Chubb (CHB) 10-Q 6 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	CB
Entity Registrant Name	CHUBB CORP
Entity Central Index Key	20171
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	229,752,692

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues
Premiums Earned	$3,105	$3,029
Investment Income	339	358
Other Revenues	2	3
Realized Investment Gains (Losses), Net
Total Other-Than-Temporary Impairment Losses on Investments	-23
Other Realized Investment Gains, Net	34	116
Total Realized Investment Gains, Net	11	116
Total Revenues	3,457	3,506
Losses and Expenses
Losses and Loss Expenses	1,920	1,845
Amortization of Deferred Policy Acquisition Costs	626	622
Other Insurance Operating Costs and Expenses	347	356
Investment Expenses	12	11
Other Expenses	4	5
Corporate Expenses	66	64
Total Losses and Expenses	2,975	2,903
Income Before Federal and Foreign Income Tax	482	603
Federal and Foreign Income Tax	107	154
Net Income	$375	$449
Net Income Per Share
Basic	$1.61	$1.81
Diluted	$1.60	$1.80
Dividends Declared Per Share	$0.57	$0.50

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$375	$449
Other Comprehensive Income (Loss), Net of Tax
Change in Unrealized Appreciation of Investments	109	235
Change in Postretirement Benefit Costs Not Yet Recognized in Net Income	17	6
Foreign Currency Translation Losses	-176	-19
Total Other Comprehensive Income (Loss) Net of Tax	-50	222
Comprehensive Income	$325	$671

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Assets
Short Term Investments	$1,220	$1,318
Fixed Maturities (cost $36,483 and $36,958)	38,457	38,780
Equity Securities (cost $1,074 and $1,089)	1,964	1,964
Other Invested Assets	1,408	1,423
TOTAL INVESTED ASSETS	43,049	43,485
Cash	52	47
Accrued Investment Income	406	410
Premiums Receivable	2,434	2,560
Reinsurance Recoverable on Unpaid Losses and Loss Expenses	1,583	1,639
Prepaid Reinsurance Premiums	249	256
Deferred Policy Acquisition Costs	1,280	1,284
Goodwill	467	467
Other Assets	1,332	1,138
TOTAL ASSETS	50,852	51,286
Liabilities
Unpaid Losses and Loss Expenses	22,515	22,678
Unearned Premiums	6,463	6,581
Long Term Debt	3,300	3,300
Dividend Payable to Shareholders	133	117
Deferred Income Tax	50	15
Accrued Expenses and Other Liabilities	2,229	2,299
TOTAL LIABILITIES	34,690	34,990
Shareholders' Equity
Common Stock - $1 Par Value; 371,980,460 Shares	372	372
Paid-In Surplus	135	171
Retained Earnings	23,762	23,520
Accumulated Other Comprehensive Income	1,060	1,110
Treasury Stock, at Cost - 142,227,768 and 139,551,071 Shares	-9,167	-8,877
TOTAL SHAREHOLDERS' EQUITY	16,162	16,296
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$50,852	$51,286

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Fixed Maturities, cost	$36,483	$36,958
Equity Securities, cost	$1,074	$1,089
Common Stock, Par Value	$1	$1
Common Stock, Shares issued	371,980,460	371,980,460
Treasury Stock, Shares	142,227,768	139,551,071

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders' Equity (USD $)	Total	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 (Losses) [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock, at Cost [Member]
In Millions
Balance, Beginning of Year at Dec. 31, 2013			$171	$21,902	$1,225	($253)	$63		($7,383)
Net Income	449			449
Repurchase of Shares									-409
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $3 and $14)			-63
Change During Period, Net of Tax	222				235	6	-19
Dividends Declared (per share $.57 and $.50)				-124
Shares Issued Under Stock-Based Employee Compensation Plans									54
Balance, End of Period at Mar. 31, 2014	16,226	372	108	22,227	1,460	-247	44	1,257	-7,738
Balance, Beginning of Year at Dec. 31, 2014	16,296		171	23,520	1,753	-589	-54		-8,877
Net Income	375			375
Repurchase of Shares									-326
Changes Related to Stock-Based Employee Compensation (includes tax benefit of $3 and $14)			-36
Change During Period, Net of Tax	-50				109	17	-176
Dividends Declared (per share $.57 and $.50)				-133
Shares Issued Under Stock-Based Employee Compensation Plans									36
Balance, End of Period at Mar. 31, 2015	$16,162	$372	$135	$23,762	$1,862	($572)	($230)	$1,060	($9,167)

Consolidated_Statements_of_Sha1

Consolidated Statements of Shareholders' Equity (Parenthetical) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Dividends Declared Per Share	$0.57	$0.50
Paid-In-Surplus [Member]
Tax benefit, Stock-Based Employee Compensation	$3	$14
Retained Earnings [Member]
Dividends Declared Per Share	$0.57	$0.50

