse development in accident years 2002 and prior, which included $83 million of incurred losses related to asbestos and toxic waste claims. The overall frequency and severity of prior period liability claims were lower than expected and the effects of underwriting changes that affected these years have been more positive than expected, especially in the commercial excess liability class. Overall favorable development of about $200 million was experienced in the professional liability classes other than fidelity. This favorable development was driven by the directors and officers liability and fiduciary liability classes, partially offset by adverse development experienced in the errors and omissions liability and employment practices liability classes. The reported loss activity was less than expected, with aggregate favorable emergence from accident years 2008 and prior partly offset by some adverse emergence in the more recent accident years. Favorable development of about $125 million in the aggregate was experienced in the personal and commercial property classes, mostly related to the 2007 through 2011 accident years. The severity and frequency of late developing property claims that emerged during 2012 were lower than expected, including those related to catastrophes, and the development of existing case reserves was more favorable than expected. Unfavorable development of about $60 million was experienced in the fidelity class due to higher than expected reported loss emergence, related mostly to accident years 2008 through 2010. Favorable development of about $45 million was experienced in the runoff of our reinsurance assumed business due primarily to better than expected reported loss activity from cedants. Favorable development of about $40 million was experienced in the personal automobile business due primarily to lower than expected frequency of prior period claims. Favorable development of about $25 million was experienced in the surety business due to lower than expected loss emergence in recent accident years.

	(c) The estimation of loss reserves relating to asbestos and toxic waste claims on insurance policies written many years ago is subject to greater uncertainty than other types of claims due to inconsistent court decisions as well as judicial interpretations and legislative actions that in some instances have tended to broaden coverage beyond the original intent of such policies and in others have expanded theories of liability. The insurance industry as a whole remains engaged in extensive litigation over coverage, accident year allocation and liability issues and is thus confronted with a continuing uncertainty in its efforts to quantify these exposures.
	Asbestos remains the most significant and difficult mass tort for the insurance industry in terms of claims volume and dollar exposure. Asbestos claims relate primarily to bodily injuries asserted by those who came in contact with asbestos or products containing asbestos. Tort theory affecting asbestos litigation has evolved over the years. Early court cases established the “continuous trigger” theory with respect to insurance coverage. Under this theory, insurance coverage is deemed to be triggered from the time a claimant is first exposed to asbestos until the manifestation of any disease. This interpretation of a policy trigger can involve insurance policies over many years and increases insurance companies’ exposure to liability.
	New asbestos claims and new exposures on existing claims have continued despite the fact that usage of asbestos has declined since the mid-1970s. Many claimants were exposed to multiple asbestos products over an extended period of time. As a result, claim filings typically name dozens of defendants. The plaintiffs’ bar has solicited new claimants through extensive advertising and through asbestos medical screenings. A vast majority of asbestos bodily injury claims have been filed by claimants who do not show any signs of asbestos related disease. New asbestos cases are often filed in those jurisdictions with a reputation for judges and juries that are sympathetic to plaintiffs.
	Approximately 110 manufacturers and distributors of asbestos products have filed for bankruptcy protection as a result of asbestos related liabilities. A bankruptcy sometimes involves an agreement to a plan between the debtor and its creditors, including the creation of a trust to pay current and future asbestos claimants for their injuries. Although the debtor is negotiating in part with its insurers’ money, insurers are generally given only limited opportunity to be heard. In addition to contributing to the overall number of claims, bankruptcy proceedings not only result in increased settlement demands against remaining solvent defendants, but also create the potential for recoveries from multiple trusts by the same claimant for the same alleged injuries.
	There have been some positive legislative and judicial developments in the asbestos environment over the past several years. Various challenges to the mass screening of claimants have occurred which have led to higher medical evidentiary standards for asbestos and other exposure-type claims. Also, a number of states have implemented legislative and judicial reforms that focus the courts’ resources on the claims of the most seriously injured. Those who allege serious injury and can present credible evidence of their injuries are receiving priority trial settings in the courts, while those who have not shown any credible disease manifestation are having their hearing dates delayed or placed on an inactive docket, which preserves the right to pursue litigation in the future. Further, a number of jurisdictions have adopted venue reform that requires plaintiffs to have a connection to the jurisdiction in order to file a complaint, although in more recent years, this type of reform has slowed. In recognition that many aspects of bankruptcy plans are unfair to certain classes of claimants and to the insurance industry, these plans are being more closely scrutinized by the courts and rejected when appropriate. Finally, a number of jurisdictions have passed or are considering legislation that will require fuller disclosure by plaintiffs of amounts received from asbestos bankruptcy trusts.
	The P&C Group’s most significant individual asbestos exposures involve products liability on the part of “traditional” defendants who were engaged in the manufacture, distribution or installation of asbestos products. The P&C Group wrote primary general liability and/or excess liability coverages for these insureds. While these insureds are relatively few in number, their exposure has been substantial due to the high volume of claims, the erosion of the underlying limits and the bankruptcies of target defendants.

	The P&C Group’s other asbestos exposures involve products and non-products liability on the part of “peripheral” defendants, including a mix of manufacturers, distributors and installers of certain products that contain asbestos in small quantities and owners or operators of properties where asbestos was present. Generally, these insureds are named defendants on a regional rather than a nationwide basis. As the financial resources of traditional asbestos defendants have been depleted, plaintiffs are targeting these viable peripheral parties with greater frequency and, in many cases, for large awards.
	Asbestos claims against the major manufacturers, distributors or installers of asbestos products were typically presented under the products liability section of primary general liability policies as well as under excess liability policies, both of which typically had aggregate limits that capped an insurer’s exposure. In recent years, a number of asbestos claims by insureds are being presented as “non-products” claims. In these instances, claimants contend that they came into contact with asbestos at premises owned or operated by the P&C Group’s insureds and/or were exposed to asbestos during asbestos installation at a particular location. These non-products claims are presented under the premises or operations section of primary general liability policies. Unlike products coverage, the premises or operations coverages in these older policies typically had no aggregate limits on coverage, creating potentially greater exposure. Further, in an effort to seek additional insurance coverage, some insureds with installation activities who have substantially eroded their products coverage are presenting new asbestos claims as non-products operations claims or attempting to reclassify previously settled products claims as non-products claims to restore a portion of previously exhausted products aggregate limits. It is difficult to predict whether insureds will be successful in asserting claims under non-products coverage or whether insurers will be successful in asserting additional defenses. Accordingly, the ultimate cost to insurers of the claims for coverage not subject to aggregate limits is uncertain.
	Various U.S. federal proposals to solve the ongoing asbestos litigation crisis have been considered by the U.S. Congress over the years, but none have yet been enacted. The prospect of federal asbestos reform legislation remains uncertain.
	In establishing asbestos reserves, the exposure presented by each insured is evaluated. As part of this evaluation, consideration is given to a variety of factors including: the available insurance coverage; limits and deductibles; the jurisdictions involved; the number of claimants; the disease mix exhibited by the claimants; the past settlement values of similar claims; the potential role of other insurance, particularly underlying coverage below excess liability policies; potential bankruptcy impact; relevant judicial interpretations; and applicable coverage defenses, including asbestos exclusions.
	Significant uncertainty remains as to the ultimate liability of the P&C Group related to asbestos related claims. This uncertainty is due to several factors including the long latency period between asbestos exposure and disease manifestation and the resulting potential for involvement of multiple policy periods for individual claims; plaintiffs’ expanding theories of liability and increased focus on peripheral defendants; the volume of claims by unimpaired plaintiffs and the extent to which they can be precluded from making claims; the volume of claims by severely impaired plaintiffs, such as those with mesothelioma, and the size of settlements and judgments received by those plaintiffs; the volume of claims by plaintiffs suffering from other malignancies such as lung cancer and their ability to establish a causal link between their disease and exposure to asbestos; the efforts by insureds to claim the right to non-products coverage not subject to aggregate limits; the number of insureds seeking bankruptcy protection as a result of asbestos related liabilities; the ability of claimants to bring a claim in a state in which they have no residency or exposure; the impact of the exhaustion of primary limits and the resulting increase in claims on excess liability policies that the P&C Group has issued; inconsistent court decisions and diverging legal interpretations; and the possibility, however remote, of federal legislation that would address the asbestos problem. These significant uncertainties are not likely to be resolved in the near future.
	Toxic waste claims relate primarily to pollution and associated cleanup costs. The P&C Group’s insureds have two potential areas of exposure: hazardous waste dump sites and pollution at the insured site primarily from underground storage tanks and manufacturing processes.

	The U.S. federal Comprehensive Environmental Response Compensation and Liability Act of 1980 (Superfund) has been interpreted to impose strict, retroactive and joint and several liability on potentially responsible parties (PRPs) for the cost of remediating hazardous waste sites.
	Most PRPs named to date are parties who have been generators, transporters, past or present landowners or past or present site operators. Most sites have multiple PRPs. Insurance policies issued to PRPs were not intended to cover claims arising from gradual pollution. Environmental remediation claims tendered by PRPs and others to insurers have frequently resulted in disputes over insurers’ contractual obligations with respect to pollution claims. The resulting litigation against insurers extends to issues of liability, coverage and other policy provisions.
	There is substantial uncertainty involved in estimating the P&C Group’s liabilities related to these claims. First, the liabilities of the claimants are extremely difficult to estimate. At any given waste site, the allocation of remediation costs among governmental authorities and the PRPs varies greatly depending on a variety of factors. Second, different courts have addressed liability and coverage issues regarding pollution claims and have reached inconsistent conclusions in their interpretation of several issues. These significant uncertainties are not likely to be resolved definitively in the near future.
	Uncertainties also remain as to the Superfund law itself. Superfund’s taxing authority expired on December 31, 1995 and has not been re-enacted. Federal legislation appears to be at a standstill. At this time, it is not possible to predict the direction that any reforms may take, when they may occur or the effect that any changes may have on the insurance industry.
	Without federal movement on Superfund reform, the enforcement of Superfund liability has occasionally shifted to the states. States are being forced to reconsider state-level cleanup statutes and regulations. As individual states move forward, the potential for conflicting state regulation becomes greater. In a few states, cases have been brought against insureds or directly against insurance companies for environmental pollution and natural resources damages. To date, only a few natural resource claims have been filed and they are being vigorously defended. Significant uncertainty remains as to the cost of remediating the state sites. Because of the large number of state sites, such sites could prove even more costly in the aggregate than Superfund sites.
	In establishing toxic waste reserves, the exposure presented by each insured is evaluated. As part of this evaluation, consideration is given to a variety of factors including: the probable liability, available insurance coverage, allocation of potential loss to the appropriate accident year, past settlement values of similar claims, relevant judicial interpretations, applicable coverage defenses as well as facts that are unique to each insured.
Based on facts currently known and the present state of the law and coverage litigation, management believes that the loss reserves carried at December 31, 2014 for asbestos and toxic waste claims were adequate. However, given the inherent uncertainties, as well as the judicial decisions and legislative actions that have broadened the scope of coverage and expanded theories of liability in the past and the possibilities of similar interpretations in the future, it is possible that the estimate of loss reserves relating to these exposures may increase in future periods as new information becomes available and as claims develop.

Debt_and_Credit_Arrangements

Debt and Credit Arrangements	12 Months Ended
Debt and Credit Arrangements	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt and Credit Arrangements	(6) Debt and Credit Arrangements
	(a) Long term debt consisted of the following:


		December 31
		2014		2013
		(in millions)
	5.75% notes due May 15, 2018	$	600	$	600
	6.6% debentures due August 15, 2018		100		100
	6.8% debentures due November 15, 2031		200		200
	6% notes due May 11, 2037		800		800
	6.5% notes due May 15, 2038		600		600
	6.375% capital securities due March 29, 2067		1,000		1,000

		$	3,300	$	3,300


	All of the outstanding notes and debentures are unsecured obligations of Chubb. Chubb generally may redeem some or all of the notes and debentures prior to maturity in accordance with the terms of each debt instrument.
	Chubb has outstanding $1.0 billion of unsecured junior subordinated capital securities. The capital securities will become due on April 15, 2037, the scheduled maturity date, but only to the extent that Chubb has received sufficient net proceeds from the sale of certain qualifying capital securities. Chubb must use its commercially reasonable efforts, subject to certain market disruption events, to sell enough qualifying capital securities to permit repayment of the capital securities on the scheduled maturity date or as soon thereafter as possible. Any remaining outstanding principal amount will be due on March 29, 2067, the final maturity date. The capital securities bear interest at a fixed rate of 6.375% through April 14, 2017. Thereafter, the capital securities will bear interest at a rate equal to the three-month LIBOR rate plus 2.25%. Subject to certain conditions, Chubb has the right to defer the payment of interest on the capital securities for a period not exceeding ten consecutive years. During any such period, interest will continue to accrue and Chubb generally may not declare or pay any dividends on or purchase any shares of its capital stock.
	In connection with the issuance of the capital securities, Chubb entered into a replacement capital covenant in which it agreed that it will not repay, redeem, or purchase the capital securities before March 29, 2047, unless, subject to certain limitations, it has received proceeds from the sale of specified replacement capital securities. The replacement capital covenant is not intended for the benefit of holders of the capital securities and may not be enforced by them. The replacement capital covenant is for the benefit of holders of one or more designated series of Chubb’s indebtedness, which initially was and continues to be its 6.8% debentures due November 15, 2031.
	Subject to the replacement capital covenant, the capital securities may be redeemed, in whole or in part, at any time on or after April 15, 2017 at a redemption price equal to the principal amount plus any accrued interest or prior to April 15, 2017 at a redemption price equal to the greater of (i) the principal amount or (ii) a make-whole amount, in each case plus any accrued interest.
	The amounts of long term debt due annually during the five years subsequent to December 31, 2014 are as follows:


	Years Ending December 31	(in millions)
	2015	$	—
	2016		—
	2017		—
	2018		700
	2019		—
	(b) Interest costs of $209 million, $213 million and $224 million were incurred in 2014, 2013 and 2012, respectively. Interest paid was $205 million, $213 million and $220 million in 2014, 2013 and 2012, respectively.
	(c) Chubb has a revolving credit agreement with a syndicate of banks that provides for up to $500 million of unsecured borrowings. The revolving credit facility is available for general corporate purposes. The agreement has a maturity date of September 24, 2017. Various interest rate options are available to Chubb, all of which are based on market interest rates. The agreement contains customary restrictive covenants, including a covenant to maintain a minimum adjusted consolidated shareholders’ equity. At December 31, 2014, Chubb was in compliance with all such covenants. Chubb is permitted to request an increase in the credit available under the agreement, no more than two times per year, up to a maximum facility amount of $750 million. Chubb is permitted to request on two occasions, at any time during the term of the agreement, an extension of the maturity date for an additional one year period. There have been no borrowings under this agreement. On the maturity date of the agreement, any borrowings then outstanding become payable.

Federal_and_Foreign_Income_Tax

Federal and Foreign Income Tax	12 Months Ended
Federal and Foreign Income Tax	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal and Foreign Income Tax	(7) Federal and Foreign Income Tax
	(a) Income tax expense and taxes paid consisted of the following components:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Income tax expense
	Current tax
	United States	$	617		$	791		$	276
	Foreign		124			91			143
	Deferred tax, principally United States		20			10			32

		$	761		$	892		$	451


	Federal and foreign income taxes paid	$	571		$	789		$	472

	Income before federal and foreign income taxes from U.S. operations was $2,424 million, $2,766 million and $1,373 million in 2014, 2013 and 2012, respectively. Income before federal and foreign income taxes from foreign operations was $437 million, $471 million and $623 million in 2014, 2013 and 2012, respectively.
	(b) The effective income tax rate is different than the statutory federal corporate tax rate. The reasons for the different effective tax rate were as follows:


		Years Ended December 31
		2014						2013						2012
		Amount			% of			Amount			% of			Amount			% of
					Pre-Tax						Pre-Tax						Pre-Tax
					Income						Income						Income
		(in millions)
	Income before federal and foreign income tax	$	2,861					$	3,237					$	1,996

	Tax at statutory federal income tax rate	$	1,001			35	%	$	1,133			35	%	$	699			35	%
	Tax exempt interest income		(212	)		(7.4	)		(222	)		(6.8	)		(233	)		(11.7	)
	Other, net		(28	)		(1.0	)		(19	)		(.6	)		(15	)		(.7	)

	Federal and foreign income tax	$	761			26.6	%	$	892			27.6	%	$	451			22.6	%

	(c) The tax effects of temporary differences that gave rise to deferred income tax assets and liabilities were as follows:


		December 31
		2014			2013
		(in millions)
	Deferred income tax assets
	Unpaid losses and loss expenses	$	509		$	524
	Unearned premiums		364			350
	Foreign tax credits		963			867
	Employee compensation		144			142
	Postretirement benefits		272			95
	Other-than-temporary impairment losses		298			291
	Other, net		29			—

	Total		2,579			2,269

	Deferred income tax liabilities
	Deferred policy acquisition costs		367			356
	Unremitted earnings of foreign subsidiaries		1,075			970
	Unrealized appreciation of investments		944			660
	Other invested assets		208			184
	Other, net		—			52

	Total		2,594			2,222

	Net deferred income tax asset (liability)	$	(15	)	$	47


Deferred income tax assets were established related to the expected future U.S. tax benefit of losses incurred by a foreign subsidiary of the Corporation. Realization of these deferred tax assets depends on the subsidiary’s ability to generate sufficient taxable income in future periods. A valuation allowance of $13 million was recorded at December 31, 2014 and 2013 to reflect management’s assessment that the realization of a portion of the deferred tax assets is uncertain due to the inability of the foreign subsidiary to generate sufficient taxable income in the near term. Although realization of the remaining deferred tax assets is not assured, management believes it is more likely than not that such deferred tax assets will be realized.
(d) Chubb and its U.S. subsidiaries file a consolidated federal income tax return with the U.S. Internal Revenue Service (IRS). The Corporation also files income tax returns with various state and foreign tax authorities. The U.S. income tax returns for years prior to 2010 are no longer subject to examination by the IRS. The examination of the U.S. income tax returns for 2010 and 2011 is expected to be completed in 2015. Management does not anticipate any assessments for tax years that remain subject to examination that would have a material effect on the Corporation’s financial position or results of operations.

Reinsurance

Reinsurance	12 Months Ended
Reinsurance	Dec. 31, 2014
Insurance [Abstract]
Reinsurance	(8) Reinsurance
	In the ordinary course of business, the P&C Group assumes and cedes reinsurance with other insurance companies. Reinsurance is ceded to provide greater diversification of risk and to limit the P&C Group’s maximum net loss arising from large risks or catastrophic events.
	A large portion of the P&C Group’s ceded reinsurance is effected under contracts known as treaties under which all risks meeting prescribed criteria are automatically covered. Most of these arrangements consist of excess of loss and catastrophe contracts that protect against a specified part or all of certain types of losses over stipulated amounts arising from any one occurrence or event. In certain circumstances, reinsurance is also effected by negotiation on individual risks.
	Ceded reinsurance contracts do not relieve the P&C Group of the primary obligation to its policyholders. Thus, an exposure exists with respect to reinsurance ceded to the extent that any reinsurer is unable or unwilling to meet its obligations assumed under the reinsurance contracts. The P&C Group monitors the financial strength of its reinsurers on an ongoing basis.
	Premiums earned and insurance losses and loss expenses are reported net of reinsurance in the consolidated statements of income.
	The effect of reinsurance on the premiums written and earned of the P&C Group was as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Direct premiums written	$	12,976		$	12,804		$	12,647
	Assumed reinsurance		596			503			423
	Ceded reinsurance		(980	)		(1,083	)		(1,200	)

	Net premiums written	$	12,592		$	12,224		$	11,870


	Direct premiums earned	$	12,776		$	12,717		$	12,596
	Assumed reinsurance		562			476			422
	Ceded reinsurance		(1,010	)		(1,127	)		(1,180	)

	Net premiums earned	$	12,328		$	12,066		$	11,838

	Ceded losses and loss expenses, which reduce losses and loss expenses incurred, were $273 million, $400 million and $586 million in 2014, 2013 and 2012, respectively.

