Cincinnati Financial (CINF) 10-Q 28 Oct 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 23, 2014
Document Documentand Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'CINF	'
Entity Registrant Name	'CINCINNATI FINANCIAL CORP	'
Entity Central Index Key	'0000020286	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	163,490,441

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Investments	'	'
Fixed maturities, at fair value (amortized cost: 2014—$8,924; 2013—$8,638)	$9,522	$9,121
Equity securities, at fair value (cost: 2014—$2,697; 2013—$2,523)	4,666	4,375
Other invested assets	67	68
Total investments	14,255	13,564
Cash and cash equivalents	412	433
Investment income receivable	119	121
Finance receivable	77	85
Premiums receivable	1,447	1,346
Reinsurance recoverable	549	547
Prepaid reinsurance premiums	28	26
Deferred policy acquisition costs	590	565
Land, building and equipment, net, for company use (accumulated depreciation: 2014—$439; 2013—$420)	198	210
Other assets	69	73
Separate accounts	730	692
Total assets	18,474	17,662
Insurance reserves	'	'
Loss and loss expense reserves	4,435	4,311
Life policy and investment contract reserves	2,484	2,390
Unearned premiums	2,128	1,976
Other liabilities	666	611
Deferred income tax	777	673
Note payable	49	104
Long-term debt and capital lease obligations	829	835
Separate accounts	730	692
Total liabilities	12,098	11,592
Commitments and contingent liabilities (Note 12)	0	0
Shareholders' Equity	'	'
Common stock, par value—$2 per share; (authorized: 2014 and 2013—500 million shares; issued: 2014 and 2013—198 million shares)	397	397
Paid-in capital	1,205	1,191
Retained earnings	4,409	4,268
Accumulated other comprehensive income	1,658	1,504
Treasury stock at cost (2014 and 2013—35 million shares)	-1,293	-1,290
Total shareholders' equity	6,376	6,070
Total liabilities and shareholders' equity	$18,474	$17,662

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, except Per Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Fixed maturities, amortized cost	$8,924	$8,638
Equity securities, cost	2,697	2,523
Land, building and equipment, accumulated depreciation	$439	$420
Common stock, par value	$2	$2
Common stock, authorized	500	500
Common stock, issued	198	198
Common stock, outstanding	198	198
Treasury stock, shares	35	35

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues [Abstract]	'	'	'	'
Earned premiums	$1,071	$992	$3,157	$2,877
Investment income, net of expenses	138	133	409	392
Realized investment gains, net	65	22	101	77
Fee revenues	3	2	9	6
Other revenues	3	3	7	7
Total revenues	1,280	1,152	3,683	3,359
Benefits and Expenses	'	'	'	'
Insurance losses and policyholder benefits	686	642	2,181	1,841
Underwriting, acquisition and insurance expenses	319	312	967	919
Interest expense	13	13	40	40
Other operating expenses	3	3	10	12
Total benefits and expenses	1,021	970	3,198	2,812
Income Before Income Taxes	259	182	485	547
Provision for Income Taxes	'	'	'	'
Current	68	46	106	137
Deferred	8	5	21	15
Total provision for income taxes	76	51	127	152
Net Income	$183	$131	$358	$395
Per Common Share	'	'	'	'
Net income-basic (in USD per share)	$1.12	$0.80	$2.19	$2.42
Net income-diluted (in USD per share)	$1.11	$0.79	$2.17	$2.39

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Income	$183	$131	$358	$395
Change in unrealized gains (losses) on investments available-for-sale, net of tax of $(42), $22, $81 and $61, respectively	-78	40	151	113
Net change in pension actuarial loss and prior service cost, net of tax of $0, $1, $0 and $3, respectively	1	1	0	4
Change in life deferred acquisition costs, life policy reserves and other, net of tax of $2, $2, $2 and $10, respectively	3	5	3	21
Other comprehensive income (loss), net of tax	-74	46	154	138
Comprehensive Income	$109	$177	$512	$533

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	($42)	$22	$81	$61
Other Comprehensive Income Loss, Pension And Other Postretirement Benefit Plans, Net Actuarial Loss And Prior Service Cost Arising During Period, Tax	0	1	0	3
Other Comprehensive Income, Change in Life Deferred Acquisition Costs, Life Policy Reserves and Other, Tax	$2	$2	$2	$10

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Shareholders' Equity (USD $)	Total	Common Stock	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
In Millions
Balance at Dec. 31, 2012	$5,453	$394	$1,134	$4,021	$1,129	($1,225)
Balance (in shares) at Dec. 31, 2012	'	163	'	'	'	'
Net Income	395	'	'	395	'	'
Other comprehensive income, net	138	'	'	'	138	'
Dividends declared	-202	'	'	-202	'	'
Stock-based awards exercised and vested	'	2	'	'	'	'
Purchases	0	'	'	'	'	0
Stockholders' Equity, Other	32	'	43	'	'	-13
Balance at Sep. 30, 2013	5,816	396	1,177	4,214	1,267	-1,238
Balance (in shares) at Sep. 30, 2013	'	164	'	'	'	'
Balance at Dec. 31, 2013	6,070	397	1,191	4,268	1,504	-1,290
Balance (in shares) at Dec. 31, 2013	198	163	'	'	'	'
Net Income	358	'	'	358	'	'
Other comprehensive income, net	154	'	'	'	154	'
Dividends declared	-217	'	'	-217	'	'
Stock-based awards exercised and vested	'	0	'	'	'	'
Purchases	-21	'	'	'	'	-21
Stockholders' Equity, Other	32	'	14	'	'	18
Balance at Sep. 30, 2014	$6,376	$397	$1,205	$4,409	$1,658	($1,293)
Balance (in shares) at Sep. 30, 2014	198	163	'	'	'	'

Condensed_Consolidated_Stateme4

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Cash Flows From Operating Activities	'	'
Net Income	$358	$395
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	38	30
Realized gains on investments, net	-101	-77
Stock-based compensation	15	14
Interest credited to contract holders	35	31
Deferred income tax expense	21	15
Changes in:	'	'
Investment income receivable	2	0
Premiums and reinsurance receivable	-105	-148
Deferred policy acquisition costs	-32	-60
Other assets	0	-5
Loss and loss expense reserves	124	77
Life policy reserves	104	53
Unearned premiums	152	234
Other liabilities	-30	15
Current income tax receivable/payable	52	-36
Net cash provided by operating activities	633	538
Cash Flows From Investing Activities	'	'
Sale of fixed maturities	26	28
Call or maturity of fixed maturities	675	711
Sale of equity securities	225	178
Purchase of fixed maturities	-974	-1,016
Purchase of equity securities	-294	-216
Investment in finance receivables	-13	-26
Collection of finance receivables	23	22
Investment in buildings and equipment, net	-6	-5
Change in other invested assets, net	7	4
Net cash used in investing activities	-331	-320
Cash Flows From Financing Activities	'	'
Payment of cash dividends to shareholders	-208	-195
Purchase of treasury shares	-21	0
Decrease in notes payable	-55	0
Proceeds from stock options exercised	14	17
Contract holders' funds deposited	66	64
Contract holders' funds withdrawn	-108	-78
Excess tax benefits on stock-based compensation	2	10
Other	-13	-12
Net cash used in financing activities	-323	-194
Net change in cash and cash equivalents	-21	24
Cash and cash equivalents at beginning of year	433	487
Cash and cash equivalents at end of period	412	511
Supplemental disclosures of cash flow information:	'	'
Interest paid	27	27
Income taxes paid	52	169
Non-cash activities:	'	'
Conversion of securities	7	59
Equipment acquired under capital lease obligations	10	21
Cashless exercise of stock options	$11	$22

Accounting_Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Accounting Policies	'
	ACCOUNTING POLICIES
	The condensed consolidated financial statements include the accounts of Cincinnati Financial Corporation and its consolidated subsidiaries, each of which is wholly owned. These statements are presented in conformity with accounting principles generally accepted in the United States of America (GAAP). All intercompany balances and transactions have been eliminated in consolidation.
	The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect amounts reported in the financial statements and accompanying notes. Our actual results could differ from those estimates. Our December 31, 2013, condensed consolidated balance sheet amounts are derived from the audited financial statements but do not include all disclosures required by GAAP.
	Our September 30, 2014, condensed consolidated financial statements are unaudited. Certain financial information that is included in annual financial statements prepared in accordance with GAAP is not required for interim reporting and has been condensed or omitted. We believe that we have made all adjustments, consisting only of normal recurring accruals, that are necessary for fair presentation. These condensed consolidated financial statements should be read in conjunction with our consolidated financial statements included in our 2013 Annual Report on Form 10-K. The results of operations for interim periods do not necessarily indicate results to be expected for the full year.
	Pending Accounting Updates
	ASU 2014-09 Revenue from Contracts with Customers
	In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers. ASU 2014-09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Insurance contracts do not fall within the scope of this ASU. The effective date of ASU 2014-09 is for annual reporting periods beginning after December 15, 2016. The ASU has not yet been adopted and will not have a material impact on our company’s financial position, cash flows or results of operations.
	ASU 2014-12, Compensation-Stock Compensation: Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period
	In June 2014, the FASB Issued ASU 2014-12, Compensation-Stock Compensation: Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. ASU 2014-12 requires that performance targets that affect vesting and that could be achieved after the requisite service period be treated as performance conditions. The effective date of ASU 2014-12 is for interim and annual reporting periods beginning after December 15, 2015. The ASU has not yet been adopted and will not have a material impact on our company’s financial position, cash flows or results of operations.