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash Flows from Operating Activities
Net Income	$375	$449
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Increase in Unpaid Losses and Loss Expenses, Net	260	51
Increase in Unearned Premiums, Net	1	33
Amortization of Premiums and Discounts on Fixed Maturities	54	46
Depreciation	12	14
Realized Investment Gains, Net	-11	-116
Other, Net	-161	-105
Net Cash Provided by Operating Activities	530	372
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	1,436	379
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	820	957
Proceeds from Sales of Equity Securities	29	101
Purchases of Fixed Maturities	-2,421	-1,810
Purchases of Equity Securities	-24	-89
Investments in Other Invested Assets, Net	17	98
Decrease in Short Term Investments, Net	82	417
Change in Receivable or Payable from Security Transactions Not Settled, Net	5	105
Purchases of Property and Equipment, Net	-18	-10
Other, Net		-3
Net Cash Provided by (Used in) Investing Activities	-74	145
Cash Flows from Financing Activities
Decrease in Funds Held Under Deposit Contracts	-1	-1
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	5	14
Repurchase of Shares	-338	-415
Dividends Paid to Shareholders	-117	-110
Net Cash Used in Financing Activities	-451	-512
Net Increase in Cash	5	5
Cash at Beginning of Year	47	52
Cash at End of Period	$52	$57

General

General	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
General	1) General
	The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include the accounts of The Chubb Corporation (Chubb) and its subsidiaries (collectively, the Corporation). Significant intercompany transactions have been eliminated in consolidation.
	The amounts included in this report are unaudited but include those adjustments, consisting of normal recurring items, that management considers necessary for a fair presentation. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes in the Notes to Consolidated Financial Statements included in Chubb’s Annual Report on Form 10-K for the year ended December 31, 2014.

Accounting_Pronouncements_Not_

Accounting Pronouncements Not Yet Adopted	3 Months Ended
	Mar. 31, 2015
Accounting Changes and Error Corrections [Abstract]
Accounting Pronouncements Not Yet Adopted	2) Accounting Pronouncements Not Yet Adopted
	In February 2015, the Financial Accounting Standards Board issued updated guidance that amends certain aspects of the current consolidation accounting guidance. In particular, the new guidance modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities and eliminates the presumption that a general partner should consolidate a limited partnership. The new guidance would be effective for the Corporation for the year beginning January 1, 2016. The Corporation is in the process of assessing the effect, if any, that the implementation of this guidance will have on its financial position and results of operations.

Invested_Assets

Invested Assets	3 Months Ended
	Mar. 31, 2015
Text Block [Abstract]
Invested Assets	3) Invested Assets
	(a) The amortized cost and fair value of fixed maturities and equity securities were as follows:
		March 31, 2015
		Amortized			Gross			Gross		Fair
		Cost			Unrealized			Unrealized		Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	19,260		$	1,179		$	24	$	20,415
	Taxable
	U.S. government and government agency and authority obligations		1,460			59			1		1,518
	Corporate bonds		8,756			402			19		9,139
	Foreign government and government agency obligations		5,844			335			2		6,177
	Residential mortgage-backed securities		175			20			1		194
	Commercial mortgage-backed securities		988			27			1		1,014
			17,223			843			24		18,042
	Total fixed maturities	$	36,483		$	2,022		$	48	$	38,457
	Equity securities	$	1,074		$	900		$	10	$	1,964
		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 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
	The fair value and amortized cost of fixed maturities at March 31, 2015 by contractual maturity were as follows:
		Fair			Amortized
		Value			Cost
		(in millions)
	Due in one year or less	$	2,460		$	2,438
	Due after one year through five years		12,329			11,794
	Due after five years through ten years		13,321			12,449
	Due after ten years		9,139			8,639
			37,249			35,320
	Residential mortgage-backed securities		194			175
	Commercial mortgage-backed securities		1,014			988
		$	38,457		$	36,483
	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 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:
		March 31			December 31
		2015			2014
		(in millions)
	Fixed maturities
	Gross unrealized appreciation	$	2,022		$	1,884
	Gross unrealized depreciation		48			62
			1,974			1,822
	Equity securities
	Gross unrealized appreciation		900			894
	Gross unrealized depreciation		10			19
			890			875
			2,864			2,697
	Deferred income tax liability		1,002			944
		$	1,862		$	1,753
The following table summarizes, for all investment securities in an unrealized loss position at March 31, 2015, 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	$	1,103		$	9		$	219	$	15	$	1,322	$	24
Taxable
U.S. government and government agency and authority obligations		170			1			10		—		180		1
Corporate bonds		474			15			311		4		785		19
Foreign government and government agency obligations		344			2			77		—		421		2
Residential mortgage-backed securities		—			—			6		1		6		1
Commercial mortgage-backed securities		14			—			83		1		97		1
		1,002			18			487		6		1,489		24
Total fixed maturities		2,105			27			706		21		2,811		48
Equity securities		59			7			3		3		62		10
	$	2,164		$	34		$	709	$	24	$	2,873	$	58
At March 31, 2015, approximately 580 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 March 31, 2015.
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 and authority obligations		936			1			36		—		972		1
Corporate bonds		1,327			23			888		17		2,215		40
Foreign government and government 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
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:
	Three Months Ended
	31-Mar
	2015			2014
	(in millions)
Change in unrealized appreciation of fixed maturities	$	152		$	362
Change in unrealized appreciation of equity securities		15			(1	)
		167			361
Deferred income tax		58			126
	$	109		$	235
(c) Realized investment gains and losses were as follows:
	Three Months Ended
	31-Mar
	2015			2014
	(in millions)
Fixed maturities
Gross realized gains	$	13		$	8
Gross realized losses		(5	)		(11	)
Other-than-temporary impairment losses		(1	)		—
		7			(3	)
Equity securities
Gross realized gains		16			66
Other-than-temporary impairment losses		(22	)		—
		(6	)		66
Other invested assets		10			53
	$	11		$	116
(d) As of March 31, 2015 and December 31, 2014, 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 $17 million and $18 million, respectively, recognized in net income.

