Loews (L) 10-Q 5 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 26, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	L
Entity Registrant Name	LOEWS CORP
Entity Central Index Key	60,086
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		314,190,649

Consolidated Condensed Balance

Consolidated Condensed Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets:
Fixed maturities, amortized cost of $38,237 and $38,861	$ 39,819	$ 42,133
Equity securities, cost of $1,306 and $1,177	1,267	1,224
Limited partnership investments	2,832	3,278
Other invested assets, primarily mortgage loans	983	945
Short term investments	3,794	4,646
Total investments	48,695	52,226
Cash	571	472
Receivables	7,836	7,613
Property, plant and equipment	15,467	15,427
Goodwill	657	659
Other assets	4,845	2,555
Deferred acquisition costs of insurance subsidiaries	654	634
Total assets	78,725	79,586
Liabilities and Equity:
Claim and claim adjustment expense	21,604	22,004
Future policy benefits	10,605	11,179
Unearned premiums	4,289	4,029
Total insurance reserves	36,498	37,212
Payable to brokers	217	60
Short term debt	149	280
Long term debt	11,311	11,253
Deferred income taxes	911	749
Other liabilities	7,753	5,466
Total liabilities	56,839	55,020
Commitments and contingent liabilities
Preferred stock, $0.10 par value: Authorized - 100,000,000 shares
Common stock, $0.01 par value: Authorized - 1,800,000,000 shares Issued - 332,739,088 and 332,487,815 shares	3	3
Additional paid-in capital	3,813	3,151
Retained earnings	16,790	16,096
Accumulated other comprehensive loss	(758)	(26)
Shareholders' equity before treasury stock, total	19,848	19,224
Less treasury stock, at cost (17,795,538 and 400,000 shares)	(896)	(20)
Total shareholders' equity	18,952	19,204
Noncontrolling interests	2,934	5,362
Total equity	21,886	24,566
Total liabilities and equity	$ 78,725	$ 79,586

Consolidated Condensed Balanc_2

Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 38,237	$ 38,861
Equity securities, cost	$ 1,306	$ 1,177
Preferred stock, par value	$ 0.10	$ 0.10
Preferred stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,800,000,000	1,800,000,000
Common stock, shares issued	332,739,088	332,487,815
Treasury stock, shares	17,795,538	400,000

Consolidated Condensed Statemen

Consolidated Condensed Statements of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Insurance premiums	$ 1,853	$ 1,806	$ 5,453	$ 5,185
Net investment income	494	557	1,551	1,639
Investment gains (losses):
Other-than-temporary impairment losses	(3)	(5)	(9)	(9)
Other net investment gains	18	21	30	102
Total investment gains	15	16	21	93
Operating revenues and other	1,246	1,142	3,754	3,263
Total	3,608	3,521	10,779	10,180
Expenses:
Insurance claims and policyholders' benefits	1,312	1,480	3,978	4,053
Amortization of deferred acquisition costs	337	309	992	926
Operating expenses and other	1,459	1,245	4,313	3,576
Interest	146	223	430	504
Total	3,254	3,257	9,713	9,059
Income before income tax	354	264	1,066	1,121
Income tax expense	(65)	(52)	(149)	(240)
Net income	289	212	917	881
Amounts attributable to noncontrolling interests	(11)	(55)	(116)	(198)
Net income attributable to Loews Corporation	$ 278	$ 157	$ 801	$ 683
Basic net income per share	$ 0.88	$ 0.46	$ 2.50	$ 2.03
Diluted net income per share	0.88	0.46	2.49	2.02
Dividends per share	$ 0.0625	$ 0.0625	$ 0.1875	$ 0.1875
Weighted average shares outstanding:
Shares of common stock	315,900	336,910	320,810	336,900
Dilutive potential shares of common stock	910	880	920	830
Total weighted average shares outstanding assuming dilution	316,810	337,790	321,730	337,730

Consolidated Condensed Statem_2

Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 289	$ 212	$ 917	$ 881
Other comprehensive income (loss), after tax Changes in:
Net unrealized gains (losses) on investments with other- than-temporary impairments	(1)	1	(11)	(3)
Net other unrealized gains (losses) on investments	(158)	23	(746)	167
Total unrealized gains (losses) on investments	(159)	24	(757)	164
Unrealized gains on cash flow hedges		1	14	1
Pension liability	8	11	27	26
Foreign currency translation		41	(41)	94
Other comprehensive income (loss)	(151)	77	(757)	285
Comprehensive income	138	289	160	1,166
Amounts attributable to noncontrolling interests	7	(64)	(34)	(228)
Total comprehensive income attributable to Loews Corporation	$ 145	$ 225	$ 126	$ 938

Consolidated Condensed Statem_3

Consolidated Condensed Statements of Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Stock Held in Treasury [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2016	$ 23,361	$ 3	$ 3,187	$ 15,196	$ (223)		$ 5,198
Net income	881			683			198
Other comprehensive income (loss)	285				255		30
Dividends paid	(180)			(63)
Dividends paid							(117)
Purchases of Loews treasury stock	(6)					$ (6)
Stock-based compensation	24		(8)				32
Other	(4)		2	(5)			(1)
Ending Balance at Sep. 30, 2017	24,361	3	3,181	15,811	32	(6)	5,340
Net income	212
Other comprehensive income (loss)	77
Ending Balance at Sep. 30, 2017	24,361	3	3,181	15,811	32	(6)	5,340
Beginning Balance at Dec. 31, 2017	24,566	3	3,151	16,096	(26)	(20)	5,362
Cumulative effect adjustment from changes in accounting standards at Dec. 31, 2017	(91)			(43)	(28)		(20)
Balance, as adjusted at Dec. 31, 2017	24,475	3	3,151	16,053	(54)	(20)	5,342
Net income	917			801			116
Other comprehensive income (loss)	(757)				(675)		(82)
Dividends paid	(170)			(60)
Dividends paid							(110)
Purchase of Boardwalk Pipeline common units	(1,718)		658		(29)		(2,347)
Purchases of Loews treasury stock	(876)					(876)
Stock-based compensation	19		10				9
Other	(4)		(6)	(4)			6
Ending Balance at Sep. 30, 2018	21,886	3	3,813	16,790	(758)	(896)	2,934
Net income	289
Other comprehensive income (loss)	(151)
Ending Balance at Sep. 30, 2018	$ 21,886	$ 3	$ 3,813	$ 16,790	$ (758)	$ (896)	$ 2,934

Consolidated Condensed Statem_4

Consolidated Condensed Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Activities:
Net income	$ 917	$ 881
Adjustments to reconcile net income to net cash provided (used) by operating activities, net	1,121	959
Changes in operating assets and liabilities, net:
Receivables	18	19
Deferred acquisition costs	(24)	(34)
Insurance reserves	108	248
Other assets	(169)	(85)
Other liabilities	(75)	(116)
Trading securities	1,499	(62)
Net cash flow operating activities	3,395	1,810
Investing Activities:
Purchases of fixed maturities	(8,244)	(6,877)
Proceeds from sales of fixed maturities	6,622	4,167
Proceeds from maturities of fixed maturities	1,838	2,635
Purchases of limited partnership investments	(381)	(85)
Proceeds from sales of limited partnership investments	382	179
Purchases of property, plant and equipment	(731)	(735)
Acquisitions	(14)	(1,218)
Dispositions	110	68
Change in short term investments	(126)	(85)
Other, net	(173)	(136)
Net cash flow investing activities	(717)	(2,087)
Financing Activities:
Dividends paid	(60)	(63)
Dividends paid to noncontrolling interests	(110)	(117)
Purchases of Loews treasury stock	(889)	(6)
Purchase of Boardwalk Pipeline common units	(1,504)
Principal payments on debt	(780)	(2,249)
Issuance of debt	693	2,808
Other, net	75	(16)
Net cash flow financing activities	(2,575)	357
Effect of foreign exchange rate on cash	(4)	9
Net change in cash	99	89
Cash, beginning of period	472	327
Cash, end of period	$ 571	$ 416

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	1. Basis of Presentation Loews Corporation is a holding company. Its subsidiaries are engaged in the following lines of business: commercial property and casualty insurance (CNA Financial Corporation (“CNA”), a 89% owned subsidiary); the operation of offshore oil and gas drilling rigs (Diamond Offshore Drilling, Inc. (“Diamond Offshore”), a 53% owned subsidiary); transportation and storage of natural gas and natural gas liquids (Boardwalk Pipeline Partners, LP (“Boardwalk Pipeline”), a wholly owned subsidiary); the operation of a chain of hotels (Loews Hotels Holding Corporation (“Loews Hotels & Co”), a wholly owned subsidiary); and the manufacture of rigid plastic packaging solutions (Consolidated Container Company LLC (“Consolidated Container”), a 99% owned subsidiary). Unless the context otherwise requires, the terms “Company,” “Loews” and “Registrant” as used herein mean Loews Corporation excluding its subsidiaries and the term “Net income attributable to Loews Corporation” as used herein means Net income attributable to Loews Corporation shareholders. In the opinion of management, the accompanying unaudited Consolidated Condensed Financial Statements reflect all adjustments (consisting of normal recurring accruals) necessary to present fairly the Company’s financial position as of September 30, 2018 and December 31, 2017, results of operations and comprehensive income for the three and nine months ended September 30, 2018 and 2017 and changes in shareholders’ equity and cash flows for the nine months ended September 30, 2018 and 2017. Net income for the third quarter and first nine months of each of the years is not necessarily indicative of net income for that entire year. These Consolidated Condensed Financial Statements should be read in conjunction with the Consolidated Financial Statements in the Company’s Annual Report on Form 10-K The Company presents basic and diluted net income per share on the Consolidated Condensed Statements of Income. Basic net income per share excludes dilution and is computed by dividing net income attributable to common stock by the weighted average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock. There were no shares and 0.4 million shares attributable to employee stock-based compensation awards excluded from the diluted weighted average shares outstanding amounts for the three and nine months ended September 30, 2018 and 2017 because the effect would have been antidilutive. Accounting changes – 2014-09, 2014-09”). On January 1, 2018, the Company adopted the updated accounting guidance using the modified retrospective method, with a cumulative effect adjustment to the opening balance sheet. Upon adoption, the new guidance was applied to all contracts subject to the standard that were not completed as of the date of adoption. Prior period amounts have not been adjusted and continue to be reported in accordance with the previous accounting guidance. At adoption, the cumulative effect adjustment decreased beginning Retained earnings by $62 million (after tax and noncontrolling interests), resulted in a deferred tax asset of $23 million and increased Other assets by approximately $1.9 billion and Other liabilities by approximately $2.0 billion. The impact of the new guidance is primarily related to revenue on CNA’s non-insurance gross-up 2014-09, In January of 2016, the FASB issued ASU 2016-01, – 825-10): 2016-01”). available-for-sale In October of 2016, the FASB issued ASU 2016-16, In February of 2018, the FASB issued ASU 2018-02, 2018-02”). security-by-security In August of 2018, the FASB issued ASU 2018-13, – Recently issued ASUs – 2016-02, 2018-11, 2014-09. In June of 2016, the FASB issued ASU 2016-13, available-for-sale available-for-sale In August of 2018, the FASB issued ASU 2018-12, – This guidance is effective for interim and annual periods beginning after December 15, 2020, and requires restatement of the prior periods presented. Early adoption is permitted. The Company is currently evaluating the method and timing of adoption and the effect the updated guidance will have on its consolidated financial statements. The annual updating of cash flow assumptions is expected to increase income statement volatility. The quarterly change in the discount rate is expected to increase volatility in the Company’s Shareholders’ equity, but that will be somewhat mitigated because Shadow Adjustments are eliminated under the new guidance. See Note 3 for further information on Shadow Adjustments. In August of 2018, the FASB issued ASU 2018-14, – – – 715-20): Disclosure – Income tax reform update non-cash one-time non-U.S. The Company is still in the process of evaluating the estimate as it relates to the tax effect of: (i) the amount of deferred tax assets and liabilities subject to the income tax rate change from 35% to 21%, including the calculation of the mandatory deemed repatriation aspect of the Tax Act and the state tax effect of adjustments made to the federal temporary differences, (ii) the ability to more likely than not realize the benefit of deferred tax assets, including net operating losses and foreign tax credits, (iii) the effect of re-computing