Investments

Investments	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Investments	'
	INVESTMENTS
	The following table provides cost or amortized cost, gross unrealized gains, gross unrealized losses and fair value for our invested assets:
	(In millions)		Cost or
			amortized			Gross unrealized						Fair
	At September 30, 2014		cost			gains			losses			value
	Fixed maturity securities:
	Corporate		$	5,134		$	449		$	13		$	5,570
	States, municipalities and political subdivisions		3,294			173			3			3,464
	Commercial mortgage-backed		250			5			1			254
	Government-sponsored enterprises		222			—			12			210
	Foreign government		10			—			—			10
	Convertibles and bonds with warrants attached		7			—			—			7
	United States government		7			—			—			7
	Subtotal		8,924			627			29			9,522
	Equity securities:
	Common equities		2,552			1,942			6			4,488
	Nonredeemable preferred equities		145			34			1			178
	Subtotal		2,697			1,976			7			4,666
	Total		$	11,621		$	2,603		$	36		$	14,188
	At December 31, 2013
	Fixed maturity securities:
	Corporate		$	5,122		$	433		$	22		$	5,533
	States, municipalities and political subdivisions		3,107			125			21			3,211
	Government-sponsored enterprises		227			—			27			200
	Commercial mortgage-backed		148			—			5			143
	Convertibles and bonds with warrants attached		17			—			—			17
	Foreign government		10			—			—			10
	United States government		7			—			—			7
	Subtotal		8,638			558			75			9,121
	Equity securities:
	Common equities		2,396			1,818			1			4,213
	Nonredeemable preferred equities		127			38			3			162
	Subtotal		2,523			1,856			4			4,375
	Total		$	11,161		$	2,414		$	79		$	13,496
	The net unrealized investment gains in our fixed-maturity portfolio are primarily the result of the continued low interest rate environment that increased the fair value of our fixed-maturity portfolio. The seven largest unrealized investment gains in our common stock portfolio are from Exxon Mobil Corporation (NYSE:XOM), The Procter & Gamble Company (NYSE:PG), Honeywell International Incorporated (NYSE:HON), Chevron Corporation (NYSE:CVX), Johnson & Johnson (NYSE:JNJ), BlackRock Inc. (NYSE:BLK), and RPM International (NYSE:RPM), which had a combined gross unrealized gain of $579 million. At September 30, 2014, BlackRock Inc. was our largest single common stock holding with a fair value of 3.1 percent of our publicly traded common stock portfolio and 1.0 percent of the total investment portfolio.
	The table below provides fair values and gross unrealized losses by investment category and by the duration of the securities’ continuous unrealized loss positions:
	(In millions)		Less than 12 months						12 months or more					Total		Total
			Fair			Unrealized			Fair			Unrealized		fair		unrealized
	At September 30, 2014		value			losses			value			losses		value		losses
	Fixed maturity securities:
	Corporate		$	224		$	9		$	114		$	4	$	338	$	13
	States, municipalities and political subdivisions		28			—			218			3		246		3
	Commercial mortgage-backed		37			—			32			1		69		1
	Government-sponsored enterprises		11			—			176			12		187		12
	Foreign government		—			—			10			—		10		—
	United States government		1			—			1			—		2		—
	Subtotal		301			9			551			20		852		29
	Equity securities:
	Common equities		105			2			80			4		185		6
	Nonredeemable preferred equities		25			—			17			1		42		1
	Subtotal		130			2			97			5		227		7
	Total		$	431		$	11		$	648		$	25	$	1,079	$	36
	At December 31, 2013
	Fixed maturity securities:
	Corporate		$	572		$	20		$	43		$	2	$	615	$	22
	States, municipalities and political subdivisions		490			18			42			3		532		21
	Government-sponsored enterprises		199			27			1			—		200		27
	Commercial mortgage-backed		125			5			—			—		125		5
	Foreign government		10			—			—			—		10		—
	United States government		1			—			—			—		1		—
	Subtotal		1,397			70			86			5		1,483		75
	Equity securities:
	Common equities		77			1			—			—		77		1
Nonredeemable preferred equities		42			3			—			—		42		3
Subtotal		119			4			—			—		119		4
Total		$	1,516		$	74		$	86		$	5	$	1,602	$	79
The following table provides investment income, realized investment gains and losses, the change in unrealized investment gains and losses, and other items:
(In millions)	Three months ended September 30,						Nine months ended September 30,
	2014			2013			2014			2013
Investment income summary:
Interest on fixed maturities	$	105		$	104		$	312		$	309
Dividends on equity securities	35			30			101			87
Other investment income	—			1			2			2
Total	140			135			415			398
Less investment expenses	2			2			6			6
Total	$	138		$	133		$	409		$	392
Realized investment gains and losses summary:
Fixed maturities:
Gross realized gains	$	6		$	5		$	12		$	10
Gross realized losses	—			—			(4		)	—
Other-than-temporary impairments	—			—			—			(2		)
Equity securities:
Gross realized gains	59			15			93			64
Gross realized losses	—			—			—			—
Other-than-temporary impairments	—			—			(1		)	—
Other	—			2			1			5
Total	$	65		$	22		$	101		$	77
Change in unrealized gains and losses summary:
Fixed maturities	$	(66	)	$	(28	)	$	115		$	(335	)
Equity securities	(54		)	90			117			509
Net change in pension actuarial loss and prior	1			2			—			7
service cost
Adjustment to deferred acquisition costs and life	4			9			(4		)	38
policy reserves
Other	1			(2		)	9			(7		)
Income taxes on above	40			(25		)	(83		)	(74		)
Total	$	(74	)	$	46		$	154		$	138
During the three months ended September 30, 2014, there were no equity securities and no fixed-maturity securities other-than-temporarily impaired. During the nine months ended September 30, 2014, there were    three equity securities and one fixed-maturity security other-than-temporarily impaired. There were no credit losses on fixed-maturity securities for which a portion of other-than-temporary impairment (OTTI) has been recognized in other comprehensive income for the three and nine months ended September 30, 2014 and 2013. At September 30, 2014, 212 fixed-maturity investments with a total unrealized loss of $20 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity investments had fair values below
70 percent of amortized cost. Four equity investments with a total unrealized loss of $5 million had been in an unrealized loss position for 12 months or more as of September 30, 2014. Of that total, no equity investments were trading below 70 percent of cost.
During 2013, we other-than-temporarily impaired seven fixed-maturity securities. At December 31, 2013, 40 fixed-maturity investments with a total unrealized loss of $5 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity investments had fair values below 70 percent of amortized cost. There were no equity investments in an unrealized loss position for 12 months or more as of December 31, 2013.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	FAIR VALUE MEASUREMENTS
	Fair Value Hierarchy
	In accordance with accounting guidance for fair value measurements and disclosures, we categorized our financial instruments, based on the priority of the observable and market-based data for the valuation technique used, into a three-level fair value hierarchy. The fair value hierarchy gives the highest priority to quoted prices with readily available independent data in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable market inputs (Level 3). When various inputs for measurement fall within different levels of the fair value hierarchy, the lowest observable input that has a significant impact on fair value measurement is used. Our valuation techniques have not changed from those used at December 31, 2013, and ultimately management determines fair value. See our 2013 Annual Report on Form 10-K, Item 8, Note 3, Fair Value Measurements, Page 121, for information on characteristics and valuation techniques used in determining fair value.
	Fair Value Disclosures for Assets
	The following tables illustrate the fair value hierarchy for those assets measured at fair value on a recurring basis at September 30, 2014, and December 31, 2013. We do not have any material liabilities carried at fair value. There were no transfers between Level 1 and Level 2.
	(In millions)		Quoted prices in			Significant other			Significant			Total
			active markets for			observable inputs			unobservable
			identical assets			(Level 2)			inputs
	At September 30, 2014		(Level 1)						(Level 3)
	Fixed maturities, available for sale:
	Corporate		$	—		$	5,542		$	28		$	5,570
	States, municipalities and political subdivisions		—			3,464			—			3,464
	Commercial mortgage-backed		—			254			—			254
	Government-sponsored enterprises		—			210			—			210
	Foreign government		—			10			—			10
	Convertibles and bonds with warrants attached		—			7			—			7
	United States government		7			—			—			7
	Subtotal		7			9,487			28			9,522
	Common equities, available for sale		4,488			—			—			4,488
	Nonredeemable preferred equities, available for sale		—			176			2			178
	Separate accounts taxable fixed maturities		—			694			—			694
	Top Hat Savings Plan mutual funds and common		17			—			—			17
	equity (included in Other assets)
	Total		$	4,512		$	10,357		$	30		$	14,899
	At December 31, 2013
	Fixed maturities, available for sale:
	Corporate		$	—		$	5,531		$	2		$	5,533
	States, municipalities and political subdivisions		—			3,211			—			3,211
	Government-sponsored enterprises		—			200			—			200
	Commercial mortgage-backed		—			143			—			143
	Convertibles and bonds with warrants attached		—			17			—			17
	Foreign government		—			10			—			10
	United States government		7			—			—			7
	Subtotal		7			9,112			2			9,121
	Common equities, available for sale		4,213			—			—			4,213
	Nonredeemable preferred equities, available for sale		—			160			2			162
	Separate accounts taxable fixed-maturities		—			682			—			682
	Top Hat Savings Plan mutual funds and common		14			—			—			14
	equity (included in Other assets)
	Total		$	4,234		$	9,954		$	4		$	14,192
	Each financial instrument that was deemed to have significant unobservable inputs when determining valuation is identified in the following tables by security type with a summary of changes in fair value as of September 30, 2014. Total Level 3 assets continue to be less than 1 percent of financial assets measured at fair value in the condensed consolidated balance sheets. Assets presented in the table below were valued based primarily on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations. The quantitative detail of these unobservable inputs is neither provided nor reasonably available to us.
	The following tables provide the change in Level 3 assets for the three months ended September 30:
	(In millions)		Asset fair value measurements using significant unobservable inputs (Level 3)
			Corporate			Commercial			States,			Nonredeemable preferred			Total
			fixed			mortgage-			municipalities			equities
			maturities			backed fixed maturities			and political
									subdivisions
									fixed maturities
	Beginning balance, June 30, 2014		$	9		$	—		$	—		$	2		$	11
	Total gains or losses (realized/unrealized):
	Included in net income		—			—			—			—			—
	Included in other comprehensive income		—			—			—			—			—
	Purchases		—			—			—			—			—
	Sales		—			—			—			—			—
	Transfers into Level 3		19			—			—			—			19
	Transfers out of Level 3		—			—			—			—			—
	Ending balance, September 30, 2014		$	28		$	—		$	—		$	2		$	30
	Beginning balance, June 30, 2013		$	3		$	—		$	1		$	2		$	6
	Total gains or losses (realized/unrealized):
	Included in net income		—			—			—			—			—
	Included in other comprehensive income		—			—			—			—			—
	Purchases		—			—			—			—			—
	Sales		—			—			(1		)	—			(1		)
Transfers into Level 3		—			—			—			—			—
Transfers out of Level 3		—			—			—			—			—
Ending balance, September 30, 2013		$	3		$	—		$	—		$	2		$	5
The following tables provide the change in Level 3 assets for the nine months ended September 30:
(In millions)	Asset fair value measurements using significant unobservable inputs (Level 3)
		Corporate			Commercial			States,			Nonredeemable preferred			Total
		fixed			mortgage-			municipalities			equities
		maturities			backed fixed maturities			and political
								subdivisions
								fixed maturities
Beginning balance, January 1, 2014		$	2		$	—		$	—		$	2		$	4
Total gains or losses (realized/unrealized):
Included in net income		—			—			—			—			—
Included in other comprehensive income		—			—			—			—			—
Purchases		—			—			—			—			—
Sales		—			—			—			—			—
Transfers into Level 3		26			5			—			—			31
Transfers out of Level 3		—			(5		)	—			—			(5		)
Ending balance, September 30, 2014		$	28		$	—		$	—		$	2		$	30
Beginning balance, January 1, 2013		$	3		$	—		$	1		$	1		$	5
Total gains or losses (realized/unrealized):
Included in net income		—			—			—			—			—
Included in other comprehensive income		—			—			—			—			—
Purchases		—			—			—			1			1
Sales		—			—			(1		)	—			(1		)
Transfers into Level 3		—			—			—			—			—
Transfers out of Level 3		—			—			—			—			—
Ending balance, September 30, 2013		$	3		$	—		$	—		$	2		$	5
Additional disclosures for the Level 3 category are not material.
Fair Value Disclosures for Assets and Liabilities Not Carried at Fair Value
The disclosures below are presented to provide timely information about the effects of current market conditions on financial instruments that are not reported at fair value in our condensed consolidated financial statements.
This table summarizes the book value and principal amounts of our long-term debt:
(In millions)						Book value						Principal amount
						September 30,			December 31,			September 30,			December 31,
Interest rate			Year of issue			2014			2013			2014			2013
6.9	%		1998	Senior debentures, due 2028		$	28		$	28		$	28		$	28
6.92	%		2005	Senior debentures, due 2028		391			391			391			391
6.125	%		2004	Senior notes, due 2034		371			371			374			374
				Total		$	790		$	790		$	793		$	793
The following table shows fair values of our note payable and long-term debt:
(In millions)		Quoted prices in			Significant other			Significant			Total
		active markets for			observable inputs			unobservable
		identical assets			(Level 2)			inputs
At September 30, 2014		(Level 1)						(Level 3)
Note payable		$	—		$	49		$	—		$	49
6.900% senior debentures, due 2028		—			33			—			33
6.920% senior debentures, due 2028		—			482			—			482
6.125% senior notes, due 2034		—			438			—			438
Total		$	—		$	1,002		$	—		$	1,002
At December 31, 2013
Note payable		$	—		$	104		$	—		$	104
6.900% senior debentures, due 2028		—			30			—			30
6.920% senior debentures, due 2028		—			458			—			458
6.125% senior notes, due 2034		—			399			—			399
Total		$	—		$	991		$	—		$	991
During the second quarter of 2014, we repaid $55 million on our revolving short-term line of credit as part of routine cash management.
The following table shows the fair value of our life policy loans, included in other invested assets:
(In millions)		Quoted prices in			Significant other			Significant			Total
		active markets for			observable inputs			unobservable
		identical assets			(Level 2)			inputs
At September 30, 2014		(Level 1)						(Level 3)
Life policy loans		$	—		$	—		$	39		$	39
At December 31, 2013
Life policy loans		$	—		$	—		$	45		$	45
Outstanding principal and interest for these life policy loans was $30 million and $36 million at September 30, 2014, and December 31, 2013, respectively.
The following table shows fair values of our deferred annuities and structured settlements, included in life policy and investment contract reserves:
(In millions)		Quoted prices in			Significant other			Significant			Total
		active markets for			observable inputs			unobservable
		identical assets			(Level 2)			inputs
At September 30, 2014		(Level 1)						(Level 3)
Deferred annuities		$	—		$	—		$	904		$	904
Structured settlements		—			220			—			220
Total		$	—		$	220		$	904		$	1,124
At December 31, 2013
Deferred annuities		$	—		$	—		$	911		$	911
Structured settlements		—			219			—			219
Total		$	—		$	219		$	911		$	1,130
Recorded reserves for the deferred annuities were $864 million and $862 million at September 30, 2014, and December 31, 2013, respectively. Recorded reserves for the structured settlements were $184 million and
$189 million at September 30, 2014, and December 31, 2013, respectively.

Property_Casualty_Loss_and_Los

Property Casualty Loss and Loss Expenses	9 Months Ended
	Sep. 30, 2014
Premiums Written, Net [Abstract]	'
Property Casualty Loss And Loss Expenses	'
	PROPERTY CASUALTY LOSS AND LOSS EXPENSES
	This table summarizes activity for our consolidated property casualty loss and loss expense reserves:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Gross loss and loss expense reserves, beginning	$	4,408		$	4,219		$	4,241		$	4,169
	of period
	Less reinsurance receivable	282			333			299			356
	Net loss and loss expense reserves, beginning of	4,126			3,886			3,942			3,813
	period
	Net incurred loss and loss expenses related to:
	Current accident year	647			631			2,125			1,840
	Prior accident years	(25		)	(38		)	(120		)	(140		)
	Total incurred	622			593			2,005			1,700
	Net paid loss and loss expenses related to:
	Current accident year	353			329			859			699
	Prior accident years	286			233			979			897
	Total paid	639			562			1,838			1,596
	Net loss and loss expense reserves, end of period	4,109			3,917			4,109			3,917
	Plus reinsurance receivable	284			321			284			321
	Gross loss and loss expense reserves, end of	$	4,393		$	4,238		$	4,393		$	4,238
	period
	We use actuarial methods, models and judgment to estimate, as of a financial statement date, the property casualty loss and loss expense reserves required to pay for and settle all outstanding insured claims, including incurred but not reported (IBNR) claims, as of that date. The actuarial estimate is subject to review and adjustment by an
	inter-departmental committee that includes actuarial management that is familiar with relevant company and industry business, claims and underwriting trends, as well as general economic and legal trends that could affect future loss and loss expense payments. The amount we will actually have to pay for claims can be highly uncertain. This uncertainty, together with the size of our reserves, makes the loss and loss expense reserves our most significant estimate. The reserve for loss and loss expenses in the condensed consolidated balance sheets also included $42 million at September 30, 2014, and $69 million at September 30, 2013, for certain life and health loss and loss expense reserves.
	For the three months ended September 30, 2014, we experienced $25 million of favorable development on prior accident years, including $24 million of favorable development in commercial lines, $5 million of adverse development in personal lines and $6 million favorable development in excess and surplus lines. This included
	$5 million from favorable development of catastrophe losses for the three months ended September 30, 2014, compared with $9 million of favorable development of catastrophe losses for the three months ended September 30, 2013. We recognized favorable reserve development during the three months ended
	September 30, 2014, of $15 million for the workers' compensation line, $8 million for each the commercial property line and the commercial casualty line and $12 million of adverse development for the commercial auto line, due to reduced uncertainty of prior accident year loss and loss adjustment expense for these lines.
	For the nine months ended September 30, 2014, we experienced $120 million of favorable development on prior accident years, including $84 million of favorable development in commercial lines, $13 million of favorable development in personal lines and $23 million favorable development in excess and surplus lines. This included
	$19 million from favorable development of catastrophe losses for the nine months ended September 30, 2014, compared with $24 million of favorable development of catastrophe losses for the nine months ended September 30, 2013. We recognized favorable reserve development during the nine months ended
	September 30, 2014, of $45 million for the workers' compensation line, $33 million for the commercial property line, $25 million for the commercial casualty line and $24 million of adverse development in the commercial auto line, due to reduced uncertainty of prior accident year loss and loss adjustment expense for these lines.