StockBased_Employee_Compensati

Stock-Based Employee Compensation Plans	12 Months Ended
Stock-Based Employee Compensation Plans	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Employee Compensation Plans	(9) Stock-Based Employee Compensation Plans
	The Corporation has a stock-based employee compensation plan, The Chubb Corporation Long-Term Incentive Plan. The compensation cost with respect to the plan was $85 million, $89 million and $84 million in 2014, 2013 and 2012, respectively. The total income tax benefit included in net income with respect to the stock-based compensation arrangement was $30 million, $31 million and $29 million in 2014, 2013 and 2012, respectively.
	As of December 31, 2014, there was $78 million of unrecognized compensation cost related to nonvested awards. That cost is expected to be reflected in operating results over a weighted average period of 1.7 years.
	The Long-Term Incentive Plan provides for the granting of restricted stock units, restricted stock, performance units, stock options and other stock-based awards to the Corporation’s employees. The maximum number of shares of Chubb’s common stock with respect to which stock-based awards may be granted under the plan most recently approved by shareholders is 7.4 million shares. Additional shares of Chubb’s common stock may also become available for grant in connection with the cancellation, forfeiture and/or settlement of awards previously granted. At December 31, 2014, 8.2 million shares were available for grant.
	Restricted Stock Units, Performance Units and Restricted Stock
	Restricted stock unit awards are payable in cash, in shares of Chubb’s common stock or in a combination of both. Restricted stock units are not considered to be outstanding shares of common stock, have no voting rights and are subject to forfeiture during the restriction period. Holders of restricted stock units may receive dividend equivalents. Performance unit awards are based on the achievement of performance goals over three year performance periods. Performance unit awards are payable in cash, in shares of Chubb’s common stock or in a combination of both. Restricted stock awards consist of shares of Chubb’s common stock granted at no cost to the employees. Shares of restricted stock become outstanding when granted, receive dividends and have voting rights. The shares are subject to forfeiture and to restrictions that prevent their sale or transfer during the restriction period.
	An amount equal to the fair value at the date of grant of restricted stock unit awards and performance unit awards is expensed over the vesting period. The weighted average fair value per share of the restricted stock units granted was $86.67, $83.75 and $68.64 in 2014, 2013 and 2012, respectively. The weighted average fair value per share of the performance units granted was $76.32, $98.46 and $63.38 in 2014, 2013 and 2012, respectively.
	Additional information with respect to restricted stock units and performance units is as follows:


			Restricted Stock Units					Performance Units*
			Number			Weighted Average		Number			Weighted Average
			of Shares			Grant Date		of Shares			Grant Date
						Fair Value					Fair Value
	Nonvested, January 1, 2014			2,127,647		$	70.23		861,141		$	79.87
	Granted			625,197			86.67		421,271			76.32
	Vested**			(762,349	)		60.53		(456,176	)		63.38
	Forfeited			(82,551	)		81.16		(4,041	)		77.87

	Nonvested, December 31, 2014			1,907,944			79.02		822,195			87.21


		*	The number of shares earned may range from 0% to 200% of the performance units shown in the table above.

		**	The performance units earned in 2014 were 35.2% of the vested shares shown in the table, or 160,574 shares.
	The total fair value of restricted stock units that vested during 2014, 2013 and 2012 was $66 million, $72 million and $74 million, respectively. The total fair value of performance units that vested during 2014, 2013 and 2012 was $17 million, $64 million and $70 million, respectively.

	Stock Options
	Stock options are granted at exercise prices not less than the fair value of Chubb’s common stock on the date of grant. The terms and conditions upon which options become exercisable may vary among grants. Options expire no later than ten years from the date of grant.
	An amount equal to the fair value of stock options at the date of grant is expensed over the vesting period. The weighted average fair value per stock option granted during 2014, 2013 and 2012 was $15.48, $14.95 and $11.95, respectively. The fair value of each stock option was estimated on the date of grant using the Black-Scholes option pricing model.

	Additional information with respect to stock options is as follows:


			Number			Weighted		Weighted Average			Aggregate
			of Shares			Average		Remaining			Intrinsic Value
						Exercise Price		Contractual Term
								(in years)			(in millions)
	Outstanding, January 1, 2014			251,687		$	62.52
	Granted			65,605			86.59
	Exercised			(54,932	)		59.08
	Forfeited			(6,949	)		82.83

	Outstanding, December 31, 2014			255,411			68.89		6.6		$	9

	Exercisable, December 31, 2014			128,880			55.24		4.8			6
	The total intrinsic value of the stock options exercised during 2014, 2013 and 2012 was $2 million, $16 million and $40 million, respectively. The Corporation received cash of $3 million, $10 million and $47 million during 2014, 2013 and 2012, respectively, from the exercise of stock options. The tax benefit realized with respect to the exercise of stock options was $1 million, $5 million and $13 million during 2014, 2013 and 2012, respectively.

Employee_Benefits

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employee Benefits	(10) Employee Benefits
	(a) The Corporation has several non-contributory defined benefit pension plans covering substantially all employees. 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 Corporation changed the formula for providing pension benefits 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. 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.
	The Corporation’s funding policy is to contribute amounts that meet regulatory requirements plus additional amounts determined by management based on actuarial valuations, market conditions and other factors. This may result in no contribution being made in a particular year.
	The Corporation also provides certain other postretirement benefits, principally health care and life insurance, to retired employees and their beneficiaries and covered dependents. Substantially all employees hired before January 1, 1999 may become eligible for these benefits upon retirement if they meet minimum age and years of service requirements. Health care coverage is contributory. Retiree contributions vary based upon a retiree’s age, type of coverage and years of service with the Corporation. Life insurance coverage is non-contributory.
	The Corporation funds a portion of the health care benefits obligation where such funding can be accomplished on a tax effective basis. Benefits are paid as covered expenses are incurred.
	The funded status of the pension and other postretirement benefit plans at December 31, 2014 and 2013 was as follows:


			Pension								Other
			Benefits								Postretirement
											Benefits
			2014				2013				2014				2013
			(in millions)
	Benefit obligation, beginning of year		$	2,777			$	2,894			$	394			$	470
	Service cost			86				95				10				13
	Interest cost			140				125				19				19
	Actuarial loss (gain)			536				(261	)			74				(97	)
	Benefits paid			(85	)			(75	)			(10	)			(11	)
	Foreign currency translation effect			(19	)			(1	)			(2	)			—

	Benefit obligation, end of year			3,435				2,777				485				394


	Plan assets at fair value, beginning of year			2,717				2,305				130				96
	Actual return on plan assets			240				409				12				27
	Employer contributions			92				82				11				18
	Benefits paid			(85	)			(75	)			(10	)			(11	)
	Foreign currency translation effect			(18	)			(4	)			—				—

	Plan assets at fair value, end of year			2,946				2,717				143				130

	Funded status at end of year, included in other liabilities		$	489			$	60			$	342			$	264

	Net actuarial loss (gain) and prior service cost included in accumulated other comprehensive income that were not yet recognized as components of net benefit costs at December 31, 2014 and 2013 were as follows:


			Pension								Other
			Benefits								Postretirement
											Benefits
			2014				2013				2014				2013
			(in millions)
	Net actuarial loss (gain)		$	842			$	396			$	58			$	(13	)
	Prior service cost			14				16				1				1

			$	856			$	412			$	59			$	(12	)


	The accumulated benefit obligation for the pension plans was $2,923 million and $2,381 million at December 31, 2014 and 2013, 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 on the previous page in that the accumulated benefit obligation includes no assumptions regarding future compensation levels.
	The weighted average assumptions used to determine the benefit obligations were as follows:


			Pension Benefits								Other
											Postretirement
											Benefits
			2014				2013				2014				2013
	Discount rate			4.3	%			5.2	%			4.3	%			5.2	%
	Rate of compensation increase			4.5				4.5				—				—
	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 for the years ended December 31, 2014, 2013 and 2012 were as follows:


			Pension Benefits												Other
			Pension Benefits												Postretirement Benefits
			2014				2013				2012				2014				2013			2012
			(in millions)
Costs reflected in net income
Service cost		$	86			$	95			$	88			$	10			$	13		$	12
Interest cost			140				125				124				19				19			20
Expected return on plan assets			(186	)			(165	)			(155	)			(9	)			(7	)		(6	)
Amortization of net actuarial loss and prior service cost and other			35				90				80				—				3			3

		$	75			$	145			$	137			$	20			$	28		$	29

Changes in plan assets and benefit obligations recognized in other comprehensive income
Net actuarial loss (gain)		$	479			$	(505	)		$	139			$	71			$	(117	)	$	(11	)
Amortization of net actuarial loss and prior service cost and other			(35	)			(90	)			(80	)			—				(3	)		(3	)

		$	444			$	(595	)		$	59			$	71			$	(120	)	$	(14	)

The estimated aggregate net actuarial loss and prior service cost that will be amortized from accumulated other comprehensive income into net benefit costs during 2015 for the pension and other postretirement benefit plans is $65 million.
The weighted average assumptions used to determine net pension and other postretirement benefit costs were as follows:


		Pension Benefits												Other
		Pension Benefits												Postretirement Benefits
		2014				2013				2012				2014				2013			2012
Discount rate			5.20%				4.40%				5.00%				5.20%				4.40%			5.00%
Rate of compensation increase			4.5				4.5				4.5				—				—			—
Expected long term rate of return on plan assets			7.5				7.5				7.75				7.5				7.5			7.75

The weighted average health care cost trend rate assumptions used to measure the expected cost of medical benefits were as follows:


		December 31
		2014				2013
Health care cost trend rate for next year			7.3	%			7.6	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)			4.5				4.5
Year that the rate reaches the ultimate trend rate			2028				2028
The health care 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, 2014 by approximately $92 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2014 by approximately $5 million. A one percent decrease in the trend rate for each year would decrease the accumulated other postretirement benefit obligation at December 31, 2014 by approximately $73 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2014 by approximately $4 million.
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 U.S. equity securities and fixed maturities. The Corporation seeks 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% to 65% invested in equity securities, with the remainder primarily invested in fixed maturities. The Corporation rebalances its pension assets to the target allocation as market conditions permit. The Corporation 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.
The fair values of the pension plan assets were as follows:


		December 31
		2014				2013
		(in millions)
Short term investments		$	48			$	37

Fixed maturities
U.S. government and government agency and authority obligations			209				224
Corporate bonds			419				371
Foreign government and government agency obligations			137				104
Mortgage-backed securities			228				217

Total fixed maturities			993				916

Equity securities			1,850				1,718

Other assets			55				46

		$	2,946			$	2,717

At December 31, 2014 and 2013, pension plan assets invested in pooled funds had a fair value of $1,556 million and $1,425 million, respectively.
At December 31, 2014 and 2013, other postretirement benefit plan assets were invested in pooled funds and had a fair value of $143 million and $130 million, respectively.

The estimated benefits expected to be paid in each of the next five years and in the aggregate for the following five years are as follows:


Years Ending December 31		Pension				Other
		Benefits				Postretirement
						Benefits
		(in millions)
2015		$	105			$	12
2016			115				14
2017			151				15
2018			132				17
2019			143				18
2020-2024			868				117
(b) The Corporation has a defined contribution benefit plan, the Capital Accumulation Plan, in which substantially all employees are eligible to participate. Under this plan, the employer makes matching contributions equal to 100% of each eligible employee’s pre-tax elective contributions, up to 4% of the employee’s eligible compensation. Contributions are invested at the election of the employee in Chubb’s common stock or in various other investment funds. The expense recognized with respect to the plan was $30 million, $29 million and $26 million in 2014, 2013 and 2012, respectively.

Comprehensive_Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Comprehensive Income	(11) Comprehensive Income
	Comprehensive income is defined as all changes in shareholders’ equity, except those arising from transactions with shareholders. Comprehensive income includes net income and other comprehensive income or loss, which for the Corporation consists of changes in unrealized appreciation or depreciation of investments carried at fair value, changes in unrealized other-than-temporary impairment losses of fixed maturities, changes in postretirement benefit costs not yet recognized in net income and changes in foreign currency translation gains or losses.
	The components of other comprehensive income or loss were as follows:


			Years Ended December 31
			2014									2013									2012
			Before			Income			Net of			Before			Income			Net of			Before			Income			Net of
			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax
												(in millions)
	Net unrealized holding gains (losses) arising		$	1,032		$	361		$	671		$	(1,000	)	$	(350	)	$	(650	)	$	556		$	195		$	361
	during the year
	Unrealized other-than-temporary			—			—			—			—			—			—			(2	)		(1	)		(1	)
	impairment losses arising during the year
	Reclassification adjustment for net realized			220			77			143			212			74			138			127			44			83
	gains included in net income

	Net unrealized gains (losses) recognized in other comprehensive income or loss			812			284			528			(1,212	)		(424	)		(788	)		427			150			277


	Postretirement benefit gain (loss) not yet			(550	)		(192	)		(358	)		622			218			404			(128	)		(45	)		(83	)
	recognized in net income arising during the year
	Reclassification adjustment for the			(35	)		(13	)		(22	)		(93	)		(33	)		(60	)		(83	)		(30	)		(53	)
	amortization of net actuarial loss and prior service cost included in net income (a)

	Net change in postretirement benefit			(515	)		(179	)		(336	)		715			251			464			(45	)		(15	)		(30	)
	costs not yet recognized in net income


	Foreign currency translation losses			(180	)		(63	)		(117	)		(111	)		(39	)		(72	)		(16	)		(5	)		(11	)

	Total other comprehensive income (loss)		$	117		$	42		$	75		$	(608	)	$	(212	)	$	(396	)	$	366		$	130		$	236


	(a)	Postretirement benefit costs recognized in net income during the period are included among several of the loss and expense components presented in the consolidated statements of income.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	12 Months Ended
Commitments and Contingent Liabilities	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	(12) Commitments and Contingent Liabilities
	(a) Chubb Financial Solutions (CFS), a wholly owned subsidiary of Chubb, participated in derivative financial instruments and has been in runoff since 2003. At December 31, 2014, CFS’s remaining derivative contracts were insignificant.
	CFS’s aggregate exposure, or retained risk, from its derivative contracts is referred to as notional amount. Notional amounts are used to calculate the exchange of contractual cash flows and are not necessarily representative of the potential for gain or loss. Notional amounts are not recorded on the balance sheet. The notional amount of future obligations under CFS’s derivative contracts at December 31, 2014 and 2013 was approximately $55 million and $80 million, respectively.
	Future obligations with respect to the derivative contracts are carried at fair value at the balance sheet date and are included in other liabilities. The fair value of future obligations under CFS’s derivative contracts at both December 31, 2014 and 2013 was approximately $2 million.
	(b) The Corporation occupies office facilities under lease agreements that expire at various dates through 2029; such leases are generally renewed or replaced by other leases. Most facility leases contain renewal options for increments ranging from two to ten years. The Corporation also leases data processing, office and transportation equipment. All leases are operating leases.
	Rent expense was as follows:


		Years Ended
		December 31
		2014		2013		2012
		(in millions)
	Office facilities	$	67	$	71	$	71
	Equipment		13		13		11

		$	80	$	84	$	82

	At December 31, 2014, future minimum rental payments required under non-cancellable operating leases were as follows:


	Years Ending December 31	(in millions)
	2015	$	63
	2016		52
	2017		47
	2018		40
	2019		30
	After 2019		81

		$	313

	(c) The Corporation had commitments totaling $860 million at December 31, 2014 to fund limited partnership investments. These commitments can be called by the partnerships (generally over a period of 5 years or less) to fund certain partnership expenses or the purchase of investments.

Segments_Information

Segments Information	12 Months Ended
Segments Information	Dec. 31, 2014
Segment Reporting [Abstract]
Segments Information	(13) Segments Information

	The principal business of the Corporation is the sale of property and casualty insurance. The profitability of the property and casualty insurance business depends on the results of both underwriting operations and investments, which are viewed as two distinct operations. The underwriting operations are managed and evaluated separately from the investment function.
	The P&C Group underwrites most lines of property and casualty insurance. Underwriting operations consist of four separate business units: personal insurance, commercial insurance, specialty insurance and reinsurance assumed. The personal segment targets the personal insurance market. The personal classes include automobile, homeowners and other personal coverages. The commercial segment includes those classes of business that are generally available in broad markets and are of a more commodity nature. Commercial classes include multiple peril, casualty, workers’ compensation and property and marine. The specialty segment includes those classes of business that are available in more limited markets since they require specialized underwriting and claim settlement. Specialty classes include professional liability coverages and surety. The reinsurance assumed business has been in runoff since the transfer of the ongoing reinsurance assumed business to a reinsurance company in 2005.
	Corporate and other includes investment income earned on corporate invested assets, corporate expenses and the results of the Corporation’s non-insurance subsidiaries.
	Performance of the property and casualty underwriting segments is measured based on statutory underwriting results. Statutory underwriting profit is arrived at by reducing premiums earned by losses and loss expenses incurred and statutory underwriting expenses incurred. Under statutory accounting principles applicable to property and casualty insurance companies, policy acquisition and other underwriting expenses are recognized immediately, not at the time premiums are earned.
	Management uses underwriting results determined in accordance with GAAP to assess the overall performance of the underwriting operations. Underwriting income determined in accordance with GAAP is defined as premiums earned less losses and loss expenses incurred and GAAP underwriting expenses incurred. To convert statutory underwriting results to a GAAP basis, certain policy acquisition expenses are deferred and amortized over the period in which the related premiums are earned.
	Investment income performance is measured based on investment income net of investment expenses, excluding realized investment gains and losses.
	Distinct investment portfolios are not maintained for each underwriting segment. Property and casualty invested assets are available for payment of losses and expenses for all classes of business. Therefore, such assets and the related investment income are not allocated to underwriting segments.

	Revenues, income before income tax and assets of each operating segment were as follows:


			Years Ended December 31
			2014				2013				2012
			(in millions)
	Revenues
	Property and casualty insurance
	Premiums earned
	Personal insurance		$	4,418			$	4,214			$	4,024
	Commercial insurance			5,281				5,237				5,144
	Specialty insurance			2,628				2,618				2,666

	Total insurance			12,327				12,069				11,834
	Reinsurance assumed			1				(3	)			4

				12,328				12,066				11,838
	Investment income			1,368				1,436				1,518

	Total property and casualty insurance			13,696				13,502				13,356
	Corporate and other			33				43				46
	Realized investment gains, net			369				402				193

	Total revenues		$	14,098			$	13,947			$	13,595

	Income (loss) before income tax
	Property and casualty insurance
	Underwriting
	Personal insurance		$	370			$	509			$	192
	Commercial insurance			492				692				44
	Specialty insurance			495				406				262

	Total insurance			1,357				1,607				498
	Reinsurance assumed			—				9				47

				1,357				1,616				545
	Increase in deferred policy acquisition costs			45				59				3

	Underwriting income			1,402				1,675				548
	Investment income			1,329				1,391				1,482
	Other income (charges)			(4	)			6				10

	Total property and casualty insurance			2,727				3,072				2,040
	Corporate and other			(235	)			(237	)			(237	)
	Realized investment gains, net			369				402				193

	Total income before income tax		$	2,861			$	3,237			$	1,996



			December 31
			2014				2013				2012
			(in millions)
	Assets
Property and casualty insurance		$	49,297			$	48,278			$	49,441
Corporate and other			2,078				2,248				2,830
Adjustments and eliminations			(89	)			(93	)			(87	)

Total assets		$	51,286			$	50,433			$	52,184


The international business of the property and casualty insurance segments is conducted primarily through subsidiaries that operate solely outside of the United States. Their assets and liabilities are located principally in the countries where the insurance risks are written. International business is also written by branch offices of a U.S. subsidiary.
Revenues of the P&C Group by geographic area were as follows:


		Years Ended December 31
		2014				2013				2012
		(in millions)
Revenues
United States		$	10,448			$	10,205			$	9,996
International			3,248
							3,297
											3,360

Total		$	13,696			$	13,502			$	13,356

Fair_Values_of_Financial_Instr

Fair Values of Financial Instruments	12 Months Ended
Fair Values of Financial Instruments	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Values of Financial Instruments	(14) Fair Values of Financial Instruments
	(a) Fair values of financial instruments are determined by management using valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Fair values are generally measured using quoted prices in active markets for identical assets or liabilities or other inputs, such as quoted prices for similar assets or liabilities, that are observable, either directly or indirectly. In those instances where observable inputs are not available, fair values are measured using unobservable inputs for the asset or liability. Unobservable inputs reflect the Corporation’s own assumptions about the assumptions that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. Fair value estimates derived from unobservable inputs are affected by the assumptions used, including the discount rates and the estimated amounts and timing of future cash flows. The derived fair value estimates cannot be substantiated by comparison to independent markets and are not necessarily indicative of the amounts that would be realized in a current market exchange. Certain financial instruments, particularly insurance contracts, are excluded from fair value disclosure requirements.
	The methods and assumptions used to estimate the fair values of financial instruments are as follows:
	(i) The carrying value of short term investments approximates fair value due to the short maturities of these investments.
	(ii) Fair values of fixed maturities are determined by management, utilizing prices obtained from a third party, nationally recognized pricing service or, in the case of securities for which prices are not provided by a pricing service, from third party brokers. For fixed maturities that have quoted prices in active markets, market quotations are provided. For fixed maturities that do not trade on a daily basis, the pricing service and brokers provide fair value estimates using a variety of inputs including, but not limited to, benchmark yields, reported trades, broker/dealer quotes, issuer spreads, bids, offers, reference data, prepayment rates and measures of volatility. Management reviews on an ongoing basis the reasonableness of the methodologies used by the relevant pricing service and brokers. In addition, management, using the prices received for the securities from the pricing service and brokers, determines the aggregate portfolio price performance and reviews it against applicable indices. If management believes that significant discrepancies exist, it will discuss these with the relevant pricing service or broker to resolve the discrepancies.
	(iii) Fair values of equity securities are determined by management, utilizing quoted market prices.
	(iv) Fair values of long term debt issued by Chubb are determined by management, utilizing prices obtained from a third party, nationally recognized pricing service.