Purchase of Boardwalk Pipeline

Purchase of Boardwalk Pipeline Common Units	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Purchase of Boardwalk Pipeline Common Units	2. Purchase of Boardwalk Pipeline Common Units On June 29, 2018, Boardwalk GP, LP (“General Partner”), the general partner of Boardwalk Pipeline and an indirect wholly owned subsidiary of the Company, elected to exercise its right to purchase all of the issued and outstanding common units representing limited partnership interests in Boardwalk Pipeline not already owned by the General Partner or its affiliates pursuant to Section 15.1(b) of Boardwalk Pipeline’s Third Amended and Restated Agreement of Limited Partnership, as amended (“Limited Partnership Agreement”) for a cash purchase price, determined in accordance with the Limited Partnership Agreement, of $12.06 per unit, or approximately $1.5 billion, in the aggregate. The purchase price of the common units was lower than the carrying value of the noncontrolling interests for Boardwalk Pipeline, resulting in an increase to Additional paid-in Following completion of the transaction on July 18, 2018, Boardwalk Pipelines Holding Corp., a wholly owned subsidiary of Loews Corporation, directly or indirectly owned all of the equity interests of Boardwalk Pipeline. As a result of the transaction, Boardwalk Pipeline has withdrawn the common units from listing on the New York Stock Exchange and from registration under Section 12(b) of the Securities Exchange Act of 1934.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	3. Investments Net investment income is as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Fixed maturity securities $ 449 $ 455 $ 1,339 $ 1,367 Limited partnership investments 34 67 142 206 Short term investments 10 5 30 13 Equity securities 10 1 32 4 Income (loss) from trading portfolio (a) (7 ) 34 13 67 Other 12 10 40 26 Total investment income 508 572 1,596 1,683 Investment expenses (14 ) (15 ) (45 ) (44 ) Net investment income $ 494 $ 557 $ 1,551 $ 1,639 (a) Net unrealized gains (losses) related to changes in fair value on securities still held were $(23) and $22 for the three months ended September 30, 2018 and 2017 and $(66) and $35 for the nine months ended September 30, 2018 and 2017. Investment gains (losses) are as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Fixed maturity securities $ 10 $ 16 $ 32 $ 92 Equity securities 2 (23 ) Derivative instruments 1 (1 ) 10 (3 ) Short term investments and other 2 1 2 4 Investment gains (a) $ 15 $ 16 $ 21 $ 93 (a) Gross realized gains on available-for-sale available-for-sale non-redeemable The components of other-than-temporary impairment (“OTTI”) losses recognized in earnings by asset type are as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 1 $ 4 $ 6 $ 8 Asset-backed 2 1 3 1 Net OTTI losses recognized in earnings $ 3 $ 5 $ 9 $ 9 The amortized cost and fair values of fixed maturity and equity securities are as follows: September 30, 2018 Cost or Gross Gross Estimated Unrealized (In millions) Fixed maturity securities: Corporate and other bonds $ 18,348 $ 887 $ 215 $ 19,020 States, municipalities and political subdivisions 10,171 994 20 11,145 Asset-backed: Residential mortgage-backed 5,024 62 115 4,971 $ (24 ) Commercial mortgage-backed 2,165 23 36 2,152 Other asset-backed 1,732 6 9 1,729 Total asset-backed 8,921 91 160 8,852 (24 ) U.S. Treasury and obligations of government-sponsored enterprises 145 2 2 145 Foreign government 457 4 6 455 Redeemable preferred stock 9 1 10 Fixed maturities available-for-sale 38,051 1,979 403 39,627 (24 ) Fixed maturities trading 186 6 192 Total fixed maturity securities $ 38,237 $ 1,985 $ 403 $ 39,819 $ (24 ) December 31, 2017 Fixed maturity securities: Corporate and other bonds $ 17,210 $ 1,625 $ 28 $ 18,807 States, municipalities and political subdivisions 12,478 1,551 2 14,027 $ (11 ) Asset-backed: Residential mortgage-backed 5,043 109 32 5,120 (27 ) Commercial mortgage-backed 1,840 46 14 1,872 Other asset-backed 1,083 16 5 1,094 Total asset-backed 7,966 171 51 8,086 (27 ) U.S. Treasury and obligations of government-sponsored enterprises 111 2 4 109 Foreign government 437 9 2 444 Redeemable preferred stock 10 1 11 Fixed maturities available-for-sale 38,212 3,359 87 41,484 (38 ) Fixed maturities trading 649 2 2 649 Total fixed maturities 38,861 3,361 89 42,133 (38 ) Equity securities: Common stock 21 7 1 27 Preferred stock 638 31 1 668 Equity securities available-for-sale 659 38 2 695 - Equity securities trading 518 92 81 529 Total equity securities 1,177 130 83 1,224 - Total fixed maturity and equity securities $ 40,038 $ 3,491 $ 172 $ 43,357 $ (38 ) The net unrealized gains on available-for-sale The available-for-sale Less than 12 Months 12 Months or Longer Total September 30, 2018 Estimated Gross Estimated Gross Estimated Gross (In millions) Fixed maturity securities: Corporate and other bonds $ 7,546 $ 197 $ 342 $ 18 $ 7,888 $ 215 States, municipalities and political subdivisions 807 19 2 1 809 20 Asset-backed: Residential mortgage-backed 3,409 89 501 26 3,910 115 Commercial mortgage-backed 968 15 322 21 1,290 36 Other asset-backed 953 9 45 998 9 Total asset-backed 5,330 113 868 47 6,198 160 U.S. Treasury and obligations of government-sponsored enterprises 35 42 2 77 2 Foreign government 188 4 64 2 252 6 Total fixed maturity securities $ 13,906 $ 333 $ 1,318 $ 70 $ 15,224 $ 403 December 31, 2017 Fixed maturity securities: Corporate and other bonds $ 1,354 $ 21 $ 168 $ 7 $ 1,522 $ 28 States, municipalities and political subdivisions 72 1 85 1 157 2 Asset-backed: Residential mortgage-backed 1,228 5 947 27 2,175 32 Commercial mortgage-backed 403 4 212 10 615 14 Other asset-backed 248 3 18 2 266 5 Total asset-backed 1,879 12 1,177 39 3,056 51 U.S. Treasury and obligations of government-sponsored enterprises 49 2 21 2 70 4 Foreign government 166 2 4 170 2 Total fixed maturity securities 3,520 38 1,455 49 4,975 87 Equity securities: Common stock 7 1 7 1 Preferred stock 93 1 93 1 Total equity securities 100 2 - - 100 2 Total fixed maturity and equity securities $ 3,620 $ 40 $ 1,455 $ 49 $ 5,075 $ 89 Based on current facts and circumstances, the Company believes the unrealized losses presented in the September 30, 2018 securities in a gross unrealized loss position table above are not indicative of the ultimate collectibility of the current amortized cost of the securities, but rather are attributable to changes in interest rates, credit spreads and other factors. The Company has no current intent to sell securities with unrealized losses, nor is it more likely than not that it will be required to sell prior to recovery of amortized cost; accordingly, the Company has determined that there are no additional OTTI losses to be recorded as of September 30, 2018. The following table presents the activity related to the pretax credit loss component reflected in Retained earnings on fixed maturity securities still held as of September 30, 2018 and 2017 for which a portion of an OTTI loss was recognized in OCI. Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Beginning balance of credit losses on fixed maturity securities $ 21 $ 30 $ 27 $ 36 Reductions for securities sold during the period (2 ) (2 ) (8 ) (8 ) Ending balance of credit losses on fixed maturity securities $ 19 $ 28 $ 19 $ 28 Contractual Maturity The following table presents available-for-sale September 30, 2018 December 31, 2017 Cost or Estimated Fair Value Cost or Estimated Fair Value (In millions) Due in one year or less $ 1,457 $ 1,473 $ 1,135 $ 1,157 Due after one year through five years 8,017 8,197 8,165 8,501 Due after five years through ten years 16,453 16,475 16,060 16,718 Due after ten years 12,124 13,482 12,852 15,108 Total $ 38,051 $ 39,627 $ 38,212 $ 41,484 Actual maturities may differ from contractual maturities because certain securities may be called or prepaid. Securities not due at a single date are allocated based on weighted average life. Derivative Financial Instruments A summary of the aggregate contractual or notional amounts and gross estimated fair values related to derivative financial instruments follows. The contractual or notional amounts for derivatives are used to calculate the exchange of contractual payments under the agreements and may not be representative of the potential for gain or loss on these instruments. Gross estimated fair values of derivative positions are currently presented in Equity securities, Receivables and Payable to brokers on the Consolidated Condensed Balance Sheets. September 30, 2018 December 31, 2017 Contractual/ Contractual/ Notional Estimated Fair Value Notional Estimated Fair Value Amount Asset (Liability) Amount Asset (Liability) (In millions) With hedge designation: Interest rate swaps $ 500 $ 22 $ 500 $ 4 Without hedge designation: Equity markets: Options – purchased 222 9 224 12 – written 201 $ (6 ) 290 $ (7 ) Futures – short 154 265 1 Commodity futures – long 47 1 44 Embedded derivative on funds withheld liability 174 6 167 (3 )

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value	4. Fair Value Fair value is the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The following fair value hierarchy is used in selecting inputs, with the highest priority given to Level 1, as these are the most transparent or reliable: • Level 1 – Quoted prices for identical instruments in active markets. • Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets. • Level 3 – Valuations derived from valuation techniques in which one or more significant inputs are not observable. Prices may fall within Level 1, 2 or 3 depending upon the methodology and inputs used to estimate fair value for each specific security. In general, the Company seeks to price securities using third party pricing services. Securities not priced by pricing services are submitted to independent brokers for valuation and, if those are not available, internally developed pricing models are used to value assets using a methodology and inputs the Company believes market participants would use to value the assets. Prices obtained from third-party pricing services or brokers are not adjusted by the Company. The Company performs control procedures over information obtained from pricing services and brokers to ensure prices received represent a reasonable estimate of fair value and to confirm representations regarding whether inputs are observable or unobservable. Procedures may include: (i) the review of pricing service methodologies or broker pricing qualifications, (ii) back-testing, where past fair value estimates are compared to actual transactions executed in the market on similar dates, (iii) exception reporting, where period-over-period changes in price are reviewed and challenged with the pricing service or broker based on exception criteria, (iv) detailed analysis, where the Company performs an independent analysis of the inputs and assumptions used to price individual securities and (v) pricing validation, where prices received are compared to prices independently estimated by the Company. Assets and liabilities measured at fair value on a recurring basis are summarized in the following tables. Corporate bonds and other includes obligations of the U.S. Treasury, government-sponsored enterprises, foreign governments and redeemable preferred stock. September 30, 2018 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 183 $ 19,259 $ 188 $ 19,630 States, municipalities and political subdivisions 11,145 11,145 Asset-backed 8,554 298 8,852 Fixed maturities available-for-sale 183 38,958 486 39,627 Fixed maturities trading 186 6 192 Total fixed maturities $ 183 $ 39,144 $ 492 $ 39,819 Equity securities $ 623 $ 625 $ 19 $ 1,267 Short term and other 2,678 1,074 3,752 Receivables 23 23 Payable to brokers (13 ) (13 ) December 31, 2017 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 128 $ 19,145 $ 98 $ 19,371 States, municipalities and political subdivisions 14,026 1 14,027 Asset-backed 7,751 335 8,086 Fixed maturities available-for-sale 128 40,922 434 41,484 Fixed maturities trading 10 635 4 649 Total fixed maturities $ 138 $ 41,557 $ 438 $ 42,133 Equity securities available-for-sale $ 91 $ 584 $ 20 $ 695 Equity securities trading 527 2 529 Total equity securities $ 618 $ 584 $ 22 $ 1,224 Short term and other $ 3,669 $ 958 $ 4,627 Receivables 1 4 5 Payable to brokers (12 ) (12 ) The following tables present reconciliations for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2018 and 2017: Net Realized Gains Unrealized (Losses) Unrealized (Losses) 2018 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 94 $ 67 $ (3 ) $ 30 $ 188 States, municipalities and political subdivisions 1 (1 ) - Asset-backed 273 $ (2 ) 55 (25 ) 29 $ (32 ) 298 $ (2 ) $ 1 Fixed maturities available-for-sale 368 (2 ) $ - 122 $ - (29 ) 59 (32 ) 486 (2 ) 1 Fixed maturities trading 7 (1 ) 6 Total fixed maturities $ 375 $ (2 ) $ - $ 122 $ (1 ) $ (29 ) $ 59 $ (32 ) $ 492 $ (2 ) $ 1 Equity securities $ 18 $ 1 $ 19 $ 1 Net Realized Gains Unrealized (Losses) 2017 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 100 $ 1 $ 1 $ 13 $ (11 ) $ 15 $ 119 States, municipalities and political subdivisions 1 1 Asset-backed 218 1 39 (13 ) 101 346 Fixed maturities available-for-sale 319 1 2 52 $ - (24 ) 116 $ - 466 $ - Fixed maturities trading 5 5 Total fixed maturities $ 324 $ 1 $ 2 $ 52 $ - $ (24 ) $ 116 $ - $ 471 $ - Equity securities available-for-sale $ 19 $ 19 Equity securities trading 1 $ 1 2 Total equity securities $ 20 $ - $ - $ 1 $ - $ - $ - $ - $ 21 $ - Life settlement contracts $ 1 $ (1 ) $ - Net Realized Gains Unrealized (Losses) Unrealized (Losses) 2018 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 98 $ (1 ) $ (1 ) $ 69 $ (5 ) $ (7 ) $ 35 $ 188 $ (2 ) States, municipalities and political subdivisions 1 (1 ) - Asset-backed 335 5 (6 ) 126 (72 ) (37 ) 42 $ (95 ) 298 $ (2 ) (2 ) Fixed maturities available-for-sale 434 4 (7 ) 195 (77 ) (45 ) 77 (95 ) 486 (2 ) (4 ) Fixed maturities trading 4 3 (1 ) 6 2 Total fixed maturities $ 438 $ 7 $ (7 ) $ 195 $ (78 ) $ (45 ) $ 77 $ (95 ) $ 492 $ - $ (4 ) Equity securities $ 22 $ (2 ) $ (1 ) $ 19 $ (2 ) Net Realized Gains Unrealized (Losses) 2017 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 130 $ 1 $ 2 $ 18 $ (1 ) $ (36 ) $ 15 $ (10 ) $ 119 States, municipalities and political subdivisions 1 1 Asset-backed 199 1 4 90 (26 ) 153 (75 ) 346 Fixed maturities available-for-sale 330 2 6 108 (1 ) (62 ) 168 (85 ) 466 $ - Fixed maturities trading 6 (1 ) 5 (1 ) Total fixed maturities $ 336 $ 1 $ 6 $ 108 $ (1 ) $ (62 ) $ 168 $ (85 ) $ 471 $ (1 ) Equity securities available-for-sale $ 19 $ 2 $ 1 $ (3 ) $ 19 Equity securities trading 1 1 2 Total equity securities $ 20 $ - $ 2 $ 2 $ (3 ) $ - $ - $ - $ 21 $ - Life settlement contracts $ 58 $ 6 $ (59 ) $ (5 ) $ - Derivative financial instruments, net - 1 (1 ) - Net realized and unrealized gains and losses are reported in Net income as follows: Major Category of Assets and Liabilities Consolidated Condensed Statements of Income Line Items Fixed maturity securities available-for-sale Investment gains (losses) Fixed maturity securities trading Net investment income Equity securities Investment gains (losses) and Net investment income Other invested assets Investment gains (losses) and Net investment income Derivative financial instruments held in a trading portfolio Net investment income Derivative financial instruments, other Investment gains (losses) and Operating revenues and other Life settlement contracts Operating revenues and other Securities may be transferred in or out of levels within the fair value hierarchy based on the availability of observable market information and quoted prices used to determine the fair value of the security. The availability of observable market information and quoted prices varies based on market conditions and trading volume. Valuation Methodologies and Inputs The following section describes the valuation methodologies and relevant inputs used to measure different financial instruments at fair value, including an indication of the level in the fair value hierarchy in which the instruments are generally classified. Fixed Maturity Securities Level 1 securities include highly liquid and exchange traded bonds and redeemable preferred stock, valued using quoted market prices. Level 2 securities include most other fixed maturity securities as the significant inputs are observable in the marketplace. All classes of Level 2 fixed maturity securities are valued using a methodology based on information generated by market transactions involving identical or comparable assets, a discounted cash flow methodology or a combination of both when necessary. Common inputs for all classes of fixed maturity securities include prices from recently executed transactions of similar securities, marketplace quotes, benchmark yields, spreads off benchmark yields, interest rates and U.S. Treasury or swap curves. Specifically for asset-backed securities, key inputs include prepayment and default projections based on past performance of the underlying collateral and current market data. Fixed maturity securities are primarily assigned to Level 3 in cases where broker/dealer quotes are significant inputs to the valuation, and there is a lack of transparency as to whether these quotes are based on information that is observable in the marketplace. Level 3 securities also include private placement debt securities whose fair value is determined using internal models with inputs that are not market observable. Equity Securities Level 1 securities include publicly traded securities valued using quoted market prices. Level 2 securities are primarily valued using pricing for similar securities, recently executed transactions and other pricing models utilizing market observable inputs. Level 3 securities are primarily priced using broker/dealer quotes and internal models with inputs that are not market observable. Derivative Financial Instruments Exchange traded derivatives are valued using quoted market prices and are classified within Level 1 of the fair value hierarchy. Level 2 derivatives primarily include currency forwards valued using observable market forward rates. Over-the-counter Short Term and Other Invested Assets Securities that are actively traded or have quoted prices are classified as Level 1. These securities include money market funds, treasury bills and exchange traded open-end Life Settlement Contracts CNA sold its life settlement contracts to a third party in 2017. The valuation of the life settlement contracts was based on the terms of sale. The contracts were classified as Level 3 as there was not an active market for life settlement contracts. Significant Unobservable Inputs The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 assets. Valuations for assets and liabilities not presented in the tables below are primarily based on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations. The quantitative detail of unobservable inputs from these broker quotes is neither provided nor reasonably available to the Company. The weighted average rate is calculated based on fair value. September 30, 2018 Estimated Fair Value Valuation Techniques Unobservable Inputs Range (Weighted Average) (In millions) Fixed maturity securities $ 198 Discounted cash flow Credit spread 1% – 12% (2%) December 31, 2017 Fixed maturity securities $ 136 Discounted cash flow Credit spread 1% – 12% (3%) For fixed maturity securities, an increase to the credit spread assumptions would result in a lower fair value measurement. Financial Assets and Liabilities Not Measured at Fair Value The carrying amount, estimated fair value and the level of the fair value hierarchy of the Company’s financial assets and liabilities which are not measured at fair value on the Consolidated Condensed Balance Sheets are presented in the following tables. The carrying amounts and estimated fair values of short term debt and long term debt exclude capital lease obligations. The carrying amounts reported on the Consolidated Condensed Balance Sheets for cash and short term investments not carried at fair value and certain other assets and liabilities approximate fair value due to the short term nature of these items. Carrying Estimated Fair Value September 30, 2018 Amount Level 1 Level 2 Level 3 Total (In millions) Assets: Other invested assets, primarily mortgage loans $ 868 $ 847 $ 847 Liabilities: Short term debt 146 $ 6 140 146 Long term debt 11,295 10,537 630 11,167 December 31, 2017 Assets: Other invested assets, primarily mortgage loans $ 839 $ 844 $ 844 Liabilities: Short term debt 278 $ 156 122 278 Long term debt 11,236 10,966 525 11,491 The fair values of mortgage loans, included in Other invested assets, were based on the present value of the expected future cash flows discounted at the current interest rate for similar financial instruments, adjusted for specific loan risk.