Life_Policy_and_Investment_Con

Life Policy and Investment Contract Reserves	9 Months Ended
	Sep. 30, 2014
Liability for Future Policy Benefits [Abstract]	'
Life Policy And Investment Contract Reserves	'
	LIFE POLICY AND INVESTMENT CONTRACT RESERVES
	We establish the reserves for traditional life insurance policies based on expected expenses, mortality, morbidity, withdrawal rates, timing of claim presentation and investment yields, including a provision for uncertainty. Once these assumptions are established, they generally are maintained throughout the lives of the contracts. We use both our own experience and industry experience, adjusted for historical trends, in arriving at our assumptions for expected mortality, morbidity and withdrawal rates as well as for expected expenses. We base our assumptions for expected investment income on our own experience adjusted for current economic conditions.
	We establish reserves for the company’s universal life, deferred annuity and structured settlement policies equal to the cumulative account balances, which include premium deposits plus credited interest less charges and withdrawals. Some of our universal life policies contain no-lapse guarantee provisions. For these policies, we establish a reserve in addition to the account balance, based on expected no-lapse guarantee benefits and expected policy assessments.
	This table summarizes our life policy and investment contract reserves:
	(In millions)	September 30,		December 31, 2013
		2014
	Ordinary/traditional life	$	863	$	815
	Universal life	527		508
	Deferred annuities	864		862
	Structured settlements	184		189
	Other	46		16
	Total life policy and investment contract reserves	$	2,484	$	2,390

Deferred_Acquisition_Costs

Deferred Acquisition Costs	9 Months Ended
	Sep. 30, 2014
Deferred Costs [Abstract]	'
Deferred Acquisition Costs	'
	DEFERRED ACQUISITION COSTS
	Expenses directly related to successfully acquired insurance policies – primarily commissions, premium taxes and underwriting costs – are deferred and amortized over the terms of the policies. We update our acquisition cost assumptions periodically to reflect actual experience, and we evaluate the costs for recoverability. The table below shows the deferred policy acquisition costs and asset reconciliation.
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Deferred policy acquisition costs asset, beginning	$	571		$	546		$	565		$	470
	of period
	Capitalized deferred policy acquisition costs	208			211			630			612
	Amortized deferred policy acquisition costs	(195		)	(190		)	(598		)	(552		)
	Amortized shadow deferred policy acquisition costs	6			9			(7		)	46
	Deferred policy acquisition costs asset, end of	$	590		$	576		$	590		$	576
	period
	No premium deficiencies were recorded in the condensed consolidated statements of income, as the sum of the anticipated loss and loss adjustment expenses, policyholder dividends and unamortized deferred acquisition expenses did not exceed the related unearned premiums and anticipated investment income.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income [Abstract]	'
Comprehensive Income (Loss) Note	'
	ACCUMULATED OTHER COMPREHENSIVE INCOME
	Accumulated other comprehensive income includes changes in unrealized gains and losses on investments available for sale and other invested assets, changes in pension obligations and changes in life deferred acquisition costs, life policy reserves and other as follows:
	(In millions)	Three months ended September 30,
		2014									2013
		Before tax			Income tax			Net			Before tax			Income tax			Net
	Accumulated unrealized gains, net, on investments available for sale,	$	2,687		$	931		$	1,756		$	1,987		$	686		$	1,301
	beginning of period
	Other comprehensive income before reclassification	(55		)	(20		)	(35		)	82			29			53
	Reclassification adjustment for realized investment gains, net,	(65		)	(22		)	(43		)	(20		)	(7		)	(13		)
	included in net income
	Effect on other comprehensive income	(120		)	(42		)	(78		)	62			22			40
	Accumulated unrealized gains, net, on investments available for sale,	$	2,567		$	889		$	1,678		$	2,049		$	708		$	1,341
	end of period
	Accumulated unrealized losses, net, for pension obligations,	$	(19	)	$	(6	)	$	(13	)	$	(96	)	$	(33	)	$	(63	)
	beginning of period
	Other comprehensive income before reclassification	—			—			—			—			—			—
	Reclassification adjustment for amortization of actuarial loss and prior	1			—			1			2			1			1
	service cost, net, included in net income
	Effect on other comprehensive income	1			—			1			2			1			1
	Accumulated unrealized losses, net, for pension obligations,	$	(18	)	$	(6	)	$	(12	)	$	(94	)	$	(32	)	$	(62	)
	end of period
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(16	)	$	(5	)	$	(11	)	$	(26	)	$	(9	)	$	(17	)
	life policy reserves and other, beginning of period
	Other comprehensive income before reclassification	5			2			3			9			2			7
	Reclassification adjustment for life deferred acquisition costs,	—			—			—			(2		)	—			(2		)
	life policy reserves and other, net, included in net income
	Effect on other comprehensive income	5			2			3			7			2			5
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(11	)	$	(3	)	$	(8	)	$	(19	)	$	(7	)	$	(12	)
	life policy reserves and other, end of period
	Accumulated other comprehensive income, beginning of period	$	2,652		$	920		$	1,732		$	1,865		$	644		$	1,221
	Change in unrealized gains, net, on investments available for sale	(120		)	(42		)	(78		)	62			22			40
	Change in pension obligations	1			—			1			2			1			1
	Change in life deferred acquisition costs, life policy reserves	5			2			3			7			2			5
	and other
	Effect on other comprehensive income	(114		)	(40		)	(74		)	71			25			46
	Accumulated other comprehensive income, end of period	$	2,538		$	880		$	1,658		$	1,936		$	669		$	1,267
	(In millions)	Nine months ended September 30,
		2014									2013
		Before tax			Income tax			Net			Before tax			Income tax			Net
	Accumulated unrealized gains, net, on investments available for sale,	$	2,335		$	808		$	1,527		$	1,875		$	647		$	1,228
	beginning of period
	Other comprehensive income before reclassification	332			115			217			246			85			161
	Reclassification adjustment for realized investment gains, net,	(100		)	(34		)	(66		)	(72		)	(24		)	(48		)
	included in net income
	Effect on other comprehensive income	232			81			151			174			61			113
	Accumulated unrealized gains, net, on investments available for sale,	$	2,567		$	889		$	1,678		$	2,049		$	708		$	1,341
	end of period
	Accumulated unrealized losses, net, for pension obligations,	$	(18	)	$	(6	)	$	(12	)	$	(101	)	$	(35	)	$	(66	)
	beginning of period
	Other comprehensive income before reclassification	—			—			—			—			—			—
	Reclassification adjustment for amortization of actuarial loss and prior	—			—			—			7			3			4
	service cost, net, included in net income
	Effect on other comprehensive income	—			—			—			7			3			4
	Accumulated unrealized losses, net, for pension obligations,	$	(18	)	$	(6	)	$	(12	)	$	(94	)	$	(32	)	$	(62	)
	end of period
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(16	)	$	(5	)	$	(11	)	$	(50	)	$	(17	)	$	(33	)
	life policy reserves and other, beginning of period
	Other comprehensive income before reclassification	6			3			3			36			12			24
	Reclassification adjustment for life deferred acquisition costs,	(1		)	(1		)	—			(5		)	(2		)	(3		)
	life policy reserves and other, net, included in net income
	Effect on other comprehensive income	5			2			3			31			10			21
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(11	)	$	(3	)	$	(8	)	$	(19	)	$	(7	)	$	(12	)
	life policy reserves and other, end of period
Accumulated other comprehensive income, beginning of period	$	2,301		$	797		$	1,504		$	1,724		$	595		$	1,129
Change in unrealized gains, net, on investments available for sale	232			81			151			174			61			113
Change in pension obligations	—			—			—			7			3			4
Change in life deferred acquisition costs, life policy reserves	5			2			3			31			10			21
and other
Effect on other comprehensive income	237			83			154			212			74			138
Accumulated other comprehensive income, end of period	$	2,538		$	880		$	1,658		$	1,936		$	669		$	1,267
The reclassification adjustment for realized gains on investments available for sale and life deferred acquisition costs, life policy reserves and other is recorded in the line item for total realized investment gains, net, on the condensed consolidated statements of income.

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2014
Reinsurance Disclosures [Abstract]	'
Reinsurance	'
	REINSURANCE
	Reinsurance mitigates the risk of highly uncertain exposures and reduces the maximum net loss that can arise from large risks or risks concentrated in areas of exposure. Management's decisions about the appropriate level of risk retention are affected by various factors, including changes in our underwriting practices, capacity to retain risks and reinsurance market conditions.
	Primary components of our property casualty reinsurance program include a property per risk treaty, property excess treaty, casualty per occurrence treaty, casualty excess treaty, property catastrophe treaty and catastrophe bonds.
	Our condensed consolidated statements of income include earned consolidated property casualty insurance premiums on assumed and ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct earned premiums	$	1,067		$	1,002		$	3,134		$	2,895
	Assumed earned premiums	3			3			8			8
	Ceded earned premiums	(45		)	(51		)	(132		)	(150		)
	Net earned premiums	$	1,025		$	954		$	3,010		$	2,753
	Our condensed consolidated statements of income include incurred consolidated property casualty insurance loss and loss expenses on assumed and ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct incurred loss and loss expenses	$	633		$	597		$	2,026		$	1,725
	Assumed incurred loss and loss expenses	1			1			5			8
	Ceded incurred loss and loss expenses	(12		)	(5		)	(26		)	(33		)
	Net incurred loss and loss expenses	$	622		$	593		$	2,005		$	1,700
	Our life insurance company purchases reinsurance for protection of a portion of the risk that is written. Primary components of our life reinsurance program include individual mortality coverage and aggregate catastrophe and accidental death coverage in excess of certain deductibles.
	Our condensed consolidated statements of income include earned life insurance premiums on ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct earned premiums	$	61		$	52		$	191		$	166
	Ceded earned premiums	(15		)	(14		)	(44		)	(42		)
	Net earned premiums	$	46		$	38		$	147		$	124
	Our condensed consolidated statements of income include life insurance contract holders' benefits incurred on ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct contract holders' benefits incurred	$	80		$	64		$	228		$	190
	Ceded contract holders' benefits incurred	(16		)	(15		)	(52		)	(49		)
	Net contract holders' benefits incurred	$	64		$	49		$	176		$	141
	The ceded benefits incurred can vary depending on the type of life insurance policy held and the year the policy was sold.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	INCOME TAXES
	As of September 30, 2014, and December 31, 2013, we had no liability for unrecognized tax benefits.
	The differences between the 35 percent statutory income tax rate and our effective income tax rate were as follows:
	(In millions)	Three months ended September 30,										Nine months ended September 30,
		2014					2013					2014					2013
	Tax at statutory rate	$	91		35	%	$	64		35	%	$	170		35	%	$	191		35	%
	Increase (decrease) resulting from:
	Tax-exempt income from municipal bonds	(9		)	(3.5	)	(8		)	(4.4	)	(25		)	(5.2	)	(24		)	(4.4	)
	Dividend received exclusion	(7		)	(2.7	)	(6		)	(3.3	)	(21		)	(4.3	)	(18		)	(3.3	)
	Other	1			0.5		1			0.7		3			0.7		3			0.5
	Provision for income taxes	$	76		29.3	%	$	51		28	%	$	127		26.2	%	$	152		27.8	%
	The change in our effective tax rate was primarily due to changes in pretax income from underwriting results and realized investment gains and losses, compared with small changes in the amount of permanent book-tax differences.

Net_Income_Per_Common_Share

Net Income Per Common Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Net Income Per Common Share	'
	NET INCOME PER COMMON SHARE
	Basic earnings per share are computed based on the weighted average number of common shares outstanding. Diluted earnings per share are computed based on the weighted average number of common and dilutive potential common shares outstanding using the treasury stock method. The table shows calculations for basic and diluted earnings per share:
	(In millions except per share data)	Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013
	Numerator:
	Net income—basic and diluted	$	183	$	131	$	358	$	395
	Denominator:
	Basic weighted-average common shares	163.5		163.7		163.5		163.5
	outstanding
	Effect of stock-based awards:
	Stock options	0.9		1.2		0.9		1.1
	Nonvested shares	0.6		0.7		0.6		0.7
	Adjusted diluted weighted-average shares	165		165.6		165		165.3
	Earnings per share:
	Basic	$	1.12	$	0.8	$	2.19	$	2.42
	Diluted	1.11		0.79		2.17		2.39
	Number of anti-dilutive share-based awards	0.7		0.3		0.7		0.4
	The sources of dilution of our common shares are certain equity-based awards. See our 2013 Annual Report on Form 10-K, Item 8, Note 17, Share-Based Associate Compensation Plans, Page 154, for information about
	equity-based awards. The above table shows the number of anti-dilutive share-based awards for the three and
	nine months ended September 30, 2014 and 2013. We did not include these share-based awards in the computation of net income per common share (diluted) because their exercise would have anti-dilutive effects.