	The carrying values and fair values of financial instruments were as follows:


			December 31
			2014						2013
			Carrying			Fair			Carrying			Fair
			Value			Value			Value			Value
			(in millions)
	Assets
	Invested assets
	Short term investments		$	1,318		$	1,318		$	2,114		$	2,114
	Fixed maturities (Note 2)			38,780			38,780			37,091			37,091
	Equity securities			1,964			1,964			1,810			1,810
	Liabilities
	Long term debt (Note 6)			3,300			4,013			3,300			3,806
	At December 31, 2014 and 2013, a pricing service provided fair value amounts for approximately 99% of the Corporation’s fixed maturities. The prices obtained from a pricing service and brokers generally are non-binding, but are reflective of current market transactions in the applicable financial instruments.
	At December 31, 2014 and 2013, the Corporation held an insignificant amount of financial instruments in its investment portfolio for which a lack of market liquidity impacted the determination of fair value.
	The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels as follows:


	Level 1 —		Unadjusted quoted prices in active markets for identical financial instruments.

	Level 2 —		Other inputs that are observable for the financial instrument, either directly or indirectly.

	Level 3 —		Significant unobservable inputs.
	The fair value of financial instruments categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:


			December 31, 2014
			Level 1			Level 2			Level 3			Total
			(in millions)
	Assets
	Short term investments		$	206		$	1,112		$	—		$	1,318

	Fixed maturities
	Tax exempt			—			19,769			3			19,772

	Taxable
	U.S. government and government agency and authority obligations			—			2,007			—			2,007
	Corporate bonds			—			8,912			116			9,028
	Foreign government and government agency obligations			—			6,663			9			6,672
	Residential mortgage-backed securities			—			210			1			211
	Commercial mortgage-backed securities			—			1,090			—			1,090

				—			18,882			126			19,008

	Total fixed maturities			—			38,651			129			38,780

	Equity securities			1,958			—			6			1,964

			$	2,164		$	39,763		$	135		$	42,062

	Liabilities
	Long term debt		$	—		$	4,013		$	—		$	4,013



		December 31, 2013
		Level 1			Level 2			Level 3			Total
		(in millions)
Assets
Short term investments		$	399		$	1,715		$	—		$	2,114

Fixed maturities
Tax exempt			—			18,416			5			18,421

Taxable
U.S. government and government agency and authority obligations			—			802			—			802
Corporate bonds			—			9,179			135			9,314
Foreign government and government agency obligations			—			6,881			9			6,890
Residential mortgage-backed securities			—			293			6			299
Commercial mortgage-backed securities			—			1,345			20			1,365

			—			18,500			170			18,670

Total fixed maturities			—			36,916			175			37,091

Equity securities			1,803			—			7			1,810


			$2,202			$38,631			$182			$41,015

Liabilities
Long term debt
Long term debt		$	—		$	3,806		$	—		$	3,806

(b) The methods and assumptions used to estimate the fair value of the Corporation’s pension plan and other postretirement benefit plan assets, other than assets invested in pooled funds, are similar to the methods and assumptions used for the Corporation’s other financial instruments. The fair value of pooled funds is based on the net asset value of the funds.
Based on the fair value hierarchy, the fair value of the Corporation’s pension plan assets categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:


		December 31, 2014
		Level 1			Level 2			Level 3			Total
		(in millions)
Short term investments		$	—		$	48		$	—		$	48

Fixed maturities
U.S. government and government agency and authority obligations			—			209			—			209
Corporate bonds			—			419			—			419
Foreign government and government agency obligations			—			137			—			137
Mortgage-backed securities			—			228			—			228

Total fixed maturities			—			993			—			993

Equity securities			629			1,221			—			1,850

Other assets			28			20			7			55

		$	657		$	2,282		$	7		$	2,946



		December 31, 2013
		Level 1			Level 2			Level 3			Total
		(in millions)
Short term investments		$	—		$	37		$	—		$	37

Fixed maturities
U.S. government and government agency			—			224			—			224
and authority obligations			—			224			—			224
Corporate bonds			—			370			1			371
Foreign government and government			—			104			—			104
agency obligations			—			104			—			104
Mortgage-backed securities			—			211			6			217

Total fixed maturities			—			909			7			916

Equity securities			573			1,145			—			1,718

Other assets			21			14			11			46

		$	594		$	2,105		$	18		$	2,717

The fair value of the Corporation’s other postretirement benefit plan assets was $143 million and $130 million at December 31, 2014 and 2013, respectively. Based on the fair value hierarchy, the fair value of these assets was categorized as Level 1 based upon the lowest level of input that was significant to the fair value measurement.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
Earnings Per Share	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	(15) Earnings Per Share
	Basic earnings per share is computed by dividing net income by the weighted average shares outstanding during the year. The computation of diluted earnings per share reflects the potential dilutive effect, using the treasury stock method, of outstanding awards under stock-based employee compensation plans.
	The following table sets forth the computation of basic and diluted earnings per share:


		Years Ended December 31
		2014		2013		2012
		(in millions except for per
		share amounts)
	Basic earnings per share:
	Net income	$	2,100	$	2,345	$	1,545

	Weighted average shares outstanding		242.9		258.2		269.5

	Basic earnings per share	$	8.65	$	9.08	$	5.73

	Diluted earnings per share:
	Net income	$	2,100	$	2,345	$	1,545

	Weighted average shares outstanding		242.9		258.2		269.5
	Additional shares from assumed issuance of shares under stock-based compensation awards		0.6		1.2		1.9

	Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share		243.5		259.4		271.4

	Diluted earnings per share	$	8.62	$	9.04	$	5.69

Shareholders_Equity

Shareholders' Equity	12 Months Ended
Shareholders' Equity	Dec. 31, 2014
Equity [Abstract]
Shareholders' Equity	(16) Shareholders’ Equity
	(a) The authorized but unissued preferred shares may be issued in one or more series and the shares of each series shall have such rights as fixed by the Board of Directors.
	(b) The activity of Chubb’s common stock was as follows:


		Years Ended December 31
		2014			2013			2012
		(number of shares)
	Common stock issued
	Balance, beginning and end of year		371,980,460			371,980,460			371,980,460

	Treasury stock
	Balance, beginning of year		123,673,969			110,217,445			99,519,509
	Repurchase of shares		16,893,455			14,887,701			13,094,640
	Share activity under stock-based employee compensation plans		(1,016,353	)		(1,431,177	)		(2,396,704	)

	Balance, end of year		139,551,071			123,673,969			110,217,445

	Common stock outstanding, end of year		232,429,389			248,306,491			261,763,015

	(c) As of December 31, 2014, $52 million remained under the share repurchase authorization that was approved by the Board of Directors on January 30, 2014. On January 29, 2015, the Board of Directors authorized the repurchase of up to $1.3 billion of Chubb’s common stock. These authorizations have no expiration date.
	(d) The property and casualty insurance subsidiaries are required to file annual statements with insurance regulatory authorities prepared on an accounting basis prescribed or permitted by such authorities (statutory basis). For such subsidiaries, statutory accounting principles differ in certain respects from GAAP.
	A comparison of shareholders’ equity on a GAAP basis and policyholders’ surplus on a statutory basis is as follows:


		December 31
		2014						2013
		GAAP			Statutory			GAAP			Statutory
		(in millions)
	P&C Group	$	17,786		$	15,127		$	17,398		$	15,024

	Corporate and other		(1,490	)					(1,301	)

		$	16,296					$	16,097

	A comparison of GAAP and statutory net income (loss) is as follows:


		Years Ended December 31
		2014						2013					2012
		GAAP			Statutory			GAAP			Statutory		GAAP			Statutory
		(in millions)
	P&C Group	$	2,330		$	2,399		$	2,480		$	2,485	$	1,791		$	1,936

	Corporate and other		(230	)					(135	)				(246	)

		$	2,100					$	2,345				$	1,545


	At December 31, 2014, the aggregate statutory capital and surplus of the property and casualty insurance subsidiaries was $15.1 billion, of which $14.8 billion related to Federal Insurance Company (Federal). Federal is a direct subsidiary of Chubb and is the direct or indirect parent of most of Chubb’s other insurance subsidiaries. A risk-based capital formula is used by U.S. state regulatory authorities to identify insurance companies that may be undercapitalized and that may merit regulatory attention. The risk-based capital requirement level is calculated as two times the authorized control level risk-based capital and is the level at or below which company or state regulatory action would be required. At December 31, 2014, the risk-based capital requirement level for Federal was $5.0 billion.
	(e) As a holding company, Chubb’s ability to continue to pay dividends to shareholders and to satisfy its obligations, including the payment of interest and principal on debt obligations, relies on the availability of liquid assets, which is dependent in large part on the dividend paying ability of its property and casualty insurance subsidiaries. The Corporation’s property and casualty insurance subsidiaries are subject to laws and regulations in the jurisdictions in which they operate that restrict the amount of dividends they may pay without the prior approval of regulatory authorities. The restrictions are generally based on net income and on certain levels of policyholders’ surplus as determined in accordance with statutory accounting principles. Dividends in excess of such thresholds are considered “extraordinary” and require prior regulatory approval. During 2014, these subsidiaries paid dividends of $2.0 billion to Chubb.
	The maximum dividend distribution that may be made by the property and casualty insurance subsidiaries to Chubb during 2015 without prior regulatory approval is approximately $1.9 billion.

Quarterly_Financial_Data

Quarterly Financial Data	12 Months Ended
Quarterly Financial Data	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	QUARTERLY FINANCIAL DATA
	Summarized unaudited quarterly financial data for 2014 and 2013 are shown below. In management’s opinion, the interim financial data contain all adjustments, consisting of normal recurring items, necessary to present fairly the results of operations for the interim periods.


		Three Months Ended
		March 31						June 30						September 30						December 31
		2014			2013			2014			2013			2014			2013			2014			2013
		(in millions except for per share amounts)
	Revenues	$	3,506		$	3,517		$	3,542		$	3,551		$	3,574		$	3,403		$	3,476		$	3,476
	Losses and expenses		2,903			2,601			2,864			2,755			2,756			2,664			2,714			2,690
	Federal and foreign income tax		154			260			179			217			224			198			204			217

	Net income	$	449		$	656		$	499		$	579		$	594		$	541		$	558		$	569

	Basic earnings per share	$	1.81		$	2.49		$	2.03		$	2.22		$	2.47		$	2.11		$	2.35		$	2.25

	Diluted earnings per share	$	1.8		$	2.48		$	2.03		$	2.21		$	2.47		$	2.1		$	2.35		$	2.24

	Underwriting ratios
	Losses to premiums earned		61.1	%		52.3	%		58.7	%		56.7	%		54	%		53	%		53.8	%		54.7	%
	Expenses to premiums written		32.1			32.3			31.3			32.1			31.8			32.7			30.5			30.8

	Combined		93.2	%		84.6	%		90	%		88.8	%		85.8	%		85.7	%		84.3	%		85.5	%

Consolidated_Summary_of_Invest

Consolidated Summary of Investments - Other Than Investments in Related Parties	12 Months Ended
	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties [Abstract]
Consolidated Summary of Investments - Other Than Investments in Related Parties	THE CHUBB CORPORATION
	Schedule I
	CONSOLIDATED SUMMARY OF INVESTMENTS — OTHER THAN INVESTMENTS IN RELATED PARTIES
	(in millions)
	December 31, 2014


	Type of Investment	Cost or		Fair		Amount
		Amortized		Value		at Which
		Cost				Shown in the
						Balance Sheet

	Short term investments	$	1,318	$	1,318	$	1,318


	Fixed maturities

	United States Government and government agencies and authorities		1,593		1,612		1,612

	States, municipalities and political subdivisions		18,983		20,167		20,167

	Foreign government and government agencies		6,380		6,672		6,672

	Public utilities		1,065		1,148		1,148

	All other corporate bonds		7,676		7,880		7,880

	Residential mortgage-backed securities		192		211		211

	Commercial mortgage-backed securities		1,069		1,090		1,090


	Total fixed maturities		36,958		38,780		38,780


	Equity securities

	Common stocks

	Public utilities		114		216		216

	Banks, trusts and insurance companies		101		185		185

	Industrial, miscellaneous and other		835		1,515		1,515


	Total common stocks		1,050		1,916		1,916

	Non-redeemable preferred stocks		39		48		48


	Total equity securities		1,089		1,964		1,964


	Other invested assets		1,423		1,423		1,423


	Total invested assets	$	40,788	$	43,485	$	43,485

Condensed_Financial_Informatio

Condensed Financial Information of Parent Company	12 Months Ended
Condensed Financial Information of Parent Company	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Financial Information of Parent Company	THE CHUBB CORPORATION
	Schedule II
	CONDENSED FINANCIAL INFORMATION OF REGISTRANT
	BALANCE SHEETS — PARENT COMPANY ONLY
	(in millions)
	December 31


			2014				2013
	Assets
	Invested Assets
	Short Term Investments		$	574			$	856
	Taxable Fixed Maturities (cost $1,213 and $1,095)			1,226				1,110
	Equity Securities (cost $— and $—)			—				2

	TOTAL INVESTED ASSETS			1,800				1,968
	Investment in Consolidated Subsidiaries			17,838				17,455
	Other Assets			168				165

	TOTAL ASSETS		$	19,806			$	19,588

	Liabilities
	Long Term Debt		$	3,300			$	3,300
	Dividend Payable to Shareholders			117				110
	Accrued Expenses and Other Liabilities			93				81

	TOTAL LIABILITIES			3,510				3,491

	Shareholders’ Equity
	Preferred Stock — Authorized 8,000,000 Shares;			—				—
	$1 Par Value; Issued — None			—				—
	Common Stock — Authorized 1,200,000,000 Shares;			372				372
	$1 Par Value; Issued 371,980,460 Shares			372				372
	Paid-In Surplus			171				171
	Retained Earnings			23,520				21,902
	Accumulated Other Comprehensive Income			1,110				1,035
	Treasury Stock, at Cost — 139,551,071 and 123,673,969 Shares			(8,877	)			(7,383	)

	TOTAL SHAREHOLDERS’ EQUITY			16,296				16,097

	TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY		$	19,806			$	19,588

	The condensed financial statements should be read in conjunction with the consolidated financial statements and notes thereto.
	THE CHUBB CORPORATION
	Schedule II
	(continued)
	CONDENSED FINANCIAL INFORMATION OF REGISTRANT
	STATEMENTS OF INCOME — PARENT COMPANY ONLY
	(in millions)
	Years Ended December 31


			2014				2013				2012
	Revenues
	Investment Income		$	26			$	29			$	38
	Other Revenues			—				6				—
	Realized Investment Gains (Losses), Net			4				99				(6	)

	TOTAL REVENUES			30				134				32

	Expenses
	Corporate Expenses			249				262				268
	Investment Expenses			3				4				2
	Other Expenses			3				8				—

TOTAL EXPENSES			255				274				270

Loss before Federal and Foreign Income Tax and Equity in Net Income of Consolidated Subsidiaries			(225	)			(140	)			(238	)

Federal and Foreign Income Tax			1				—				4


Loss before Equity in Net Income of Consolidated Subsidiaries			(226	)			(140	)			(242	)

Equity in Net Income of Consolidated Subsidiaries			2,326				2,485				1,787

NET INCOME			2,100				2,345				1,545
Other Comprehensive Income (Loss), Net of Tax			75				(396	)			236

COMPREHENSIVE INCOME		$	2,175			$	1,949			$	1,781

Chubb and its U.S. subsidiaries file a consolidated federal income tax return. The federal income tax provision represents an allocation under the Corporation’s tax allocation agreements.
The condensed financial statements should be read in conjunction with the consolidated financial statements and notes thereto.
THE CHUBB CORPORATION
Schedule II
(continued)
CONDENSED FINANCIAL INFORMATION OF REGISTRANT
STATEMENTS OF CASH FLOWS — PARENT COMPANY ONLY
(in millions)
Years Ended December 31


		2014				2013				2012
Cash Flows from Operating Activities
Net Income		$	2,100			$	2,345			$	1,545
Adjustments to Reconcile Net Income to Net Cash Used in Operating Activities
Equity in Net Income of Consolidated Subsidiaries			(2,326	)			(2,485	)			(1,787	)
Realized Investment Losses (Gains), Net			(4	)			(99	)			6
Other, Net			9				21				57

NET CASH USED IN OPERATING ACTIVITIES			(221	)			(218	)			(179	)

Cash Flows from Investing Activities
Proceeds from Fixed Maturities
Sales			382				227				24
Maturities, Calls and Redemptions			46				150				673
Proceeds from Sales of Equity Securities			2				296				—
Purchases of Fixed Maturities			(551	)			(198	)			(1,046	)
Investments in Other Invested Assets, Net			—				22				—
Decrease in Short Term Investments, Net			282				85				89
Dividends Received from Consolidated Insurance Subsidiaries			2,021				1,564				1,760
Distributions Received from Consolidated Non-Insurance Subsidiaries			1				1				1
Other, Net			38				46				1

NET CASH PROVIDED BY INVESTING ACTIVITIES			2,221				2,193				1,502

Cash Flows from Financing Activities
Repayment of Long Term Debt			—				(275	)			—
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans			22				38				74
Repurchase of Shares			(1,547	)			(1,288	)			(959	)
Dividends Paid to Shareholders			(475	)			(450	)			(438	)

NET CASH USED IN FINANCING ACTIVITIES			(2,000	)			(1,975	)			(1,323	)

Net Increase in Cash			—				—				—
Cash at Beginning of Year			—				—				—

CASH AT END OF YEAR		$	—			$	—			$	—


The condensed financial statements should be read in conjunction with the consolidated financial statements and notes thereto.
In 2013, Chubb exchanged its holdings of common stock and warrants of Alterra Capital Holdings Limited, with a cost basis of $177 million and a carrying value of $63 million, respectively, for common stock of Markel Corporation, valued at $226 million, and cash of $98 million, as a result of a business combination. The noncash portions of the transaction have been excluded from the statement of cash flows.

Consolidated_Supplementary_Ins

Consolidated Supplementary Insurance Information	12 Months Ended
Consolidated Supplementary Insurance Information	Dec. 31, 2014
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Consolidated Supplementary Insurance Information	THE CHUBB CORPORATION
	Schedule III
	CONSOLIDATED SUPPLEMENTARY INSURANCE INFORMATION
	(in millions)


			December 31						Year Ended December 31
	Segment		Deferred		Unpaid		Unearned		Premiums			Net		Insurance			Amortization		Other			Premiums
			Policy		Losses		Premiums		Earned			Investment		Losses			of Deferred		Insurance			Written
			Acquisition									Income (a)					Policy		Operating
			Costs														Acquisition		Costs and
																	Costs		Expenses (b)
	2014

	Property and Casualty Insurance
	Personal		$	517	$	2,272	$	2,278	$	4,418				$	2,540		$	1,053	$	438		$	4,508
	Commercial			504		13,161		2,876		5,281					3,111			995		663			5,402
	Specialty			263		6,847		1,426		2,628					1,333			497		295			2,681
	Reinsurance Assumed			—		398		1		1					1			3		(3	)		1
	Investments											$	1,329

			$	1,284	$	22,678	$	6,581	$	12,328		$	1,329	$	6,985		$	2,548	$	1,393		$	12,592

	2013

	Property and Casualty Insurance
	Personal		$	505	$	2,235	$	2,216	$	4,214				$	2,224		$	982	$	465		$	4,322
	Commercial			493		13,147		2,792		5,237					2,891			970		665			5,273
	Specialty			257		7,307		1,412		2,618					1,417			502		287			2,633
	Reinsurance Assumed			—		457		3		(3	)				(12	)		—		—			(4	)
	Investments											$	1,391

			$	1,255	$	23,146	$	6,423	$	12,066		$	1,391	$	6,520		$	2,454	$	1,417		$	12,224

	2012

	Property and Casualty Insurance
	Personal		$	477	$	2,493	$	2,133	$	4,024				$	2,417		$	942	$	458		$	4,125
	Commercial			477		13,288		2,794		5,144					3,512			970		620			5,174
	Specialty			252		7,622		1,429		2,666					1,622			499		293			2,568
	Reinsurance Assumed			—		560		5		4					(44	)		—		1			3
	Investments											$	1,482

			$	1,206	$	23,963	$	6,361	$	11,838		$	1,482	$	7,507		$	2,411	$	1,372		$	11,870


	(a)	Property and casualty assets are available for payment of losses and expenses for all classes of business; therefore, such assets and the related investment income have not been allocated to the underwriting segments.