Claim and Claim Adjustment Expe

Claim and Claim Adjustment Expense Reserves	9 Months Ended
	Sep. 30, 2018
Insurance [Abstract]
Claim and Claim Adjustment Expense Reserves	5. Claim and Claim Adjustment Expense Reserves CNA’s property and casualty insurance claim and claim adjustment expense reserves represent the estimated amounts necessary to resolve all outstanding claims, including incurred but not reported (“IBNR”) claims as of the reporting date. CNA’s reserve projections are based primarily on detailed analysis of the facts in each case, CNA’s experience with similar cases and various historical development patterns. Consideration is given to such historical patterns as claim reserving trends and settlement practices, loss payments, pending levels of unpaid claims and product mix, as well as court decisions, economic conditions including inflation and public attitudes. All of these factors can affect the estimation of claim and claim adjustment expense reserves. Establishing claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves for catastrophic events that have occurred, is an estimation process. Many factors can ultimately affect the final settlement of a claim and, therefore, the necessary reserve. Changes in the law, results of litigation, medical costs, the cost of repair materials and labor rates can affect ultimate claim costs. In addition, time can be a critical part of reserving determinations since the longer the span between the incidence of a loss and the payment or settlement of the claim, the more variable the ultimate settlement amount can be. Accordingly, short-tail claims, such as property damage claims, tend to be more reasonably estimable than long-tail claims, such as workers’ compensation, general liability and professional liability claims. Adjustments to prior year reserve estimates, if necessary, are reflected in the results of operations in the period that the need for such adjustments is determined. There can be no assurance that CNA’s ultimate cost for insurance losses will not exceed current estimates. Catastrophes are an inherent risk of the property and casualty insurance business and have contributed to material period-to-period Liability for Unpaid Claim and Claim Adjustment Expenses Rollforward The following table presents a reconciliation between beginning and ending claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves of Other Insurance Operations. Nine Months Ended September 30 2018 2017 (In millions) Reserves, beginning of year: Gross $ 22,004 $ 22,343 Ceded 3,934 4,094 Net reserves, beginning of year 18,070 18,249 Net incurred claim and claim adjustment expenses: Provision for insured events of current year 3,866 3,949 Decrease in provision for insured events of prior years (173 ) (284 ) Amortization of discount 136 138 Total net incurred (a) 3,829 3,803 Net payments attributable to: Current year events (658 ) (560 ) Prior year events (3,415 ) (3,401 ) Total net payments (4,073 ) (3,961 ) Foreign currency translation adjustment and other (80 ) 110 Net reserves, end of period 17,746 18,201 Ceded reserves, end of period 3,858 4,008 Gross reserves, end of period $ 21,604 $ 22,209 (a) Total net incurred above does not agree to Insurance claims and policyholders’ benefits as reflected in the Consolidated Condensed Statements of Income due to amounts related to retroactive reinsurance deferred gain accounting, uncollectible reinsurance and loss deductible receivables and benefit expenses related to future policy benefits, which are not reflected in the table above. Net Prior Year Development Changes in estimates of claim and claim adjustment expense reserves net of reinsurance, for prior years are defined as net prior year loss reserve development. These changes can be favorable or unfavorable. Favorable net prior year development of $62 million and $115 million for the three months ended September 30, 2018 and 2017 and $160 million and $227 million for the nine months ended September 30, 2018 and 2017 was recorded for CNA’s commercial property and casualty operations (“Property & Casualty Operations”). The following table and discussion present details of the net prior year claim and claim adjustment expense reserve development in CNA’s Property & Casualty Operations: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Medical professional liability $ 15 $ 8 $ 38 $ 30 Other professional liability and management liability (45 ) (19 ) (113 ) (88 ) Surety (20 ) (82 ) (50 ) (82 ) Commercial auto 1 (12 ) (37 ) General liability (5 ) (2 ) 13 (19 ) Workers’ compensation (2 ) 9 (14 ) (38 ) Other (6 ) (17 ) (34 ) 7 Total pretax (favorable) unfavorable development $ (62 ) $ (115 ) $ (160 ) $ (227 ) Three Months 2018 Unfavorable development in medical professional liability was primarily driven by higher than expected frequency and severity in aging services in accident years 2014 through 2017. Favorable development in other professional liability and management liability was primarily driven by favorable outcomes on individual claims in accident years 2013 and prior in financial institutions. Favorable development in surety was due to continued lower than expected loss emergence for accident years 2017 and prior. 2017 Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency in accident years 2012 through 2015, primarily for professional liability products. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2015 and prior. Nine Months 2018 Unfavorable development for medical professional liability was primarily due to higher than expected severity in accident years 2014 and 2017 in CNA’s hospitals business and higher than expected frequency and severity in aging services in accident years 2014 through 2017. Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency for accident years 2013 through 2017 related to financial institutions and professional liability errors and omissions (“E&O”). Favorable severity for accident years 2012 and prior related to professional liability E&O, and favorable outcomes on individual claims in financial institutions in accident years 2013 and prior. Favorable development for surety was due to lower than expected loss emergence for accident years 2017 and prior. Favorable development for other coverages was due to lower than expected claim severity in catastrophes in accident year 2017 for property, better than expected frequency in the liability portion of the package business in Canada and general liability in Europe for casualty, better than expected large loss frequency in the energy book in recent accident years for energy and marine and lower than expected frequency in accident years 2015 and prior related to healthcare in Europe for healthcare and technology. This favorable development was partially offset by unfavorable development driven by higher than expected severity in Canada and higher than expected frequency in CNA Hardy, both in accident year 2017, for property and increased severity in accident year 2017 related to professional indemnity. 2017 Unfavorable development in medical professional liability was primarily due to continued higher than expected frequency in aging services. Favorable development in other professional liability and management liability was primarily due to favorable settlements on closed claims and a lower frequency of large losses for accident years 2011 through 2016 for professional and management liability, lower than expected claim frequency in accident years 2012 through 2015 for professional liability and lower than expected severity in accident years 2014 through 2016 for professional liability. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2015 and prior. Favorable development for commercial auto was primarily due to lower than expected severity in accident years 2013 through 2016, as well as a large favorable recovery on a claim in accident year 2012. Favorable development for general liability was due to lower than expected severity in life sciences. Favorable development for workers’ compensation was primarily related to decreases in frequency and severity in recent accident years, partially attributable to California reforms related to decreases in medical costs. This was partially offset by unfavorable development related to an adverse arbitration ruling on reinsurance recoverables from older accident years as well as the recognition of loss estimates associated with favorable premium development. Asbestos and Environmental Pollution (“A&EP”) Reserves In 2010, Continental Casualty Company (“CCC”) together with several of CNA’s other insurance subsidiaries completed a transaction with National Indemnity Company (“NICO”), a subsidiary of Berkshire Hathaway Inc., under which substantially all of CNA’s legacy A&EP liabilities were ceded to NICO through a loss portfolio transfer (“loss portfolio transfer” or “LPT”). At the effective date of the transaction, CNA ceded approximately $1.6 billion of net A&EP claim and allocated claim adjustment expense reserves to NICO under a retroactive reinsurance agreement with an aggregate limit of $4.0 billion. The $1.6 billion of claim and allocated claim adjustment expense reserves ceded to NICO was net of $1.2 billion of ceded claim and allocated claim adjustment expense reserves under existing third party reinsurance contracts. The NICO LPT aggregate reinsurance limit also covers credit risk on the existing third party reinsurance related to these liabilities. CNA paid NICO a reinsurance premium of $2.0 billion and transferred to NICO billed third party reinsurance receivables related to A&EP claims with a net book value of $215 million, resulting in total consideration of $2.2 billion. In years subsequent to the effective date of the LPT, CNA recognized adverse prior year development on its A&EP reserves resulting in additional amounts ceded under the LPT. As a result, the cumulative amounts ceded under the LPT have exceeded the $2.2 billion consideration paid, resulting in the NICO LPT moving into a gain position, requiring retroactive reinsurance accounting. Under retroactive reinsurance accounting, this gain is deferred and only recognized in earnings in proportion to actual paid recoveries under the LPT. Over the life of the contract, there is no economic impact as long as any additional losses incurred are within the limit of the LPT. In a period in which CNA recognizes a change in the estimate of A&EP reserves that increases or decreases the amounts ceded under the LPT, the proportion of actual paid recoveries to total ceded losses is affected and the change in the deferred gain is recognized in earnings as if the revised estimate of ceded losses was available at the effective date of the LPT. The effect of the deferred retroactive reinsurance benefit is recorded in Insurance claims and policyholders’ benefits in the Consolidated Condensed Statements of Income. The following table presents the impact of the loss portfolio transfer on the Consolidated Condensed Statements of Income. Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Additional amounts ceded under LPT: Net A&EP adverse development before consideration of LPT $ - $ - $ 113 $ 60 Provision for uncollectible third-party reinsurance on A&EP (16 ) Total additional amounts ceded under LPT - - 97 60 Retroactive reinsurance benefit recognized (12 ) (17 ) (84 ) (60 ) Pretax impact of deferred retroactive reinsurance $ (12 ) $ (17 ) $ 13 $ - Based upon CNA’s annual A&EP reserve review, net unfavorable prior year development of $113 million and $60 million was recognized before consideration of cessions to the LPT for the nine months ended September 30, 2018 and 2017. Additionally, in 2018, CNA released a portion of its provision for uncollectible third party reinsurance. The 2018 unfavorable development was driven by higher than anticipated defense costs on direct asbestos environmental accounts and paid losses on assumed reinsurance exposures. The 2017 unfavorable development was driven by modestly higher anticipated payouts on claims from known sources of asbestos exposure. CNA expects to complete another A&EP reserve review in the fourth quarter of 2018 and intends to maintain that timing going forward annually. As of September 30, 2018 and December 31, 2017, the cumulative amounts ceded under the LPT were $3.0 billion and $2.9 billion. The unrecognized deferred retroactive reinsurance benefit was $339 million and $326 million as of September 30, 2018 and December 31, 2017. NICO established a collateral trust account as security for its obligations to CNA. The fair value of the collateral trust account was $3.2 billion and $3.1 billion as of September 30, 2018 and December 31, 2017. In addition, Berkshire Hathaway Inc. guaranteed the payment obligations of NICO up to the aggregate reinsurance limit as well as certain of NICO’s performance obligations under the trust agreement. NICO is responsible for claims handling and billing and collection from third-party reinsurers related to CNA’s A&EP claims.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Shareholders' Equity	6. Shareholders’ Equity Accumulated other comprehensive income (loss) The tables below present the changes in AOCI by component for the three and nine months ended September 30, 2017 and 2018: OTTI Unrealized Cash Flow Hedges Pension Foreign Total (In millions) Balance, July 1, 2017 $ 23 $ 705 $ (2 ) $ (632 ) $ (130 ) $ (36 ) Other comprehensive income (loss) before reclassifications, after tax of $0, $(20), $0, $0 and $0 1 35 (2 ) 41 75 Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $0, $4, $0, $(6) and $0 (12 ) 3 11 2 Other comprehensive income 1 23 1 11 41 77 Amounts attributable to noncontrolling interests (3 ) (1 ) (1 ) (4 ) (9 ) Balance, September 30, 2017 $ 24 $ 725 $ (2 ) $ (622 ) $ (93 ) $ 32 Balance, July 1, 2018 $ 17 $ 244 $ 13 $ (774 ) $ (125 ) $ (625 ) Other comprehensive loss before reclassifications, after tax of $0, $40, $(2), $0 and $0 (1 ) (148 ) (149 ) Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $0, $2, $0, $(1) and $0 (10 ) 8 (2 ) Other comprehensive income (loss) (1 ) (158 ) - 8 - (151 ) Amounts attributable to noncontrolling interests 17 1 18 Balance, September 30, 2018 $ 16 $ 103 $ 13 $ (765 ) $ (125 ) $ (758 ) OTTI Unrealized Cash Flow Pension Foreign Total (In millions) Balance, January 1, 2017 $ 27 $ 576 $ (2 ) $ (646 ) $ (178 ) $ (223 ) Other comprehensive income (loss) before reclassifications, after tax of $0, $(130), $0, $0 and $0 228 (3 ) 94 319 Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $1, $28, $0, $(13) and $0 (3 ) (61 ) 4 26 (34 ) Other comprehensive income (loss) (3 ) 167 1 26 94 285 Amounts attributable to noncontrolling interests (18 ) (1 ) (2 ) (9 ) (30 ) Balance, September 30, 2017 $ 24 $ 725 $ (2 ) $ (622 ) $ (93 ) $ 32 Balance, January 1, 2018, as reported $ 22 $ 673 $ - $ (633 ) $ (88 ) $ (26 ) Cumulative effect adjustment for adoption of ASU 2016-01 (25 ) (25 ) Cumulative effect adjustment for adoption of ASU 2018-02 4 123 (130 ) (3 ) Balance, January 1, 2018, as adjusted 26 771 - (763 ) (88 ) (54 ) Other comprehensive income (loss) before reclassifications, after tax of $3, $190, $(4), $0 and $0 (12 ) (718 ) 12 (41 ) (759 ) Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $0, $7, $0, $(6) and $0 1 (28 ) 2 27 2 Other comprehensive income (loss) (11 ) (746 ) 14 27 (41 ) (757 ) Amounts attributable to noncontrolling interests 1 78 (1 ) 4 82 Purchase of Boardwalk Pipeline common units (1 ) (28 ) (29 ) Balance, September 30, 2018 $ 16 $ 103 $ 13 $ (765 ) $ (125 ) $ (758 ) (a) For information regarding this accounting standard see Note 1. Amounts reclassified from AOCI shown above are reported in Net income as follows: Major Category of AOCI Affected Line Item OTTI gains (losses) Investment gains (losses) Unrealized gains (losses) on investments Investment gains (losses) Cash flow hedges Operating revenues and other and Operating expenses and other Pension liability Operating expenses and other Treasury Stock The Company repurchased 17.4 million and 0.1 million shares of Loews common stock at aggregate costs of $876 million and $6 million during the nine months ended September 30, 2018 and 2017.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	7. Revenue from Contracts with Customers Disaggregation of revenues Three Months Ended Nine Months Ended 2018 2017 (a) 2018 2017 (a) (In millions) Non-insurance $ 258 $ 99 $ 744 $ 290 Contract drilling – Diamond Offshore 287 366 851 1,139 Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipeline 274 290 886 944 Lodging and related services – Loews Hotels & Co 167 162 550 510 Rigid plastic packaging and recycled resin – Corporate 223 202 652 293 Total revenues from contracts with customers 1,209 1,119 3,683 3,176 Other revenues 37 23 71 87 Operating revenues and other $ 1,246 $ 1,142 $ 3,754 $ 3,263 (a) Prior period amounts have not been adjusted under the modified retrospective method of adoption for ASU 2014-09. CNA’s non-insurance Non-insurance non-insurance Diamond Offshore’s contract drilling revenues primarily result from providing a drilling rig and the crew and supplies necessary to operate the rig, mobilizing and demobilizing the rig to and from the drill site and performing rig preparation activities and/or modifications required for the contract. Consideration received for performing these activities may consist of dayrate drilling revenue, mobilization and demobilization revenue, contract preparation revenue and reimbursement revenue for the purchase of supplies, equipment, personnel services and other services requested by the customer. Diamond Offshore accounts for these integrated services provided within its drilling contracts as a single performance obligation satisfied over time and comprised of a series of distinct time increments in which drilling services are provided. The total transaction price is determined for each individual contract by estimating both fixed and variable consideration expected to be earned over the term of the contract. The standard contract term ranges from two to 60 months. Boardwalk Pipeline primarily earns revenues by providing transportation and storage services for natural gas and natural gas liquids and hydrocarbons (referred to together as “NGLs”) on a firm and interruptible basis and provides interruptible natural gas parking and lending services. The majority of Boardwalk Pipeline’s operating subsidiaries are subject to Federal Energy Regulatory Commission (“FERC”) regulations and certain revenues collected, under certain circumstances, may be subject to possible refunds to its customers. An estimated refund liability is recorded considering regulatory proceedings, advice of counsel and estimated total exposure. The majority of Boardwalk Pipeline’s revenues are from firm service contracts which are accounted for as a single promise to stand ready each month of the contract term to provide the committed capacity for either transportation or storage services. The transaction price is comprised of a fixed fee based on the capacity reserved plus a usage fee paid on the volume of commodity transported or injected and withdrawn from storage. Both the fixed and the usage fees are allocated to the single performance obligation of providing transportation or storage service and recognized over time as control is passed to the customer. These service contracts can range in term from one to 20 years and are invoiced monthly. Loews Hotels & Co provides lodging and related goods and services as well as management and marketing services. Loews Hotels & Co allocates the lodging transaction price to the distinct goods and services based on the market price. Lodging and related revenues are recognized as the guest takes possession of the goods or receives the services. Management and marketing services revenues are recognized as the services are provided and billed on a monthly basis. In addition, Loews Hotels & Co recognizes revenue for the reimbursement of payroll expenses incurred on behalf of the owners of joint venture and managed hotel properties. Consolidated Container manufactures rigid plastic packaging and recycled resins and provides packaging solutions to end markets such as beverage, food and household chemicals through a network of manufacturing locations across North America. Consolidated Container recognizes revenue as control is transferred to the customer. Receivables from contracts with customers Deferred revenue non-insurance Contract costs non-insurance For CNA’s non-insurance Performance obligations non-insurance