Employee_Retirement_Benefits

Employee Retirement Benefits	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Employee Retirement Benefits	'
	EMPLOYEE RETIREMENT BENEFITS
	The following summarizes the components of net periodic costs for our qualified and supplemental pension plans:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost	$	3		$	4		$	8		$	10
	Interest cost	4			4			11			10
	Expected return on plan assets	(5		)	(5		)	(13		)	(13		)
	Amortization of actuarial loss and prior service	1			2			2			7
	cost
	Net periodic benefit cost	$	3		$	5		$	8		$	14
	See our 2013 Annual Report on Form 10-K, Item 8, Note 13, Employee Retirement Benefits, Page 148, for information on our retirement benefits. We made matching contributions of $3 million and $2 million to our
	401(k) and Top Hat savings plans during the third quarter of 2014 and 2013 and contributions of $9 million and
	$7 million for the first nine months of 2014 and 2013, respectively.
	We contributed $5 million to our qualified pension plan during the first quarter of 2014. We do not anticipate further contributions to our qualified pension plan during the remainder of 2014.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments And Contingent Liabilities	'
	COMMITMENTS AND CONTINGENT LIABILITIES
	In the ordinary course of conducting business, the company and its subsidiaries are named as defendants in various legal proceedings. Most of these proceedings are claims litigation involving the company's insurance subsidiaries in which the company is either defending or providing indemnity for third-party claims brought against insureds or litigating first-party coverage claims. The company accounts for such activity through the establishment of unpaid loss and loss adjustment expense reserves. We believe that the ultimate liability, if any, with respect to such ordinary-course claims litigation, after consideration of provisions made for potential losses and costs of defense, is immaterial to our consolidated financial condition, results of operations and cash flows.
	The company and its subsidiaries also are occasionally involved in other legal and regulatory proceedings, some of which assert claims for substantial amounts. These actions include, among others, putative class actions seeking certification of a state or national class. Such proceedings have alleged, for example, breach of an alleged duty to search national databases to ascertain unreported deaths of insureds under life insurance policies. The company's insurance subsidiaries also are occasionally parties to individual actions in which extra-contractual damages, punitive damages or penalties are sought, such as claims alleging bad faith handling of insurance claims or writing unauthorized coverage or claims alleging discrimination by former or current associates.
	On a quarterly basis, we review these outstanding matters. Under current accounting guidance, we establish accruals when it is probable that a loss has been incurred and we can reasonably estimate its potential exposure. The company accounts for such probable and estimable losses, if any, through the establishment of legal expense reserves. Based on our quarterly review, we believe that our accruals for probable and estimable losses are reasonable and that the amounts accrued do not have a material effect on our consolidated financial condition or results of operations. However, if any one or more of these matters results in a judgment against us or settlement for an amount that is significantly greater than the amount accrued, the resulting liability could have a material effect on the company's consolidated results of operations or cash flows. Based on our most recent review, our estimate for any other matters for which the risk of loss is not probable, but more than remote, is less than $1 million.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	SEGMENT INFORMATION
	We operate primarily in two industries, property casualty insurance and life insurance. We regularly review our reporting segments to make decisions about allocating resources and assessing performance:
	•	Commercial lines property casualty insurance
	•	Personal lines property casualty insurance
	•	Excess and surplus lines property casualty insurance
	•	Life insurance
	•	Investments
	We report as Other the noninvestment operations of the parent company and its noninsurer subsidiary, CFC Investment Company. See our 2013 Annual Report on Form 10-K, Item 8, Note 18, Segment Information, Page 156, for a description of revenue, income or loss before income taxes and identifiable assets for each of the five segments.
	Segment information is summarized in the following table:
	(In millions)		Three months ended September 30,						Nine months ended September 30,
			2014			2013			2014			2013
	Revenues:
	Commercial lines insurance
	Commercial casualty		$	237		$	221		$	695		$	636
	Commercial property		186			161			537			460
	Commercial auto		133			124			391			355
	Workers' compensation		93			95			280			270
	Specialty packages		27			38			93			114
	Management liability and surety		32			30			94			89
	Machinery and equipment		12			11			36			32
	Commercial lines insurance premiums		720			680			2,126			1,956
	Fee revenue		1			1			3			2
	Total commercial lines insurance		721			681			2,129			1,958
	Personal lines insurance
	Personal auto		121			112			354			328
	Homeowner		110			103			330			298
	Other personal lines		32			29			91			86
	Personal lines insurance premiums		263			244			775			712
	Fee revenue		1			—			2			1
	Total personal lines insurance		264			244			777			713
	Excess and surplus lines insurance		42			30			109			85
	Life insurance premiums		46			38			147			124
	Separate account investment management fees		1			1			4			3
	Total life insurance		47			39			151			127
	Investment operations
	Investment income, net of expenses		138			133			409			392
	Realized investment gains, net		65			22			101			77
	Total investments		203			155			510			469
	Other		3			3			7			7
	Total revenues		$	1,280		$	1,152		$	3,683		$	3,359
	Income (loss) before income taxes:
	Insurance underwriting results
	Commercial lines insurance		$	67		$	43		$	97		$	135
	Personal lines insurance		14			14			(33		)	33
	Excess and surplus lines insurance		13			4			22			5
	Life insurance		(4		)	—			(5		)	10
	Investment operations		182			134			448			409
	Other		(13		)	(13		)	(44		)	(45		)
	Total income before income taxes		$	259		$	182		$	485		$	547
	Identifiable assets:		September 30,			December 31, 2013
			2014
	Property casualty insurance		$	2,434		$	2,455
	Life insurance		1,269			1,225
	Investment operations		14,322			13,618
	Other		449			364
	Total		$	18,474		$	17,662

Accounting_Policies_Pending_Ac

Accounting Policies Pending Accounting Updates (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Revenue Recognition, Policy [Policy Text Block]	'
	ASU 2014-09 Revenue from Contracts with Customers
	In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers. ASU 2014-09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Insurance contracts do not fall within the scope of this ASU. The effective date of ASU 2014-09 is for annual reporting periods beginning after December 15, 2016. The ASU has not yet been adopted and will not have a material impact on our company’s financial position, cash flows or results of operations.
Compensation Related Costs, Policy [Policy Text Block]	'
	ASU 2014-12, Compensation-Stock Compensation: Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period
	In June 2014, the FASB Issued ASU 2014-12, Compensation-Stock Compensation: Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. ASU 2014-12 requires that performance targets that affect vesting and that could be achieved after the requisite service period be treated as performance conditions. The effective date of ASU 2014-12 is for interim and annual reporting periods beginning after December 15, 2015. The ASU has not yet been adopted and will not have a material impact on our company’s financial position, cash flows or results of operations.

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Analysis Of Cost Or Amortized Cost, Gross Unrealized Gains And Losses And Fair Value for Investments	'
	The following table provides cost or amortized cost, gross unrealized gains, gross unrealized losses and fair value for our invested assets:
	(In millions)		Cost or
			amortized			Gross unrealized						Fair
	At September 30, 2014		cost			gains			losses			value
	Fixed maturity securities:
	Corporate		$	5,134		$	449		$	13		$	5,570
	States, municipalities and political subdivisions		3,294			173			3			3,464
	Commercial mortgage-backed		250			5			1			254
	Government-sponsored enterprises		222			—			12			210
	Foreign government		10			—			—			10
	Convertibles and bonds with warrants attached		7			—			—			7
	United States government		7			—			—			7
	Subtotal		8,924			627			29			9,522
	Equity securities:
	Common equities		2,552			1,942			6			4,488
	Nonredeemable preferred equities		145			34			1			178
	Subtotal		2,697			1,976			7			4,666
	Total		$	11,621		$	2,603		$	36		$	14,188
	At December 31, 2013
	Fixed maturity securities:
	Corporate		$	5,122		$	433		$	22		$	5,533
	States, municipalities and political subdivisions		3,107			125			21			3,211
	Government-sponsored enterprises		227			—			27			200
	Commercial mortgage-backed		148			—			5			143
	Convertibles and bonds with warrants attached		17			—			—			17
	Foreign government		10			—			—			10
	United States government		7			—			—			7
	Subtotal		8,638			558			75			9,121
	Equity securities:
	Common equities		2,396			1,818			1			4,213
	Nonredeemable preferred equities		127			38			3			162
	Subtotal		2,523			1,856			4			4,375
	Total		$	11,161		$	2,414		$	79		$	13,496
Fair Values And Unrealized Losses by Investment Category And By The Duration Of The Securities' Continuous Unrealized Loss Position	'
	The table below provides fair values and gross unrealized losses by investment category and by the duration of the securities’ continuous unrealized loss positions:
	(In millions)		Less than 12 months						12 months or more					Total		Total
			Fair			Unrealized			Fair			Unrealized		fair		unrealized
	At September 30, 2014		value			losses			value			losses		value		losses
	Fixed maturity securities:
	Corporate		$	224		$	9		$	114		$	4	$	338	$	13
	States, municipalities and political subdivisions		28			—			218			3		246		3
	Commercial mortgage-backed		37			—			32			1		69		1
	Government-sponsored enterprises		11			—			176			12		187		12
	Foreign government		—			—			10			—		10		—
	United States government		1			—			1			—		2		—
	Subtotal		301			9			551			20		852		29
	Equity securities:
	Common equities		105			2			80			4		185		6
	Nonredeemable preferred equities		25			—			17			1		42		1
	Subtotal		130			2			97			5		227		7
	Total		$	431		$	11		$	648		$	25	$	1,079	$	36
	At December 31, 2013
	Fixed maturity securities:
	Corporate		$	572		$	20		$	43		$	2	$	615	$	22
	States, municipalities and political subdivisions		490			18			42			3		532		21
	Government-sponsored enterprises		199			27			1			—		200		27
	Commercial mortgage-backed		125			5			—			—		125		5
	Foreign government		10			—			—			—		10		—
	United States government		1			—			—			—		1		—
	Subtotal		1,397			70			86			5		1,483		75
	Equity securities:
	Common equities		77			1			—			—		77		1
	Nonredeemable preferred equities		42			3			—			—		42		3
	Subtotal		119			4			—			—		119		4
	Total		$	1,516		$	74		$	86		$	5	$	1,602	$	79
Investment Income, Realized Investment Gains And Losses And Change In Unrealized Investment Gains And Losses	'
	The following table provides investment income, realized investment gains and losses, the change in unrealized investment gains and losses, and other items:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Investment income summary:
	Interest on fixed maturities	$	105		$	104		$	312		$	309
	Dividends on equity securities	35			30			101			87
	Other investment income	—			1			2			2
	Total	140			135			415			398
	Less investment expenses	2			2			6			6
	Total	$	138		$	133		$	409		$	392
	Realized investment gains and losses summary:
	Fixed maturities:
	Gross realized gains	$	6		$	5		$	12		$	10
	Gross realized losses	—			—			(4		)	—
	Other-than-temporary impairments	—			—			—			(2		)
	Equity securities:
	Gross realized gains	59			15			93			64
	Gross realized losses	—			—			—			—
	Other-than-temporary impairments	—			—			(1		)	—
	Other	—			2			1			5
	Total	$	65		$	22		$	101		$	77
	Change in unrealized gains and losses summary:
	Fixed maturities	$	(66	)	$	(28	)	$	115		$	(335	)
	Equity securities	(54		)	90			117			509
	Net change in pension actuarial loss and prior	1			2			—			7
	service cost
	Adjustment to deferred acquisition costs and life	4			9			(4		)	38
	policy reserves
	Other	1			(2		)	9			(7		)
	Income taxes on above	40			(25		)	(83		)	(74		)
	Total	$	(74	)	$	46		$	154		$	138