	(b)	Other insurance operating costs and expenses does not include other income and charges.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	(a)	Basis of Presentation
	The Chubb Corporation (Chubb) is a holding company with subsidiaries principally engaged in the property and casualty insurance business. The property and casualty insurance subsidiaries (the P&C Group) underwrite most lines of property and casualty insurance in the United States, Canada, Europe, Australia and parts of Latin America and Asia. The geographic distribution of property and casualty business in the United States is broad with a particularly strong market presence in the Northeast.
	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include the accounts of Chubb and its subsidiaries (collectively, the Corporation). Significant intercompany transactions have been eliminated in consolidation. The results of our operations in Australia, Brazil and other smaller foreign locations are recorded on a three month lag in our consolidated financial statements. Specific events having significant financial impact that occur during the lag period are included in the current period results.
	The consolidated financial statements include amounts based on informed estimates and judgments of management for transactions that are not yet complete. Such estimates and judgments affect the reported amounts of assets and liabilities and 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. Actual results could differ from those estimates.
	Certain amounts in the consolidated financial statements for prior years have been reclassified to conform with the 2014 presentation.
Invested Assets	(b)	Invested Assets
	Short term investments, which have an original maturity of one year or less, are carried at amortized cost, which approximates fair value.
	Fixed maturities, which include taxable and tax exempt bonds, are classified as available-for-sale and carried at fair value as of the balance sheet date. Taxable bonds include U.S. government and government agency and authority obligations, including taxable bonds issued by states, municipalities and political subdivisions within the United States, and foreign government and government agency obligations, corporate bonds and mortgage-backed securities. Corporate bonds include redeemable preferred stocks. Tax exempt bonds consist of bonds issued by states, municipalities and political subdivisions within the United States. Fixed maturities are purchased to support the investment strategies of the Corporation. These strategies are developed based on many factors including rate of return, maturity, credit risk, tax considerations and regulatory requirements. Fixed maturities may be sold prior to maturity to support the investment strategies of the Corporation.
	Premiums and discounts arising from the purchase of fixed maturities are amortized using the interest method over the estimated remaining term of the securities. For mortgage-backed securities, prepayment assumptions are reviewed periodically and revised as necessary.
	Equity securities, which include common stocks and non-redeemable preferred stocks, are carried at fair value as of the balance sheet date.
	Unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of fixed maturities and equity securities carried at fair value is excluded from net income and is included, net of applicable deferred income tax, in other comprehensive income.

	Other invested assets primarily include private equity limited partnerships, which are carried at the Corporation’s equity in the net assets of the partnerships based on valuations provided by the manager of each partnership. 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. Changes in the Corporation’s equity in the net assets of the partnerships are included in net income as realized investment gains or losses. Other invested assets also include warrants, which are carried at fair value as of the balance sheet date. Changes in the fair value of warrants are included in net income as realized investment gains or losses.
	Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold and are included in net income.
	When the fair value of an investment is lower than its cost, an assessment is made to determine whether the decline is temporary or other than temporary. The assessment of other-than-temporary impairment of fixed maturities and equity securities is based on both quantitative criteria and qualitative information. A number of factors are considered including, but not limited to, the length of time and the extent to which the fair value has been less than the cost, the financial condition and near term prospects of the issuer, whether the issuer is current on contractually obligated interest and principal payments, general market conditions and industry or sector specific factors.
	In determining whether fixed maturities are other than temporarily impaired, the Corporation is required to recognize an other-than-temporary impairment loss when it concludes it has the intent to sell or it is more likely than not it will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value or it is likely it will not recover the entire amortized cost value of an impaired security. If the Corporation has the intent to sell or it is more likely than not that the Corporation will be required to sell an impaired fixed maturity before the security recovers to its amortized cost value, the security is written down to fair value and the entire amount of the writedown is included in net income as a realized investment loss. For all other impaired fixed maturities, when the impairment is determined to be other than temporary, the impairment loss is separated into the amount representing the credit loss and the amount representing the loss related to all other factors. The amount of the impairment loss that represents the credit loss is included in net income as a realized investment loss and the amount of the impairment loss that relates to all other factors is included in other comprehensive income.
	For fixed maturities, the split between the amount of other-than-temporary impairment losses that represents credit losses and the amount that relates to all other factors is principally based on assumptions regarding the amount and timing of projected cash flows. For fixed maturities other than mortgage-backed securities, cash flow estimates are based on assumptions regarding the probability of default and estimates regarding the timing and amount of recoveries associated with a default. For mortgage-backed securities, cash flow estimates are based on assumptions regarding future prepayment rates, default rates, loss severity and timing of recoveries. The Corporation has developed the estimates of projected cash flows using information based on historical market data, industry analyst reports and forecasts and other data relevant to the collectibility of a security.
	In determining whether equity securities are other than temporarily impaired, the Corporation considers its intent and ability to hold a security for a period of time sufficient to allow for the recovery of cost. If the decline in the fair value of an equity security is deemed to be other than temporary, the security is written down to fair value and the amount of the writedown is included in net income as a realized investment loss.
Premium Revenues and Related Expenses	(c)	Premium Revenues and Related Expenses
	Insurance premiums are earned on a monthly pro rata basis over the terms of the policies and include estimates of audit premiums and premiums on retrospectively rated policies. Assumed reinsurance premiums are earned over the terms of the reinsurance contracts. Unearned premiums represent the portion of direct and assumed premiums written applicable to the unexpired terms of the insurance policies and reinsurance contracts in force.
	Ceded reinsurance premiums are reflected in operating results over the terms of the reinsurance contracts. Prepaid reinsurance premiums represent the portion of premiums ceded to reinsurers applicable to the unexpired terms of the reinsurance contracts in force.
	Reinsurance reinstatement premiums are recognized in the same period as the loss event that gave rise to the reinstatement premiums.
	Acquisition costs that are directly related to the successful acquisition of new or renewal insurance contracts are deferred and amortized over the period in which the related premiums are earned. Such costs include commissions, premium taxes and certain other underwriting and policy issuance costs. Commissions received related to reinsurance premiums ceded are considered in determining net acquisition costs eligible for deferral. Deferred policy acquisition costs are reviewed to determine whether they are recoverable from future income. If such costs are deemed to be unrecoverable, they are expensed. Anticipated investment income is considered in the determination of the recoverability of deferred policy acquisition costs.
Unpaid Losses and Loss Expenses	(d)	Unpaid Losses and Loss Expenses
	Unpaid losses and loss expenses (also referred to as loss reserves) include the accumulation of individual case estimates for claims that have been reported and estimates of claims that have been incurred but not reported as well as estimates of the expenses associated with processing and settling all reported and unreported claims, less estimates of anticipated salvage and subrogation recoveries. Estimates are based upon past loss experience modified for current trends as well as prevailing economic, legal and social conditions. Loss reserves are not discounted to present value.
	Loss reserves are regularly reviewed using a variety of actuarial techniques. Reserve estimates are updated as historical loss experience develops, additional claims are reported and/or settled and new information becomes available. Any changes in estimates are reflected in operating results in the period in which the estimates are changed.
	Reinsurance recoverable on unpaid losses and loss expenses represents an estimate of the portion of gross loss reserves that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated using assumptions that are consistent with those used in estimating the gross losses associated with the reinsured policies. A provision for estimated uncollectible reinsurance is recorded based on periodic evaluations of balances due from reinsurers, the financial condition of the reinsurers, coverage disputes and other relevant factors.
Financial Products	(e)	Financial Products
	Derivatives are carried at fair value as of the balance sheet date. Changes in fair value are recognized in net income in the period of the change and are included in other revenues.
	Assets and liabilities related to these derivatives are included in other assets and other liabilities.
Goodwill	(f)	Goodwill
	Goodwill represents the excess of the cost of an acquired entity over the fair value of net assets acquired. Goodwill is tested for impairment at least annually.
Property and Equipment	(g)	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.
Real Estate	(h)	Real Estate
	Real estate properties are carried at cost less accumulated depreciation and any writedowns for impairment. Real estate properties are reviewed for impairment whenever events or circumstances indicate that the carrying value of such properties may not be recoverable. Measurement of such impairment is based on the fair value of the property. Real estate properties are included in other assets.
Income Taxes	(i)	Income Taxes
	Deferred income tax assets and liabilities are recognized for the expected future tax effects attributable to temporary differences between the financial reporting and tax bases of assets and liabilities, based on enacted tax rates and other provisions of tax law. The effect on deferred tax assets and liabilities of a change in tax laws or rates is recognized in net income in the period in which such change is enacted. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized.
	The Corporation does not consider the earnings of its foreign subsidiaries to be permanently reinvested. Accordingly, provision has been made for the expected U.S. federal income tax liabilities applicable to undistributed earnings of foreign subsidiaries.
Stock-Based Employee Compensation	(j)	Stock-Based Employee Compensation
	The fair value method of accounting is used for stock-based employee compensation plans. Under the fair value method, compensation cost is measured based on the fair value of the award at the grant date and recognized over the requisite service period.
Foreign Exchange	(k)	Foreign Exchange
	Assets and liabilities relating to foreign operations are translated into U.S. dollars using current exchange rates as of the balance sheet date. Revenues and expenses are translated into U.S. dollars using the average exchange rates during the year.
	The functional currency of foreign operations is generally the currency of the local operating environment since business is primarily transacted in such local currency. Translation gains and losses, net of applicable income tax, are excluded from net income and are credited or charged directly to other comprehensive income.
Cash Flow Information	(l)	Cash Flow Information
	In the statement of cash flows, short term investments are not considered to be cash equivalents. The effect of changes in foreign exchange rates on cash balances was insignificant.
	In 2013, the Corporation exchanged its holdings of common stock and warrants of Alterra Capital Holdings Limited, with a cost basis of $177 million and a carrying value of $63 million, respectively, for common stock of Markel Corporation, valued at $226 million, and cash of $98 million, as a result of a business combination. The noncash portions of the transaction have been excluded from the statement of cash flows.

Invested_Assets_and_Related_In1

Invested Assets and Related Income (Tables)	12 Months Ended
Invested Assets and Related Income (Tables)	Dec. 31, 2014
Text Block [Abstract]
Amortized Cost and Fair Value of Fixed Maturities and Equity Securities	(a) The amortized cost and fair value of fixed maturities and equity securities were as follows:


		December 31, 2014
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	18,614		$	1,174		$	16		$	19,772

	Taxable
	U.S. government and government agency and		1,962			46			1			2,007
	authority obligations		1,962			46			1			2,007
	Corporate bonds		8,741			327			40			9,028
	Foreign government and government agency obligations		6,380			295			3			6,672
	Residential mortgage-backed securities		192			20			1			211
	Commercial mortgage-backed securities		1,069			22			1			1,090

			18,344			710			46			19,008

	Total fixed maturities	$	36,958		$	1,884		$	62		$	38,780

	Equity securities	$	1,089		$	894		$	19		$	1,964



		December 31, 2013
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	17,808		$	802		$	189		$	18,421

	Taxable
	U.S. government and government agency and authority obligations		784			27			9			802
	Corporate bonds		9,032			370			88			9,314
	Foreign government and government agency obligations		6,719			206			35			6,890
	Residential mortgage-backed securities		277			23			1			299
	Commercial mortgage-backed securities		1,339			29			3			1,365

			18,151			655			136			18,670

	Total fixed maturities	$	35,959		$	1,457		$	325		$	37,091

	Equity securities	$	1,057		$	756		$	3		$	1,810

Summary of Fair Value of Tax Exempt Fixed Maturities	The following table summarizes the fair value of the tax exempt fixed maturities at December 31, 2014 and 2013:


		2014			2013
		(in millions)
	Special revenue bonds	$	12,936		$	11,717
	State general obligation bonds		2,415			2,292
	Municipal and political subdivision general obligation bonds		2,378			2,220
	Pre-refunded bonds		2,043			2,192

		$	19,772		$	18,421

Fair Value and Amortized Cost of Tax Exempt Fixed Maturities Other Than Pre-Refunded Bonds	The following table summarizes the fair value and amortized cost of the tax exempt fixed maturities other than pre-refunded bonds held at December 31, 2014 and 2013, for the five states having the largest concentration of issuers within the tax exempt fixed maturity portfolio. The remainder of tax exempt fixed maturities were issued by a broad range of other states and municipalities and political subdivisions within those states. In the following table, “state” identifies the issuer or the location of the issuing municipality or political subdivision within a state.


		December 31, 2014
		Fair Value
	State	Special			Municipal			State			Total		Amortized
		Revenue			and Political			General					Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
	New York	$	2,046		$	173		$	43		$	2,262	$	2,135
	Texas		883			852			211			1,946		1,829
	California		1,098			153			256			1,507		1,422
	Illinois		608			381			97			1,086		1,022
	Florida		850			63			167			1,080		1,017


		December 31, 2013
		Fair Value
	State	Special			Municipal			State			Total		Amortized
		Revenue			and Political			General					Cost
		Bonds			Subdivision			Obligations
					General
					Obligations
		(in millions)
	Texas	$	930		$	830		$	230		$	1,990	$	1,904
	New York		1,611			197			31			1,839		1,809
	California		859			82			198			1,139		1,093
	Illinois		577			483			56			1,116		1,094
	Florida		757			38			108			903		877
Fair Value and Amortized Cost of Foreign Government and Government Agency Fixed Maturities	The following table summarizes the fair value and amortized cost of the foreign government and government agency fixed maturities held at December 31, 2014 and 2013, for the five countries having the largest concentration of issuers within the foreign government and government agency fixed maturity portfolio. In the following table, “country” identifies the issuer or the location of the issuing government agency or regional government within a country.


		2014						2013
	Country	Fair			Amortized			Fair			Amortized
	Country	Value			Cost			Value			Cost
		(in millions)
	Canada	$	1,893		$	1,823		$	1,993		$	1,953
	United Kingdom		1,230			1,163			1,026			1,004
	Germany		1,102			1,045			1,241			1,211
	Australia		746			700			739			700
	Brazil		232			231			270			270
Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity	The fair value and amortized cost of fixed maturities at December 31, 2014 by contractual maturity were as follows:


		Fair			Amortized
		Value			Cost
		(in millions)
	Due in one year or less	$	2,947		$	2,922
	Due after one year through five years		12,906			12,406
	Due after five years through ten years		12,814			12,041
	Due after ten years		8,812			8,328

			37,479			35,697
	Residential mortgage-backed securities		211			192
	Commercial mortgage-backed securities		1,090			1,069

		$	38,780		$	36,958

Components of Unrealized Appreciation or Depreciation of Investments	(b) The components of unrealized appreciation or depreciation, including unrealized other-than-temporary impairment losses, of investments carried at fair value were as follows:


		December 31
		2014			2013
		(in millions)
	Fixed maturities
	Gross unrealized appreciation	$	1,884		$	1,457
	Gross unrealized depreciation		62			325

			1,822			1,132

	Equity securities
	Gross unrealized appreciation		894			756
	Gross unrealized depreciation		19			3

			875			753

			2,697			1,885
	Deferred income tax liability		944			660

		$	1,753		$	1,225

Fair Value and Gross Unrealized Depreciation of Investments in Unrealized Loss Position	The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2014, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.


		Less Than 12 Months						12 Months or More					Total
		Fair			Gross			Fair			Gross		Fair		Gross
		Value			Unrealized			Value			Unrealized		Value		Unrealized
					Depreciation						Depreciation				Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	422		$	3		$	305		$	13	$	727	$	16

	Taxable
	U.S. government and government agency		936			1			36			—		972		1
	and authority obligations		936			1			36			—		972		1
	Corporate bonds		1,327			23			888			17		2,215		40
	Foreign government and government		318			1			207			2		525		3
	agency obligations		318			1			207			2		525		3
	Residential mortgage-backed securities		—			—			7			1		7		1
	Commercial mortgage-backed securities		106			—			67			1		173		1

			2,687			25			1,205			21		3,892		46

	Total fixed maturities		3,109			28			1,510			34		4,619		62

	Equity securities		67			11			11			8		78		19

		$	3,176		$	39		$	1,521		$	42	$	4,697	$	81

	At December 31, 2014, approximately 735 individual fixed maturities and 15 individual equity securities were in an unrealized loss position. The Corporation does not have the intent to sell and it is not more likely than not that the Corporation will be required to sell these fixed maturities before the securities recover to their amortized cost value. In addition, the Corporation believes that none of the declines in the fair values of these fixed maturities relate to credit losses. The Corporation has the intent and ability to hold the equity securities in an unrealized loss position for a period of time sufficient to allow for the recovery of cost. The Corporation believes that none of the declines in the fair value of these fixed maturities and equity securities were other than temporary at December 31, 2014.
	The following table summarizes, for all investment securities in an unrealized loss position at December 31, 2013, the aggregate fair value and gross unrealized depreciation, including unrealized other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position.


		Less Than 12 Months						12 Months or More					Total
		Fair			Gross			Fair			Gross		Fair		Gross
		Value			Unrealized			Value			Unrealized		Value		Unrealized
					Depreciation						Depreciation				Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	3,417		$	144		$	307		$	45	$	3,724	$	189

	Taxable
	U.S. government and government agency and authority obligations		213			6			35			3		248		9
	Corporate bonds		2,526			76			222			12		2,748		88
	Foreign government and government agency obligations		1,735			32			75			3		1,810		35
	Residential mortgage-backed securities		4			—			14			1		18		1
	Commercial mortgage-backed securities		153			1			39			2		192		3

			4,631			115			385			21		5,016		136

	Total fixed maturities		8,048			259			692			66		8,740		325

	Equity securities		41			3			—			—		41		3

		$	8,089		$	262		$	692		$	66	$	8,781	$	328

Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value	The change in unrealized appreciation or depreciation of investments carried at fair value, including the change in unrealized other-than-temporary impairment losses, was as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Change in unrealized appreciation of fixed maturities	$	690		$	(1,546	)	$	256
	Change in unrealized appreciation of equity securities		122			334			171

			812			(1,212	)		427
	Deferred income tax (credit)		284			(424	)		150

		$	528		$	(788	)	$	277

Sources of Net Investment Income	(c) The sources of net investment income were as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Fixed maturities	$	1,314		$	1,380		$	1,465
	Equity securities		41			38			40
	Short term investments		18			16			18
	Other		21			31			33

	Gross investment income		1,394			1,465			1,556
	Investment expenses		42			49			38

		$	1,352		$	1,416		$	1,518

Realized Investment Gains and Losses	(d) Realized investment gains and losses were as follows:


		Years Ended
		December 31
		2014			2013			2012
		(in millions)
	Fixed maturities
	Gross realized gains	$	126		$	62		$	124
	Gross realized losses		(36	)		(42	)		(20	)
	Other-than-temporary impairment losses		(5	)		(2	)		(5	)

			85			18			99

	Equity securities
	Gross realized gains		137			204			68
	Gross realized losses		—			(1	)		—
	Other-than-temporary impairment losses		(2	)		(9	)		(40	)

			135			194			28

	Other invested assets		149			190			66

		$	369		$	402		$	193

Deferred_Policy_Acquisition_Co1

Deferred Policy Acquisition Costs (Tables)	12 Months Ended
Deferred Policy Acquisition Costs (Tables)	Dec. 31, 2014
Text Block [Abstract]
Policy Acquisition Costs Deferred and Related Amortization Reflected in Operating Results	Policy acquisition costs deferred and the related amortization reflected in operating results were as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Balance, beginning of year	$	1,255		$	1,206		$	1,210

	Costs deferred during year
	Commissions and brokerage		2,073			1,979			1,919
	Premium taxes and assessments		258			263			247
	Underwriting and policy issuance costs		262			271			248

			2,593			2,513			2,414

	Foreign currency translation effect		(16	)		(10	)		(7	)

	Amortization during year		(2,548	)		(2,454	)		(2,411	)

	Balance, end of year	$	1,284		$	1,255		$	1,206

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment included in other assets were as follows:


		December 31
		2014		2013
		(in millions)
	Cost	$	488	$	501
	Accumulated depreciation		239		243

		$	249	$	258

Unpaid_Losses_and_Loss_Expense1

Unpaid Losses and Loss Expenses (Tables)	12 Months Ended
Unpaid Losses and Loss Expenses (Tables)	Dec. 31, 2014
Insurance [Abstract]
Reconciliation of Beginning and Ending Liability for Unpaid Losses and Loss Expenses	A reconciliation of the beginning and ending liability for unpaid losses and loss expenses, net of reinsurance recoverable, and a reconciliation of the net liability to the corresponding liability on a gross basis is as follows:


		2014			2013			2012
		(in millions)
	Gross liability, beginning of year	$	23,146		$	23,963		$	23,068
	Reinsurance recoverable, beginning of year		1,802			1,941			1,739

	Net liability, beginning of year		21,344			22,022			21,329

	Net incurred losses and loss expenses related to
	Current year		7,621			7,232			8,121
	Prior years		(636	)		(712	)		(614	)