Benefit Plans

Benefit Plans	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Benefit Plans	8. Benefit Plans The Company and its subsidiaries have several non-contributory The following table presents the components of net periodic (benefit) cost for the plans: Pension Benefits Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Service cost $ 2 $ 2 $ 6 $ 6 Interest cost 27 30 82 89 Expected return on plan assets (44 ) (43 ) (134 ) (129 ) Amortization of unrecognized net loss 11 10 32 32 Settlement charge 7 7 10 Net periodic (benefit) cost $ (4 ) $ 6 $ (7 ) $ 8 Other Postretirement Benefits Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Interest cost $ 1 $ 1 $ 2 $ 2 Expected return on plan assets (1 ) (1 ) (3 ) (3 ) Amortization of unrecognized prior service benefit (1 ) (1 ) (2 ) (2 ) Amortization of unrecognized net gain (1 ) (1 ) Net periodic (benefit) cost $ (2 ) $ (1 ) $ (4 ) $ (3 )

Legal Proceedings

Legal Proceedings	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	9. Legal Proceedings The Company and its subsidiaries are from time to time parties to litigation arising in the ordinary course of business. While it is difficult to predict the outcome or effect of any litigation, management does not believe that the outcome of any such pending litigation will materially affect the Company’s results of operations or equity.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies CNA Guarantees In the course of selling business entities and assets to third parties, CNA agreed to guarantee the performance of certain obligations of previously owned subsidiaries and to indemnify purchasers for losses arising out of breaches of representations and warranties with respect to the business entities or assets sold, including, in certain cases, losses arising from undisclosed liabilities or certain named litigation. Such guarantee and indemnification agreements in effect for sales of business entities, assets and third party loans may include provisions that survive indefinitely. As of September 30, 2018, the aggregate amount related to quantifiable guarantees was $375 million and the aggregate amount related to quantifiable indemnification agreements was $252 million. In certain cases, should CNA be required to make payments under any such guarantee, it would have the right to seek reimbursement from an affiliate of a previously owned subsidiary. In addition, CNA has agreed to provide indemnification to third party purchasers for certain losses associated with sold business entities or assets that are not limited by a contractual monetary amount. As of September 30, 2018, CNA had outstanding unlimited indemnifications in connection with the sales of certain of its business entities or assets that included tax liabilities arising prior to a purchaser’s ownership of an entity or asset, defects in title at the time of sale, employee claims arising prior to closing and in some cases losses arising from certain litigation and undisclosed liabilities. Certain provisions of the indemnification agreements survive indefinitely while others survive until the applicable statutes of limitation expire, or until the agreed upon contract terms expire. CNA also provided guarantees, if the primary obligor fails to perform, to holders of structured settlement annuities provided by a previously owned subsidiary. As of September 30, 2018, the potential amount of future payments CNA could be required to pay under these guarantees was approximately $1.8 billion, which will be paid over the lifetime of the annuitants. CNA does not believe any payment is likely under these guarantees, as CNA is the beneficiary of a trust that must be maintained at a level that approximates the discounted reserves for these annuities. CNA Small Business Premium Rate Adjustment In 2016 and 2017, CNA identified rating errors related to its multi-peril package product and workers’ compensation policies within its Small Business unit and determined that it would voluntarily issue premium refunds along with interest on affected policies. After the rating errors were identified, written and earned premium were reported net of any impact from the premium rate adjustments. The policyholder refunds for the multi-peril package product were issued in the third quarter of 2017. The policyholder refunds for workers’ compensation policies were largely completed in the third quarter of 2018. For the nine months ended September 30, 2017, earned premium was reduced by $37 million. Earned premium increased by $6 million for the three and nine months ended September 30, 2018 as a result of a change in estimate of the refund payments to policyholders. Additionally, Interest expense increased for interest due to policyholders on the premium rate adjustments by $1 million and $7 million for the three and nine months ended September 30, 2017 and $1 million for the nine months ended September 30, 2018.

Segments

Segments	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segments	11. Segments The Company has five reportable segments comprised of four individual operating subsidiaries, CNA, Diamond Offshore, Boardwalk Pipeline and Loews Hotels & Co; and the Corporate segment. The operations of Consolidated Container are included in the Corporate segment for the three and nine months ended September 30, 2018 and the period from the acquisition date, May 22, 2017 through September 30, 2017. Each of the operating subsidiaries is headed by a chief executive officer who is responsible for the operation of its business and has the duties and authority commensurate with that position. For additional disclosures regarding the composition of the Company’s segments, see Note 19 of the Consolidated Financial Statements in the Company’s Annual Report on Form 10-K The following tables present the reportable segments of the Company and their contribution to the Consolidated Condensed Statements of Income. Amounts presented will not necessarily be the same as those in the individual financial statements of the Company’s subsidiaries due to adjustments for purchase accounting, income taxes and noncontrolling interests. Statements of Income by segment are presented in the following tables. Three Months Ended September 30, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,853 $ 1,853 Net investment income 487 $ 2 $ 5 494 Investment gains 15 15 Operating revenues and other 267 287 $ 279 $ 190 223 1,246 Total 2,622 289 279 190 228 3,608 Expenses: Insurance claims and policyholders’ benefits 1,312 1,312 Amortization of deferred acquisition costs 337 337 Operating expenses and other 538 311 197 169 244 1,459 Interest 34 34 44 7 27 146 Total 2,221 345 241 176 271 3,254 Income (loss) before income tax 401 (56 ) 38 14 (43 ) 354 Income tax (expense) benefit (66 ) 5 (10 ) (3 ) 9 (65 ) Net income (loss) 335 (51 ) 28 11 (34 ) 289 Amounts attributable to noncontrolling interests (35 ) 24 - - - (11 ) Net income (loss) attributable to Loews Corporation $ 300 $ (27 ) $ 28 $ 11 $ (34 ) $ 278 Three Months Ended September 30, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,806 $ 1,806 Net investment income 509 $ 48 557 Investment gains 16 16 Operating revenues and other 110 $ 368 $ 301 $ 162 201 1,142 Total 2,441 368 301 162 249 3,521 Expenses: Insurance claims and policyholders’ benefits 1,480 1,480 Amortization of deferred acquisition costs 309 309 Operating expenses and other 379 307 191 147 221 1,245 Interest 83 64 41 7 28 223 Total 2,251 371 232 154 249 3,257 Income (loss) before income tax 190 (3 ) 69 8 - 264 Income tax (expense) benefit (44 ) 14 (18 ) (4 ) (52 ) Net income 146 11 51 4 - 212 Amounts attributable to noncontrolling interests (16 ) (5 ) (34 ) (55 ) Net income attributable to Loews Corporation $ 130 $ 6 $ 17 $ 4 $ - $ 157 Nine Months Ended September 30, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 5,453 $ 5,453 Net investment income 1,483 $ 6 $ 1 $ 61 1,551 Investment gains 21 21 Operating revenues and other 774 853 $ 901 573 653 3,754 Total 7,731 859 901 574 714 10,779 Expenses: Insurance claims and policyholders’ benefits 3,978 3,978 Amortization of deferred acquisition costs 992 992 Operating expenses and other 1,580 927 598 494 714 4,313 Interest 104 92 131 22 81 430 Total 6,654 1,019 729 516 795 9,713 Income (loss) before income tax 1,077 (160 ) 172 58 (81 ) 1,066 Income tax (expense) benefit (181 ) 59 (24 ) (17 ) 14 (149 ) Net income (loss) 896 (101 ) 148 41 (67 ) 917 Amounts attributable to noncontrolling interests (95 ) 47 (68 ) - - (116 ) Net income (loss) attributable to Loews Corporation $ 801 $ (54 ) $ 80 $ 41 $ (67 ) $ 801 Nine Months Ended September 30, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 5,185 $ 5,185 Net investment income 1,529 $ 1 $ 109 1,639 Investment gains 93 93 Operating revenues and other 329 1,143 $ 987 $ 510 294 3,263 Total 7,136 1,144 987 510 403 10,180 Expenses: Insurance claims and policyholders’ benefits 4,053 4,053 Amortization of deferred acquisition costs 926 926 Operating expenses and other 1,086 1,012 646 443 389 3,576 Interest 166 119 131 20 68 504 Total 6,231 1,131 777 463 457 9,059 Income (loss) before income tax 905 13 210 47 (54 ) 1,121 Income tax (expense) benefit (226 ) 35 (46 ) (23 ) 20 (240 ) Net income (loss) 679 48 164 24 (34 ) 881 Amounts attributable to noncontrolling interests (71 ) (23 ) (104 ) (198 ) Net income (loss) attributable to Loews Corporation $ 608 $ 25 $ 60 $ 24 $ (34 ) $ 683