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'
Fair Value Hierarchy for Assets Measured at Fair Value on a Recurring Basis	'
	The following tables illustrate the fair value hierarchy for those assets measured at fair value on a recurring basis at September 30, 2014, and December 31, 2013. We do not have any material liabilities carried at fair value. There were no transfers between Level 1 and Level 2.
	(In millions)		Quoted prices in			Significant other			Significant			Total
			active markets for			observable inputs			unobservable
			identical assets			(Level 2)			inputs
	At September 30, 2014		(Level 1)						(Level 3)
	Fixed maturities, available for sale:
	Corporate		$	—		$	5,542		$	28		$	5,570
	States, municipalities and political subdivisions		—			3,464			—			3,464
	Commercial mortgage-backed		—			254			—			254
	Government-sponsored enterprises		—			210			—			210
	Foreign government		—			10			—			10
	Convertibles and bonds with warrants attached		—			7			—			7
	United States government		7			—			—			7
	Subtotal		7			9,487			28			9,522
	Common equities, available for sale		4,488			—			—			4,488
	Nonredeemable preferred equities, available for sale		—			176			2			178
	Separate accounts taxable fixed maturities		—			694			—			694
	Top Hat Savings Plan mutual funds and common		17			—			—			17
	equity (included in Other assets)
	Total		$	4,512		$	10,357		$	30		$	14,899
	At December 31, 2013
	Fixed maturities, available for sale:
	Corporate		$	—		$	5,531		$	2		$	5,533
	States, municipalities and political subdivisions		—			3,211			—			3,211
	Government-sponsored enterprises		—			200			—			200
	Commercial mortgage-backed		—			143			—			143
	Convertibles and bonds with warrants attached		—			17			—			17
	Foreign government		—			10			—			10
	United States government		7			—			—			7
	Subtotal		7			9,112			2			9,121
	Common equities, available for sale		4,213			—			—			4,213
	Nonredeemable preferred equities, available for sale		—			160			2			162
	Separate accounts taxable fixed-maturities		—			682			—			682
	Top Hat Savings Plan mutual funds and common		14			—			—			14
	equity (included in Other assets)
	Total		$	4,234		$	9,954		$	4		$	14,192
Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)	'
	The following tables provide the change in Level 3 assets for the three months ended September 30:
	(In millions)		Asset fair value measurements using significant unobservable inputs (Level 3)
			Corporate			Commercial			States,			Nonredeemable preferred			Total
			fixed			mortgage-			municipalities			equities
			maturities			backed fixed maturities			and political
									subdivisions
									fixed maturities
	Beginning balance, June 30, 2014		$	9		$	—		$	—		$	2		$	11
	Total gains or losses (realized/unrealized):
	Included in net income		—			—			—			—			—
	Included in other comprehensive income		—			—			—			—			—
	Purchases		—			—			—			—			—
	Sales		—			—			—			—			—
	Transfers into Level 3		19			—			—			—			19
	Transfers out of Level 3		—			—			—			—			—
	Ending balance, September 30, 2014		$	28		$	—		$	—		$	2		$	30
	Beginning balance, June 30, 2013		$	3		$	—		$	1		$	2		$	6
	Total gains or losses (realized/unrealized):
	Included in net income		—			—			—			—			—
	Included in other comprehensive income		—			—			—			—			—
	Purchases		—			—			—			—			—
	Sales		—			—			(1		)	—			(1		)
	Transfers into Level 3		—			—			—			—			—
	Transfers out of Level 3		—			—			—			—			—
	Ending balance, September 30, 2013		$	3		$	—		$	—		$	2		$	5
	The following tables provide the change in Level 3 assets for the nine months ended September 30:
	(In millions)	Asset fair value measurements using significant unobservable inputs (Level 3)
			Corporate			Commercial			States,			Nonredeemable preferred			Total
			fixed			mortgage-			municipalities			equities
			maturities			backed fixed maturities			and political
									subdivisions
									fixed maturities
	Beginning balance, January 1, 2014		$	2		$	—		$	—		$	2		$	4
	Total gains or losses (realized/unrealized):
	Included in net income		—			—			—			—			—
	Included in other comprehensive income		—			—			—			—			—
	Purchases		—			—			—			—			—
	Sales		—			—			—			—			—
	Transfers into Level 3		26			5			—			—			31
	Transfers out of Level 3		—			(5		)	—			—			(5		)
	Ending balance, September 30, 2014		$	28		$	—		$	—		$	2		$	30
	Beginning balance, January 1, 2013		$	3		$	—		$	1		$	1		$	5
	Total gains or losses (realized/unrealized):
	Included in net income		—			—			—			—			—
	Included in other comprehensive income		—			—			—			—			—
	Purchases		—			—			—			1			1
	Sales		—			—			(1		)	—			(1		)
	Transfers into Level 3		—			—			—			—			—
	Transfers out of Level 3		—			—			—			—			—
	Ending balance, September 30, 2013		$	3		$	—		$	—		$	2		$	5
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	'
	This table summarizes the book value and principal amounts of our long-term debt:
	(In millions)						Book value						Principal amount
							September 30,			December 31,			September 30,			December 31,
	Interest rate			Year of issue			2014			2013			2014			2013
	6.9	%		1998	Senior debentures, due 2028		$	28		$	28		$	28		$	28
	6.92	%		2005	Senior debentures, due 2028		391			391			391			391
	6.125	%		2004	Senior notes, due 2034		371			371			374			374
					Total		$	790		$	790		$	793		$	793
Fair Value of Life Policy Loans	'
	The following table shows the fair value of our life policy loans, included in other invested assets:
	(In millions)		Quoted prices in			Significant other			Significant			Total
			active markets for			observable inputs			unobservable
			identical assets			(Level 2)			inputs
	At September 30, 2014		(Level 1)						(Level 3)
	Life policy loans		$	—		$	—		$	39		$	39
	At December 31, 2013
	Life policy loans		$	—		$	—		$	45		$	45
Debt	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'
Fair Values of Deferred Annuities, Structured Settlements and Other Items	'
	The following table shows fair values of our note payable and long-term debt:
	(In millions)		Quoted prices in			Significant other			Significant			Total
			active markets for			observable inputs			unobservable
			identical assets			(Level 2)			inputs
	At September 30, 2014		(Level 1)						(Level 3)
	Note payable		$	—		$	49		$	—		$	49
	6.900% senior debentures, due 2028		—			33			—			33
	6.920% senior debentures, due 2028		—			482			—			482
	6.125% senior notes, due 2034		—			438			—			438
	Total		$	—		$	1,002		$	—		$	1,002
	At December 31, 2013
	Note payable		$	—		$	104		$	—		$	104
	6.900% senior debentures, due 2028		—			30			—			30
	6.920% senior debentures, due 2028		—			458			—			458
	6.125% senior notes, due 2034		—			399			—			399
	Total		$	—		$	991		$	—		$	991
Deferred Annuities, Structured Settlements, And Other	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'
Fair Values of Deferred Annuities, Structured Settlements and Other Items	'
	The following table shows fair values of our deferred annuities and structured settlements, included in life policy and investment contract reserves:
	(In millions)		Quoted prices in			Significant other			Significant			Total
			active markets for			observable inputs			unobservable
			identical assets			(Level 2)			inputs
	At September 30, 2014		(Level 1)						(Level 3)
	Deferred annuities		$	—		$	—		$	904		$	904
	Structured settlements		—			220			—			220
	Total		$	—		$	220		$	904		$	1,124
	At December 31, 2013
	Deferred annuities		$	—		$	—		$	911		$	911
	Structured settlements		—			219			—			219
	Total		$	—		$	219		$	911		$	1,130

Property_Casualty_Loss_and_Los1

Property Casualty Loss and Loss Expenses (Tables)	9 Months Ended
	Sep. 30, 2014
Premiums Written, Net [Abstract]	'
Consolidated Property Casualty Loss And Loss Expense Reserves	'
	This table summarizes activity for our consolidated property casualty loss and loss expense reserves:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Gross loss and loss expense reserves, beginning	$	4,408		$	4,219		$	4,241		$	4,169
	of period
	Less reinsurance receivable	282			333			299			356
	Net loss and loss expense reserves, beginning of	4,126			3,886			3,942			3,813
	period
	Net incurred loss and loss expenses related to:
	Current accident year	647			631			2,125			1,840
	Prior accident years	(25		)	(38		)	(120		)	(140		)
	Total incurred	622			593			2,005			1,700
	Net paid loss and loss expenses related to:
	Current accident year	353			329			859			699
	Prior accident years	286			233			979			897
	Total paid	639			562			1,838			1,596
	Net loss and loss expense reserves, end of period	4,109			3,917			4,109			3,917
	Plus reinsurance receivable	284			321			284			321
	Gross loss and loss expense reserves, end of	$	4,393		$	4,238		$	4,393		$	4,238
	period

Life_Policy_and_Investment_Con1

Life Policy and Investment Contract Reserves (Tables)	9 Months Ended
	Sep. 30, 2014
Liability for Future Policy Benefits [Abstract]	'
Reserve For Losses Loss Adjustment Expenses Table [Text Block]	'
	This table summarizes our life policy and investment contract reserves:
	(In millions)	September 30,		December 31, 2013
		2014
	Ordinary/traditional life	$	863	$	815
	Universal life	527		508
	Deferred annuities	864		862
	Structured settlements	184		189
	Other	46		16
	Total life policy and investment contract reserves	$	2,484	$	2,390

Deferred_Acquisition_Costs_Tab

Deferred Acquisition Costs (Tables)	9 Months Ended
	Sep. 30, 2014
Deferred Costs [Abstract]	'
Deferred Policy Acquisition Costs And Asset Reconciliation, Including the Amortized Deferred Policy Acquisition Costs	'
	The table below shows the deferred policy acquisition costs and asset reconciliation.
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Deferred policy acquisition costs asset, beginning	$	571		$	546		$	565		$	470
	of period
	Capitalized deferred policy acquisition costs	208			211			630			612
	Amortized deferred policy acquisition costs	(195		)	(190		)	(598		)	(552		)
	Amortized shadow deferred policy acquisition costs	6			9			(7		)	46
	Deferred policy acquisition costs asset, end of	$	590		$	576		$	590		$	576
	period

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	(In millions)	Three months ended September 30,
		2014									2013
		Before tax			Income tax			Net			Before tax			Income tax			Net
	Accumulated unrealized gains, net, on investments available for sale,	$	2,687		$	931		$	1,756		$	1,987		$	686		$	1,301
	beginning of period
	Other comprehensive income before reclassification	(55		)	(20		)	(35		)	82			29			53
	Reclassification adjustment for realized investment gains, net,	(65		)	(22		)	(43		)	(20		)	(7		)	(13		)
	included in net income
	Effect on other comprehensive income	(120		)	(42		)	(78		)	62			22			40
	Accumulated unrealized gains, net, on investments available for sale,	$	2,567		$	889		$	1,678		$	2,049		$	708		$	1,341
	end of period
	Accumulated unrealized losses, net, for pension obligations,	$	(19	)	$	(6	)	$	(13	)	$	(96	)	$	(33	)	$	(63	)
	beginning of period
	Other comprehensive income before reclassification	—			—			—			—			—			—
	Reclassification adjustment for amortization of actuarial loss and prior	1			—			1			2			1			1
	service cost, net, included in net income
	Effect on other comprehensive income	1			—			1			2			1			1
	Accumulated unrealized losses, net, for pension obligations,	$	(18	)	$	(6	)	$	(12	)	$	(94	)	$	(32	)	$	(62	)
	end of period
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(16	)	$	(5	)	$	(11	)	$	(26	)	$	(9	)	$	(17	)
	life policy reserves and other, beginning of period
	Other comprehensive income before reclassification	5			2			3			9			2			7
	Reclassification adjustment for life deferred acquisition costs,	—			—			—			(2		)	—			(2		)
	life policy reserves and other, net, included in net income
	Effect on other comprehensive income	5			2			3			7			2			5
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(11	)	$	(3	)	$	(8	)	$	(19	)	$	(7	)	$	(12	)
	life policy reserves and other, end of period
	Accumulated other comprehensive income, beginning of period	$	2,652		$	920		$	1,732		$	1,865		$	644		$	1,221
	Change in unrealized gains, net, on investments available for sale	(120		)	(42		)	(78		)	62			22			40
	Change in pension obligations	1			—			1			2			1			1
	Change in life deferred acquisition costs, life policy reserves	5			2			3			7			2			5
	and other
	Effect on other comprehensive income	(114		)	(40		)	(74		)	71			25			46
	Accumulated other comprehensive income, end of period	$	2,538		$	880		$	1,658		$	1,936		$	669		$	1,267
	(In millions)	Nine months ended September 30,
		2014									2013
		Before tax			Income tax			Net			Before tax			Income tax			Net
	Accumulated unrealized gains, net, on investments available for sale,	$	2,335		$	808		$	1,527		$	1,875		$	647		$	1,228
	beginning of period
	Other comprehensive income before reclassification	332			115			217			246			85			161
	Reclassification adjustment for realized investment gains, net,	(100		)	(34		)	(66		)	(72		)	(24		)	(48		)
	included in net income
	Effect on other comprehensive income	232			81			151			174			61			113
	Accumulated unrealized gains, net, on investments available for sale,	$	2,567		$	889		$	1,678		$	2,049		$	708		$	1,341
	end of period
	Accumulated unrealized losses, net, for pension obligations,	$	(18	)	$	(6	)	$	(12	)	$	(101	)	$	(35	)	$	(66	)
	beginning of period
	Other comprehensive income before reclassification	—			—			—			—			—			—
	Reclassification adjustment for amortization of actuarial loss and prior	—			—			—			7			3			4
	service cost, net, included in net income
	Effect on other comprehensive income	—			—			—			7			3			4
	Accumulated unrealized losses, net, for pension obligations,	$	(18	)	$	(6	)	$	(12	)	$	(94	)	$	(32	)	$	(62	)
	end of period
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(16	)	$	(5	)	$	(11	)	$	(50	)	$	(17	)	$	(33	)
	life policy reserves and other, beginning of period
	Other comprehensive income before reclassification	6			3			3			36			12			24
	Reclassification adjustment for life deferred acquisition costs,	(1		)	(1		)	—			(5		)	(2		)	(3		)
	life policy reserves and other, net, included in net income
	Effect on other comprehensive income	5			2			3			31			10			21
	Accumulated unrealized losses, net, on life deferred acquisition costs,	$	(11	)	$	(3	)	$	(8	)	$	(19	)	$	(7	)	$	(12	)
	life policy reserves and other, end of period
	Accumulated other comprehensive income, beginning of period	$	2,301		$	797		$	1,504		$	1,724		$	595		$	1,129
	Change in unrealized gains, net, on investments available for sale	232			81			151			174			61			113
Change in pension obligations	—			—			—			7			3			4
Change in life deferred acquisition costs, life policy reserves	5			2			3			31			10			21
and other
Effect on other comprehensive income	237			83			154			212			74			138
Accumulated other comprehensive income, end of period	$	2,538		$	880		$	1,658		$	1,936		$	669		$	1,267