			6,985			6,520			7,507

	Net payments for losses and loss expenses related to
	Current year		2,496			2,150			2,323
	Prior years		4,534			4,952			4,493

			7,030			7,102			6,816


	Foreign currency translation effect		(260	)		(96	)		2


	Net liability, end of year		21,039			21,344			22,022
	Reinsurance recoverable, end of year		1,639			1,802			1,941

	Gross liability, end of year	$	22,678		$	23,146		$	23,963

Debt_and_Credit_Arrangements_T

Debt and Credit Arrangements (Tables)	12 Months Ended
Debt and Credit Arrangements (Tables)	Dec. 31, 2014
Debt Disclosure [Abstract]
Long Term Debt	(a) Long term debt consisted of the following:


		December 31
		2014		2013
		(in millions)
	5.75% notes due May 15, 2018	$	600	$	600
	6.6% debentures due August 15, 2018		100		100
	6.8% debentures due November 15, 2031		200		200
	6% notes due May 11, 2037		800		800
	6.5% notes due May 15, 2038		600		600
	6.375% capital securities due March 29, 2067		1,000		1,000

		$	3,300	$	3,300

Amounts of Long Term Debt due Annually	The amounts of long term debt due annually during the five years subsequent to December 31, 2014 are as follows:


	Years Ending December 31	(in millions)
	2015	$	—
	2016		—
	2017		—
	2018		700
	2019		—

Federal_and_Foreign_Income_Tax1

Federal and Foreign Income Tax (Tables)	12 Months Ended
Federal and Foreign Income Tax (Tables)	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Expense and Taxes Paid	Income tax expense and taxes paid consisted of the following components:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Income tax expense
	Current tax
	United States	$	617		$	791		$	276
	Foreign		124			91			143
	Deferred tax, principally United States		20			10			32

		$	761		$	892		$	451


	Federal and foreign income taxes paid	$	571		$	789		$	472

Reconciliation of Effective Income Tax Rate and Statutory Federal Corporate Tax Rate	The effective income tax rate is different than the statutory federal corporate tax rate. The reasons for the different effective tax rate were as follows:


		Years Ended December 31
		2014						2013						2012
		Amount			% of			Amount			% of			Amount			% of
					Pre-Tax						Pre-Tax						Pre-Tax
					Income						Income						Income
		(in millions)
	Income before federal and foreign income tax	$	2,861					$	3,237					$	1,996

	Tax at statutory federal income tax rate	$	1,001			35	%	$	1,133			35	%	$	699			35	%
	Tax exempt interest income		(212	)		(7.4	)		(222	)		(6.8	)		(233	)		(11.7	)
	Other, net		(28	)		(1.0	)		(19	)		(.6	)		(15	)		(.7	)

	Federal and foreign income tax	$	761			26.6	%	$	892			27.6	%	$	451			22.6	%

Tax Effects of Temporary Differences that Gave Rise to Deferred Income Tax Assets and Liabilities	The tax effects of temporary differences that gave rise to deferred income tax assets and liabilities were as follows:


		December 31
		2014			2013
		(in millions)
	Deferred income tax assets
	Unpaid losses and loss expenses	$	509		$	524
	Unearned premiums		364			350
	Foreign tax credits		963			867
	Employee compensation		144			142
	Postretirement benefits		272			95
	Other-than-temporary impairment losses		298			291
	Other, net		29			—

	Total		2,579			2,269

	Deferred income tax liabilities
	Deferred policy acquisition costs		367			356
	Unremitted earnings of foreign subsidiaries		1,075			970
	Unrealized appreciation of investments		944			660
	Other invested assets		208			184
	Other, net		—			52

	Total		2,594			2,222

	Net deferred income tax asset (liability)	$	(15	)	$	47

Reinsurance_Tables

Reinsurance (Tables)	12 Months Ended
Reinsurance (Tables)	Dec. 31, 2014
Insurance [Abstract]
Effect of Reinsurance on Premiums Written and Earned	The effect of reinsurance on the premiums written and earned of the P&C Group was as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Direct premiums written	$	12,976		$	12,804		$	12,647
	Assumed reinsurance		596			503			423
	Ceded reinsurance		(980	)		(1,083	)		(1,200	)

	Net premiums written	$	12,592		$	12,224		$	11,870


	Direct premiums earned	$	12,776		$	12,717		$	12,596
	Assumed reinsurance		562			476			422
	Ceded reinsurance		(1,010	)		(1,127	)		(1,180	)

	Net premiums earned	$	12,328		$	12,066		$	11,838

StockBased_Employee_Compensati1

Stock-Based Employee Compensation Plans (Tables)	12 Months Ended
Stock-Based Employee Compensation Plans (Tables)	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Additional Information With Respect to Restricted Stock Units and Performance Units	Additional information with respect to restricted stock units and performance units is as follows:


			Restricted Stock Units					Performance Units*
			Number			Weighted Average		Number			Weighted Average
			of Shares			Grant Date		of Shares			Grant Date
						Fair Value					Fair Value
	Nonvested, January 1, 2014			2,127,647		$	70.23		861,141		$	79.87
	Granted			625,197			86.67		421,271			76.32
	Vested**			(762,349	)		60.53		(456,176	)		63.38
	Forfeited			(82,551	)		81.16		(4,041	)		77.87

	Nonvested, December 31, 2014			1,907,944			79.02		822,195			87.21


		*	The number of shares earned may range from 0% to 200% of the performance units shown in the table above.

		**	The performance units earned in 2014 were 35.2% of the vested shares shown in the table, or 160,574 shares.
Additional Information with Respect to Stock Options	Additional information with respect to stock options is as follows:


			Number			Weighted		Weighted Average			Aggregate
			of Shares			Average		Remaining			Intrinsic Value
						Exercise Price		Contractual Term
								(in years)			(in millions)
	Outstanding, January 1, 2014			251,687		$	62.52
	Granted			65,605			86.59
	Exercised			(54,932	)		59.08
	Forfeited			(6,949	)		82.83

	Outstanding, December 31, 2014			255,411			68.89		6.6		$	9

	Exercisable, December 31, 2014			128,880			55.24		4.8			6

Employee_Benefits_Tables

Employee Benefits (Tables)	12 Months Ended
Employee Benefits (Tables)	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Funded Status of Pension and Other Postretirement Benefit Plans	The funded status of the pension and other postretirement benefit plans at December 31, 2014 and 2013 was as follows:


		Pension						Other
		Benefits						Postretirement
								Benefits
		2014			2013			2014			2013
		(in millions)
	Benefit obligation, beginning of year	$	2,777		$	2,894		$	394		$	470
	Service cost		86			95			10			13
	Interest cost		140			125			19			19
	Actuarial loss (gain)		536			(261	)		74			(97	)
	Benefits paid		(85	)		(75	)		(10	)		(11	)
	Foreign currency translation effect		(19	)		(1	)		(2	)		—

	Benefit obligation, end of year		3,435			2,777			485			394


	Plan assets at fair value, beginning of year		2,717			2,305			130			96
	Actual return on plan assets		240			409			12			27
	Employer contributions		92			82			11			18
	Benefits paid		(85	)		(75	)		(10	)		(11	)
	Foreign currency translation effect		(18	)		(4	)		—			—

	Plan assets at fair value, end of year		2,946			2,717			143			130

	Funded status at end of year, included in other liabilities	$	489		$	60		$	342		$	264

Net Actuarial Loss (Gain) and Prior Service Cost Included in Accumulated Other Comprehensive Income	Net actuarial loss (gain) and prior service cost included in accumulated other comprehensive income that were not yet recognized as components of net benefit costs at December 31, 2014 and 2013 were as follows:


		Pension						Other
		Benefits						Postretirement
								Benefits
		2014			2013			2014			2013
		(in millions)
	Net actuarial loss (gain)	$	842		$	396		$	58		$	(13	)
	Prior service cost		14			16			1			1

		$	856		$	412		$	59		$	(12	)

Weighted Average Assumptions Used to Determine Benefit Obligations	The weighted average assumptions used to determine the benefit obligations were as follows:


		Pension Benefits						Other
								Postretirement
								Benefits
		2014			2013			2014			2013
	Discount rate		4.3	%		5.2	%		4.3	%		5.2	%
	Rate of compensation increase		4.5			4.5			—			—
Components of Net Pension and Other Postretirement Benefit Costs Reflected in Net Income	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 for the years ended December 31, 2014, 2013 and 2012 were as follows:


		Pension Benefits									Other
		Pension Benefits									Postretirement Benefits
		2014			2013			2012			2014			2013			2012
		(in millions)
	Costs reflected in net income
	Service cost	$	86		$	95		$	88		$	10		$	13		$	12
	Interest cost		140			125			124			19			19			20
	Expected return on plan assets		(186	)		(165	)		(155	)		(9	)		(7	)		(6	)
	Amortization of net actuarial loss and prior service cost and other		35			90			80			—			3			3

		$	75		$	145		$	137		$	20		$	28		$	29

Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income	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 for the years ended December 31, 2014, 2013 and 2012 were as follows:


		Pension Benefits									Other
		Pension Benefits									Postretirement Benefits
		2014			2013			2012			2014			2013			2012
		(in millions)
	Costs reflected in net income
	Service cost	$	86		$	95		$	88		$	10		$	13		$	12
	Interest cost		140			125			124			19			19			20
	Expected return on plan assets		(186	)		(165	)		(155	)		(9	)		(7	)		(6	)
	Amortization of net actuarial loss and prior service cost and other		35			90			80			—			3			3

		$	75		$	145		$	137		$	20		$	28		$	29

	Changes in plan assets and benefit obligations recognized in other comprehensive income
	Net actuarial loss (gain)	$	479		$	(505	)	$	139		$	71		$	(117	)	$	(11	)
	Amortization of net actuarial loss and prior service cost and other		(35	)		(90	)		(80	)		—			(3	)		(3	)

		$	444		$	(595	)	$	59		$	71		$	(120	)	$	(14	)

Weighted Average Assumptions Used to Determine Net Pension and Other Postretirement Benefit Costs	The weighted average assumptions used to determine net pension and other postretirement benefit costs were as follows:


		Pension Benefits									Other
		Pension Benefits									Postretirement Benefits
		2014			2013			2012			2014			2013			2012
	Discount rate		5.20%			4.40%			5.00%			5.20%			4.40%			5.00%
	Rate of compensation increase		4.5			4.5			4.5			—			—			—
	Expected long term rate of return on plan assets		7.5			7.5			7.75			7.5			7.5			7.75
Weighted Average Health Care Cost Trend Rate Assumptions	The weighted average health care cost trend rate assumptions used to measure the expected cost of medical benefits were as follows:


		December 31
		2014			2013
	Health care cost trend rate for next year		7.3	%		7.6	%
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.5			4.5
	Year that the rate reaches the ultimate trend rate		2028			2028
Fair Values of Pension Plan Assets	The fair values of the pension plan assets were as follows:


		December 31
		2014			2013
		(in millions)
	Short term investments	$	48		$	37

	Fixed maturities
	U.S. government and government agency and authority obligations		209			224
	Corporate bonds		419			371
	Foreign government and government agency obligations		137			104
	Mortgage-backed securities		228			217

	Total fixed maturities		993			916

	Equity securities		1,850			1,718

	Other assets		55			46

		$	2,946		$	2,717

Estimated Benefits Expected to be Paid	The estimated benefits expected to be paid in each of the next five years and in the aggregate for the following five years are as follows:


	Years Ending December 31	Pension			Other
		Benefits			Postretirement
					Benefits
		(in millions)
	2015	$	105		$	12
	2016		115			14
	2017		151			15
	2018		132			17
	2019		143			18
	2020-2024		868			117

Comprehensive_Income_Tables

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Components of Other Comprehensive Income or Loss	The components of other comprehensive income or loss were as follows:


			Years Ended December 31
			2014									2013									2012
			Before			Income			Net of			Before			Income			Net of			Before			Income			Net of
			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax			Tax
												(in millions)
	Net unrealized holding gains (losses) arising		$	1,032		$	361		$	671		$	(1,000	)	$	(350	)	$	(650	)	$	556		$	195		$	361
	during the year
	Unrealized other-than-temporary			—			—			—			—			—			—			(2	)		(1	)		(1	)
	impairment losses arising during the year
	Reclassification adjustment for net realized			220			77			143			212			74			138			127			44			83
	gains included in net income

	Net unrealized gains (losses) recognized in other comprehensive income or loss			812			284			528			(1,212	)		(424	)		(788	)		427			150			277


	Postretirement benefit gain (loss) not yet			(550	)		(192	)		(358	)		622			218			404			(128	)		(45	)		(83	)
	recognized in net income arising during the year
	Reclassification adjustment for the			(35	)		(13	)		(22	)		(93	)		(33	)		(60	)		(83	)		(30	)		(53	)
	amortization of net actuarial loss and prior service cost included in net income (a)

	Net change in postretirement benefit			(515	)		(179	)		(336	)		715			251			464			(45	)		(15	)		(30	)
	costs not yet recognized in net income


	Foreign currency translation losses			(180	)		(63	)		(117	)		(111	)		(39	)		(72	)		(16	)		(5	)		(11	)

	Total other comprehensive income (loss)		$	117		$	42		$	75		$	(608	)	$	(212	)	$	(396	)	$	366		$	130		$	236


	(a)	Postretirement benefit costs recognized in net income during the period are included among several of the loss and expense components presented in the consolidated statements of income.

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Tables)	12 Months Ended
Commitments and Contingent Liabilities (Tables)	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Rent Expense	Rent expense was as follows:


		Years Ended
		December 31
		2014		2013		2012
		(in millions)
	Office facilities	$	67	$	71	$	71
	Equipment		13		13		11

		$	80	$	84	$	82

Future Minimum Rental Payments Required Under Non-Cancellable Operating Leases	At December 31, 2014, future minimum rental payments required under non-cancellable operating leases were as follows:


	Years Ending December 31	(in millions)
	2015	$	63
	2016		52
	2017		47
	2018		40
	2019		30
	After 2019		81

		$	313

Segments_Information_Tables

Segments Information (Tables)	12 Months Ended
Segments Information (Tables)	Dec. 31, 2014
Segment Reporting [Abstract]
Revenues, Income Before Income Tax and Assets of Each Operating Segment	Revenues, income before income tax and assets of each operating segment were as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Revenues
	Property and casualty insurance
	Premiums earned
	Personal insurance	$	4,418		$	4,214		$	4,024
	Commercial insurance		5,281			5,237			5,144
	Specialty insurance		2,628			2,618			2,666

	Total insurance		12,327			12,069			11,834
	Reinsurance assumed		1			(3	)		4

			12,328			12,066			11,838
	Investment income		1,368			1,436			1,518

	Total property and casualty insurance		13,696			13,502			13,356
	Corporate and other		33			43			46
	Realized investment gains, net		369			402			193

	Total revenues	$	14,098		$	13,947		$	13,595

	Income (loss) before income tax
	Property and casualty insurance
	Underwriting
	Personal insurance	$	370		$	509		$	192
	Commercial insurance		492			692			44
	Specialty insurance		495			406			262

	Total insurance		1,357			1,607			498
	Reinsurance assumed		—			9			47

			1,357			1,616			545
	Increase in deferred policy acquisition costs		45			59			3

	Underwriting income		1,402			1,675			548
	Investment income		1,329			1,391			1,482
	Other income (charges)		(4	)		6			10

	Total property and casualty insurance		2,727			3,072			2,040
	Corporate and other		(235	)		(237	)		(237	)
	Realized investment gains, net		369			402			193

	Total income before income tax	$	2,861		$	3,237		$	1,996



		December 31
		2014			2013			2012
		(in millions)
	Assets
	Property and casualty insurance	$	49,297		$	48,278		$	49,441
	Corporate and other		2,078			2,248			2,830
	Adjustments and eliminations		(89	)		(93	)		(87	)

	Total assets	$	51,286		$	50,433		$	52,184

Revenues of Property and Casualty Group by Geographic Area	Revenues of the P&C Group by geographic area were as follows:


		Years Ended December 31
		2014			2013			2012
		(in millions)
	Revenues
	United States	$	10,448		$	10,205		$	9,996
	International		3,248
						3,297
									3,360

	Total	$	13,696		$	13,502		$	13,356

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	12 Months Ended
Fair Values of Financial Instruments (Tables)	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Carrying Values and Fair Values of Financial Instruments	The carrying values and fair values of financial instruments were as follows:


		December 31
		2014				2013
		Carrying		Fair		Carrying		Fair
		Value		Value		Value		Value
		(in millions)
	Assets
	Invested assets
	Short term investments	$	1,318	$	1,318	$	2,114	$	2,114
	Fixed maturities (Note 2)		38,780		38,780		37,091		37,091
	Equity securities		1,964		1,964		1,810		1,810
	Liabilities
	Long term debt (Note 6)		3,300		4,013		3,300		3,806
Fair Value of Financial Instruments Categorized Based Upon Lowest Level of Input
	The fair value of financial instruments categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:


		December 31, 2014
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	206	$	1,112	$	—	$	1,318

	Fixed maturities
	Tax exempt		—		19,769		3		19,772

	Taxable
	U.S. government and government agency and authority obligations		—		2,007		—		2,007
	Corporate bonds		—		8,912		116		9,028
	Foreign government and government agency obligations		—		6,663		9		6,672
	Residential mortgage-backed securities		—		210		1		211
	Commercial mortgage-backed securities		—		1,090		—		1,090

			—		18,882		126		19,008

	Total fixed maturities		—		38,651		129		38,780

	Equity securities		1,958		—		6		1,964

		$	2,164	$	39,763	$	135	$	42,062

	Liabilities
	Long term debt	$	—	$	4,013	$	—	$	4,013



		December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	399	$	1,715	$	—	$	2,114

	Fixed maturities
	Tax exempt		—		18,416		5		18,421

	Taxable
	U.S. government and government agency and authority obligations		—		802		—		802
	Corporate bonds		—		9,179		135		9,314
	Foreign government and government agency obligations		—		6,881		9		6,890
	Residential mortgage-backed securities		—		293		6		299
	Commercial mortgage-backed securities		—		1,345		20		1,365

			—		18,500		170		18,670

	Total fixed maturities		—		36,916		175		37,091

	Equity securities		1,803		—		7		1,810


			$2,202		$38,631		$182		$41,015

	Liabilities
	Long term debt
	Long term debt	$	—	$	3,806	$	—	$	3,806


Fair Values of Pension Plan Assets Categorized Based Upon Lowest Level of Input	Based on the fair value hierarchy, the fair value of the Corporation’s pension plan assets categorized based upon the lowest level of input that was significant to the fair value measurement was as follows:


		December 31, 2014
		Level 1		Level 2		Level 3		Total
		(in millions)
	Short term investments	$	—	$	48	$	—	$	48

	Fixed maturities
	U.S. government and government agency and authority obligations		—		209		—		209
	Corporate bonds		—		419		—		419
	Foreign government and government agency obligations		—		137		—		137
	Mortgage-backed securities		—		228		—		228

	Total fixed maturities		—		993		—		993

	Equity securities		629		1,221		—		1,850

	Other assets		28		20		7		55

		$	657	$	2,282	$	7	$	2,946



		December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in millions)
	Short term investments	$	—	$	37	$	—	$	37

	Fixed maturities
	U.S. government and government agency		—		224		—		224
	and authority obligations		—		224		—		224
	Corporate bonds		—		370		1		371
	Foreign government and government		—		104		—		104
	agency obligations		—		104		—		104
	Mortgage-backed securities		—		211		6		217

	Total fixed maturities		—		909		7		916

	Equity securities		573		1,145		—		1,718

	Other assets		21		14		11		46

		$	594	$	2,105	$	18	$	2,717

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
Earnings Per Share (Tables)	Dec. 31, 2014
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share:


		Years Ended December 31
		2014		2013		2012
		(in millions except for per
		share amounts)
	Basic earnings per share:
	Net income	$	2,100	$	2,345	$	1,545

	Weighted average shares outstanding		242.9		258.2		269.5

	Basic earnings per share	$	8.65	$	9.08	$	5.73

	Diluted earnings per share:
	Net income	$	2,100	$	2,345	$	1,545

	Weighted average shares outstanding		242.9		258.2		269.5
	Additional shares from assumed issuance of shares under stock-based compensation awards		0.6		1.2		1.9

	Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share		243.5		259.4		271.4

	Diluted earnings per share	$	8.62	$	9.04	$	5.69

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	12 Months Ended
Shareholders' Equity (Tables)	Dec. 31, 2014
Equity [Abstract]
Common Stock Activity	The activity of Chubb’s common stock was as follows:


		Years Ended December 31
		2014			2013			2012
		(number of shares)
	Common stock issued
	Balance, beginning and end of year		371,980,460			371,980,460			371,980,460

	Treasury stock
	Balance, beginning of year		123,673,969			110,217,445			99,519,509
	Repurchase of shares		16,893,455			14,887,701			13,094,640
	Share activity under stock-based employee compensation plans		(1,016,353	)		(1,431,177	)		(2,396,704	)

	Balance, end of year		139,551,071			123,673,969			110,217,445

	Common stock outstanding, end of year		232,429,389			248,306,491			261,763,015

Comparison of Shareholders' Equity on GAAP Basis and Policyholders' Surplus on Statutory Basis	A comparison of shareholders’ equity on a GAAP basis and policyholders’ surplus on a statutory basis is as follows:


		December 31
		2014						2013
		GAAP			Statutory			GAAP			Statutory
		(in millions)
	P&C Group	$	17,786		$	15,127		$	17,398		$	15,024

	Corporate and other		(1,490	)					(1,301	)

		$	16,296					$	16,097

Comparison of GAAP and Statutory Net Income (Loss)	A comparison of GAAP and statutory net income (loss) is as follows:


		Years Ended December 31
		2014						2013					2012
		GAAP			Statutory			GAAP			Statutory		GAAP			Statutory
		(in millions)
	P&C Group	$	2,330		$	2,399		$	2,480		$	2,485	$	1,791		$	1,936

	Corporate and other		(230	)					(135	)				(246	)

		$	2,100					$	2,345				$	1,545

Quarterly_Financial_Data_Table

Quarterly Financial Data (Tables)	12 Months Ended
Quarterly Financial Data (Tables)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Data	Summarized unaudited quarterly financial data for 2014 and 2013 are shown below. In management’s opinion, the interim financial data contain all adjustments, consisting of normal recurring items, necessary to present fairly the results of operations for the interim periods.