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Accounting	Loews Corporation is a holding company. Its subsidiaries are engaged in the following lines of business: commercial property and casualty insurance (CNA Financial Corporation (“CNA”), a 89% owned subsidiary); the operation of offshore oil and gas drilling rigs (Diamond Offshore Drilling, Inc. (“Diamond Offshore”), a 53% owned subsidiary); transportation and storage of natural gas and natural gas liquids (Boardwalk Pipeline Partners, LP (“Boardwalk Pipeline”), a wholly owned subsidiary); the operation of a chain of hotels (Loews Hotels Holding Corporation (“Loews Hotels & Co”), a wholly owned subsidiary); and the manufacture of rigid plastic packaging solutions (Consolidated Container Company LLC (“Consolidated Container”), a 99% owned subsidiary). Unless the context otherwise requires, the terms “Company,” “Loews” and “Registrant” as used herein mean Loews Corporation excluding its subsidiaries and the term “Net income attributable to Loews Corporation” as used herein means Net income attributable to Loews Corporation shareholders. In the opinion of management, the accompanying unaudited Consolidated Condensed Financial Statements reflect all adjustments (consisting of normal recurring accruals) necessary to present fairly the Company’s financial position as of September 30, 2018 and December 31, 2017, results of operations and comprehensive income for the three and nine months ended September 30, 2018 and 2017 and changes in shareholders’ equity and cash flows for the nine months ended September 30, 2018 and 2017. Net income for the third quarter and first nine months of each of the years is not necessarily indicative of net income for that entire year. These Consolidated Condensed Financial Statements should be read in conjunction with the Consolidated Financial Statements in the Company’s Annual Report on Form 10-K
Income Per Share	The Company presents basic and diluted net income per share on the Consolidated Condensed Statements of Income. Basic net income per share excludes dilution and is computed by dividing net income attributable to common stock by the weighted average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock. There were no shares and 0.4 million shares attributable to employee stock-based compensation awards excluded from the diluted weighted average shares outstanding amounts for the three and nine months ended September 30, 2018 and 2017 because the effect would have been antidilutive.
Revenue from Contracts with Customers	In May of 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) ASU 2014-09, 2014-09”). On January 1, 2018, the Company adopted the updated accounting guidance using the modified retrospective method, with a cumulative effect adjustment to the opening balance sheet. Upon adoption, the new guidance was applied to all contracts subject to the standard that were not completed as of the date of adoption. Prior period amounts have not been adjusted and continue to be reported in accordance with the previous accounting guidance. At adoption, the cumulative effect adjustment decreased beginning Retained earnings by $62 million (after tax and noncontrolling interests), resulted in a deferred tax asset of $23 million and increased Other assets by approximately $1.9 billion and Other liabilities by approximately $2.0 billion. The impact of the new guidance is primarily related to revenue on CNA’s non-insurance gross-up 2014-09,
Recognition and Measurement of Financial Assets and Financial Liabilities	In January of 2016, the FASB issued ASU 2016-01, – 825-10): 2016-01”). available-for-sale
Income Taxes	In October of 2016, the FASB issued ASU 2016-16,
Income Statement-Reporting Comprehensive Income	In February of 2018, the FASB issued ASU 2018-02, 2018-02”). security-by-security
Fair Value Measurement	In August of 2018, the FASB issued ASU 2018-13, –
Recently issued ASUs	Recently issued ASUs – 2016-02, 2018-11, 2014-09. In June of 2016, the FASB issued ASU 2016-13, available-for-sale available-for-sale In August of 2018, the FASB issued ASU 2018-12, – This guidance is effective for interim and annual periods beginning after December 15, 2020, and requires restatement of the prior periods presented. Early adoption is permitted. The Company is currently evaluating the method and timing of adoption and the effect the updated guidance will have on its consolidated financial statements. The annual updating of cash flow assumptions is expected to increase income statement volatility. The quarterly change in the discount rate is expected to increase volatility in the Company’s Shareholders’ equity, but that will be somewhat mitigated because Shadow Adjustments are eliminated under the new guidance. See Note 3 for further information on Shadow Adjustments. In August of 2018, the FASB issued ASU 2018-14, – – – 715-20): Disclosure – Income tax reform update non-cash one-time non-U.S. The Company is still in the process of evaluating the estimate as it relates to the tax effect of: (i) the amount of deferred tax assets and liabilities subject to the income tax rate change from 35% to 21%, including the calculation of the mandatory deemed repatriation aspect of the Tax Act and the state tax effect of adjustments made to the federal temporary differences, (ii) the ability to more likely than not realize the benefit of deferred tax assets, including net operating losses and foreign tax credits, (iii) the effect of re-computing

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Net Investment Income and Investment Gains (Losses)	Net investment income is as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Fixed maturity securities $ 449 $ 455 $ 1,339 $ 1,367 Limited partnership investments 34 67 142 206 Short term investments 10 5 30 13 Equity securities 10 1 32 4 Income (loss) from trading portfolio (a) (7 ) 34 13 67 Other 12 10 40 26 Total investment income 508 572 1,596 1,683 Investment expenses (14 ) (15 ) (45 ) (44 ) Net investment income $ 494 $ 557 $ 1,551 $ 1,639 (a) Net unrealized gains (losses) related to changes in fair value on securities still held were $(23) and $22 for the three months ended September 30, 2018 and 2017 and $(66) and $35 for the nine months ended September 30, 2018 and 2017. Investment gains (losses) are as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Fixed maturity securities $ 10 $ 16 $ 32 $ 92 Equity securities 2 (23 ) Derivative instruments 1 (1 ) 10 (3 ) Short term investments and other 2 1 2 4 Investment gains (a) $ 15 $ 16 $ 21 $ 93 (a) Gross realized gains on available-for-sale available-for-sale non-redeemable
Components of OTTI Losses Recognized in Earnings by Asset Type	The components of other-than-temporary impairment (“OTTI”) losses recognized in earnings by asset type are as follows: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 1 $ 4 $ 6 $ 8 Asset-backed 2 1 3 1 Net OTTI losses recognized in earnings $ 3 $ 5 $ 9 $ 9
Amortized Cost and Fair Values of Fixed Maturity and Equity Securities	The amortized cost and fair values of fixed maturity and equity securities are as follows: September 30, 2018 Cost or Gross Gross Estimated Unrealized (In millions) Fixed maturity securities: Corporate and other bonds $ 18,348 $ 887 $ 215 $ 19,020 States, municipalities and political subdivisions 10,171 994 20 11,145 Asset-backed: Residential mortgage-backed 5,024 62 115 4,971 $ (24 ) Commercial mortgage-backed 2,165 23 36 2,152 Other asset-backed 1,732 6 9 1,729 Total asset-backed 8,921 91 160 8,852 (24 ) U.S. Treasury and obligations of government-sponsored enterprises 145 2 2 145 Foreign government 457 4 6 455 Redeemable preferred stock 9 1 10 Fixed maturities available-for-sale 38,051 1,979 403 39,627 (24 ) Fixed maturities trading 186 6 192 Total fixed maturity securities $ 38,237 $ 1,985 $ 403 $ 39,819 $ (24 ) December 31, 2017 Fixed maturity securities: Corporate and other bonds $ 17,210 $ 1,625 $ 28 $ 18,807 States, municipalities and political subdivisions 12,478 1,551 2 14,027 $ (11 ) Asset-backed: Residential mortgage-backed 5,043 109 32 5,120 (27 ) Commercial mortgage-backed 1,840 46 14 1,872 Other asset-backed 1,083 16 5 1,094 Total asset-backed 7,966 171 51 8,086 (27 ) U.S. Treasury and obligations of government-sponsored enterprises 111 2 4 109 Foreign government 437 9 2 444 Redeemable preferred stock 10 1 11 Fixed maturities available-for-sale 38,212 3,359 87 41,484 (38 ) Fixed maturities trading 649 2 2 649 Total fixed maturities 38,861 3,361 89 42,133 (38 ) Equity securities: Common stock 21 7 1 27 Preferred stock 638 31 1 668 Equity securities available-for-sale 659 38 2 695 - Equity securities trading 518 92 81 529 Total equity securities 1,177 130 83 1,224 - Total fixed maturity and equity securities $ 40,038 $ 3,491 $ 172 $ 43,357 $ (38 )
Securities Available-for-Sale in Gross Unrealized Loss Position	The available-for-sale Less than 12 Months 12 Months or Longer Total September 30, 2018 Estimated Gross Estimated Gross Estimated Gross (In millions) Fixed maturity securities: Corporate and other bonds $ 7,546 $ 197 $ 342 $ 18 $ 7,888 $ 215 States, municipalities and political subdivisions 807 19 2 1 809 20 Asset-backed: Residential mortgage-backed 3,409 89 501 26 3,910 115 Commercial mortgage-backed 968 15 322 21 1,290 36 Other asset-backed 953 9 45 998 9 Total asset-backed 5,330 113 868 47 6,198 160 U.S. Treasury and obligations of government-sponsored enterprises 35 42 2 77 2 Foreign government 188 4 64 2 252 6 Total fixed maturity securities $ 13,906 $ 333 $ 1,318 $ 70 $ 15,224 $ 403 December 31, 2017 Fixed maturity securities: Corporate and other bonds $ 1,354 $ 21 $ 168 $ 7 $ 1,522 $ 28 States, municipalities and political subdivisions 72 1 85 1 157 2 Asset-backed: Residential mortgage-backed 1,228 5 947 27 2,175 32 Commercial mortgage-backed 403 4 212 10 615 14 Other asset-backed 248 3 18 2 266 5 Total asset-backed 1,879 12 1,177 39 3,056 51 U.S. Treasury and obligations of government-sponsored enterprises 49 2 21 2 70 4 Foreign government 166 2 4 170 2 Total fixed maturity securities 3,520 38 1,455 49 4,975 87 Equity securities: Common stock 7 1 7 1 Preferred stock 93 1 93 1 Total equity securities 100 2 - - 100 2 Total fixed maturity and equity securities $ 3,620 $ 40 $ 1,455 $ 49 $ 5,075 $ 89
Pretax Credit Loss Component Reflected in Retained Earnings on Fixed Maturity Securities	The following table presents the activity related to the pretax credit loss component reflected in Retained earnings on fixed maturity securities still held as of September 30, 2018 and 2017 for which a portion of an OTTI loss was recognized in OCI. Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Beginning balance of credit losses on fixed maturity securities $ 21 $ 30 $ 27 $ 36 Reductions for securities sold during the period (2 ) (2 ) (8 ) (8 ) Ending balance of credit losses on fixed maturity securities $ 19 $ 28 $ 19 $ 28
Available-for-Sale Fixed Maturity Securities by Contractual Maturity	The following table presents available-for-sale September 30, 2018 December 31, 2017 Cost or Estimated Fair Value Cost or Estimated Fair Value (In millions) Due in one year or less $ 1,457 $ 1,473 $ 1,135 $ 1,157 Due after one year through five years 8,017 8,197 8,165 8,501 Due after five years through ten years 16,453 16,475 16,060 16,718 Due after ten years 12,124 13,482 12,852 15,108 Total $ 38,051 $ 39,627 $ 38,212 $ 41,484
Summary of Aggregate Contractual or Notional Amount and Estimated Fair Value Related to Derivative Financial Instruments	Gross estimated fair values of derivative positions are currently presented in Equity securities, Receivables and Payable to brokers on the Consolidated Condensed Balance Sheets. September 30, 2018 December 31, 2017 Contractual/ Contractual/ Notional Estimated Fair Value Notional Estimated Fair Value Amount Asset (Liability) Amount Asset (Liability) (In millions) With hedge designation: Interest rate swaps $ 500 $ 22 $ 500 $ 4 Without hedge designation: Equity markets: Options – purchased 222 9 224 12 – written 201 $ (6 ) 290 $ (7 ) Futures – short 154 265 1 Commodity futures – long 47 1 44 Embedded derivative on funds withheld liability 174 6 167 (3 )