Reinsurance_Tables

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2014
Reinsurance Disclosures [Abstract]	'
Earned Consolidated Property Casualty Insurance Premiums On Assumed And Ceded Business	'
	Our condensed consolidated statements of income include earned consolidated property casualty insurance premiums on assumed and ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct earned premiums	$	1,067		$	1,002		$	3,134		$	2,895
	Assumed earned premiums	3			3			8			8
	Ceded earned premiums	(45		)	(51		)	(132		)	(150		)
	Net earned premiums	$	1,025		$	954		$	3,010		$	2,753
Incurred Consolidated Property Casualty Insurance Loss And Loss Expenses On Assumed And Ceded Business	'
	Our condensed consolidated statements of income include incurred consolidated property casualty insurance loss and loss expenses on assumed and ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct incurred loss and loss expenses	$	633		$	597		$	2,026		$	1,725
	Assumed incurred loss and loss expenses	1			1			5			8
	Ceded incurred loss and loss expenses	(12		)	(5		)	(26		)	(33		)
	Net incurred loss and loss expenses	$	622		$	593		$	2,005		$	1,700
Earned Life Insurance Premiums On Ceded Business	'
	Our condensed consolidated statements of income include earned life insurance premiums on ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct earned premiums	$	61		$	52		$	191		$	166
	Ceded earned premiums	(15		)	(14		)	(44		)	(42		)
	Net earned premiums	$	46		$	38		$	147		$	124
Life Insurance Contract Holders' Benefits Incurred On Ceded Business	'
	Our condensed consolidated statements of income include life insurance contract holders' benefits incurred on ceded business:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Direct contract holders' benefits incurred	$	80		$	64		$	228		$	190
	Ceded contract holders' benefits incurred	(16		)	(15		)	(52		)	(49		)
	Net contract holders' benefits incurred	$	64		$	49		$	176		$	141

Income_Taxes_Tables

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Differences Between The 35 Percent Statutory Income Tax Rate And Effective Income Tax Rate	'
	The differences between the 35 percent statutory income tax rate and our effective income tax rate were as follows:
	(In millions)	Three months ended September 30,										Nine months ended September 30,
		2014					2013					2014					2013
	Tax at statutory rate	$	91		35	%	$	64		35	%	$	170		35	%	$	191		35	%
	Increase (decrease) resulting from:
	Tax-exempt income from municipal bonds	(9		)	(3.5	)	(8		)	(4.4	)	(25		)	(5.2	)	(24		)	(4.4	)
	Dividend received exclusion	(7		)	(2.7	)	(6		)	(3.3	)	(21		)	(4.3	)	(18		)	(3.3	)
	Other	1			0.5		1			0.7		3			0.7		3			0.5
	Provision for income taxes	$	76		29.3	%	$	51		28	%	$	127		26.2	%	$	152		27.8	%

Net_Income_Per_Common_Share_Ta

Net Income Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Calculations For Basic And Diluted Earnings Per Share	'
	The table shows calculations for basic and diluted earnings per share:
	(In millions except per share data)	Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013
	Numerator:
	Net income—basic and diluted	$	183	$	131	$	358	$	395
	Denominator:
	Basic weighted-average common shares	163.5		163.7		163.5		163.5
	outstanding
	Effect of stock-based awards:
	Stock options	0.9		1.2		0.9		1.1
	Nonvested shares	0.6		0.7		0.6		0.7
	Adjusted diluted weighted-average shares	165		165.6		165		165.3
	Earnings per share:
	Basic	$	1.12	$	0.8	$	2.19	$	2.42
	Diluted	1.11		0.79		2.17		2.39
	Number of anti-dilutive share-based awards	0.7		0.3		0.7		0.4

Employee_Retirement_Benefits_T

Employee Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Schedule of Defined Benefit Plans Disclosures	'
	The following summarizes the components of net periodic costs for our qualified and supplemental pension plans:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost	$	3		$	4		$	8		$	10
	Interest cost	4			4			11			10
	Expected return on plan assets	(5		)	(5		)	(13		)	(13		)
	Amortization of actuarial loss and prior service	1			2			2			7
	cost
	Net periodic benefit cost	$	3		$	5		$	8		$	14

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment information is summarized in the following table:
	(In millions)	Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Revenues:
	Commercial lines insurance
	Commercial casualty	$	237		$	221		$	695		$	636
	Commercial property	186			161			537			460
	Commercial auto	133			124			391			355
	Workers' compensation	93			95			280			270
	Specialty packages	27			38			93			114
	Management liability and surety	32			30			94			89
	Machinery and equipment	12			11			36			32
	Commercial lines insurance premiums	720			680			2,126			1,956
	Fee revenue	1			1			3			2
	Total commercial lines insurance	721			681			2,129			1,958
	Personal lines insurance
	Personal auto	121			112			354			328
	Homeowner	110			103			330			298
	Other personal lines	32			29			91			86
	Personal lines insurance premiums	263			244			775			712
	Fee revenue	1			—			2			1
	Total personal lines insurance	264			244			777			713
	Excess and surplus lines insurance	42			30			109			85
	Life insurance premiums	46			38			147			124
	Separate account investment management fees	1			1			4			3
	Total life insurance	47			39			151			127
	Investment operations
	Investment income, net of expenses	138			133			409			392
	Realized investment gains, net	65			22			101			77
	Total investments	203			155			510			469
	Other	3			3			7			7
	Total revenues	$	1,280		$	1,152		$	3,683		$	3,359
	Income (loss) before income taxes:
	Insurance underwriting results
	Commercial lines insurance	$	67		$	43		$	97		$	135
	Personal lines insurance	14			14			(33		)	33
	Excess and surplus lines insurance	13			4			22			5
	Life insurance	(4		)	—			(5		)	10
	Investment operations	182			134			448			409
	Other	(13		)	(13		)	(44		)	(45		)
	Total income before income taxes	$	259		$	182		$	485		$	547
	Identifiable assets:	September 30,			December 31, 2013
		2014
	Property casualty insurance	$	2,434		$	2,455
	Life insurance	1,269			1,225
	Investment operations	14,322			13,618
	Other	449			364
	Total	$	18,474		$	17,662

Investments_Analysis_of_Cost_o

Investments - Analysis of Cost or Amortized Cost, Gross Unrealized Gains and Losses and Fair Value for Investments (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Debt Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	$8,924	$8,638
Gross Unrealized Gains	627	558
Gross Unrealized Losses	29	75
Fair Value	9,522	9,121
Debt Securities | States, Municipalities And Political Subdivisions	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	3,294	3,107
Gross Unrealized Gains	173	125
Gross Unrealized Losses	3	21
Fair Value	3,464	3,211
Debt Securities | Convertibles And Bonds With Warrants Attached	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	7	17
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	7	17
Debt Securities | United States Government	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	7	7
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	7	7
Debt Securities | Government-Sponsored Enterprises	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	222	227
Gross Unrealized Gains	0	0
Gross Unrealized Losses	12	27
Fair Value	210	200
Debt Securities | Foreign Government	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	10	10
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	10	10
Debt Securities | Commercial Mortgage Backed Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	250	148
Gross Unrealized Gains	5	0
Gross Unrealized Losses	1	5
Fair Value	254	143
Debt Securities | Corporate Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	5,134	5,122
Gross Unrealized Gains	449	433
Gross Unrealized Losses	13	22
Fair Value	5,570	5,533
Equity Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	2,697	2,523
Gross Unrealized Gains	1,976	1,856
Gross Unrealized Losses	7	4
Fair Value	4,666	4,375
Equity Securities | Common Stock	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	2,552	2,396
Gross Unrealized Gains	1,942	1,818
Gross Unrealized Losses	6	1
Fair Value	4,488	4,213
Equity Securities | Preferred Stock	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	145	127
Gross Unrealized Gains	34	38
Gross Unrealized Losses	1	3
Fair Value	178	162
Fixed Maturities And Equity Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost or Amortized Cost	11,621	11,161
Gross Unrealized Gains	2,603	2,414
Gross Unrealized Losses	36	79
Fair Value	$14,188	$13,496

Investments_Fair_Values_and_Un

Investments - Fair Values and Unrealized Losses by Investment Category and by Duration of Securities' Continuous Unrealized Loss Position (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	$431	$1,516
Less than 12 months Unrealized Losses	11	74
12 months or more Fair Value	648	86
12 months or more Unrealized Losses	25	5
Total Fair Value	1,079	1,602
Total Unrealized Losses	36	79
Fixed Maturities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	301	1,397
Less than 12 months Unrealized Losses	9	70
12 months or more Fair Value	551	86
12 months or more Unrealized Losses	20	5
Total Fair Value	852	1,483
Total Unrealized Losses	29	75
Fixed Maturities | States, Municipalities And Political Subdivisions	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	28	490
Less than 12 months Unrealized Losses	0	18
12 months or more Fair Value	218	42
12 months or more Unrealized Losses	3	3
Total Fair Value	246	532
Total Unrealized Losses	3	21
Fixed Maturities | United States Government	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	1	1
Less than 12 months Unrealized Losses	0	0
12 months or more Fair Value	1	0
12 months or more Unrealized Losses	0	0
Total Fair Value	2	1
Total Unrealized Losses	0	0
Fixed Maturities | Government-Sponsored Enterprises	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	11	199
Less than 12 months Unrealized Losses	0	27
12 months or more Fair Value	176	1
12 months or more Unrealized Losses	12	0
Total Fair Value	187	200
Total Unrealized Losses	12	27
Fixed Maturities | Foreign Government Debt Securities [Member]	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	0	10
Less than 12 months Unrealized Losses	0	0
12 months or more Fair Value	10	0
12 months or more Unrealized Losses	0	0
Total Fair Value	10	10
Total Unrealized Losses	0	0
Fixed Maturities | Commercial Mortgage Backed Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	37	125
Less than 12 months Unrealized Losses	0	5
12 months or more Fair Value	32	0
12 months or more Unrealized Losses	1	0
Total Fair Value	69	125
Total Unrealized Losses	1	5
Fixed Maturities | Corporate Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	224	572
Less than 12 months Unrealized Losses	9	20
12 months or more Fair Value	114	43
12 months or more Unrealized Losses	4	2
Total Fair Value	338	615
Total Unrealized Losses	13	22
Equity Securities	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	130	119
Less than 12 months Unrealized Losses	2	4
12 months or more Fair Value	97	0
12 months or more Unrealized Losses	5	0
Total Fair Value	227	119
Total Unrealized Losses	7	4
Equity Securities | Common Stock	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	105	77
Less than 12 months Unrealized Losses	2	1
12 months or more Fair Value	80	0
12 months or more Unrealized Losses	4	0
Total Fair Value	185	77
Total Unrealized Losses	6	1
Equity Securities | Preferred Stock	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Less than 12 months Fair Value	25	42
Less than 12 months Unrealized Losses	0	3
12 months or more Fair Value	17	0
12 months or more Unrealized Losses	1	0
Total Fair Value	42	42
Total Unrealized Losses	$1	$3

Investments_Realized_Investmen

Investments - Realized Investment Gains and Losses and Change in Unrealized Investment Gains and Losses and Other Items (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investment income summary:	'	'	'	'
Interest on fixed maturities	$105	$104	$312	$309
Dividends on equity securities	35	30	101	87
Other investment income	0	1	2	2
Gross investment income	140	135	415	398
Less investment expenses	2	2	6	6
Total	138	133	409	392
Realized investment gains and losses summary:	'	'	'	'
Other	1	-2	9	-7
Realized investment gains, net	65	22	101	77
Change in unrealized gains and losses summary:	'	'	'	'
Unrealized gains (losses) on investments available-for-sale	-78	40	151	113
Adjustment to deferred acquisition costs and life policy reserves	4	9	-4	38
Amortization of pension actuarial loss and prior service cost	1	2	0	7
Other	1	-2	9	-7
Income taxes on above	40	-25	83	74
Other comprehensive income (loss), net of tax	-74	46	154	138
Fixed Maturities	'	'	'	'
Realized investment gains and losses summary:	'	'	'	'
Gross realized gains	6	5	12	10
Gross realized losses	0	0	-4	0
Other-than-temporary impairments	0	0	0	-2
Change in unrealized gains and losses summary:	'	'	'	'
Unrealized gains (losses) on investments available-for-sale	-66	-28	115	-335
Equity Securities	'	'	'	'
Realized investment gains and losses summary:	'	'	'	'
Gross realized gains	59	15	93	64
Gross realized losses	0	0	0	0
Other-than-temporary impairments	0	0	-1	0
Other	0	2	1	5
Realized investment gains, net	65	22	'	'
Change in unrealized gains and losses summary:	'	'	'	'
Unrealized gains (losses) on investments available-for-sale	-54	90	117	509
Other	$0	$2	$1	$5