		Three Months Ended
		March 31						June 30						September 30						December 31
		2014			2013			2014			2013			2014			2013			2014			2013
		(in millions except for per share amounts)
	Revenues	$	3,506		$	3,517		$	3,542		$	3,551		$	3,574		$	3,403		$	3,476		$	3,476
	Losses and expenses		2,903			2,601			2,864			2,755			2,756			2,664			2,714			2,690
	Federal and foreign income tax		154			260			179			217			224			198			204			217

	Net income	$	449		$	656		$	499		$	579		$	594		$	541		$	558		$	569

	Basic earnings per share	$	1.81		$	2.49		$	2.03		$	2.22		$	2.47		$	2.11		$	2.35		$	2.25

	Diluted earnings per share	$	1.8		$	2.48		$	2.03		$	2.21		$	2.47		$	2.1		$	2.35		$	2.24

	Underwriting ratios
	Losses to premiums earned		61.1	%		52.3	%		58.7	%		56.7	%		54	%		53	%		53.8	%		54.7	%
	Expenses to premiums written		32.1			32.3			31.3			32.1			31.8			32.7			30.5			30.8

	Combined		93.2	%		84.6	%		90	%		88.8	%		85.8	%		85.7	%		84.3	%		85.5	%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2011
Conversion of Stock [Line Items]
Cash	$52	$47	$50	$58
Alterra Common Stock [Member]
Conversion of Stock [Line Items]
Holdings of common stock and warrants, cost basis	177
Alterra Warrants [Member]
Conversion of Stock [Line Items]
Holdings of common stock and warrants, cost basis	63
Markel Corporation [Member]
Conversion of Stock [Line Items]
Transferred, common stock value	226
Cash	$98

Invested_Assets_and_Related_In2

Invested Assets and Related Income - Amortized Cost and Fair Value of Fixed Maturities and Equity Securities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	$36,958	$35,959
Fixed maturities, Gross Unrealized Appreciation	1,884	1,457
Fixed maturities, Gross Unrealized Depreciation	62	325
Fixed maturities, Fair Value	38,780	37,091
Equity securities, Amortized Cost	1,089	1,057
Equity securities, Gross Unrealized Appreciation	894	756
Equity securities, Gross Unrealized Depreciation	19	3
Equity securities, Fair Value	1,964	1,810
Tax Exempt [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	18,614	17,808
Fixed maturities, Gross Unrealized Appreciation	1,174	802
Fixed maturities, Gross Unrealized Depreciation	16	189
Fixed maturities, Fair Value	19,772	18,421
Taxable [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	18,344	18,151
Fixed maturities, Gross Unrealized Appreciation	710	655
Fixed maturities, Gross Unrealized Depreciation	46	136
Fixed maturities, Fair Value	19,008	18,670
Taxable [Member] \| Residential Mortgage-backed Securities [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	192	277
Fixed maturities, Gross Unrealized Appreciation	20	23
Fixed maturities, Gross Unrealized Depreciation	1	1
Fixed maturities, Fair Value	211	299
Taxable [Member] \| Commercial Mortgage-backed Securities [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	1,069	1,339
Fixed maturities, Gross Unrealized Appreciation	22	29
Fixed maturities, Gross Unrealized Depreciation	1	3
Fixed maturities, Fair Value	1,090	1,365
Taxable [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	1,962	784
Fixed maturities, Gross Unrealized Appreciation	46	27
Fixed maturities, Gross Unrealized Depreciation	1	9
Fixed maturities, Fair Value	2,007	802
Taxable [Member] \| Corporate Bonds [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	8,741	9,032
Fixed maturities, Gross Unrealized Appreciation	327	370
Fixed maturities, Gross Unrealized Depreciation	40	88
Fixed maturities, Fair Value	9,028	9,314
Taxable [Member] \| Foreign Government and Government Agency Obligations [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	6,380	6,719
Fixed maturities, Gross Unrealized Appreciation	295	206
Fixed maturities, Gross Unrealized Depreciation	3	35
Fixed maturities, Fair Value	$6,672	$6,890

Invested_Assets_and_Related_In3

Invested Assets and Related Income - Summary of Fair Value of Tax Exempt Fixed Maturities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturities, Fair Value	$38,780	$37,091
Tax Exempt [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturities, Fair Value	19,772	18,421
Tax Exempt [Member] \| Tax Exempt Fixed Maturities [Member] \| Special Revenue Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturities, Fair Value	12,936	11,717
Tax Exempt [Member] \| Tax Exempt Fixed Maturities [Member] \| State General Obligation Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturities, Fair Value	2,415	2,292
Tax Exempt [Member] \| Tax Exempt Fixed Maturities [Member] \| Municipal and Political Subdivision General Obligation Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturities, Fair Value	2,378	2,220
Tax Exempt [Member] \| Tax Exempt Fixed Maturities [Member] \| Pre-Refunded Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fixed maturities, Fair Value	$2,043	$2,192

Invested_Assets_and_Related_In4

Invested Assets and Related Income - Fair Value and Amortized Cost of Tax Exempt Fixed Maturities Other Than Pre-Refunded Bonds (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	$2,262	$1,839
Amortized Cost	2,135	1,809
Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,946	1,990
Amortized Cost	1,829	1,904
California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,507	1,139
Amortized Cost	1,422	1,093
Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,086	1,116
Amortized Cost	1,022	1,094
Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,080	903
Amortized Cost	1,017	877
Special Revenue Bonds [Member] \| New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	2,046	1,611
Special Revenue Bonds [Member] \| Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	883	930
Special Revenue Bonds [Member] \| California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,098	859
Special Revenue Bonds [Member] \| Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	608	577
Special Revenue Bonds [Member] \| Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	850	757
Municipal and Political Subdivision General Obligation Bonds [Member] \| New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	173	197
Municipal and Political Subdivision General Obligation Bonds [Member] \| Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	852	830
Municipal and Political Subdivision General Obligation Bonds [Member] \| California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	153	82
Municipal and Political Subdivision General Obligation Bonds [Member] \| Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	381	483
Municipal and Political Subdivision General Obligation Bonds [Member] \| Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	63	38
State General Obligation Bonds [Member] \| New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	43	31
State General Obligation Bonds [Member] \| Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	211	230
State General Obligation Bonds [Member] \| California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	256	198
State General Obligation Bonds [Member] \| Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	97	56
State General Obligation Bonds [Member] \| Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	$167	$108

Invested_Assets_and_Related_In5

Invested Assets and Related Income - Fair Value and Amortized Cost of Foreign Government and Government Agency Fixed Maturities (Detail) (Foreign Government and Government Agency Obligations [Member], USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Canada [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	$1,893	$1,993
Amortized Cost	1,823	1,953
United Kingdom [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,230	1,026
Amortized Cost	1,163	1,004
Germany [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,102	1,241
Amortized Cost	1,045	1,211
Australia [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	746	739
Amortized Cost	700	700
Brazil [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	232	270
Amortized Cost	$231	$270

Invested_Assets_and_Related_In6

Invested Assets and Related Income - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Investment	Dec. 31, 2013
Schedule of Available-For-Sale Securities [Line Items]
Fixed maturities, Fair Value	$38,780	$37,091
Approximate number of individual fixed maturities in unrealized loss position	735
Approximate number of individual equity securities in unrealized loss position	15
Cumulative credit-related losses recognized in net income	18	20
Taxable [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fixed maturities, Fair Value	19,008	18,670
Taxable [Member] \| Supranational Organization Issued [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fixed maturities, Fair Value	$469	$547

Invested_Assets_and_Related_In7

Invested Assets and Related Income - Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-For-Sale Securities [Line Items]
Due in one year or less, Fair Value	$2,947
Due after one year through five years, Fair Value	12,906
Due after five years through ten years, Fair Value	12,814
Due after ten years, Fair Value	8,812
Subtotal fixed maturities, Fair Value	37,479
Total fixed maturities, Fair Value	38,780	37,091
Due in one year or less, Amortized Cost	2,922
Due after one year through five years, Amortized Cost	12,406
Due after five years through ten years, Amortized Cost	12,041
Due after ten years, Amortized Cost	8,328
Subtotal fixed maturities, Amortized Cost	35,697
Fixed maturities, Amortized Cost	36,958	35,959
Residential Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	211
Taxable, Amortized Cost	192
Commercial Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	1,090
Taxable, Amortized Cost	$1,069

Invested_Assets_and_Related_In8

Invested Assets and Related Income - Components of Unrealized Appreciation or Depreciation of Investments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Fixed maturities, Gross Unrealized Appreciation	$1,884	$1,457
Fixed maturities, Gross Unrealized Depreciation	62	325
Fixed maturities, Unrealized appreciation (depreciation), Net	1,822	1,132
Equity securities, Gross Unrealized Appreciation	894	756
Equity securities, Gross Unrealized Depreciation	19	3
AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainLossBeforeTax	875	753
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net	2,697	1,885
Deferred income tax liability	944	660
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax	$1,753	$1,225

Invested_Assets_and_Related_In9

Invested Assets and Related Income - Fair Value and Gross Unrealized Depreciation of Investments in Unrealized Loss Position (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	$3,176	$8,089
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	39	262
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	1,521	692
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	42	66
Investment securities, Continuous unrealized loss position, Fair Value, Total	4,697	8,781
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	81	328
Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	3,109	8,048
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	28	259
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	1,510	692
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	34	66
Investment securities, Continuous unrealized loss position, Fair Value, Total	4,619	8,740
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	62	325
Equity Securities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	67	41
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	11	3
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	11
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	8
Investment securities, Continuous unrealized loss position, Fair Value, Total	78	41
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	19	3
Tax Exempt [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	422	3,417
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	3	144
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	305	307
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	13	45
Investment securities, Continuous unrealized loss position, Fair Value, Total	727	3,724
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	16	189
Taxable [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	2,687	4,631
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	25	115
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	1,205	385
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	21	21
Investment securities, Continuous unrealized loss position, Fair Value, Total	3,892	5,016
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	46	136
Taxable [Member] \| U.S. Government and Government Agency and Authority Obligations [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	936	213
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	1	6
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	36	35
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation		3
Investment securities, Continuous unrealized loss position, Fair Value, Total	972	248
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	1	9
Taxable [Member] \| Corporate Bonds [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	1,327	2,526
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	23	76
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	888	222
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	17	12
Investment securities, Continuous unrealized loss position, Fair Value, Total	2,215	2,748
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	40	88
Taxable [Member] \| Foreign Government and Government Agency Obligations [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	318	1,735
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	1	32
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	207	75
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	2	3
Investment securities, Continuous unrealized loss position, Fair Value, Total	525	1,810
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	3	35
Residential Mortgage-backed Securities [Member] \| Taxable [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value		4
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	7	14
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	1	1
Investment securities, Continuous unrealized loss position, Fair Value, Total	7	18
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	1	1
Commercial Mortgage-backed Securities [Member] \| Taxable [Member] \| Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	106	153
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation		1
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	67	39
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	1	2
Investment securities, Continuous unrealized loss position, Fair Value, Total	173	192
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	$1	$3

Recovered_Sheet1

Invested Assets and Related Income - Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Change in unrealized appreciation of fixed maturities	$690	($1,546)	$256
Change in unrealized appreciation of equity securities	122	334	171
Change in unrealized appreciation of fixed maturities and equity securities	812	-1,212	427
Deferred income tax (credit)	284	-424	150
Total change in unrealized appreciation (depreciation) of fixed maturities and equity securities, Net of tax	$528	($788)	$277

Recovered_Sheet2

Invested Assets and Related Income - Sources of Net Investment Income (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gross investment income	$1,394	$1,465	$1,556
Investment Expenses	42	49	38
Net Investment income	1,352	1,416	1,518
Fixed Maturities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gross investment income	1,314	1,380	1,465
Equity Securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gross investment income	41	38	40
Short Term Investments [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gross investment income	18	16	18
Other [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gross investment income	$21	$31	$33

Recovered_Sheet3

Invested Assets and Related Income - Realized Investment Gains and Losses (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Fixed maturities, Gross realized gains	$126	$62	$124
Fixed maturities, Gross realized losses	-36	-42	-20
Fixed maturities, Other-than-temporary impairment losses	-5	-2	-5
Total fixed maturities	85	18	99
Equity securities, Gross realized gains	137	204	68
Equity securities, Gross realized losses		-1
Equity securities, Other-than-temporary impairment losses	-2	-9	-40
Total equity securities	135	194	28
Other invested assets	149	190	66
Total Realized Investment Gains, Net	$369	$402	$193

Deferred_Policy_Acquisition_Co2

Deferred Policy Acquisition Costs - Policy Acquisition Costs Deferred and Related Amortization Reflected in Operating Results (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Balance, beginning of year	$1,255	$1,206	$1,210
Costs deferred during year
Commissions and brokerage	2,073	1,979	1,919
Premium taxes and assessments	258	263	247
Underwriting and policy issuance costs	262	271	248
Total costs deferred during year	2,593	2,513	2,414
Foreign currency translation effect	-16	-10	-7
Amortization during year	-2,548	-2,454	-2,411
Balance, end of year	$1,284	$1,255	$1,206

Property_and_Equipment_Schedul

Property and Equipment - Schedule of Property and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Cost	$488	$501
Accumulated depreciation	239	243
Property and Equipment, net of accumulated depreciation	$249	$258

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Depreciation expense related to property and equipment	$54	$55	$54

Unpaid_Losses_and_Loss_Expense2

Unpaid Losses and Loss Expenses - Reconciliation of Beginning and Ending Liability for Unpaid Losses and Loss Expenses (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance [Abstract]
Gross liability, beginning of year	$23,146	$23,963	$23,068
Reinsurance recoverable, beginning of year	1,802	1,941	1,739
Net liability, beginning of year	21,344	22,022	21,329
Net incurred losses and loss expenses related to
Current year	7,621	7,232	8,121
Prior years	-636	-712	-614
Net incurred losses and loss expenses, total	6,985	6,520	7,507
Net payments for losses and loss expenses related to
Current year	2,496	2,150	2,323
Prior years	4,534	4,952	4,493
Net payments for losses and loss expenses, total	7,030	7,102	6,816
Foreign currency translation effect	-260	-96	2
Net liability, end of year	21,039	21,344	22,022
Reinsurance recoverable, end of year	1,639	1,802	1,941
Gross liability, end of year	$22,678	$23,146	$23,963

Unpaid_Losses_and_Loss_Expense3

Unpaid Losses and Loss Expenses - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Manufacturers_Distributors
	Areas
Insurance [Abstract]
Favorable development on net unpaid losses and loss expenses established as of the previous year end	$636	$712	$614
Favorable development experienced in the professional liability classes other than fidelity	320	260	200
Aggregate favorable development experienced in the personal and commercial liability classes	205	160	250
Adverse development for losses related to asbestos and toxic waste claims	100	106	83
Aggregate favorable development experienced in the personal and commercial property classes	60	265	125
Favorable development experienced in workers' compensation class	50
Amount related to catastrophes		30
Adverse development experienced in the fidelity class		50	60
Favorable development experienced in the personal automobile business		35	40
Favorable development experienced in the surety business		30	25
Favorable development experienced in the runoff of the reinsurance assumed business			$45
Number of manufacturers and distributors of asbestos products that filed for bankruptcy protection	110
Number of areas of exposure for P&C Group's insureds	2

Debt_and_Credit_Arrangements_L

Debt and Credit Arrangements - Long Term Debt (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long Term Debt	$3,300	$3,300
5.75% Notes due May 15, 2018 [Member]
Debt Instrument [Line Items]
Long Term Debt	600	600
6.6% Debentures due August 15, 2018 [Member]
Debt Instrument [Line Items]
Long Term Debt	100	100
6.8% Debentures due November 15, 2031 [Member]
Debt Instrument [Line Items]
Long Term Debt	200	200
6% Notes due May 11, 2037 [Member]
Debt Instrument [Line Items]
Long Term Debt	800	800
6.5% Notes due May 15, 2038 [Member]
Debt Instrument [Line Items]
Long Term Debt	600	600
6.375% Capital Securities due March 29, 2067 [Member]
Debt Instrument [Line Items]
Long Term Debt	$1,000	$1,000

Debt_and_Credit_Arrangements_L1

Debt and Credit Arrangements - Long Term Debt (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2014
Debt Instrument [Line Items]
Interest rate of capital securities march 29, 2067	6.38%
5.75% Notes due May 15, 2018 [Member]
Debt Instrument [Line Items]
Interest rate due on notes and debentures	5.75%
Debt instrument maturity date	15-May-18
6.6% Debentures due August 15, 2018 [Member]
Debt Instrument [Line Items]
Interest rate due on notes and debentures	6.60%
Debt instrument maturity date	15-Aug-18
6.8% Debentures due November 15, 2031 [Member]
Debt Instrument [Line Items]
Interest rate due on notes and debentures	6.80%
Debt instrument maturity date	15-Nov-31
6% Notes due May 11, 2037 [Member]
Debt Instrument [Line Items]
Interest rate due on notes and debentures	6.00%
Debt instrument maturity date	11-May-37
6.5% Notes due May 15, 2038 [Member]
Debt Instrument [Line Items]
Interest rate due on notes and debentures	6.50%
Debt instrument maturity date	15-May-38
6.375% Capital Securities due March 29, 2067 [Member]
Debt Instrument [Line Items]
Interest rate of capital securities march 29, 2067	6.38%
Debt instrument maturity date	29-Mar-67

Debt_and_Credit_Arrangements_A

Debt and Credit Arrangements - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Times	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long Term Debt	$3,300	$3,300
Interest rate of capital securities through April 14, 2017	6.38%
Interest rate on capital securities after April 14, 2017, plus three-month LIBOR rate	2.25%
Consecutive years payment of interest may be deferred on capital securities	10 years
End date of restrictions to redeem capital securities	29-Mar-47
Capital securities redeemable date	15-Apr-17
Interest costs incurred	209	213	224
Interest paid	205	213	220
Maximum unsecured borrowings permitted under credit agreement	500	500
Revolving credit agreement maturity date	24-Sep-17
Number of times permitted for increase in available credit, per year	2
Maximum facility amount permitted to request an increase in the credit available	750
Extended additional maturity period	1 year
Borrowings under credit agreement	0
6.375% Capital Securities due March 29, 2067 [Member]
Debt Instrument [Line Items]
Long Term Debt	1,000	1,000
Scheduled maturity date	15-Apr-37
Final maturity date	29-Mar-67
Interest rate of capital securities through April 14, 2017	6.38%
Debt instrument maturity date	29-Mar-67
6.8% Debentures due November 15, 2031 [Member]
Debt Instrument [Line Items]
Long Term Debt	$200	$200
Interest rate due on notes and debentures	6.80%
Debt instrument maturity date	15-Nov-31

Debt_and_Credit_Arrangements_A1

Debt and Credit Arrangements - Amounts of Long Term Debt due Annually (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Debt Disclosure [Abstract]
2015
2016
2017
2018	700
2019

Federal_and_Foreign_Income_Tax2

Federal and Foreign Income Tax - Income Tax Expense and Taxes Paid (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income tax expense and taxes paid
Current tax, United States									$617	$791	$276
Current tax, Foreign									124	91	143
Deferred tax, principally United States									20	10	32
Federal and foreign income tax	204	224	179	154	217	198	217	260	761	892	451
Federal and foreign income taxes paid									$571	$789	$472