Comprehensive_Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Comprehensive Income	4) 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:
		Three Months Ended March 31, 2015
		Before			Income			Net of
		Tax			Tax			Tax
		(in millions)
	Net unrealized holding gains arising during the period	$	168		$	58		$	110
	Reclassification adjustment for net realized gains included in net income		1			0			1
	Net unrealized gains recognized in other comprehensive income		167			58			109
	Postretirement benefit gain not yet recognized in net income arising during the year		9			3			6
	Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income (a)		(16	)		(5	)		(11	)
	Net change in postretirement benefit costs not yet recognized in net income		25			8			17
	Foreign currency translation losses		(270	)		(94	)		(176	)
	Total other comprehensive loss	$	(78	)	$	(28	)	$	(50	)
		Three Months Ended March 31, 2014
		Before			Income			Net of
		Tax			Tax			Tax
		(in millions)
	Net unrealized holding gains arising during the period	$	424		$	148		$	276
	Reclassification adjustment for net realized gains included in net income		63			22			41
	Net unrealized gains recognized in other comprehensive income		361			126			235
	Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income (a)		(9	)		(3	)		(6	)
	Net change in postretirement benefit costs not yet recognized in net income		9			3			6
	Foreign currency translation losses		(28	)		(9	)		(19	)
	Total other comprehensive income	$	342		$	120		$	222
	(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.

Segments_Information

Segments Information	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segments Information	5) 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 property and casualty insurance subsidiaries underwrite 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.
	Revenues and income before income tax of each operating segment were as follows:
		Three Months Ended March 31
		2015			2014
		(in millions)
	Revenues
	Property and casualty insurance
	Premiums earned
	Personal insurance	$	1,113		$	1,076
	Commercial insurance		1,342			1,300
	Specialty insurance		650			653
	Total insurance		3,105			3,029
	Investment income		332			351
	Total property and casualty insurance		3,437			3,380
	Corporate and other		9			10
	Realized investment gains, net		11			116
	Total revenues	$	3,457		$	3,506
	Income (loss) before income tax
	Property and casualty insurance
	Underwriting
	Personal insurance	$	(30	)	$	2
	Commercial insurance		91			111
	Specialty insurance		127			82
	Total insurance		188			195
	Increase in deferred policy acquisition costs		17			13
	Underwriting income		205			208
	Investment income		321			341
	Other income (charges)		7			(2	)
	Total property and casualty insurance		533			547
	Corporate and other		(62	)		(60	)
	Realized investment gains, net		11			116
	Total income before income tax	$	482		$	603

Fair_Values_of_Financial_Instr

Fair Values of Financial Instruments	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Values of Financial Instruments	6) Fair Values of Financial Instruments
	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:
			March 31, 2015				December 31, 2014
			Carrying		Fair		Carrying		Fair
			Value		Value		Value		Value
			(in millions)
	Assets
	Invested assets
	Short term investments		$	1,220	$	1,220	$	1,318	$	1,318
	Fixed maturities			38,457		38,457		38,780		38,780
	Equity securities			1,964		1,964		1,964		1,964
	Liabilities
	Long term debt			3,300		4,046		3,300		4,013
	At March 31, 2015 and December 31, 2014, 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 March 31, 2015 and December 31, 2014, 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:
			March 31, 2015
			Level 1		Level 2		Level 3		Total
			(in millions)
	Assets
	Short term investments		$	192	$	1,028	$	—	$	1,220
	Fixed maturities
	Tax exempt			—		20,413		2		20,415
	Taxable
	U.S. government and government agency and authority obligations			—		1,518		—		1,518
	Corporate bonds			—		8,954		185		9,139
	Foreign government and government agency obligations			—		6,169		8		6,177
	Residential mortgage-backed securities			—		193		1		194
	Commercial mortgage-backed securities			—		1,014		—		1,014
				—		17,848		194		18,042
	Total fixed maturities			—		38,261		196		38,457
	Equity securities			1,958		—		6		1,964
			$	2,150	$	39,289	$	202	$	41,641
	Liabilities
	Long term debt		$	—	$	4,046	$	—	$	4,046
			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