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended	3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014
			Fixed Maturities	Fixed Maturities	Fixed Maturities	Fixed Maturities	Equity Securities	Equity Securities	Equity Securities	Procter And Gamble Company, Exxon Mobile Corporation And Chevron Corporation [Member]	Common Stock
			security	security	security	security	security	security
Gain (Loss) on Investments [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Number of securities	'	'	'	'	'	'	'	'	'	'	7
Unrealized investment gains due to a net gain position	'	'	$627	$627	'	$558	$1,976	$1,976	$1,856	$579	'
Largest equity holdings to total equity portfolio	3.10%	'	'	'	'	'	'	'	'	'	'
Largest equity holdings to total portfolio	1.00%	'	'	'	'	'	'	'	'	'	'
Number Of Securities Other Than Temporary Impairment Losses1	'	'	0	1	7	'	0	3	'	'	'
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months	'	'	212	212	'	40	4	4	'	'	'
Unrealized losses 12 months or more (equity investment less than $500,000)	$25	$5	$20	$20	'	$5	$5	$5	$0	'	'
Fixed maturity investments, Percentage of amortized costs	70.00%	70.00%	'	'	'	'	'	'	'	'	'

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Value Hierarchy for Assets Measured at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	$9,522	$9,121
Equity securities, at fair value	4,666	4,375
Separate accounts	730	692
Fair value of asset	14,899	14,192
Multiemployer Plan, Plan Information, Not Available [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other investments	17	14
Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	9,522	9,121
Debt Securities | States, Municipalities And Political Subdivisions	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	3,464	3,211
Debt Securities | Convertibles And Bonds With Warrants Attached	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	7	17
Debt Securities | United States Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	7	7
Debt Securities | Government-Sponsored Enterprises	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	210	200
Debt Securities | Foreign Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	10	10
Debt Securities | Commercial Mortgage Backed Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	254	143
Debt Securities | Corporate Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	5,570	5,533
Equity Securities | Common Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	4,488	4,213
Equity Securities | Preferred Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	178	162
Taxable Fixed Maturities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Separate accounts	694	682
Quoted prices in active markets for identical assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of asset	4,512	4,234
Quoted prices in active markets for identical assets (Level 1) | Multiemployer Plan, Plan Information, Not Available [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other investments	17	14
Quoted prices in active markets for identical assets (Level 1) | Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	7	7
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | States, Municipalities And Political Subdivisions	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Convertibles And Bonds With Warrants Attached	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | United States Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	7	7
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Government-Sponsored Enterprises	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Foreign Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Commercial Mortgage Backed Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Corporate Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Equity Securities | Common Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	4,488	4,213
Quoted prices in active markets for identical assets (Level 1) | Equity Securities | Preferred Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Taxable Fixed Maturities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Separate accounts	0	0
Significant other observable inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of asset	10,357	9,954
Significant other observable inputs (Level 2) | Multiemployer Plan, Plan Information, Not Available [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other investments	0	0
Significant other observable inputs (Level 2) | Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	9,487	9,112
Significant other observable inputs (Level 2) | Debt Securities | States, Municipalities And Political Subdivisions	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	3,464	3,211
Significant other observable inputs (Level 2) | Debt Securities | Convertibles And Bonds With Warrants Attached	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	7	17
Significant other observable inputs (Level 2) | Debt Securities | United States Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant other observable inputs (Level 2) | Debt Securities | Government-Sponsored Enterprises	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	210	200
Significant other observable inputs (Level 2) | Debt Securities | Foreign Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	10	10
Significant other observable inputs (Level 2) | Debt Securities | Commercial Mortgage Backed Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	254	143
Significant other observable inputs (Level 2) | Debt Securities | Corporate Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	5,542	5,531
Significant other observable inputs (Level 2) | Equity Securities | Common Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	0	0
Significant other observable inputs (Level 2) | Equity Securities | Preferred Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	176	160
Significant other observable inputs (Level 2) | Taxable Fixed Maturities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Separate accounts	694	682
Significant unobservable inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of asset	30	4
Significant unobservable inputs (Level 3) | Multiemployer Plan, Plan Information, Not Available [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Other investments	0	0
Significant unobservable inputs (Level 3) | Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	28	2
Significant unobservable inputs (Level 3) | Debt Securities | States, Municipalities And Political Subdivisions	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Convertibles And Bonds With Warrants Attached	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | United States Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Government-Sponsored Enterprises	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Foreign Government	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Commercial Mortgage Backed Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Corporate Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturities, at fair value	28	2
Significant unobservable inputs (Level 3) | Equity Securities | Common Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	0	0
Significant unobservable inputs (Level 3) | Equity Securities | Preferred Stock	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities, at fair value	2	2
Significant unobservable inputs (Level 3) | Taxable Fixed Maturities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Separate accounts	$0	$0

Fair_Value_Measurements_Change

Fair Value Measurements - Change in Level 3 Assets (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Beginning balance	$11	$6	$4	$5
Total gains or losses (realized/unrealized):	'	'	'	'
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	0	0
Purchases	0	0	0	1
Sales	0	-1	0	-1
Transfers into Level 3	19	0	31	0
Transfers out of Level 3	0	0	-5	0
Ending balance	30	5	30	5
Corporate Fixed Maturities	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Beginning balance	9	3	2	3
Total gains or losses (realized/unrealized):	'	'	'	'
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Transfers into Level 3	19	0	26	0
Transfers out of Level 3	0	0	0	0
Ending balance	28	3	28	3
Commercial Mortgage Backed Securities	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Beginning balance	0	0	0	0
Total gains or losses (realized/unrealized):	'	'	'	'
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Transfers into Level 3	0	0	5	0
Transfers out of Level 3	0	0	-5	0
Ending balance	0	0	0	0
States, Municipalities And Political Subdivisions Fixed Maturities	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Beginning balance	0	1	0	1
Total gains or losses (realized/unrealized):	'	'	'	'
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	-1	0	-1
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	0	0	0	0
Preferred Equities	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Beginning balance	2	2	2	1
Total gains or losses (realized/unrealized):	'	'	'	'
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	0	0
Purchases	0	0	0	1
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	$2	$2	$2	$2

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Book Value and Principal Amounts of Long-Term Debt (Detail) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Book value	$790	$790
Principal amount of debt	793	793
Senior Debentures 6.900% Due 2028	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.90%	6.90%
Debt issuance year	'1998	'1998
Book value	28	28
Principal amount of debt	28	28
Senior Debentures 6.920% Due 2028	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.92%	6.92%
Debt issuance year	'2005	'2005
Book value	391	391
Principal amount of debt	391	391
Senior Notes 6.152% Due 2034	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.13%	6.13%
Debt issuance year	'2004	'2004
Book value	371	371
Principal amount of debt	$374	$374

Fair_Value_Measurements_Fair_V1

Fair Value Measurements - Fair Values of Note Payable and Long-Term Debt (Detail) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of note payable	$49	$104
Total	1,002	991
Senior Debentures 6.900 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Interest rate	6.90%	6.90%
Debt instrument, year of maturity	'2028	'2028
Fair value of senior debt	33	30
Senior Debentures 6.920 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Interest rate	6.92%	6.92%
Debt instrument, year of maturity	'2028	'2028
Fair value of senior debt	482	458
Senior Notes 6.125 % Due 2034	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Interest rate	6.13%	6.13%
Debt instrument, year of maturity	'2034	'2034
Fair value of senior debt	438	399
Quoted prices in active markets for identical assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of note payable	0	0
Total	0	0
Quoted prices in active markets for identical assets (Level 1) | Senior Debentures 6.900 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	0	0
Quoted prices in active markets for identical assets (Level 1) | Senior Debentures 6.920 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	0	0
Quoted prices in active markets for identical assets (Level 1) | Senior Notes 6.125 % Due 2034	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	0	0
Significant other observable inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of note payable	49	104
Total	1,002	991
Significant other observable inputs (Level 2) | Senior Debentures 6.900 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	33	30
Significant other observable inputs (Level 2) | Senior Debentures 6.920 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	482	458
Significant other observable inputs (Level 2) | Senior Notes 6.125 % Due 2034	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	438	399
Significant unobservable inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of note payable	0	0
Total	0	0
Significant unobservable inputs (Level 3) | Senior Debentures 6.900 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	0	0
Significant unobservable inputs (Level 3) | Senior Debentures 6.920 % Due 2028	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	0	0
Significant unobservable inputs (Level 3) | Senior Notes 6.125 % Due 2034	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of senior debt	$0	$0

Fair_Value_Measurements_Fair_V2

Fair Value Measurements - Fair Value of Life Policy Loans (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of life policy loans	$39	$45
Quoted prices in active markets for identical assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of life policy loans	0	0
Significant other observable inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of life policy loans	0	0
Significant unobservable inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of life policy loans	$39	$45

Fair_Value_Measurements_Fair_V3

Fair Value Measurements - Fair Values of Deferred Annuities, Structured Settlements and Other Items (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	$1,124	$1,130
Deferred Annuities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	904	911
Structured Settlements	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	220	219
Quoted prices in active markets for identical assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | Deferred Annuities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) | Structured Settlements	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	0	0
Significant other observable inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	220	219
Significant other observable inputs (Level 2) | Deferred Annuities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	0	0
Significant other observable inputs (Level 2) | Structured Settlements	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	220	219
Significant unobservable inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	904	911
Significant unobservable inputs (Level 3) | Deferred Annuities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	904	911
Significant unobservable inputs (Level 3) | Structured Settlements	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair Value of life insurance liabilities	$0	$0

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Repayments of Notes Payable	$55	$55	$0	'
Finance receivable	77	77	'	85
Loss and loss expense reserves	4,435	4,435	'	4,311
Life Policy Loans	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Finance receivable	30	30	'	36
Deferred Annuities And Structured Settlements	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Liability for Future Policy Benefits, Individual and Group Annuities and Supplementary Contracts	864	864	'	862
Loss and loss expense reserves	$184	$184	'	$189
Maximum	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'
Percentage Of Level 3 Assets To Total Financial Instruments Measured At Fair Value	1.00%	1.00%	'	'

Property_Casualty_Loss_and_Los2

Property Casualty Loss and Loss Expenses - Consolidated Property Casualty Loss and Loss Expense Reserves (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Summary of Consolidated Property Casualty Loss and Loss Expense Reserves [Roll Forward]	'	'	'	'
Gross loss and loss expense reserves, beginning of period	$4,408	$4,219	$4,241	$4,169
Less reinsurance receivable	282	333	299	356
Net loss and loss expense reserves, beginning of period	4,126	3,886	3,942	3,813
Current accident year	647	631	2,125	1,840
Prior accident years	-25	-38	-120	-140
Total incurred	622	593	2,005	1,700
Current accident year	353	329	859	699
Prior accident years	286	233	979	897
Total paid	639	562	1,838	1,596
Net loss and loss expense reserves, end of period	4,109	3,917	4,109	3,917
Plus reinsurance receivable	284	321	284	321
Gross loss and loss expense reserves, end of period	$4,393	$4,238	$4,393	$4,238

Property_Casualty_Loss_and_Los3

Property Casualty Loss and Loss Expenses - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Reserve for loss and loss expenses	$4,393	$4,238	$4,393	$4,238	$4,408	$4,241	$4,219	$4,169
Prior accident years	25	38	120	140	'	'	'	'
Life and Health Loss Reserves	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Reserve for loss and loss expenses	42	69	42	69	'	'	'	'
Commercial Lines	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	24	'	84	'	'	'	'	'
Commercial Lines | Commercial Property	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	8	'	33	'	'	'	'	'
Commercial Lines | Workers' Compensation	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	15	'	45	'	'	'	'	'
Commercial Lines | Commercial Casualty	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	8	'	25	'	'	'	'	'
Personal Lines	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	-5	'	13	'	'	'	'	'
Personal Lines | Commercial Auto	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	-12	'	-24	'	'	'	'	'
Excess and Surplus Lines Insurance	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	6	'	23	'	'	'	'	'
Consolidated Property and Casualty Insurance Entity | Catastrophe Development	'	'	'	'	'	'	'	'
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]	'	'	'	'	'	'	'	'
Prior accident years	$5	$9	$19	$24	'	'	'	'

Reserves_in_Addition_to_Accoun

Reserves in Addition to Account Balance, Based on Expected No-Lapse Guarantee Benefits and Expected Policy Assessments (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Liability for Future Policy Benefit, by Product Segment [Line Items]	'	'
Life policy and investment contract reserves	$2,484	$2,390
Ordinary/Traditional Life	'	'
Liability for Future Policy Benefit, by Product Segment [Line Items]	'	'
Life policy and investment contract reserves	863	815
Universal Life	'	'
Liability for Future Policy Benefit, by Product Segment [Line Items]	'	'
Life policy and investment contract reserves	527	508
Deferred Annuities	'	'
Liability for Future Policy Benefit, by Product Segment [Line Items]	'	'
Life policy and investment contract reserves	864	862
Structured Settlements	'	'
Liability for Future Policy Benefit, by Product Segment [Line Items]	'	'
Life policy and investment contract reserves	184	189
Other	'	'
Liability for Future Policy Benefit, by Product Segment [Line Items]	'	'
Life policy and investment contract reserves	$46	$16

Deferred_Acquisition_Costs_Def

Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]	'	'	'	'
Deferred policy acquisition costs asset, beginning of period	$571	$546	$565	$470
Capitalized deferred policy acquisition costs	208	211	630	612
Amortized deferred policy acquisition costs	-195	-190	-598	-552
Amortized shadow deferred policy acquisition costs	6	9	-7	46
Deferred policy acquisition costs asset, end of period	$590	$576	$590	$576