Federal_and_Foreign_Income_Tax3

Federal and Foreign Income Tax - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Income before federal and foreign income taxes from U.S. operations	$2,424	$2,766	$1,373
Income before federal and foreign income taxes from foreign operations	437	471	623
Deferred income tax assets valuation allowance	$13	$13

Federal_and_Foreign_Income_Tax4

Federal and Foreign Income Tax - Reconciliation of Effective Income Tax Rate and Statutory Federal Corporate Tax Rate (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Income before federal and foreign income tax									$2,861	$3,237	$1,996
Tax at statutory federal income tax rate									1,001	1,133	699
Tax exempt interest income									-212	-222	-233
Other, net									-28	-19	-15
Federal and foreign income tax	$204	$224	$179	$154	$217	$198	$217	$260	$761	$892	$451
Income before federal and foreign income tax, percentage of Pre-Tax Income
Tax at statutory federal income tax rate, percentage of Pre-Tax Income									35.00%	35.00%	35.00%
Tax exempt interest income, percentage of Pre-Tax Income									-7.40%	-6.80%	-11.70%
Other, net, percentage of Pre-Tax Income									-1.00%	-0.60%	-0.70%
Federal and foreign income tax, percentage of Pre-Tax Income									26.60%	27.60%	22.60%

Federal_and_Foreign_Income_Tax5

Federal and Foreign Income Tax - Tax Effects of Temporary Differences that Gave Rise to Deferred Income Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred income tax assets
Unpaid losses and loss expenses	$509	$524
Unearned premiums	364	350
Foreign tax credits	963	867
Employee compensation	144	142
Postretirement benefits	272	95
Other-than-temporary impairment losses	298	291
Other, net	29
Total deferred income tax assets	2,579	2,269
Deferred income tax liabilities
Deferred policy acquisition costs	367	356
Unremitted earnings of foreign subsidiaries	1,075	970
Unrealized appreciation of investments	944	660
Other invested assets	208	184
Other, net		52
Total deferred income tax liabilities	2,594	2,222
Net deferred income tax asset (liability)	($15)	$47

Reinsurance_Effect_of_Reinsura

Reinsurance - Effect of Reinsurance on Premiums Written and Earned (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance [Abstract]
Direct premiums written	$12,976	$12,804	$12,647
Assumed reinsurance	596	503	423
Ceded reinsurance	-980	-1,083	-1,200
Net premiums written	12,592	12,224	11,870
Direct premiums earned	12,776	12,717	12,596
Assumed reinsurance	562	476	422
Ceded reinsurance	-1,010	-1,127	-1,180
Net premiums earned	$12,328	$12,066	$11,838

Reinsurance_Additional_Informa

Reinsurance - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance [Abstract]
Ceded losses and loss expenses incurred	$273	$400	$586

StockBased_Employee_Compensati2

Stock-Based Employee Compensation Plans - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost related to stock-based compensation plan	$85	$89	$84
Total income tax benefit related to stock-based compensation plan	30	31	29
Unrecognized compensation cost related to nonvested awards	78
Weighted average period of years over which unrecognized compensation cost will be reflected in operating results	1 year 8 months 12 days
Maximum number of shares in respect to which stock-based awards may be granted under the plan most recently approved by shareholders	7,400,000
Shares available for grant	8,200,000
Performance period in which performance unit awards are based	3 years
Stock option expiration period	10 years
Weighted average fair value per stock option granted	$15.48	$14.95	$11.95
Total intrinsic value of stock options exercised	2	16	40
Cash received from the exercise of stock options	3	10	47
Tax benefit realized with respect to the exercise of stock options	1	5	13
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per share of the restricted stock units and performance units granted	$86.67	$83.75	$68.64
Total fair value of the restricted stock units and performance units vested	66	72	74
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value per share of the restricted stock units and performance units granted	$76.32	$98.46	$63.38
Total fair value of the restricted stock units and performance units vested	$17	$64	$70

StockBased_Employee_Compensati3

Stock-Based Employee Compensation Plans - Additional Information With Respect to Restricted Stock Units and Performance Units (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Nonvested, January 1, 2014	2,127,647
Number of Shares, Granted	625,197
Number of Shares, Vested	-762,349
Number of Shares, Forfeited	-82,551
Number of Shares, Nonvested, December 31, 2014	1,907,944	2,127,647
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, January 1, 2014	$70.23
Weighted Average Grant Date Fair Value on Number of Shares, Granted	$86.67	$83.75	$68.64
Weighted Average Grant Date Fair Value on Number of Shares, Vested	$60.53
Weighted Average Grant Date Fair Value on Number of Shares, Forfeited	$81.16
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, December 31, 2014	$79.02	$70.23
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Nonvested, January 1, 2014	861,141
Number of Shares, Granted	421,271
Number of Shares, Vested	-456,176
Number of Shares, Forfeited	-4,041
Number of Shares, Nonvested, December 31, 2014	822,195	861,141
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, January 1, 2014	$79.87
Weighted Average Grant Date Fair Value on Number of Shares, Granted	$76.32	$98.46	$63.38
Weighted Average Grant Date Fair Value on Number of Shares, Vested	$63.38
Weighted Average Grant Date Fair Value on Number of Shares, Forfeited	$77.87
Weighted Average Grant Date Fair Value on Number of Shares, Nonvested, December 31, 2014	$87.21	$79.87

StockBased_Employee_Compensati4

Stock-Based Employee Compensation Plans - Additional Information With Respect to Restricted Stock Units and Performance Units (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Percentage of number of shares that may be earned related to performance units, Minimum	0.00%
Percentage of number of shares that may be earned related to performance units, Maximum	200.00%
Percentage of performance units earned as it relates to vested shares	35.20%
Number of performance units earned as it relates to vested shares	160,574

StockBased_Employee_Compensati5

Stock-Based Employee Compensation Plans - Additional Information with Respect to Stock Options (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares Outstanding, January 1, 2014	251,687
Number of Shares, Granted	65,605
Number of Shares, Exercised	-54,932
Number of Shares, Forfeited	-6,949
Number of Shares Outstanding, December 31, 2014	255,411
Number of Shares Exercisable, December 31, 2014	128,880
Weighted Average Exercise Price on Number of Shares Outstanding, January 1, 2014	$62.52
Weighted Average Exercise Price on Number of Shares, Granted	$86.59
Weighted Average Exercise Price on Number of Shares, Exercised	$59.08
Weighted Average Exercise Price on Number of Shares, Forfeited	$82.83
Weighted Average Exercise Price on Number of Shares Outstanding, December 31, 2014	$68.89
Weighted Average Exercise Price on Number of Shares Exercisable, December 31, 2014	$55.24
Weighted Average Remaining Contractual Term (in years) on Number of Shares Outstanding	6 years 7 months 6 days
Weighted Average Remaining Contractual Term (in years) on Number of Shares Exercisable, December 31, 2014	4 years 9 months 18 days
Aggregate Intrinsic Value on Number of Shares Outstanding, December 31, 2014	$9
Aggregate Intrinsic Value on Number of Shares Exercisable, December 31, 2014	$6

Employee_Benefits_Funded_Statu

Employee Benefits - Funded Status of Pension and Other Postretirement Benefit Plans (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$2,946	$2,717
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, beginning of year	2,777	2,894
Service cost	86	95	88
Interest cost	140	125	124
Actuarial loss (gain)	536	-261
Benefits paid	-85	-75
Foreign currency translation effect	-19	-1
Benefit obligation, end of year	3,435	2,777	2,894
Plan assets at fair value, beginning of year	2,717	2,305
Actual return on plan assets	240	409
Employer contributions	92	82
Benefits paid	-85	-75
Foreign currency translation effect	-18	-4
Plan assets at fair value, end of year	2,946	2,717	2,305
Funded status at end of year, included in other liabilities	489	60
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, beginning of year	394	470
Service cost	10	13	12
Interest cost	19	19	20
Actuarial loss (gain)	74	-97
Benefits paid	-10	-11
Foreign currency translation effect	-2
Benefit obligation, end of year	485	394	470
Plan assets at fair value, beginning of year	130	96
Actual return on plan assets	12	27
Employer contributions	11	18
Benefits paid	-10	-11
Plan assets at fair value, end of year	143	130	96
Funded status at end of year, included in other liabilities	$342	$264

Employee_Benefits_Net_Actuaria

Employee Benefits - Net Actuarial Loss (Gain) and Prior Service Cost Included in Accumulated Other Comprehensive Income (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	$842	$396
Prior service cost	14	16
Total net actuarial loss and prior service cost included in accumulated other comprehensive income	856	412
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	58	-13
Prior service cost	1	1
Total net actuarial loss and prior service cost included in accumulated other comprehensive income	$59	($12)

Employee_Benefits_Additional_I

Employee Benefits - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for the pension plans	$2,923	$2,381
Estimated aggregate net actuarial loss and prior service cost to be amortized next year	65
Effect of one percent increase in health care cost trend rate on the accumulated other postretirement benefit obligation	92
Effect of one percent decrease in health care cost trend rate on the accumulated other postretirement benefit obligation	73
Effect of one percent increase in health care cost trend rate on net other postretirement benefit cost	5
Effect of one percent decrease in health care cost trend rate on net other postretirement benefit cost	4
Postretirement benefit, description	The health care 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, 2014 by approximately $92 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2014 by approximately $5 million. A one percent decrease in the trend rate for each year would decrease the accumulated other postretirement benefit obligation at December 31, 2014 by approximately $73 million and the aggregate of the service and interest cost components of net other postretirement benefit cost for the year ended December 31, 2014 by approximately $4 million.
Employer elective matching contributions related to employee's eligible pre-tax contributions	Equal to 100%
Employer contributions for Capital Accumulation Plan	30	29	26
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
The portion of employer elective matching contribution related to employee's eligible pre-tax contributions	4.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum range of portfolio allocation to equity securities	55.00%
Maximum range of portfolio allocation to equity securities	65.00%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets invested in pooled funds	1,556	1,425
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets invested in pooled funds	$143	$130

Employee_Benefits_Weighted_Ave

Employee Benefits - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.30%	5.20%
Rate of compensation increase	4.50%	4.50%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.30%	5.20%
Rate of compensation increase

Employee_Benefits_Components_o

Employee Benefits - Components of Net Pension and Other Postretirement Benefit Costs Reflected in Net Income (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Components of net pension and other postretirement benefit costs reflected in net income
Service cost	$86	$95	$88
Interest cost	140	125	124
Expected return on plan assets	-186	-165	-155
Amortization of net actuarial loss and prior service cost and other	35	90	80
Total benefit costs reflected in net income	75	145	137
Other Postretirement Benefits [Member]
Components of net pension and other postretirement benefit costs reflected in net income
Service cost	10	13	12
Interest cost	19	19	20
Expected return on plan assets	-9	-7	-6
Amortization of net actuarial loss and prior service cost and other		3	3
Total benefit costs reflected in net income	$20	$28	$29

Employee_Benefits_Changes_in_P

Employee Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net actuarial loss (gain)	$479	($505)	$139
Amortization of net actuarial loss and prior service cost and other	-35	-90	-80
Total changes in plan assets and benefit obligations recognized in other comprehensive income	444	-595	59
Other Postretirement Benefits [Member]
Changes in plan assets and benefit obligations recognized in other comprehensive income
Net actuarial loss (gain)	71	-117	-11
Amortization of net actuarial loss and prior service cost and other		-3	-3
Total changes in plan assets and benefit obligations recognized in other comprehensive income	$71	($120)	($14)

Employee_Benefits_Weighted_Ave1

Employee Benefits - Weighted Average Assumptions Used to Determine Net Pension and Other Postretirement Benefit Costs (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.20%	4.40%	5.00%
Rate of compensation increase	4.50%	4.50%	4.50%
Expected long term rate of return on plan assets	7.50%	7.50%	7.75%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.20%	4.40%	5.00%
Rate of compensation increase
Expected long term rate of return on plan assets	7.50%	7.50%	7.75%

Employee_Benefits_Weighted_Ave2

Employee Benefits - Weighted Average Health Care Cost Trend Rate Assumptions (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Health care cost trend rate for next year	7.30%	7.60%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.50%	4.50%
Year that the rate reaches the ultimate trend rate	2028	2028

Employee_Benefits_Fair_Values_

Employee Benefits - Fair Values of Pension Plan Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$2,946	$2,717
Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	37
Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	993	916
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,850	1,718
Mortgage-backed Securities [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	228	217
U.S. Government and Government Agency and Authority Obligations [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	209	224
Corporate Bonds [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	419	371
Foreign Government and Government Agency Obligations [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	137	104
Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$55	$46

Employee_Benefits_Estimated_Be

Employee Benefits - Estimated Benefits Expected to be Paid (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2015	$105
2016	115
2017	151
2018	132
2019	143
2020-2024	868
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2015	12
2016	14
2017	15
2018	17
2019	18
2020-2024	$117

Comprehensive_Income_Component

Comprehensive Income - Components of Other Comprehensive Income or Loss (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net unrealized holding gains (losses) arising during the year, Before Tax	$1,032	($1,000)	$556
Unrealized other-than-temporary impairment losses arising during the year, Before Tax			-2
Reclassification adjustment for net realized gains included in net income, Before Tax	220	212	127
Net unrealized gains (losses) recognized in other comprehensive income or loss, Before Tax	812	-1,212	427
Postretirement benefit gain (loss) not yet recognized in net income arising during the year, Before Tax	-550	622	-128
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Before Tax	-35	-93	-83
Net change in postretirement benefit costs not yet recognized in net income, Before Tax	-515	715	-45
Foreign currency translation losses, Before Tax	-180	-111	-16
Total other comprehensive income (loss), Before Tax	117	-608	366
Net unrealized holding gains (losses) arising during the year, Income Tax	361	-350	195
Unrealized other-than-temporary impairment losses arising during the year, Income Tax			-1
Reclassification adjustment for net realized gains included in net income, Income Tax	77	74	44
Net unrealized gains (losses) recognized in other comprehensive income or loss, Income Tax	284	-424	150
Postretirement benefit gain (loss) not yet recognized in net income arising during the year, Income Tax	-192	218	-45
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Income Tax	-13	-33	-30
Net change in postretirement benefit costs not yet recognized in net income, Income Tax	-179	251	-15
Foreign currency translation losses, Income Tax	-63	-39	-5
Total other comprehensive income (loss), Income Tax	42	-212	130
Net unrealized holding gains (losses) arising during the year, Net of Tax	671	-650	361
Unrealized other-than-temporary impairment losses arising during the year, Net of Tax			-1
Reclassification adjustment for net realized gains included in net income, Net of Tax	143	138	83
Net unrealized gains (losses) recognized in other comprehensive income or loss, Net of Tax	528	-788	277
Postretirement benefit gain (loss) not yet recognized in net income arising during the period, Net of Tax	-358	404	-83
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Net of Tax	-22	-60	-53
Net change in postretirement benefit costs not yet recognized in net income, Net of Tax	-336	464	-30
Foreign currency translation losses, Net of Tax	-117	-72	-11
Total Other Comprehensive Income (Loss) Net of Tax	$75	($396)	$236

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Notional amount of future obligations under Chubb Financial Solutions' (CFS) derivative contracts	$55	$80
Fair value of future obligations under Chubb Financial Solutions' derivative contracts	2	2
Year through which office facilities under lease agreements will expire	2029
Office facility leases renewal options in years, Lower end of range	2 years
Office facility leases renewal options in years, Higher end of range	10 years
Commitments to fund limited partnership investments	$860
Period for which commitments can be called by the partnerships	5 years or less

Commitments_and_Contingent_Lia3

Commitments and Contingent Liabilities - Rent Expense (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Rent expense	$80	$84	$82
Office Facilities [Member]
Property, Plant and Equipment [Line Items]
Rent expense	67	71	71
Equipment [Member]
Property, Plant and Equipment [Line Items]
Rent expense	$13	$13	$11

Commitments_and_Contingent_Lia4

Commitments and Contingent Liabilities - Future Minimum Rental Payments Required Under Non-Cancellable Operating Leases (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
2015	$63
2016	52
2017	47
2018	40
2019	30
After 2019	81
Total	$313

Segments_Information_Additiona

Segments Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
	Operations
	Business_Unit
Segment Reporting [Abstract]
Number of segment operations	2
Number of business units	4

Segments_Information_Revenues_

Segments Information - Revenues, Income Before Income Tax and Assets of Each Operating Segment (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Premiums earned related to insurance business									$12,327	$12,069	$11,834
Premiums earned related to reinsurance assumed									1	-3	4
Net Premiums earned									12,328	12,066	11,838
Investment Income									1,394	1,465	1,556
Corporate and other									33	43	46
Realized investment gains, net									369	402	193
TOTAL REVENUES	3,476	3,574	3,542	3,506	3,476	3,403	3,551	3,517	14,098	13,947	13,595
Insurance underwriting income (loss)									1,357	1,607	498
Reinsurance assumed underwriting income										9	47
Underwriting income before deferred policy acquisition costs									1,357	1,616	545
Increase in deferred policy acquisition costs									45	59	3
Underwriting income									1,402	1,675	548
Investment income									1,352	1,416	1,518
Total property and casualty insurance									2,727	3,072	2,040
Corporate and other									-235	-237	-237
Realized investment gains, net									369	402	193
INCOME BEFORE FEDERAL AND FOREIGN INCOME TAX									2,861	3,237	1,996
Assets
Total assets	51,286				50,433				51,286	50,433	52,184
Property and Casualty Insurance [Member]
Revenues
Investment Income									1,368	1,436	1,518
TOTAL REVENUES									13,696	13,502	13,356
Investment income									1,329	1,391	1,482
Other income (charges)									-4	6	10
Operating Segments [Member]
Assets
Total assets	49,297				48,278				49,297	48,278	49,441
Operating Segments [Member] \| Personal Insurance [Member]
Revenues
Premiums earned related to insurance business									4,418	4,214	4,024
Insurance underwriting income (loss)									370	509	192
Operating Segments [Member] \| Commercial Insurance [Member]
Revenues
Premiums earned related to insurance business									5,281	5,237	5,144
Insurance underwriting income (loss)									492	692	44
Operating Segments [Member] \| Specialty Insurance [Member]
Revenues
Premiums earned related to insurance business									2,628	2,618	2,666
Insurance underwriting income (loss)									495	406	262
Corporate and Other [Member]
Assets
Total assets	2,078				2,248				2,078	2,248	2,830
Adjustments and Eliminations [Member]
Assets
Total assets	($89)				($93)				($89)	($93)	($87)

Segments_Information_Revenues_1

Segments Information - Revenues of Property and Casualty Group by Geographic Area (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues by geographic area
Revenues	$3,476	$3,574	$3,542	$3,506	$3,476	$3,403	$3,551	$3,517	$14,098	$13,947	$13,595
P&C Group [Member]
Revenues by geographic area
Revenues									13,696	13,502	13,356
Reportable Geographical Components [Member] \| P&C Group [Member] \| United States [Member]
Revenues by geographic area
Revenues									10,448	10,205	9,996
Reportable Geographical Components [Member] \| P&C Group [Member] \| International [Member]
Revenues by geographic area
Revenues									$3,248	$3,297	$3,360

Fair_Values_of_Financial_Instr2

Fair Values of Financial Instruments - Carrying Values and Fair Values of Financial Instruments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	$1,318	$2,114
Fixed maturities	38,780	37,091
Equity securities	1,964	1,810
Long Term Debt	3,300	3,300
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	1,318	2,114
Fixed maturities	38,780	37,091
Equity securities	1,964	1,810
Long Term Debt	3,300	3,300
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	1,318	2,114
Fixed maturities	38,780	37,091
Equity securities	1,964	1,810
Long Term Debt	$4,013	$3,806

Fair_Values_of_Financial_Instr3

Fair Values of Financial Instruments - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Percentage of fair value amounts for fixed maturities provided by a pricing service	99.00%	99.00%
Plan assets at fair value	$2,946	$2,717
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$143	$130	$96