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	7) Earnings Per Share
	The following table sets forth the computation of basic and diluted earnings per share:
		Three Months Ended March 31
		2015		2014
		(in millions, except for
		per share amounts)
	Basic earnings per share:
	Net income	$	375	$	449
	Weighted average shares outstanding		233.5		248.6
	Basic earnings per share	$	1.61	$	1.81
	Diluted earnings per share:
	Net income	$	375	$	449
	Weighted average shares outstanding		233.5		248.6
	Additional shares from assumed issuance of shares under stock-based compensation awards		0.7		0.6
	Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share		234.2		249.2
	Diluted earnings per share	$	1.6	$	1.8

Accounting_Pronouncements_Not_1

Accounting Pronouncements Not Yet Adopted (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Changes and Error Corrections [Abstract]
Accounting Pronouncements Not Yet Adopted	In February 2015, the Financial Accounting Standards Board issued updated guidance that amends certain aspects of the current consolidation accounting guidance. In particular, the new guidance modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities and eliminates the presumption that a general partner should consolidate a limited partnership. The new guidance would be effective for the Corporation for the year beginning January 1, 2016. The Corporation is in the process of assessing the effect, if any, that the implementation of this guidance will have on its financial position and results of operations.

Invested_Assets_Tables

Invested Assets (Tables)	3 Months Ended
	Mar. 31, 2015
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:
		March 31, 2015
		Amortized			Gross			Gross		Fair
		Cost			Unrealized			Unrealized		Value
					Appreciation			Depreciation
		(in millions)
	Fixed maturities
	Tax exempt	$	19,260		$	1,179		$	24	$	20,415
	Taxable
	U.S. government and government agency and authority obligations		1,460			59			1		1,518
	Corporate bonds		8,756			402			19		9,139
	Foreign government and government agency obligations		5,844			335			2		6,177
	Residential mortgage-backed securities		175			20			1		194
	Commercial mortgage-backed securities		988			27			1		1,014
			17,223			843			24		18,042
	Total fixed maturities	$	36,483		$	2,022		$	48	$	38,457
	Equity securities	$	1,074		$	900		$	10	$	1,964
		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 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
Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity	The fair value and amortized cost of fixed maturities at March 31, 2015 by contractual maturity were as follows:
		Fair			Amortized
		Value			Cost
		(in millions)
	Due in one year or less	$	2,460		$	2,438
	Due after one year through five years		12,329			11,794
	Due after five years through ten years		13,321			12,449
	Due after ten years		9,139			8,639
			37,249			35,320
	Residential mortgage-backed securities		194			175
	Commercial mortgage-backed securities		1,014			988
		$	38,457		$	36,483
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:
		March 31			December 31
		2015			2014
		(in millions)
	Fixed maturities
	Gross unrealized appreciation	$	2,022		$	1,884
	Gross unrealized depreciation		48			62
			1,974			1,822
	Equity securities
	Gross unrealized appreciation		900			894
	Gross unrealized depreciation		10			19
			890			875
			2,864			2,697
	Deferred income tax liability		1,002			944
		$	1,862		$	1,753
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 March 31, 2015, 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	$	1,103		$	9		$	219	$	15	$	1,322	$	24
	Taxable
	U.S. government and government agency and authority obligations		170			1			10		—		180		1
	Corporate bonds		474			15			311		4		785		19
	Foreign government and government agency obligations		344			2			77		—		421		2
	Residential mortgage-backed securities		—			—			6		1		6		1
	Commercial mortgage-backed securities		14			—			83		1		97		1
			1,002			18			487		6		1,489		24
	Total fixed maturities		2,105			27			706		21		2,811		48
	Equity securities		59			7			3		3		62		10
		$	2,164		$	34		$	709	$	24	$	2,873	$	58
	At March 31, 2015, approximately 580 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 March 31, 2015.
	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 and authority obligations		936			1			36		—		972		1
	Corporate bonds		1,327			23			888		17		2,215		40
	Foreign government and government 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
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:
		Three Months Ended March 31
		2015			2014
		(in millions)
	Change in unrealized appreciation of fixed maturities	$	152		$	362
	Change in unrealized appreciation of equity securities		15			(1	)
			167			361
	Deferred income tax		58			126
		$	109		$	235
Realized Investment Gains and Losses	(c) Realized investment gains and losses were as follows:
		Three Months Ended
		31-Mar
		2015			2014
		(in millions)
	Fixed maturities
	Gross realized gains	$	13		$	8
	Gross realized losses		(5	)		(11	)
	Other-than-temporary impairment losses		(1	)		—
			7			(3	)
	Equity securities
	Gross realized gains		16			66
	Other-than-temporary impairment losses		(22	)		—
			(6	)		66
	Other invested assets		10			53
		$	11		$	116