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, net of tax, beginning of period	$1,658	'	$1,658	'	'	$1,504	'	'
Accumulated other comprehensive income, net of tax, end of period	1,658	'	1,658	'	'	1,504	'	'
Accumulated Net Unrealized Investment Gain (Loss)	'	'	'	'	'	'	'	'
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, before tax, beginning of period	2,687	1,987	2,335	1,875	'	'	'	'
Other comprehensive income before reclassification, before tax	-55	82	332	246	'	'	'	'
Reclassification adjustment, before tax	-65	-20	-100	-72	'	'	'	'
Effect on other comprehensive income, before tax	-120	62	232	174	'	'	'	'
Accumulated other comprehensive income, before tax, end of period	2,567	2,049	2,567	2,049	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, tax, beginning of period	931	686	808	647	'	'	'	'
Other comprehensive income before reclassification, tax	-20	29	115	85	'	'	'	'
Reclassification adjustment, tax	-22	-7	-34	-24	'	'	'	'
Effect on other comprehensive income, tax	-42	22	81	61	'	'	'	'
Accumulated other comprehensive income, tax, end of period	889	708	889	708	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, net of tax, beginning of period	1,678	1,341	1,678	1,341	1,756	1,527	1,301	1,228
Other comprehensive income before reclassification, net of tax	-35	53	217	161	'	'	'	'
Reclassification adjustment, net of tax	-43	-13	-66	-48	'	'	'	'
Effect on other comprehensive income, net of tax	-78	40	151	113	'	'	'	'
Accumulated other comprehensive income, net of tax, end of period	1,678	1,341	1,678	1,341	1,756	1,527	1,301	1,228
Accumulated Defined Benefit Plans Adjustment	'	'	'	'	'	'	'	'
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, before tax, beginning of period	-19	-96	-18	-101	'	'	'	'
Other comprehensive income before reclassification, before tax	0	0	0	0	'	'	'	'
Reclassification adjustment, before tax	1	2	0	7	'	'	'	'
Effect on other comprehensive income, before tax	1	2	0	7	'	'	'	'
Accumulated other comprehensive income, before tax, end of period	-18	-94	-18	-94	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, tax, beginning of period	-6	-33	-6	-35	'	'	'	'
Other comprehensive income before reclassification, tax	0	0	0	0	'	'	'	'
Reclassification adjustment, tax	0	1	0	3	'	'	'	'
Effect on other comprehensive income, tax	0	1	0	3	'	'	'	'
Accumulated other comprehensive income, tax, end of period	-6	-32	-6	-32	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, net of tax, beginning of period	-12	-62	-12	-62	-13	-12	-63	-66
Other comprehensive income before reclassification, net of tax	0	0	0	0	'	'	'	'
Reclassification adjustment, net of tax	1	1	0	4	'	'	'	'
Effect on other comprehensive income, net of tax	1	1	0	4	'	'	'	'
Accumulated other comprehensive income, net of tax, end of period	-12	-62	-12	-62	-13	-12	-63	-66
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other	'	'	'	'	'	'	'	'
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, before tax, beginning of period	-16	-26	-16	-50	'	'	'	'
Other comprehensive income before reclassification, before tax	5	9	6	36	'	'	'	'
Reclassification adjustment, before tax	0	-2	-1	-5	'	'	'	'
Effect on other comprehensive income, before tax	5	7	5	31	'	'	'	'
Accumulated other comprehensive income, before tax, end of period	-11	-19	-11	-19	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, tax, beginning of period	-5	-9	-5	-17	'	'	'	'
Other comprehensive income before reclassification, tax	2	2	3	12	'	'	'	'
Reclassification adjustment, tax	0	0	-1	-2	'	'	'	'
Effect on other comprehensive income, tax	2	2	2	10	'	'	'	'
Accumulated other comprehensive income, tax, end of period	-3	-7	-3	-7	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, net of tax, beginning of period	-8	-12	-8	-12	-11	-11	-17	-33
Other comprehensive income before reclassification, net of tax	3	7	3	24	'	'	'	'
Reclassification adjustment, net of tax	0	-2	0	-3	'	'	'	'
Effect on other comprehensive income, net of tax	3	5	3	21	'	'	'	'
Accumulated other comprehensive income, net of tax, end of period	-8	-12	-8	-12	-11	-11	-17	-33
Accumulated Other Comprehensive Income (Loss)	'	'	'	'	'	'	'	'
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, before tax, beginning of period	2,652	1,865	2,301	1,724	'	'	'	'
Change in unrealized gains, net, on investments available for sale, before tax	-120	62	232	174	'	'	'	'
Change in pension obligations, before tax	1	2	0	7	'	'	'	'
Change in life deferred acquisition costs, life policy reserves and other, before tax	5	7	5	31	'	'	'	'
Effect on other comprehensive income, before tax	-114	71	237	212	'	'	'	'
Accumulated other comprehensive income, before tax, end of period	2,538	1,936	2,538	1,936	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, tax, beginning of period	920	644	797	595	'	'	'	'
Change in unrealized gains, net, on investments available for sale, tax	-42	22	81	61	'	'	'	'
Change in pension obligations, tax	0	1	0	3	'	'	'	'
Change in life deferred acquisition costs, life policy reserves and other, tax	2	2	2	10	'	'	'	'
Effect on other comprehensive income, tax	-40	25	83	74	'	'	'	'
Accumulated other comprehensive income, tax, end of period	880	669	880	669	'	'	'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'	'	'	'	'	'	'
Accumulated other comprehensive income, net of tax, beginning of period	1,658	1,267	1,658	1,267	1,732	1,504	1,221	1,129
Change in unrealized gains, net, on investments available for sale, net of tax	-78	40	151	113	'	'	'	'
Change in pension obligations, net of tax	1	1	0	4	'	'	'	'
Change in life deferred acquisition costs, life policy reserves and other, net of tax	3	5	3	21	'	'	'	'
Effect on other comprehensive income, net of tax	-74	46	154	138	'	'	'	'
Accumulated other comprehensive income, net of tax, end of period	$1,658	$1,267	$1,658	$1,267	$1,732	$1,504	$1,221	$1,129

Reinsurance_Earned_Consolidate

Reinsurance - Earned Consolidated Property Casualty Insurance Premiums on Assumed and Ceded Business (Detail) (Consolidated Property and Casualty Insurance Entity, USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Consolidated Property and Casualty Insurance Entity	'	'	'	'
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]	'	'	'	'
Direct earned premiums	$1,067	$1,002	$3,134	$2,895
Assumed earned premiums	3	3	8	8
Ceded earned premiums	-45	-51	-132	-150
Net earned premiums	$1,025	$954	$3,010	$2,753

Reinsurance_Incurred_Consolida

Reinsurance - Incurred Consolidated Property Casualty Insurance Loss and Loss Expenses on Assumed and Ceded Business (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]	'	'	'	'
Net incurred loss and loss expenses	$686	$642	$2,181	$1,841
Consolidated Property and Casualty Insurance Entity	'	'	'	'
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]	'	'	'	'
Direct incurred loss and loss expenses	633	597	2,026	1,725
Assumed incurred loss and loss expenses	1	1	5	8
Ceded incurred loss and loss expenses	-12	-5	-26	-33
Net incurred loss and loss expenses	$622	$593	$2,005	$1,700

Reinsurance_Earned_Life_Insura

Reinsurance - Earned Life Insurance Premiums on Ceded Business (Detail) (Life Insurance Segment, USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Life Insurance Segment	'	'	'	'
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]	'	'	'	'
Direct earned premiums	$61	$52	$191	$166
Ceded earned premiums	-15	-14	-44	-42
Net earned premiums	$46	$38	$147	$124

Reinsurance_Life_Insurance_Con

Reinsurance - Life Insurance Contract Holders' Benefits Incurred on Ceded Business (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]	'	'	'	'
Insurance losses and policyholder benefits	$686	$642	$2,181	$1,841
Life Insurance Segment	'	'	'	'
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]	'	'	'	'
Direct contract holders' benefits incurred	80	64	228	190
Ceded contract holders' benefits incurred	-16	-15	-52	-49
Insurance losses and policyholder benefits	$64	$49	$176	$141

Income_Taxes_Differences_Betwe

Income Taxes - Differences Between 35 Percent Statutory Income Tax Rate and Effective Income Tax Rate (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Tax at statutory rate	$91	$64	$170	$191
Increase (decrease) resulting from:	'	'	'	'
Tax-exempt income from municipal bonds	-9	-8	-25	-24
Dividend received exclusion	-7	-6	-21	-18
Other	1	1	3	3
Total provision for income taxes	$76	$51	$127	$152
Tax at statutory rate	35.00%	35.00%	35.00%	35.00%
Increase (decrease) resulting from:	'	'	'	'
Tax-exempt income from municipal bonds	-3.50%	-4.40%	-5.20%	-4.40%
Dividend received exclusion	-2.70%	-3.30%	-4.30%	-3.30%
Other	0.50%	0.70%	0.70%	0.50%
Provision for income taxes	29.30%	28.00%	26.20%	27.80%

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Tax at statutory rate, percentage	35.00%	35.00%	35.00%	35.00%

Net_Income_Per_Common_Share_Ca

Net Income Per Common Share - Calculations for Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:	'	'	'	'
Net income-basic and diluted	$183	$131	$358	$395
Denominator:	'	'	'	'
Basic weighted-average common shares outstanding (in shares)	163.5	163.7	163.5	163.5
Adjusted diluted weighted-average shares (in shares)	165	165.6	165	165.3
Earnings per share:	'	'	'	'
Basic (in USD per share)	$1.12	$0.80	$2.19	$2.42
Diluted (in USD per share)	$1.11	$0.79	$2.17	$2.39
Number of anti-dilutive stock-based awards (in shares)	0.7	0.3	0.7	0.4
Stock Options	'	'	'	'
Denominator:	'	'	'	'
Effect of stock-based awards (in shares)	0.9	1.2	0.9	1.1
Nonvested shares	'	'	'	'
Denominator:	'	'	'	'
Effect of stock-based awards (in shares)	0.6	0.7	0.6	0.7

Employee_Retirement_Benefits_C

Employee Retirement Benefits - Components of Net Periodic Costs for Qualified and Supplemental Pension Plans (Detail) (Qualified Pension Plans [Member], USD $)	3 Months Ended			9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Qualified Pension Plans [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Service cost	$3	'	$4	$8	$10
Interest cost	4	'	4	11	10
Expected return on plan assets	-5	'	-5	-13	-13
Amortization of actuarial loss and prior service cost	1	'	2	2	7
Net periodic benefit cost	3	'	5	8	14
Pension contributions	'	5	'	'	'
Expected contributions by employer in the remainder of year	$0	'	'	$0	'

Employee_Retirement_Benefits_D

Employee Retirement Benefits - Defined Contribution Plan (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Compensation and Retirement Disclosure [Abstract]	'	'	'	'
Matching contributions to 401(k) and Top Hat plans	$3	$2	$9	$7

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Narrative) (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Estimate for which the risk of loss is more than remote but not probable	$1

Segment_Information_Detail

Segment Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	$1,071	$992	$3,157	$2,877	'
Fee revenues	3	2	9	6	'
Investment income, net of expenses	138	133	409	392	'
Realized investment gains, net	65	22	101	77	'
Other	3	3	7	7	'
Revenues	1,280	1,152	3,683	3,359	'
Income (loss) before income taxes	259	182	485	547	'
Identifiable assets	18,474	'	18,474	'	17,662
Consolidated Property and Casualty Insurance Entity	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Identifiable assets	2,434	'	2,434	'	2,455
Life Insurance Segment	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Identifiable assets	1,269	'	1,269	'	1,225
Investments Segment	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Identifiable assets	14,322	'	14,322	'	13,618
Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	720	680	2,126	1,956	'
Fee revenues	1	1	3	2	'
Revenues	721	681	2,129	1,958	'
Income (loss) before income taxes	67	43	97	135	'
Operating Segments | Personal Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	263	244	775	712	'
Fee revenues	1	0	2	1	'
Revenues	264	244	777	713	'
Income (loss) before income taxes	14	14	-33	33	'
Operating Segments | Excess and Surplus Lines Insurance	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	42	30	109	85	'
Income (loss) before income taxes	13	4	22	5	'
Operating Segments | Life Insurance Segment	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	46	38	147	124	'
Fee revenues	1	1	4	3	'
Revenues	47	39	151	127	'
Income (loss) before income taxes	-4	0	-5	10	'
Operating Segments | Investments Segment	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Investment income, net of expenses	138	133	409	392	'
Realized investment gains, net	65	22	101	77	'
Revenues	203	155	510	469	'
Income (loss) before income taxes	182	134	448	409	'
Corporate and Other Non-Segment	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Other	3	3	7	7	'
Income (loss) before income taxes	-13	-13	-44	-45	'
Identifiable assets	449	'	449	'	364
Commercial Casualty | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	237	221	695	636	'
Commercial Property | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	186	161	537	460	'
Commercial Auto | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	133	124	391	355	'
Workers' Compensation | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	93	95	280	270	'
Specialty Packages | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	27	38	93	114	'
Management Liability and Surety | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	32	30	94	89	'
Machinery and Equipment | Operating Segments | Commercial Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	12	11	36	32	'
Personal Auto | Operating Segments | Personal Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	121	112	354	328	'
Home Owner Segment | Operating Segments | Personal Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	110	103	330	298	'
Other Personal Lines | Operating Segments | Personal Lines	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Earned premiums	$32	$29	$91	$86	'

Segment_Information_Narrative_

Segment Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2014
	segment
	industry
Segment Reporting [Abstract]	'
Number of Industries Operating In	2
Number of Reportable Segments	5