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized in the following tables. Corporate bonds and other includes obligations of the U.S. Treasury, government-sponsored enterprises, foreign governments and redeemable preferred stock. September 30, 2018 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 183 $ 19,259 $ 188 $ 19,630 States, municipalities and political subdivisions 11,145 11,145 Asset-backed 8,554 298 8,852 Fixed maturities available-for-sale 183 38,958 486 39,627 Fixed maturities trading 186 6 192 Total fixed maturities $ 183 $ 39,144 $ 492 $ 39,819 Equity securities $ 623 $ 625 $ 19 $ 1,267 Short term and other 2,678 1,074 3,752 Receivables 23 23 Payable to brokers (13 ) (13 ) December 31, 2017 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 128 $ 19,145 $ 98 $ 19,371 States, municipalities and political subdivisions 14,026 1 14,027 Asset-backed 7,751 335 8,086 Fixed maturities available-for-sale 128 40,922 434 41,484 Fixed maturities trading 10 635 4 649 Total fixed maturities $ 138 $ 41,557 $ 438 $ 42,133 Equity securities available-for-sale $ 91 $ 584 $ 20 $ 695 Equity securities trading 527 2 529 Total equity securities $ 618 $ 584 $ 22 $ 1,224 Short term and other $ 3,669 $ 958 $ 4,627 Receivables 1 4 5 Payable to brokers (12 ) (12 )
Reconciliations of Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The following tables present reconciliations for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2018 and 2017: Net Realized Gains Unrealized (Losses) Unrealized (Losses) 2018 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 94 $ 67 $ (3 ) $ 30 $ 188 States, municipalities and political subdivisions 1 (1 ) - Asset-backed 273 $ (2 ) 55 (25 ) 29 $ (32 ) 298 $ (2 ) $ 1 Fixed maturities available-for-sale 368 (2 ) $ - 122 $ - (29 ) 59 (32 ) 486 (2 ) 1 Fixed maturities trading 7 (1 ) 6 Total fixed maturities $ 375 $ (2 ) $ - $ 122 $ (1 ) $ (29 ) $ 59 $ (32 ) $ 492 $ (2 ) $ 1 Equity securities $ 18 $ 1 $ 19 $ 1 Net Realized Gains Unrealized (Losses) 2017 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 100 $ 1 $ 1 $ 13 $ (11 ) $ 15 $ 119 States, municipalities and political subdivisions 1 1 Asset-backed 218 1 39 (13 ) 101 346 Fixed maturities available-for-sale 319 1 2 52 $ - (24 ) 116 $ - 466 $ - Fixed maturities trading 5 5 Total fixed maturities $ 324 $ 1 $ 2 $ 52 $ - $ (24 ) $ 116 $ - $ 471 $ - Equity securities available-for-sale $ 19 $ 19 Equity securities trading 1 $ 1 2 Total equity securities $ 20 $ - $ - $ 1 $ - $ - $ - $ - $ 21 $ - Life settlement contracts $ 1 $ (1 ) $ - Net Realized Gains Unrealized (Losses) Unrealized (Losses) 2018 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 98 $ (1 ) $ (1 ) $ 69 $ (5 ) $ (7 ) $ 35 $ 188 $ (2 ) States, municipalities and political subdivisions 1 (1 ) - Asset-backed 335 5 (6 ) 126 (72 ) (37 ) 42 $ (95 ) 298 $ (2 ) (2 ) Fixed maturities available-for-sale 434 4 (7 ) 195 (77 ) (45 ) 77 (95 ) 486 (2 ) (4 ) Fixed maturities trading 4 3 (1 ) 6 2 Total fixed maturities $ 438 $ 7 $ (7 ) $ 195 $ (78 ) $ (45 ) $ 77 $ (95 ) $ 492 $ - $ (4 ) Equity securities $ 22 $ (2 ) $ (1 ) $ 19 $ (2 ) Net Realized Gains Unrealized (Losses) 2017 Balance, Included in Included in Purchases Sales Settlements Transfers Transfers Balance, Liabilities Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 130 $ 1 $ 2 $ 18 $ (1 ) $ (36 ) $ 15 $ (10 ) $ 119 States, municipalities and political subdivisions 1 1 Asset-backed 199 1 4 90 (26 ) 153 (75 ) 346 Fixed maturities available-for-sale 330 2 6 108 (1 ) (62 ) 168 (85 ) 466 $ - Fixed maturities trading 6 (1 ) 5 (1 ) Total fixed maturities $ 336 $ 1 $ 6 $ 108 $ (1 ) $ (62 ) $ 168 $ (85 ) $ 471 $ (1 ) Equity securities available-for-sale $ 19 $ 2 $ 1 $ (3 ) $ 19 Equity securities trading 1 1 2 Total equity securities $ 20 $ - $ 2 $ 2 $ (3 ) $ - $ - $ - $ 21 $ - Life settlement contracts $ 58 $ 6 $ (59 ) $ (5 ) $ - Derivative financial instruments, net - 1 (1 ) - Net realized and unrealized gains and losses are reported in Net income as follows: Major Category of Assets and Liabilities Consolidated Condensed Statements of Income Line Items Fixed maturity securities available-for-sale Investment gains (losses) Fixed maturity securities trading Net investment income Equity securities Investment gains (losses) and Net investment income Other invested assets Investment gains (losses) and Net investment income Derivative financial instruments held in a trading portfolio Net investment income Derivative financial instruments, other Investment gains (losses) and Operating revenues and other Life settlement contracts Operating revenues and other
Quantitative Information about Significant Unobservable Inputs Utilized by Company in Fair Value Measurements of Level 3 Assets	The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 assets. Valuations for assets and liabilities not presented in the tables below are primarily based on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations. The quantitative detail of unobservable inputs from these broker quotes is neither provided nor reasonably available to the Company. The weighted average rate is calculated based on fair value. September 30, 2018 Estimated Fair Value Valuation Techniques Unobservable Inputs Range (Weighted Average) (In millions) Fixed maturity securities $ 198 Discounted cash flow Credit spread 1% – 12% (2%) December 31, 2017 Fixed maturity securities $ 136 Discounted cash flow Credit spread 1% – 12% (3%)
Carrying Amount, Estimated Fair Value and Level of Fair Value Hierarchy of Company's Financial Assets and Liabilities	The carrying amounts reported on the Consolidated Condensed Balance Sheets for cash and short term investments not carried at fair value and certain other assets and liabilities approximate fair value due to the short term nature of these items. Carrying Estimated Fair Value September 30, 2018 Amount Level 1 Level 2 Level 3 Total (In millions) Assets: Other invested assets, primarily mortgage loans $ 868 $ 847 $ 847 Liabilities: Short term debt 146 $ 6 140 146 Long term debt 11,295 10,537 630 11,167 December 31, 2017 Assets: Other invested assets, primarily mortgage loans $ 839 $ 844 $ 844 Liabilities: Short term debt 278 $ 156 122 278 Long term debt 11,236 10,966 525 11,491

Claim and Claim Adjustment Ex_2

Claim and Claim Adjustment Expense Reserves (Tables)	9 Months Ended
	Sep. 30, 2018
Insurance [Abstract]
Reconciliation of Claim and Claim Adjustment Expense Reserves	The following table presents a reconciliation between beginning and ending claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves of Other Insurance Operations. Nine Months Ended September 30 2018 2017 (In millions) Reserves, beginning of year: Gross $ 22,004 $ 22,343 Ceded 3,934 4,094 Net reserves, beginning of year 18,070 18,249 Net incurred claim and claim adjustment expenses: Provision for insured events of current year 3,866 3,949 Decrease in provision for insured events of prior years (173 ) (284 ) Amortization of discount 136 138 Total net incurred (a) 3,829 3,803 Net payments attributable to: Current year events (658 ) (560 ) Prior year events (3,415 ) (3,401 ) Total net payments (4,073 ) (3,961 ) Foreign currency translation adjustment and other (80 ) 110 Net reserves, end of period 17,746 18,201 Ceded reserves, end of period 3,858 4,008 Gross reserves, end of period $ 21,604 $ 22,209 (a) Total net incurred above does not agree to Insurance claims and policyholders’ benefits as reflected in the Consolidated Condensed Statements of Income due to amounts related to retroactive reinsurance deferred gain accounting, uncollectible reinsurance and loss deductible receivables and benefit expenses related to future policy benefits, which are not reflected in the table above.
Details of the Net Prior Year Development in CNA's Property and Casualty Operations	The following table and discussion present details of the net prior year claim and claim adjustment expense reserve development in CNA’s Property & Casualty Operations: Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Medical professional liability $ 15 $ 8 $ 38 $ 30 Other professional liability and management liability (45 ) (19 ) (113 ) (88 ) Surety (20 ) (82 ) (50 ) (82 ) Commercial auto 1 (12 ) (37 ) General liability (5 ) (2 ) 13 (19 ) Workers’ compensation (2 ) 9 (14 ) (38 ) Other (6 ) (17 ) (34 ) 7 Total pretax (favorable) unfavorable development $ (62 ) $ (115 ) $ (160 ) $ (227 )
Schedule of Impact of Loss Portfolio Transfer on the Consolidated Statement of Operations	The following table presents the impact of the loss portfolio transfer on the Consolidated Condensed Statements of Income. Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Additional amounts ceded under LPT: Net A&EP adverse development before consideration of LPT $ - $ - $ 113 $ 60 Provision for uncollectible third-party reinsurance on A&EP (16 ) Total additional amounts ceded under LPT - - 97 60 Retroactive reinsurance benefit recognized (12 ) (17 ) (84 ) (60 ) Pretax impact of deferred retroactive reinsurance $ (12 ) $ (17 ) $ 13 $ -

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Components of Accumulated Other Comprehensive Income	The tables below present the changes in AOCI by component for the three and nine months ended September 30, 2017 and 2018: OTTI Unrealized Cash Flow Hedges Pension Foreign Total (In millions) Balance, July 1, 2017 $ 23 $ 705 $ (2 ) $ (632 ) $ (130 ) $ (36 ) Other comprehensive income (loss) before reclassifications, after tax of $0, $(20), $0, $0 and $0 1 35 (2 ) 41 75 Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $0, $4, $0, $(6) and $0 (12 ) 3 11 2 Other comprehensive income 1 23 1 11 41 77 Amounts attributable to noncontrolling interests (3 ) (1 ) (1 ) (4 ) (9 ) Balance, September 30, 2017 $ 24 $ 725 $ (2 ) $ (622 ) $ (93 ) $ 32 Balance, July 1, 2018 $ 17 $ 244 $ 13 $ (774 ) $ (125 ) $ (625 ) Other comprehensive loss before reclassifications, after tax of $0, $40, $(2), $0 and $0 (1 ) (148 ) (149 ) Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $0, $2, $0, $(1) and $0 (10 ) 8 (2 ) Other comprehensive income (loss) (1 ) (158 ) - 8 - (151 ) Amounts attributable to noncontrolling interests 17 1 18 Balance, September 30, 2018 $ 16 $ 103 $ 13 $ (765 ) $ (125 ) $ (758 ) OTTI Unrealized Cash Flow Pension Foreign Total (In millions) Balance, January 1, 2017 $ 27 $ 576 $ (2 ) $ (646 ) $ (178 ) $ (223 ) Other comprehensive income (loss) before reclassifications, after tax of $0, $(130), $0, $0 and $0 228 (3 ) 94 319 Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $1, $28, $0, $(13) and $0 (3 ) (61 ) 4 26 (34 ) Other comprehensive income (loss) (3 ) 167 1 26 94 285 Amounts attributable to noncontrolling interests (18 ) (1 ) (2 ) (9 ) (30 ) Balance, September 30, 2017 $ 24 $ 725 $ (2 ) $ (622 ) $ (93 ) $ 32 Balance, January 1, 2018, as reported $ 22 $ 673 $ - $ (633 ) $ (88 ) $ (26 ) Cumulative effect adjustment for adoption of ASU 2016-01 (25 ) (25 ) Cumulative effect adjustment for adoption of ASU 2018-02 4 123 (130 ) (3 ) Balance, January 1, 2018, as adjusted 26 771 - (763 ) (88 ) (54 ) Other comprehensive income (loss) before reclassifications, after tax of $3, $190, $(4), $0 and $0 (12 ) (718 ) 12 (41 ) (759 ) Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $0, $7, $0, $(6) and $0 1 (28 ) 2 27 2 Other comprehensive income (loss) (11 ) (746 ) 14 27 (41 ) (757 ) Amounts attributable to noncontrolling interests 1 78 (1 ) 4 82 Purchase of Boardwalk Pipeline common units (1 ) (28 ) (29 ) Balance, September 30, 2018 $ 16 $ 103 $ 13 $ (765 ) $ (125 ) $ (758 ) (a) For information regarding this accounting standard see Note 1.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenues	The following table presents revenues from contracts with customers disaggregated by revenue type along with the reportable segment and a reconciliation to Operating revenues and other as reported in Note 11: Three Months Ended Nine Months Ended 2018 2017 (a) 2018 2017 (a) (In millions) Non-insurance $ 258 $ 99 $ 744 $ 290 Contract drilling – Diamond Offshore 287 366 851 1,139 Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipeline 274 290 886 944 Lodging and related services – Loews Hotels & Co 167 162 550 510 Rigid plastic packaging and recycled resin – Corporate 223 202 652 293 Total revenues from contracts with customers 1,209 1,119 3,683 3,176 Other revenues 37 23 71 87 Operating revenues and other $ 1,246 $ 1,142 $ 3,754 $ 3,263 (a) Prior period amounts have not been adjusted under the modified retrospective method of adoption for ASU 2014-09.