Comprehensive_Income_Tables

Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Components of Other Comprehensive Income or Loss	The components of other comprehensive income or loss were as follows:
		Three Months Ended March 31, 2015
		Before			Income			Net of
		Tax			Tax			Tax
		(in millions)
	Net unrealized holding gains arising during the period	$	168		$	58		$	110
	Reclassification adjustment for net realized gains included in net income		1			0			1
	Net unrealized gains recognized in other comprehensive income		167			58			109
	Postretirement benefit gain not yet recognized in net income arising during the year		9			3			6
	Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income (a)		(16	)		(5	)		(11	)
	Net change in postretirement benefit costs not yet recognized in net income		25			8			17
	Foreign currency translation losses		(270	)		(94	)		(176	)
	Total other comprehensive loss	$	(78	)	$	(28	)	$	(50	)
		Three Months Ended March 31, 2014
		Before			Income			Net of
		Tax			Tax			Tax
		(in millions)
	Net unrealized holding gains arising during the period	$	424		$	148		$	276
	Reclassification adjustment for net realized gains included in net income		63			22			41
	Net unrealized gains recognized in other comprehensive income		361			126			235
	Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income (a)		(9	)		(3	)		(6	)
	Net change in postretirement benefit costs not yet recognized in net income		9			3			6
	Foreign currency translation losses		(28	)		(9	)		(19	)
	Total other comprehensive income	$	342		$	120		$	222
	(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.

Segments_Information_Tables

Segments Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Revenues and Income Before Income Tax of Each Operating Segment	Revenues and income before income tax of each operating segment were as follows:
		Three Months Ended March 31
		2015			2014
		(in millions)
	Revenues
	Property and casualty insurance
	Premiums earned
	Personal insurance	$	1,113		$	1,076
	Commercial insurance		1,342			1,300
	Specialty insurance		650			653
	Total insurance		3,105			3,029
	Investment income		332			351
	Total property and casualty insurance		3,437			3,380
	Corporate and other		9			10
	Realized investment gains, net		11			116
	Total revenues	$	3,457		$	3,506
	Income (loss) before income tax
	Property and casualty insurance
	Underwriting
	Personal insurance	$	(30	)	$	2
	Commercial insurance		91			111
	Specialty insurance		127			82
	Total insurance		188			195
	Increase in deferred policy acquisition costs		17			13
	Underwriting income		205			208
	Investment income		321			341
	Other income (charges)		7			(2	)
	Total property and casualty insurance		533			547
	Corporate and other		(62	)		(60	)
	Realized investment gains, net		11			116
	Total income before income tax	$	482		$	603

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Carrying Values and Fair Values of Financial Instruments	The carrying values and fair values of financial instruments were as follows:
		March 31, 2015				December 31, 2014
		Carrying		Fair		Carrying		Fair
		Value		Value		Value		Value
		(in millions)
	Assets
	Invested assets
	Short term investments	$	1,220	$	1,220	$	1,318	$	1,318
	Fixed maturities		38,457		38,457		38,780		38,780
	Equity securities		1,964		1,964		1,964		1,964
	Liabilities
	Long term debt		3,300		4,046		3,300		4,013
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:
		March 31, 2015
		Level 1		Level 2		Level 3		Total
		(in millions)
	Assets
	Short term investments	$	192	$	1,028	$	—	$	1,220
	Fixed maturities
	Tax exempt		—		20,413		2		20,415
	Taxable
	U.S. government and government agency and authority obligations		—		1,518		—		1,518
	Corporate bonds		—		8,954		185		9,139
	Foreign government and government agency obligations		—		6,169		8		6,177
	Residential mortgage-backed securities		—		193		1		194
	Commercial mortgage-backed securities		—		1,014		—		1,014
			—		17,848		194		18,042
	Total fixed maturities		—		38,261		196		38,457
	Equity securities		1,958		—		6		1,964
		$	2,150	$	39,289	$	202	$	41,641
	Liabilities
	Long term debt	$	—	$	4,046	$	—	$	4,046
		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

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
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:
		Three Months Ended March 31
		2015		2014
		(in millions, except for
		per share amounts)
	Basic earnings per share:
	Net income	$	375	$	449
	Weighted average shares outstanding		233.5		248.6
	Basic earnings per share	$	1.61	$	1.81
	Diluted earnings per share:
	Net income	$	375	$	449
	Weighted average shares outstanding		233.5		248.6
	Additional shares from assumed issuance of shares under stock-based compensation awards		0.7		0.6
	Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share		234.2		249.2
	Diluted earnings per share	$	1.6	$	1.8