Fair_Values_of_Financial_Instr4

Fair Values of Financial Instruments - Fair Value of Financial Instruments Categorized Based Upon Lowest Level of Input (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short Term Investments	$1,318	$2,114
Fixed maturities, Fair Value	38,780	37,091
Equity securities	1,964	1,810
Long Term Debt	3,300	3,300
Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short Term Investments	1,318	2,114
Fixed maturities, Fair Value	38,780	37,091
Equity securities	1,964	1,810
Total fixed maturities, equity securities and other invested assets, Fair Value	42,062	41,015
Long Term Debt	4,013	3,806
Tax Exempt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	19,772	18,421
Tax Exempt [Member] \| Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	19,772	18,421
Taxable [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	19,008	18,670
Taxable [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	2,007	802
Taxable [Member] \| Corporate Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	9,028	9,314
Taxable [Member] \| Foreign Government and Government Agency Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	6,672	6,890
Taxable [Member] \| Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	19,008	18,670
Taxable [Member] \| Fair Value [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	2,007	802
Taxable [Member] \| Fair Value [Member] \| Corporate Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	9,028	9,314
Taxable [Member] \| Fair Value [Member] \| Foreign Government and Government Agency Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	6,672	6,890
Taxable [Member] \| Fair Value [Member] \| Residential Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	211	299
Taxable [Member] \| Fair Value [Member] \| Commercial Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	1,090	1,365
Level 1 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short Term Investments	206	399
Fixed maturities, Fair Value
Equity securities	1,958	1,803
Total fixed maturities, equity securities and other invested assets, Fair Value	2,164	2,202
Long Term Debt
Level 1 [Member] \| Tax Exempt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 1 [Member] \| Taxable [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 1 [Member] \| Taxable [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 1 [Member] \| Taxable [Member] \| Corporate Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 1 [Member] \| Taxable [Member] \| Foreign Government and Government Agency Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 1 [Member] \| Taxable [Member] \| Residential Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 1 [Member] \| Taxable [Member] \| Commercial Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 2 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short Term Investments	1,112	1,715
Fixed maturities, Fair Value	38,651	36,916
Equity securities
Total fixed maturities, equity securities and other invested assets, Fair Value	39,763	38,631
Long Term Debt	4,013	3,806
Level 2 [Member] \| Tax Exempt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	19,769	18,416
Level 2 [Member] \| Taxable [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	18,882	18,500
Level 2 [Member] \| Taxable [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	2,007	802
Level 2 [Member] \| Taxable [Member] \| Corporate Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	8,912	9,179
Level 2 [Member] \| Taxable [Member] \| Foreign Government and Government Agency Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	6,663	6,881
Level 2 [Member] \| Taxable [Member] \| Residential Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	210	293
Level 2 [Member] \| Taxable [Member] \| Commercial Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	1,090	1,345
Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short Term Investments
Fixed maturities, Fair Value	129	175
Equity securities	6	7
Total fixed maturities, equity securities and other invested assets, Fair Value	135	182
Long Term Debt
Level 3 [Member] \| Tax Exempt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	3	5
Level 3 [Member] \| Taxable [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	126	170
Level 3 [Member] \| Taxable [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value
Level 3 [Member] \| Taxable [Member] \| Corporate Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	116	135
Level 3 [Member] \| Taxable [Member] \| Foreign Government and Government Agency Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	9	9
Level 3 [Member] \| Taxable [Member] \| Residential Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value	1	6
Level 3 [Member] \| Taxable [Member] \| Commercial Mortgage-backed Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fixed maturities, Fair Value		$20

Fair_Values_of_Financial_Instr5

Fair Values of Financial Instruments - Fair Values of Pension Plan Assets Categorized Based Upon Lowest Level of Input (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$2,946	$2,717
Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	37
Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	993	916
Fixed Maturities [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	209	224
Fixed Maturities [Member] \| Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	419	371
Fixed Maturities [Member] \| Foreign Government and Government Agency Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	137	104
Fixed Maturities [Member] \| Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	228	217
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,850	1,718
Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	55	46
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	657	594
Level 1 [Member] \| Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 1 [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 1 [Member] \| Fixed Maturities [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 1 [Member] \| Fixed Maturities [Member] \| Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 1 [Member] \| Fixed Maturities [Member] \| Foreign Government and Government Agency Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 1 [Member] \| Fixed Maturities [Member] \| Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 1 [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	629	573
Level 1 [Member] \| Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	28	21
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	2,282	2,105
Level 2 [Member] \| Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	37
Level 2 [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	993	909
Level 2 [Member] \| Fixed Maturities [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	209	224
Level 2 [Member] \| Fixed Maturities [Member] \| Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	419	370
Level 2 [Member] \| Fixed Maturities [Member] \| Foreign Government and Government Agency Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	137	104
Level 2 [Member] \| Fixed Maturities [Member] \| Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	228	211
Level 2 [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,221	1,145
Level 2 [Member] \| Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	20	14
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	7	18
Level 3 [Member] \| Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 3 [Member] \| Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value		7
Level 3 [Member] \| Fixed Maturities [Member] \| U.S. Government and Government Agency and Authority Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 3 [Member] \| Fixed Maturities [Member] \| Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value		1
Level 3 [Member] \| Fixed Maturities [Member] \| Foreign Government and Government Agency Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 3 [Member] \| Fixed Maturities [Member] \| Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value		6
Level 3 [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value
Level 3 [Member] \| Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$7	$11

Earnings_Per_Share_Computation

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic earnings per share:
Net Income	$558	$594	$499	$449	$569	$541	$579	$656	$2,100	$2,345	$1,545
Weighted average shares outstanding									242.9	258.2	269.5
Basic earnings per share	$2.35	$2.47	$2.03	$1.81	$2.25	$2.11	$2.22	$2.49	$8.65	$9.08	$5.73
Diluted earnings per share:
Net Income	$558	$594	$499	$449	$569	$541	$579	$656	$2,100	$2,345	$1,545
Weighted average shares outstanding									242.9	258.2	269.5
Additional shares from assumed issuance of shares under stock-based compensation awards									0.6	1.2	1.9
Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share									243.5	259.4	271.4
Diluted earnings per share	$2.35	$2.47	$2.03	$1.80	$2.24	$2.10	$2.21	$2.48	$8.62	$9.04	$5.69

Shareholders_Equity_Common_Sto

Shareholders' Equity - Common Stock Activity (Detail)	12 Months Ended
Shareholders' Equity - Common Stock Activity (Detail)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Treasury stock balance, beginning of year	123,673,969	110,217,445	99,519,509
Repurchase of shares	16,893,455	14,887,701	13,094,640
Share activity under stock-based employee compensation plans	-1,016,353	-1,431,177	-2,396,704
Treasury stock balance, end of year	139,551,071	123,673,969	110,217,445
Common stock outstanding, end of year	232,429,389	248,306,491	261,763,015
Common Stock [Member]
Balance, beginning of year				371,980,460
Balance, end of year	371,980,460	371,980,460	371,980,460	371,980,460

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Remaining under the share repurchase authorization	$52,000,000
Authorized repurchase of the Corporation's common stock	1,300,000,000
Dividends paid by domestic property and casualty insurance subsidiaries to parent	2,000,000,000
Maximum [Member]
Class of Stock [Line Items]
Maximum dividend distribution that may be made by the property and casualty insurance subsidiaries to parent company during 2015 without prior regulatory approval	1,900,000,000
Federal Insurance Company [Member]
Class of Stock [Line Items]
Aggregate statutory capital and surplus	14,800,000,000
Risk-based capital requirement	5,000,000,000
P&C Group [Member]
Class of Stock [Line Items]
Aggregate statutory capital and surplus	$15,127,000,000	$15,024,000,000

Shareholders_Equity_Comparison

Shareholders' Equity - Comparison of Shareholders' Equity on GAAP Basis and Policyholders' Surplus on Statutory Basis (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis
Shareholders' equity	$16,296	$16,097	$15,827
P&C Group [Member]
Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis
Shareholders' equity	17,786	17,398
Policyholders' surplus	15,127	15,024
Corporate and Other [Member]
Comparison of shareholders' equity on a GAAP basis and policyholders' surplus on a statutory basis
Shareholders' equity	($1,490)	($1,301)

Shareholders_Equity_Comparison1

Shareholders' Equity - Comparison of GAAP and Statutory Net Income (Loss) (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Comparison of GAAP and statutory net income (loss)
GAAP net income (loss)	$558	$594	$499	$449	$569	$541	$579	$656	$2,100	$2,345	$1,545
P&C Group [Member]
Comparison of GAAP and statutory net income (loss)
GAAP net income (loss)									2,330	2,480	1,791
Statutory net income									2,399	2,485	1,936
Corporate and Other [Member]
Comparison of GAAP and statutory net income (loss)
GAAP net income (loss)									($230)	($135)	($246)

Quarterly_Financial_Data_Summa

Quarterly Financial Data - Summary of Quarterly Financial Data (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenues	$3,476	$3,574	$3,542	$3,506	$3,476	$3,403	$3,551	$3,517	$14,098	$13,947	$13,595
Losses and expenses	2,714	2,756	2,864	2,903	2,690	2,664	2,755	2,601
Federal and Foreign Income Tax	204	224	179	154	217	198	217	260	761	892	451
NET INCOME	$558	$594	$499	$449	$569	$541	$579	$656	$2,100	$2,345	$1,545
Basic earnings per share	$2.35	$2.47	$2.03	$1.81	$2.25	$2.11	$2.22	$2.49	$8.65	$9.08	$5.73
Diluted earnings per share	$2.35	$2.47	$2.03	$1.80	$2.24	$2.10	$2.21	$2.48	$8.62	$9.04	$5.69
Underwriting ratios
Losses to premiums earned	53.8	54	58.7	61.1	54.7	53	56.7	52.3
Expenses to premiums written	30.5	31.8	31.3	32.1	30.8	32.7	32.1	32.3
Combined	84.3	85.8	90	93.2	85.5	85.7	88.8	84.6

Consolidated_Summary_of_Invest1

Consolidated Summary of Investments - Other Than Investments in Related Parties (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	$40,788
Fair Value	43,485
Amount at Which Shown in the Balance Sheet	43,485
Foreign Government and Government Agency Obligations [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	6,380
Fair Value	6,672
Amount at Which Shown in the Balance Sheet	6,672
Residential Mortgage-backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	192
Fair Value	211
Amount at Which Shown in the Balance Sheet	211
Commercial Mortgage-backed Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,069
Fair Value	1,090
Amount at Which Shown in the Balance Sheet	1,090
Short Term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,318
Fair Value	1,318
Amount at Which Shown in the Balance Sheet	1,318
Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	36,958
Fair Value	38,780
Amount at Which Shown in the Balance Sheet	38,780
United States Government and Government Agencies and Authorities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,593
Fair Value	1,612
Amount at Which Shown in the Balance Sheet	1,612
States, Municipalities and Political Subdivisions [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	18,983
Fair Value	20,167
Amount at Which Shown in the Balance Sheet	20,167
Public Utilities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,065
Fair Value	1,148
Amount at Which Shown in the Balance Sheet	1,148
All Other Corporate Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	7,676
Fair Value	7,880
Amount at Which Shown in the Balance Sheet	7,880
Public Utilities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	114
Fair Value	216
Amount at Which Shown in the Balance Sheet	216
Banks, Trusts and Insurance Companies [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	101
Fair Value	185
Amount at Which Shown in the Balance Sheet	185
Industrial, Miscellaneous and Other [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	835
Fair Value	1,515
Amount at Which Shown in the Balance Sheet	1,515
Total Common Stocks [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,050
Fair Value	1,916
Amount at Which Shown in the Balance Sheet	1,916
Non-redeemable Preferred Stocks [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	39
Fair Value	48
Amount at Which Shown in the Balance Sheet	48
Total Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,089
Fair Value	1,964
Amount at Which Shown in the Balance Sheet	1,964
Other Invested Assets [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,423
Fair Value	1,423
Amount at Which Shown in the Balance Sheet	$1,423

Condensed_Financial_Informatio1

Condensed Financial Information of Parent Company - Balance Sheets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Short Term Investments	$1,318	$2,114
Taxable Fixed Maturities (cost $1,213 and $1,095)	38,780	37,091
Equity Securities (cost $- and $-)	1,964	1,810
TOTAL INVESTED ASSETS	43,485	42,613
Other Assets	1,138	1,205
TOTAL ASSETS	51,286	50,433	52,184
Liabilities
Long Term Debt	3,300	3,300
Dividend Payable to Shareholders	117	110
Accrued Expenses and Other Liabilities	2,299	1,357
TOTAL LIABILITIES	34,990	34,336
Shareholders' Equity
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372
Paid-In Surplus	171	171
Retained Earnings	23,520	21,902
Accumulated Other Comprehensive Income	1,110	1,035
Treasury Stock, at Cost - 139,551,071 and 123,673,969 Shares	-8,877	-7,383
TOTAL SHAREHOLDERS' EQUITY	16,296	16,097	15,827
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	51,286	50,433
Parent Company [Member]
Assets
Short Term Investments	574	856
Taxable Fixed Maturities (cost $1,213 and $1,095)	1,226	1,110
Equity Securities (cost $- and $-)		2
TOTAL INVESTED ASSETS	1,800	1,968
Investment in Consolidated Subsidiaries	17,838	17,455
Other Assets	168	165
TOTAL ASSETS	19,806	19,588
Liabilities
Long Term Debt	3,300	3,300
Dividend Payable to Shareholders	117	110
Accrued Expenses and Other Liabilities	93	81
TOTAL LIABILITIES	3,510	3,491
Shareholders' Equity
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372
Paid-In Surplus	171	171
Retained Earnings	23,520	21,902
Accumulated Other Comprehensive Income	1,110	1,035
Treasury Stock, at Cost - 139,551,071 and 123,673,969 Shares	-8,877	-7,383
TOTAL SHAREHOLDERS' EQUITY	16,296	16,097
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$19,806	$19,588

Condensed_Financial_Informatio2

Condensed Financial Information of Parent Company - Balance Sheets (Parenthetical) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fixed Maturities, cost	$36,958	$35,959
Equity Securities, cost	1,089	1,057
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Par Value	$1	$1
Preferred Stock, Shares Issued	0	0
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Common Stock, Par Value	$1	$1
Common Stock, Shares Issued	371,980,460	371,980,460
Treasury Stock, Shares	139,551,071	123,673,969	110,217,445	99,519,509
Parent Company [Member]
Fixed Maturities, cost	1,213	1,095
Equity Securities, cost
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Par Value	$1	$1
Preferred Stock, Shares Issued	0	0
Common Stock, Shares Authorized	1,200,000,000	1,200,000,000
Common Stock, Par Value	$1	$1
Common Stock, Shares Issued	371,980,460	371,980,460
Treasury Stock, Shares	139,551,071	123,673,969

Condensed_Financial_Informatio3

Condensed Financial Information of Parent Company - Statements of Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Investment Income									$1,394	$1,465	$1,556
Other Revenues									7	14	8
Realized Investment Gains (Losses), Net									369	402	193
TOTAL REVENUES	3,476	3,574	3,542	3,506	3,476	3,403	3,551	3,517	14,098	13,947	13,595
Expenses
Corporate Expenses									249	254	270
Investment Expenses									42	49	38
Other Expenses									16	22	11
Federal and Foreign Income Tax	204	224	179	154	217	198	217	260	761	892	451
NET INCOME	558	594	499	449	569	541	579	656	2,100	2,345	1,545
Other Comprehensive Income (Loss), Net of Tax									75	-396	236
COMPREHENSIVE INCOME									2,175	1,949	1,781
Parent Company [Member]
Revenues
Investment Income									26	29	38
Other Revenues										6
Realized Investment Gains (Losses), Net									4	99	-6
TOTAL REVENUES									30	134	32
Expenses
Corporate Expenses									249	262	268
Investment Expenses									3	4	2
Other Expenses									3	8
TOTAL EXPENSES									255	274	270
Loss before Federal and Foreign Income Tax and Equity in Net Income of Consolidated Subsidiaries									-225	-140	-238
Federal and Foreign Income Tax									1		4
Loss before Equity in Net Income of Consolidated Subsidiaries									-226	-140	-242
Equity in Net Income of Consolidated Subsidiaries									2,326	2,485	1,787
NET INCOME									2,100	2,345	1,545
Other Comprehensive Income (Loss), Net of Tax									75	-396	236
COMPREHENSIVE INCOME									$2,175	$1,949	$1,781

Condensed_Financial_Informatio4

Condensed Financial Information of Parent Company - Statements of Cash Flows (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows from Operating Activities
Net Income	$2,100	$2,345	$1,545
Adjustments to Reconcile Net Income to Net Cash Used in Operating Activities
Realized Investment Losses (Gains), Net	-369	-402	-193
Other, Net	-47	-26	7
NET CASH PROVIDED BY OPERATING ACTIVITIES	2,153	1,731	2,299
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	4,229	2,449	2,271
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	4,231	4,909	4,290
Proceeds from Sales of Equity Securities	213	545	160
Purchases of Fixed Maturities	-9,987	-8,275	-7,247
Investments in Other Invested Assets, Net	315	498	293
Decrease in Short Term Investments, Net	780	383	-629
Other, Net		-6
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	-156	252	-972
Cash Flows from Financing Activities
Repayment of Long Term Debt		-275
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	22	38	74
Repurchase of Shares	-1,547	-1,288	-959
Dividends Paid to Shareholders	-475	-450	-438
NET CASH USED IN FINANCING ACTIVITIES	-2,002	-1,981	-1,335
Net Increase (Decrease) in Cash	-5	2	-8
Cash at Beginning of Year	52	50	58
CASH AT END OF YEAR	47	52	50
Parent Company [Member]
Cash Flows from Operating Activities
Net Income	2,100	2,345	1,545
Adjustments to Reconcile Net Income to Net Cash Used in Operating Activities
Equity in Net Income of Consolidated Subsidiaries	-2,326	-2,485	-1,787
Realized Investment Losses (Gains), Net	-4	-99	6
Other, Net	9	21	57
NET CASH PROVIDED BY OPERATING ACTIVITIES	-221	-218	-179
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	382	227	24
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	46	150	673
Proceeds from Sales of Equity Securities	2	296
Purchases of Fixed Maturities	-551	-198	-1,046
Investments in Other Invested Assets, Net		22
Decrease in Short Term Investments, Net	282	85	89
Dividends Received from Consolidated Insurance Subsidiaries	2,021	1,564	1,760
Distributions Received from Consolidated Non-Insurance Subsidiaries	1	1	1
Other, Net	38	46	1
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	2,221	2,193	1,502
Cash Flows from Financing Activities
Repayment of Long Term Debt		-275
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	22	38	74
Repurchase of Shares	-1,547	-1,288	-959
Dividends Paid to Shareholders	-475	-450	-438
NET CASH USED IN FINANCING ACTIVITIES	-2,000	-1,975	-1,323
Net Increase (Decrease) in Cash
Cash at Beginning of Year
CASH AT END OF YEAR

Condensed_Financial_Informatio5

Condensed Financial Information of Parent Company - Statements of Cash Flows (Parenthetical) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash	$52
Alterra Common Stock [Member]
Condensed Financial Statements, Captions [Line Items]
Holdings of common stock and warrants, cost basis	177
Alterra Warrants [Member]
Condensed Financial Statements, Captions [Line Items]
Holdings of common stock and warrants, cost basis	63
Markel Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Transferred, common stock value	226
Cash	$98

Consolidated_Supplementary_Ins1

Consolidated Supplementary Insurance Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs	$1,284	$1,255	$1,206
Unpaid Losses	22,678	23,146	23,963
Unearned Premiums	6,581	6,423	6,361
Premiums Earned	12,328	12,066	11,838
Net Investment Income	1,329	1,391	1,482
Insurance Losses	6,985	6,520	7,507
Amortization of Deferred Policy Acquisition Costs	2,548	2,454	2,411
Other Insurance Operating Costs and Expenses	1,393	1,417	1,372
Premiums Written	12,592	12,224	11,870
Personal Insurance [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs	517	505	477
Unpaid Losses	2,272	2,235	2,493
Unearned Premiums	2,278	2,216	2,133
Premiums Earned	4,418	4,214	4,024
Net Investment Income
Insurance Losses	2,540	2,224	2,417
Amortization of Deferred Policy Acquisition Costs	1,053	982	942
Other Insurance Operating Costs and Expenses	438	465	458
Premiums Written	4,508	4,322	4,125
Commercial Insurance [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs	504	493	477
Unpaid Losses	13,161	13,147	13,288
Unearned Premiums	2,876	2,792	2,794
Premiums Earned	5,281	5,237	5,144
Net Investment Income
Insurance Losses	3,111	2,891	3,512
Amortization of Deferred Policy Acquisition Costs	995	970	970
Other Insurance Operating Costs and Expenses	663	665	620
Premiums Written	5,402	5,273	5,174
Specialty Insurance [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs	263	257	252
Unpaid Losses	6,847	7,307	7,622
Unearned Premiums	1,426	1,412	1,429
Premiums Earned	2,628	2,618	2,666
Net Investment Income
Insurance Losses	1,333	1,417	1,622
Amortization of Deferred Policy Acquisition Costs	497	502	499
Other Insurance Operating Costs and Expenses	295	287	293
Premiums Written	2,681	2,633	2,568
Reinsurance Assumed [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs
Unpaid Losses	398	457	560
Unearned Premiums	1	3	5
Premiums Earned	1	-3	4
Net Investment Income
Insurance Losses	1	-12	-44
Amortization of Deferred Policy Acquisition Costs	3
Other Insurance Operating Costs and Expenses	-3		1
Premiums Written	1	-4	3
Investments [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Policy Acquisition Costs
Unpaid Losses
Unearned Premiums
Premiums Earned
Net Investment Income	1,329	1,391	1,482
Insurance Losses
Amortization of Deferred Policy Acquisition Costs
Other Insurance Operating Costs and Expenses
Premiums Written