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	The following table presents the components of net periodic (benefit) cost for the plans: Pension Benefits Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Service cost $ 2 $ 2 $ 6 $ 6 Interest cost 27 30 82 89 Expected return on plan assets (44 ) (43 ) (134 ) (129 ) Amortization of unrecognized net loss 11 10 32 32 Settlement charge 7 7 10 Net periodic (benefit) cost $ (4 ) $ 6 $ (7 ) $ 8 Other Postretirement Benefits Three Months Ended Nine Months Ended 2018 2017 2018 2017 (In millions) Interest cost $ 1 $ 1 $ 2 $ 2 Expected return on plan assets (1 ) (1 ) (3 ) (3 ) Amortization of unrecognized prior service benefit (1 ) (1 ) (2 ) (2 ) Amortization of unrecognized net gain (1 ) (1 ) Net periodic (benefit) cost $ (2 ) $ (1 ) $ (4 ) $ (3 )

Segments (Tables)

Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Consolidating Statement of Income and Total Assets by Segment	Statements of Income by segment are presented in the following tables. Three Months Ended September 30, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,853 $ 1,853 Net investment income 487 $ 2 $ 5 494 Investment gains 15 15 Operating revenues and other 267 287 $ 279 $ 190 223 1,246 Total 2,622 289 279 190 228 3,608 Expenses: Insurance claims and policyholders’ benefits 1,312 1,312 Amortization of deferred acquisition costs 337 337 Operating expenses and other 538 311 197 169 244 1,459 Interest 34 34 44 7 27 146 Total 2,221 345 241 176 271 3,254 Income (loss) before income tax 401 (56 ) 38 14 (43 ) 354 Income tax (expense) benefit (66 ) 5 (10 ) (3 ) 9 (65 ) Net income (loss) 335 (51 ) 28 11 (34 ) 289 Amounts attributable to noncontrolling interests (35 ) 24 - - - (11 ) Net income (loss) attributable to Loews Corporation $ 300 $ (27 ) $ 28 $ 11 $ (34 ) $ 278 Three Months Ended September 30, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,806 $ 1,806 Net investment income 509 $ 48 557 Investment gains 16 16 Operating revenues and other 110 $ 368 $ 301 $ 162 201 1,142 Total 2,441 368 301 162 249 3,521 Expenses: Insurance claims and policyholders’ benefits 1,480 1,480 Amortization of deferred acquisition costs 309 309 Operating expenses and other 379 307 191 147 221 1,245 Interest 83 64 41 7 28 223 Total 2,251 371 232 154 249 3,257 Income (loss) before income tax 190 (3 ) 69 8 - 264 Income tax (expense) benefit (44 ) 14 (18 ) (4 ) (52 ) Net income 146 11 51 4 - 212 Amounts attributable to noncontrolling interests (16 ) (5 ) (34 ) (55 ) Net income attributable to Loews Corporation $ 130 $ 6 $ 17 $ 4 $ - $ 157 Nine Months Ended September 30, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 5,453 $ 5,453 Net investment income 1,483 $ 6 $ 1 $ 61 1,551 Investment gains 21 21 Operating revenues and other 774 853 $ 901 573 653 3,754 Total 7,731 859 901 574 714 10,779 Expenses: Insurance claims and policyholders’ benefits 3,978 3,978 Amortization of deferred acquisition costs 992 992 Operating expenses and other 1,580 927 598 494 714 4,313 Interest 104 92 131 22 81 430 Total 6,654 1,019 729 516 795 9,713 Income (loss) before income tax 1,077 (160 ) 172 58 (81 ) 1,066 Income tax (expense) benefit (181 ) 59 (24 ) (17 ) 14 (149 ) Net income (loss) 896 (101 ) 148 41 (67 ) 917 Amounts attributable to noncontrolling interests (95 ) 47 (68 ) - - (116 ) Net income (loss) attributable to Loews Corporation $ 801 $ (54 ) $ 80 $ 41 $ (67 ) $ 801 Nine Months Ended September 30, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 5,185 $ 5,185 Net investment income 1,529 $ 1 $ 109 1,639 Investment gains 93 93 Operating revenues and other 329 1,143 $ 987 $ 510 294 3,263 Total 7,136 1,144 987 510 403 10,180 Expenses: Insurance claims and policyholders’ benefits 4,053 4,053 Amortization of deferred acquisition costs 926 926 Operating expenses and other 1,086 1,012 646 443 389 3,576 Interest 166 119 131 20 68 504 Total 6,231 1,131 777 463 457 9,059 Income (loss) before income tax 905 13 210 47 (54 ) 1,121 Income tax (expense) benefit (226 ) 35 (46 ) (23 ) 20 (240 ) Net income (loss) 679 48 164 24 (34 ) 881 Amounts attributable to noncontrolling interests (71 ) (23 ) (104 ) (198 ) Net income (loss) attributable to Loews Corporation $ 608 $ 25 $ 60 $ 24 $ (34 ) $ 683

Basis of presentation - Additio

Basis of presentation - Additional Information (Detail) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summary Of Significant Accounting Policies [Line Items]
Shares excluded from diluted EPS calculation			0			400,000	0	400,000
Other assets		$ 2,555	$ 4,845		$ 2,555		$ 4,845
Other liabilities		$ 5,466	7,753		5,466		$ 7,753
Non-cash increase in net income					200
Increase to net income for uncertain tax positions				$ 23
Tax rate		35.00%					21.00%
CNA Financial [Member]
Summary Of Significant Accounting Policies [Line Items]
Subsidiary ownership percentage							89.00%
Diamond Offshore Drilling, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Subsidiary ownership percentage							53.00%
Consolidated Container [Member]
Summary Of Significant Accounting Policies [Line Items]
Subsidiary ownership percentage							99.00%
Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	$ (62)
Accounting Standards Update 2016-01 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	25
Accounting Standards Update 2016-16 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	(9)
Accounting Standards Update 2018-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	3
Accumulated Other Comprehensive Income (Loss) [Member] | Accounting Standards Update 2018-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update	(3)
Deferred Tax Asset [Member] | Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update	23
Other Assets [Member] | Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update	1,900
Other Liabilities [Member] | Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update	2,000
Pension Liability [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Accounting Standards Update 2018-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update	(130)
Pretax Loss on Investments [Member] | Accounting Standards Update 2016-01 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update			1				$ (22)
Other Comprehensive Income (Loss) [Member] | Accounting Standards Update 2016-01 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update						$ 2		$ 8
Unrealized Gain Loss on Investments [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Accounting Standards Update 2018-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update	$ 127
Operating Revenues and Other [Member] | Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update			145				419
Operating Expenses and Other [Member] | Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Changes due to adoption of new accounting standards update			149				423
Prior to Adoption of Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Other assets		$ 2,600	2,700		2,600		2,700
Other liabilities		$ 5,500	$ 5,500		$ 5,500		$ 5,500

Purchase of Boardwalk Pipelin_2

Purchase of Boardwalk Pipeline Common Units - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jun. 29, 2018	Sep. 30, 2018
Business Acquisition [Line Items]
Purchase of Boardwalk Pipeline common units		$ (1,718)
Boardwalk Pipeline [Member]
Business Acquisition [Line Items]
Increase to deferred income tax liabilities		213
Additional Paid-in Capital [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipeline common units		658
Additional Paid-in Capital [Member] | Boardwalk Pipeline [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipeline common units		658
Accumulated Other Comprehensive Income (Loss) [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipeline common units		(29)
Accumulated Other Comprehensive Income (Loss) [Member] | Boardwalk Pipeline [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipeline common units		$ (29)
Subsidiaries [Member] | Boardwalk Gp Lp [Member] | Boardwalk Pipeline [Member]
Business Acquisition [Line Items]
Purchase price	$ 1,500
Purchase price, per unit	$ 12.06

Investments - Net Investment In

Investments - Net Investment Income and Investment Gains (Losses) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net Investment Income [Line Items]
Total investment income	$ 508	$ 572	$ 1,596	$ 1,683
Investment expenses	(14)	(15)	(45)	(44)
Investment gains (losses)	15	16	21	93
Net investment income	494	557	1,551	1,639
Fixed Maturity Securities [Member]
Net Investment Income [Line Items]
Total investment income	449	455	1,339	1,367
Investment gains (losses)	10	16	32	92
Equity Securities [Member]
Net Investment Income [Line Items]
Total investment income	10	1	32	4
Investment gains (losses)	2		(23)
Derivative Instruments [Member]
Net Investment Income [Line Items]
Investment gains (losses)	1	(1)	10	(3)
Short Term and Other [Member]
Net Investment Income [Line Items]
Total investment income	10	5	30	13
Investment gains (losses)	2	1	2	4
Limited Partnership Investments [Member]
Net Investment Income [Line Items]
Total investment income	34	67	142	206
Income (Loss) from Trading Portfolio [Member]
Net Investment Income [Line Items]
Total investment income	(7)	34	13	67
Other [Member]
Net Investment Income [Line Items]
Total investment income	$ 12	$ 10	$ 40	$ 26

Investments - Net Investment _2

Investments - Net Investment Income and Investment Gains (Losses) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net Investment Income [Line Items]
Net unrealized gains (losses) on trading securities	$ (23)	$ 22	$ (66)	$ 35
Fixed Maturity Securities [Member]
Net Investment Income [Line Items]
Gross realized gains on available-for-sale securities	42	34	148	140
Gross realized losses on available-for-sale securities	32	$ 18	116	$ 48
Fixed Maturity Securities [Member] | Nonredeemable Preferred Stock [Member]
Net Investment Income [Line Items]
Net realized gains (losses) on trading securities	$ 2		$ (23)

Investments - Components of OTT

Investments - Components of OTTI Losses Recognized in Earnings by Asset Type (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	$ 3	$ 5	$ 9	$ 9
Corporate Bonds and Other [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	1	4	6	8
Total Asset-Backed [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	$ 2	$ 1	$ 3	$ 1

Investments - Amortized Cost an

Investments - Amortized Cost and Fair Values of Fixed Maturity and Equity Securities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	$ 38,237	$ 40,038
Gross Unrealized Gains	1,985	3,491
Gross Unrealized Losses	403	172
Estimated Fair Value	39,819	43,357
Unrealized OTTI Losses (Gains)	(24)	(38)
Corporate Bonds and Other [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	18,348	17,210
Gross Unrealized Gains	887	1,625
Gross Unrealized Losses	215	28
Estimated Fair Value	19,020	18,807
States, Municipalities and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	10,171	12,478
Gross Unrealized Gains	994	1,551
Gross Unrealized Losses	20	2
Estimated Fair Value	11,145	14,027
Unrealized OTTI Losses (Gains)		(11)
Residential Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	5,024	5,043
Gross Unrealized Gains	62	109
Gross Unrealized Losses	115	32
Estimated Fair Value	4,971	5,120
Unrealized OTTI Losses (Gains)	(24)	(27)
Commercial Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	2,165	1,840
Gross Unrealized Gains	23	46
Gross Unrealized Losses	36	14
Estimated Fair Value	2,152	1,872
Other Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	1,732	1,083
Gross Unrealized Gains	6	16
Gross Unrealized Losses	9	5
Estimated Fair Value	1,729	1,094
Total Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	8,921	7,966
Gross Unrealized Gains	91	171
Gross Unrealized Losses	160	51
Estimated Fair Value	8,852	8,086
Unrealized OTTI Losses (Gains)	(24)	(27)
U.S. Treasury and Obligations of Government-Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	145	111
Gross Unrealized Gains	2	2
Gross Unrealized Losses	2	4
Estimated Fair Value	145	109
Foreign Government [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	457	437
Gross Unrealized Gains	4	9
Gross Unrealized Losses	6	2
Estimated Fair Value	455	444
Redeemable Preferred Stock [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	9	10
Gross Unrealized Gains	1	1
Estimated Fair Value	10	11
Total Fixed Maturities Available-for-Sale [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	38,051	38,212
Gross Unrealized Gains	1,979	3,359
Gross Unrealized Losses	403	87
Estimated Fair Value	39,627	41,484
Unrealized OTTI Losses (Gains)	(24)	(38)
Fixed Maturities Trading [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	186	649
Gross Unrealized Gains	6	2
Gross Unrealized Losses		2
Estimated Fair Value	$ 192	649
Fixed Maturity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost		38,861
Gross Unrealized Gains		3,361
Gross Unrealized Losses		89
Estimated Fair Value		42,133
Unrealized OTTI Losses (Gains)		(38)
Common Stock [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost		21
Gross Unrealized Gains		7
Gross Unrealized Losses		1
Estimated Fair Value		27
Preferred Stock [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost		638
Gross Unrealized Gains		31
Gross Unrealized Losses		1
Estimated Fair Value		668
Equity Securities Available-for-Sale [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost		659
Gross Unrealized Gains		38
Gross Unrealized Losses		2
Estimated Fair Value		695
Equity Securities Trading [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost		518
Gross Unrealized Gains		92
Gross Unrealized Losses		81
Estimated Fair Value		529
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost		1,177
Gross Unrealized Gains		130
Gross Unrealized Losses		83
Estimated Fair Value		$ 1,224

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Shadow Adjustments	$ 997,000,000	$ 1,300,000,000
Additional other than temporary impairment losses	$ 0

Investments - Securities Availa

Investments - Securities Available-for-Sale in Gross Unrealized Loss Position (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months		$ 3,620
Gross Unrealized Losses, Less than 12 Months		40
Estimated Fair Value, 12 Months or Longer		1,455
Gross Unrealized Losses, 12 Months or Longer		49
Total Estimated Fair Value		5,075
Total Gross Unrealized Losses		89
Corporate Bonds and Other [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	$ 7,546	1,354
Gross Unrealized Losses, Less than 12 Months	197	21
Estimated Fair Value, 12 Months or Longer	342	168
Gross Unrealized Losses, 12 Months or Longer	18	7
Total Estimated Fair Value	7,888	1,522
Total Gross Unrealized Losses	215	28
States, Municipalities and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	807	72
Gross Unrealized Losses, Less than 12 Months	19	1
Estimated Fair Value, 12 Months or Longer	2	85
Gross Unrealized Losses, 12 Months or Longer	1	1
Total Estimated Fair Value	809	157
Total Gross Unrealized Losses	20	2
Residential Mortgage-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	3,409	1,228
Gross Unrealized Losses, Less than 12 Months	89	5
Estimated Fair Value, 12 Months or Longer	501	947
Gross Unrealized Losses, 12 Months or Longer	26	27
Total Estimated Fair Value	3,910	2,175
Total Gross Unrealized Losses	115	32
Commercial Mortgage-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	968	403
Gross Unrealized Losses, Less than 12 Months	15	4
Estimated Fair Value, 12 Months or Longer	322	212
Gross Unrealized Losses, 12 Months or Longer	21	10
Total Estimated Fair Value	1,290	615
Total Gross Unrealized Losses	36	14
Other Asset-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	953	248
Gross Unrealized Losses, Less than 12 Months	9	3
Estimated Fair Value, 12 Months or Longer	45	18
Gross Unrealized Losses, 12 Months or Longer		2
Total Estimated Fair Value	998	266
Total Gross Unrealized Losses	9	5
Total Asset-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	5,330	1,879
Gross Unrealized Losses, Less than 12 Months	113	12
Estimated Fair Value, 12 Months or Longer	868	1,177
Gross Unrealized Losses, 12 Months or Longer	47	39
Total Estimated Fair Value	6,198	3,056
Total Gross Unrealized Losses	160	51
U.S. Treasury and Obligations of Government-Sponsored Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	35	49
Gross Unrealized Losses, Less than 12 Months		2
Estimated Fair Value, 12 Months or Longer	42	21
Gross Unrealized Losses, 12 Months or Longer	2	2
Total Estimated Fair Value	77	70
Total Gross Unrealized Losses	2	4
Foreign Government [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	188	166
Gross Unrealized Losses, Less than 12 Months	4	2
Estimated Fair Value, 12 Months or Longer	64	4
Gross Unrealized Losses, 12 Months or Longer	2
Total Estimated Fair Value	252	170
Total Gross Unrealized Losses	6	2
Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	13,906	3,520
Gross Unrealized Losses, Less than 12 Months	333	38
Estimated Fair Value, 12 Months or Longer	1,318	1,455
Gross Unrealized Losses, 12 Months or Longer	70	49
Total Estimated Fair Value	15,224	4,975
Total Gross Unrealized Losses	$ 403	87
Common Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months		7
Gross Unrealized Losses, Less than 12 Months		1
Total Estimated Fair Value		7
Total Gross Unrealized Losses		1
Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months		93
Gross Unrealized Losses, Less than 12 Months		1
Total Estimated Fair Value		93
Total Gross Unrealized Losses		1
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months		100
Gross Unrealized Losses, Less than 12 Months		2
Total Estimated Fair Value		100
Total Gross Unrealized Losses		$ 2