Invested_Assets_Amortized_Cost

Invested Assets - Amortized Cost and Fair Value of Fixed Maturities and Equity Securities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	$36,483	$36,958
Fixed maturities, Gross Unrealized Appreciation	2,022	1,884
Fixed maturities, Gross Unrealized Depreciation	48	62
Fixed maturities, Fair Value	38,457	38,780
Equity securities, Amortized Cost	1,074	1,089
Equity securities, Gross Unrealized Appreciation	900	894
Equity securities, Gross Unrealized Depreciation	10	19
Equity securities, Fair Value	1,964	1,964
Tax Exempt [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	19,260	18,614
Fixed maturities, Gross Unrealized Appreciation	1,179	1,174
Fixed maturities, Gross Unrealized Depreciation	24	16
Fixed maturities, Fair Value	20,415	19,772
Taxable [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	17,223	18,344
Fixed maturities, Gross Unrealized Appreciation	843	710
Fixed maturities, Gross Unrealized Depreciation	24	46
Fixed maturities, Fair Value	18,042	19,008
Taxable [Member] | Residential Mortgage-backed Securities [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	175	192
Fixed maturities, Gross Unrealized Appreciation	20	20
Fixed maturities, Gross Unrealized Depreciation	1	1
Fixed maturities, Fair Value	194	211
Taxable [Member] | Commercial Mortgage-backed Securities [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	988	1,069
Fixed maturities, Gross Unrealized Appreciation	27	22
Fixed maturities, Gross Unrealized Depreciation	1	1
Fixed maturities, Fair Value	1,014	1,090
Taxable [Member] | U.S. Government and Government Agency and Authority Obligations [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	1,460	1,962
Fixed maturities, Gross Unrealized Appreciation	59	46
Fixed maturities, Gross Unrealized Depreciation	1	1
Fixed maturities, Fair Value	1,518	2,007
Taxable [Member] | Corporate Bonds [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	8,756	8,741
Fixed maturities, Gross Unrealized Appreciation	402	327
Fixed maturities, Gross Unrealized Depreciation	19	40
Fixed maturities, Fair Value	9,139	9,028
Taxable [Member] | Foreign Government and Government Agency Obligations [Member]
Investment Holdings [Line Items]
Fixed maturities, Amortized Cost	5,844	6,380
Fixed maturities, Gross Unrealized Appreciation	335	295
Fixed maturities, Gross Unrealized Depreciation	2	3
Fixed maturities, Fair Value	$6,177	$6,672

Invested_Assets_Fair_Value_and

Invested Assets - Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Schedule of Available-For-Sale Securities [Line Items]
Due in one year or less, Fair Value	$2,460
Due after one year through five years, Fair Value	12,329
Due after five years through ten years, Fair Value	13,321
Due after ten years, Fair Value	9,139
Subtotal fixed maturities, Fair Value	37,249
Total fixed maturities, Fair Value	38,457	38,780
Due in one year or less, Amortized Cost	2,438
Due after one year through five years, Amortized Cost	11,794
Due after five years through ten years, Amortized Cost	12,449
Due after ten years, Amortized Cost	8,639
Subtotal fixed maturities, Amortized Cost	35,320
Fixed maturities, Amortized Cost	36,483	36,958
Residential Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	194
Taxable, Amortized Cost	175
Commercial Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	1,014
Taxable, Amortized Cost	$988

Invested_Assets_Components_of_

Invested Assets - Components of Unrealized Appreciation or Depreciation of Investments (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]
Fixed maturities, Gross Unrealized Appreciation	$2,022	$1,884
Fixed maturities, Gross Unrealized Depreciation	48	62
Fixed maturities, Unrealized appreciation (depreciation), Net	1,974	1,822
Equity securities, Gross Unrealized Appreciation	900	894
Equity securities, Gross Unrealized Depreciation	10	19
Equity securities, Unrealized appreciation (depreciation), Net	890	875
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net	2,864	2,697
Deferred income tax liability	1,002	944
Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax	$1,862	$1,753

Invested_Assets_Fair_Value_and1

Invested Assets - Fair Value and Gross Unrealized Depreciation of Investments in Unrealized Loss Position (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	$2,164	$3,176
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	34	39
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	709	1,521
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	24	42
Investment securities, Continuous unrealized loss position, Fair Value, Total	2,873	4,697
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	58	81
Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	2,105	3,109
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	27	28
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	706	1,510
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	21	34
Investment securities, Continuous unrealized loss position, Fair Value, Total	2,811	4,619
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	48	62
Equity Securities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	59	67
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	7	11
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	3	11
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	3	8
Investment securities, Continuous unrealized loss position, Fair Value, Total	62	78
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	10	19
Tax Exempt [Member] | Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	1,103	422
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	9	3
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	219	305
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	15	13
Investment securities, Continuous unrealized loss position, Fair Value, Total	1,322	727
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	24	16
Taxable [Member] | Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	1,002	2,687
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	18	25
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	487	1,205
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	6	21
Investment securities, Continuous unrealized loss position, Fair Value, Total	1,489	3,892
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	24	46
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	170	936
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	1	1
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	10	36
Investment securities, Continuous unrealized loss position, Fair Value, Total	180	972
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	1	1
Taxable [Member] | Corporate Bonds [Member] | Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Fair Value	474	1,327
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	15	23
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	311	888
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	4	17
Investment securities, Continuous unrealized loss position, Fair Value, Total	785	2,215
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	19	40
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	344	318
Investment securities, Continuous unrealized loss position, Less Than 12 Months, Gross Unrealized Depreciation	2	1
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	77	207
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation		2
Investment securities, Continuous unrealized loss position, Fair Value, Total	421	525
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	2	3
Residential Mortgage-backed Securities [Member] | Taxable [Member] | Fixed Maturities [Member]
Investment Holdings [Line Items]
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	6	7
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	1	1
Investment securities, Continuous unrealized loss position, Fair Value, Total	6	7
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	14	106
Investment securities, Continuous unrealized loss position, 12 Months or More, Fair Value	83	67
Investment securities, Continuous unrealized loss position, 12 Months or More, Gross Unrealized Depreciation	1	1
Investment securities, Continuous unrealized loss position, Fair Value, Total	97	173
Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total	$1	$1

Invested_Assets_Additional_Inf

Invested Assets - Additional Information (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Investment
Investments, Debt and Equity Securities [Abstract]
Approximate number of individual fixed maturities in unrealized loss position	580
Approximate number of individual equity securities in unrealized loss position	15
Cumulative credit-related losses recognized in net income	$17	$18

Invested_Assets_Change_in_Unre

Invested Assets - Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Change in unrealized appreciation of fixed maturities	$152	$362
Change in unrealized appreciation of equity securities	15	-1
Change in unrealized appreciation of fixed maturities and equity securities	167	361
Deferred income tax	58	126
Total change in unrealized appreciation (depreciation) of fixed maturities and equity securities, Net of tax	$109	$235

Invested_Assets_Realized_Inves

Invested Assets - Realized Investment Gains and Losses (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Fixed maturities, Gross realized gains	$13	$8
Fixed maturities, Gross realized losses	-5	-11
Fixed maturities, Other-than-temporary impairment losses	-1
Total fixed maturities	7	-3
Equity securities, Gross realized gains	16	66
Equity securities, Other-than-temporary impairment losses	-22
Total equity securities	-6	66
Other invested assets	10	53
Total Realized Investment Gains, Net	$11	$116

Comprehensive_Income_Component

Comprehensive Income - Components of Other Comprehensive Income or Loss (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net unrealized holding gains arising during the period, Before Tax	$168	$424
Reclassification adjustment for net realized gains included in net income, Before Tax	1	63
Change in unrealized appreciation of fixed maturities and equity securities	167	361
Postretirement benefit gain not yet recognized in net income arising during the year, Before Tax	9
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Before Tax	-16	-9
Net change in postretirement benefit costs not yet recognized in net income, Before Tax	25	9
Foreign currency translation losses, Before Tax	-270	-28
Total other comprehensive income (loss), Before Tax	-78	342
Net unrealized holding gains arising during the period, Income Tax	58	148
Reclassification adjustment for net realized gains included in net income, Income Tax		22
Net unrealized gains recognized in other comprehensive income, Income Tax	58	126
Postretirement benefit gain not yet recognized in net income arising during the year, Income Tax	3
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Income Tax	-5	-3
Net change in postretirement benefit costs not yet recognized in net income, Income Tax	8	3
Foreign currency translation losses, Income Tax	-94	-9
Total other comprehensive income (loss), Income Tax	-28	120
Net unrealized holding gains arising during the period, Net of Tax	110	276
Reclassification adjustment for net realized gains included in net income, Net of Tax	1	41
Net unrealized gains recognized in other comprehensive income, Net of Tax	109	235
Postretirement benefit gain not yet recognized in net income arising during the year, Net of Tax	6
Reclassification adjustment for the amortization of net actuarial loss and prior service cost included in net income, Net of Tax	-11	-6
Net change in postretirement benefit costs not yet recognized in net income, Net of Tax	17	6
Foreign currency translation losses, Net of Tax	-176	-19
Total Other Comprehensive Income (Loss) Net of Tax	($50)	$222

Segments_Information_Additiona

Segments Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
	Operations
	Business_Unit
Segment Reporting [Abstract]
Number of segment operations	2
Number of business units	4

Segments_Information_Revenues_

Segments Information - Revenues and Income Before Income Tax of Each Operating Segment (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues
Net Premiums earned	$3,105	$3,029
Investment Income	339	358
Corporate and other	9	10
Realized investment gains, net	11	116
Total Revenues	3,457	3,506
Insurance underwriting income (loss)	188	195
Increase in deferred policy acquisition costs	17	13
Underwriting income	205	208
Total property and casualty insurance	533	547
Corporate and other	-62	-60
Realized investment gains, net	11	116
Income Before Federal and Foreign Income Tax	482	603
Property and Casualty Insurance [Member]
Revenues
Investment Income	332	351
Total Revenues	3,437	3,380
Investment income	321	341
Other income (charges)	7	-2
Operating Segments [Member] | Personal Insurance [Member]
Revenues
Premiums earned related to insurance business	1,113	1,076
Insurance underwriting income (loss)	-30	2
Operating Segments [Member] | Commercial Insurance [Member]
Revenues
Premiums earned related to insurance business	1,342	1,300
Insurance underwriting income (loss)	91	111
Operating Segments [Member] | Specialty Insurance [Member]
Revenues
Premiums earned related to insurance business	650	653
Insurance underwriting income (loss)	$127	$82

Fair_Values_of_Financial_Instr2

Fair Values of Financial Instruments - Carrying Values and Fair Values of Financial Instruments (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	$1,220	$1,318
Fixed maturities	38,457	38,780
Equity securities	1,964	1,964
Long Term Debt	3,300	3,300
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	1,220	1,318
Fixed maturities	38,457	38,780
Equity securities	1,964	1,964
Long Term Debt	3,300	3,300
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	1,220	1,318
Fixed maturities	38,457	38,780
Equity securities	1,964	1,964
Long Term Debt	$4,046	$4,013

Fair_Values_of_Financial_Instr3

Fair Values of Financial Instruments - Additional Information (Detail)	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument Fair Value Carrying Value [Abstract]
Percentage of fair value amounts for fixed maturities provided by a pricing service	99.00%	99.00%

Fair_Values_of_Financial_Instr4

Fair Values of Financial Instruments - Fair Value of Financial Instruments Categorized Based Upon Lowest Level of Input (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	$1,220	$1,318
Fixed maturities, Fair Value	38,457	38,780
Equity securities	1,964	1,964
Long Term Debt	3,300	3,300
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	1,220	1,318
Fixed maturities, Fair Value	38,457	38,780
Equity securities	1,964	1,964
Total fixed maturities, equity securities and other invested assets, Fair Value	41,641	42,062
Long Term Debt	4,046	4,013
Tax Exempt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	20,415	19,772
Tax Exempt [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	20,415	19,772
Taxable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	18,042	19,008
Taxable [Member] | U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	1,518	2,007
Taxable [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	9,139	9,028
Taxable [Member] | Foreign Government and Government Agency Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	6,177	6,672
Taxable [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	18,042	19,008
Taxable [Member] | Fair Value [Member] | U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	1,518	2,007
Taxable [Member] | Fair Value [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	9,139	9,028
Taxable [Member] | Fair Value [Member] | Foreign Government and Government Agency Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	6,177	6,672
Taxable [Member] | Fair Value [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	194	211
Taxable [Member] | Fair Value [Member] | Commercial Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	1,014	1,090
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	192	206
Equity securities	1,958	1,958
Total fixed maturities, equity securities and other invested assets, Fair Value	2,150	2,164
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short Term Investments	1,028	1,112
Fixed maturities, Fair Value	38,261	38,651
Total fixed maturities, equity securities and other invested assets, Fair Value	39,289	39,763
Long Term Debt	4,046	4,013
Level 2 [Member] | Tax Exempt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	20,413	19,769
Level 2 [Member] | Taxable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	17,848	18,882
Level 2 [Member] | Taxable [Member] | U.S. Government and Government Agency and Authority Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	1,518	2,007
Level 2 [Member] | Taxable [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	8,954	8,912
Level 2 [Member] | Taxable [Member] | Foreign Government and Government Agency Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	6,169	6,663
Level 2 [Member] | Taxable [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	193	210
Level 2 [Member] | Taxable [Member] | Commercial Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	1,014	1,090
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	196	129
Equity securities	6	6
Total fixed maturities, equity securities and other invested assets, Fair Value	202	135
Level 3 [Member] | Tax Exempt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	2	3
Level 3 [Member] | Taxable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	194	126
Level 3 [Member] | Taxable [Member] | Corporate Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	185	116
Level 3 [Member] | Taxable [Member] | Foreign Government and Government Agency Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	8	9
Level 3 [Member] | Taxable [Member] | Residential Mortgage-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturities, Fair Value	$1	$1

Earnings_Per_Share_Computation

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Basic earnings per share:
Net Income	$375	$449
Weighted average shares outstanding	233.5	248.6
Basic earnings per share	$1.61	$1.81
Diluted earnings per share:
Net Income	$375	$449
Weighted average shares outstanding	233.5	248.6
Additional shares from assumed issuance of shares under stock-based compensation awards	0.7	0.6
Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share	234.2	249.2
Diluted earnings per share	$1.60	$1.80