Investments - Pretax Credit Los

Investments - Pretax Credit Loss Component Reflected in Retained Earnings on Fixed Maturity Securities (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Beginning balance of credit losses on fixed maturity securities	$ 21	$ 30	$ 27	$ 36
Reductions for securities sold during the period	(2)	(2)	(8)	(8)
Ending balance of credit losses on fixed maturity securities	$ 19	$ 28	$ 19	$ 28

Investments - Available-for-Sal

Investments - Available-for-Sale Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Cost or Amortized Cost, Due in one year or less	$ 1,457	$ 1,135
Cost or Amortized Cost, Due after one year through five years	8,017	8,165
Cost or Amortized Cost, Due after five years through ten years	16,453	16,060
Cost or Amortized Cost, Due after ten years	12,124	12,852
Cost or Amortized Cost, Total	38,051	38,212
Estimated Fair Value, Due in one year or less	1,473	1,157
Estimated Fair Value, Due after one year through five years	8,197	8,501
Estimated Fair Value, Due after five years through ten years	16,475	16,718
Estimated Fair Value, Due after ten years	13,482	15,108
Estimated Fair Value, Total	$ 39,627	$ 41,484

Investments - Summary of Aggreg

Investments - Summary of Aggregate Contractual or Notional Amounts and Estimated Fair Values Related to Derivative Financial Instruments (Detail) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Embedded Derivative on Funds Withheld Liability [Member]
Derivative [Line Items]
Contractual/Notional Amount	$ 174,000,000	$ 167,000,000
Estimated Fair Value, Asset	6,000,000
Estimated Fair Value, (Liability)		(3,000,000)
With Hedge Designation [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Contractual/Notional Amount	500,000,000	500,000,000
Estimated Fair Value, Asset	22,000,000	4,000,000
Without Hedge Designation [Member] | Equity Markets, Options - Purchased [Member]
Derivative [Line Items]
Contractual/Notional Amount	222,000,000	224,000,000
Estimated Fair Value, Asset	9,000,000	12,000,000
Without Hedge Designation [Member] | Equity Markets, Options - Written [Member]
Derivative [Line Items]
Contractual/Notional Amount	201,000,000	290,000,000
Estimated Fair Value, (Liability)	(6,000,000)	(7,000,000)
Without Hedge Designation [Member] | Equity Futures [Member] | Short [Member]
Derivative [Line Items]
Contractual/Notional Amount	154,000,000	265,000,000
Estimated Fair Value, Asset		1,000,000
Without Hedge Designation [Member] | Commodity Futures [Member] | Long [Member]
Derivative [Line Items]
Contractual/Notional Amount	47,000,000	$ 44,000,000
Estimated Fair Value, Asset	$ 1,000,000

Fair Value - Assets and Liabili

Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Payable to Brokers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities, measured on a recurring basis	$ (13)	$ (12)
Corporate Bonds and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	19,630	19,371
States, Municipalities and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	11,145	14,027
Total Asset-Backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	8,852	8,086
Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	39,627	41,484
Fixed Maturities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	192	649
Fixed Maturity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	39,819	42,133
Equity Securities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		695
Equity Securities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		529
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,267	1,224
Receivables [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	23	5
Short Term and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	3,752	4,627
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Payable to Brokers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities, measured on a recurring basis	(13)	(12)
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Bonds and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	183	128
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	183	128
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Maturities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		10
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Maturity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	183	138
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		91
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		527
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	623	618
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Receivables [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		1
Level 1 [Member] | Short Term and Other [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	2,678	3,669
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Bonds and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	19,259	19,145
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | States, Municipalities and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	11,145	14,026
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Total Asset-Backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	8,554	7,751
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	38,958	40,922
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Maturities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	186	635
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Maturity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	39,144	41,557
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		584
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	625	584
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Receivables [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	23	4
Level 2 [Member] | Short Term and Other [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	1,074	958
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Bonds and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	188	98
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | States, Municipalities and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		1
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Total Asset-Backed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	298	335
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	486	434
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Maturities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	6	4
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Maturity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	492	438
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities Available-for-Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		20
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities Trading [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis		2
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	$ 19	$ 22

Fair Value - Reconciliations of

Fair Value - Reconciliations of Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Corporate Bonds and Other [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 94	$ 100	$ 98	$ 130
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)		1	(1)	1
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		1	(1)	2
Purchases	67	13	69	18
Sales			(5)	(1)
Settlements	(3)	(11)	(7)	(36)
Transfers into Level 3	30	15	35	15
Transfers out of Level 3				(10)
Ending balance	188	119	188	119
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities			(2)
States, Municipalities and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1	1	1	1
Settlements	(1)		(1)
Ending balance		1		1
Total Asset-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	273	218	335	199
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)	(2)		5	1
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		1	(6)	4
Purchases	55	39	126	90
Sales			(72)
Settlements	(25)	(13)	(37)	(26)
Transfers into Level 3	29	101	42	153
Transfers out of Level 3	(32)		(95)	(75)
Ending balance	298	346	298	346
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	(2)		(2)
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	1		(2)
Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	368	319	434	330
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)	(2)	1	4	2
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		2	(7)	6
Purchases	122	52	195	108
Sales			(77)	(1)
Settlements	(29)	(24)	(45)	(62)
Transfers into Level 3	59	116	77	168
Transfers out of Level 3	(32)		(95)	(85)
Ending balance	486	466	486	466
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	(2)		(2)
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	1		(4)
Fixed Maturities Trading [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	7	5	4	6
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)			3	(1)
Sales	(1)		(1)
Ending balance	6	5	6	5
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities			2	(1)
Fixed Maturity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	375	324	438	336
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)	(2)	1	7	1
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		2	(7)	6
Purchases	122	52	195	108
Sales	(1)		(78)	(1)
Settlements	(29)	(24)	(45)	(62)
Transfers into Level 3	59	116	77	168
Transfers out of Level 3	(32)		(95)	(85)
Ending balance	492	471	492	471
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	(2)			(1)
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	1		(4)
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	18	20	22	20
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)	1		(2)
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI				2
Purchases		1		2
Sales			(1)	(3)
Ending balance	19	21	19	21
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	$ 1		$ (2)
Equity Securities Available-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		19		19
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI				2
Purchases				1
Sales				(3)
Ending balance		19		19
Equity Securities Trading [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		1		1
Purchases		1		1
Ending balance		2		2
Life Settlement Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		1		58
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)				6
Sales		(1)		(59)
Settlements				(5)
Derivative Instruments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative financial instruments, net, Beginning balance				0
Derivative financial instruments, net, Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income (Loss)				1
Derivative financial instruments, net, Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI				0
Derivative financial instruments, net, Purchases				0
Derivative financial instruments, net, Sales				(1)
Derivative financial instruments, net, Settlements				0
Derivative financial instruments, net, Transfers into Level 3				0
Derivative financial instruments, net, Transfers out of Level 3				0
Derivative financial instruments, net, Ending balance		$ 0		0
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities				$ 0

Fair Value - Quantitative Infor

Fair Value - Quantitative Information about Significant Unobservable Inputs Utilized by Company in Fair Value Measurements of Level 3 Assets (Detail) $ in Millions	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair value	$ 39,627	$ 41,484
Level 3 [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair value	$ 198	$ 136
Minimum [Member] | Level 3 [Member] | Credit Spread [Member] | Discounted Cash Flow [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input	0.01	0.01
Maximum [Member] | Level 3 [Member] | Credit Spread [Member] | Discounted Cash Flow [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input	0.12	0.12
Weighted Average [Member] | Level 3 [Member] | Credit Spread [Member] | Discounted Cash Flow [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input	0.02	0.03

Fair Value - Carrying Amount, E

Fair Value - Carrying Amount, Estimated Fair Value and Level of Fair Value Hierarchy of Company's Financial Assets and Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Estimate Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	$ 847	$ 844
Short term debt	146	278
Long term debt	11,167	11,491
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	868	839
Short term debt	146	278
Long term debt	11,295	11,236
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short term debt	6	156
Long term debt	10,537	10,966
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	847	844
Short term debt	140	122
Long term debt	$ 630	$ 525

Claim and Claim Adjustment Ex_3

Claim and Claim Adjustment Expense Reserves - Additional Information (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2010	Dec. 31, 2017
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses, net of reinsurance	$ 46	$ 269	$ 106	$ 342
Catastrophe-related reinsurance reinstatement premium				6
Net A&EP adverse development before consideration of LPT			113	60
Fair value of the collateral trust account	3,200		3,200			$ 3,100
Hurricanes Harvey [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses, net of reinsurance				149
Hurricane Irma [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses, net of reinsurance				95
Hurricane Maria [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses, net of reinsurance				20
Hurricane Florence [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses, net of reinsurance			35
Asbestos and Environmental Pollution Reserves [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net A&EP claim and allocated claim adjustment expense reserves					$ 1,600
Aggregate limit under A&EP Loss Portfolio Transfer					4,000
Ceded A&EP claim and allocated claim adjustment expense reserves					1,200
Reinsurance premium paid to NICO under A&EP Loss Portfolio Transfer					2,000
Net reinsurance receivables transferred to NICO under A&EP Loss Portfolio Transfer					215
Total consideration					$ 2,200
Cumulative amounts ceded under the Loss Portfolio Transfer	3,000		3,000			2,900
Remaining unrecognized retroactive reinsurance benefit	339		339			$ 326
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Favorable net prior year development	$ 62	$ 115	$ 160	$ 227

Claim and Claim Adjustment Ex_4

Claim and Claim Adjustment Expense Reserves - Reconciliation of Claim and Claim Adjustment Expense Reserves (Detail) - CNA Financial [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross reserves, beginning of year	$ 22,004	$ 22,343
Ceded reserves, beginning of year	3,934	4,094
Net reserves, beginning of year	18,070	18,249
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	3,866	3,949
Decrease in provision for insured events of prior years	(173)	(284)
Amortization of discount	136	138
Total net incurred	3,829	3,803
Net payments attributable to:
Current year events	(658)	(560)
Prior year events	(3,415)	(3,401)
Total net payments	(4,073)	(3,961)
Foreign currency translation adjustment and other	(80)	110
Net reserves, end of period	17,746	18,201
Ceded reserves, end of period	3,858	4,008
Gross reserves, end of period	$ 21,604	$ 22,209

Claim and Claim Adjustment Ex_5

Claim and Claim Adjustment Expense Reserves - Net Prior Year Development in CNA's Property and Casualty Operations (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Medical professional liability	$ 15	$ 8	$ 38	$ 30
Other professional liability and management liability	(45)	(19)	(113)	(88)
Surety	(20)	(82)	(50)	(82)
Commercial auto	1	(12)		(37)
General liability	(5)	(2)	13	(19)
Workers' compensation	(2)	9	(14)	(38)
Other	(6)	(17)	(34)	7
Total pretax (favorable) unfavorable development	$ (62)	$ (115)	$ (160)	$ (227)

Claim and Claim Adjustment Ex_6

Claim and Claim Adjustment Expense Reserves - Schedule of Impact of Loss Portfolio Transfer on the Consolidated Statement of Operations (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Additional amounts ceded under LPT:
Net A&EP adverse development before consideration of LPT			$ 113	$ 60
Provision for uncollectible third-party reinsurance on A&EP			(16)
Total additional amounts ceded under LPT			97	60
Retroactive reinsurance benefit recognized	$ (12)	$ (17)	(84)	$ (60)
Pretax impact of deferred retroactive reinsurance	$ (12)	$ (17)	$ 13

Shareholders' Equity - Componen

Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 24,566	$ 23,361
Cumulative effect adjustment from changes in accounting standards			(91)
Balance, as adjusted			24,475
Other comprehensive income (loss)	$ (151)	$ 77	(757)	285
Purchase of Boardwalk Pipeline common units			(1,718)
Ending Balance	21,886	24,361	21,886	24,361
OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	17	23	22	27
Balance, as adjusted			26
Other comprehensive income (loss) before reclassifications, after tax	(1)	1	(12)
Reclassification of (gains) losses from accumulated other comprehensive income, after tax			1	(3)
Other comprehensive income (loss)	(1)	1	(11)	(3)
Amounts attributable to noncontrolling interests			1
Ending Balance	16	24	16	24
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	244	705	673	576
Balance, as adjusted			771
Other comprehensive income (loss) before reclassifications, after tax	(148)	35	(718)	228
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	(10)	(12)	(28)	(61)
Other comprehensive income (loss)	(158)	23	(746)	167
Amounts attributable to noncontrolling interests	17	(3)	78	(18)
Ending Balance	103	725	103	725
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	13	(2)		(2)
Other comprehensive income (loss) before reclassifications, after tax		(2)	12	(3)
Reclassification of (gains) losses from accumulated other comprehensive income, after tax		3	2	4
Other comprehensive income (loss)		1	14	1
Amounts attributable to noncontrolling interests		(1)		(1)
Purchase of Boardwalk Pipeline common units			(1)
Ending Balance	13	(2)	13	(2)
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(774)	(632)	(633)	(646)
Balance, as adjusted			(763)
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	8	11	27	26
Other comprehensive income (loss)	8	11	27	26
Amounts attributable to noncontrolling interests	1	(1)	(1)	(2)
Purchase of Boardwalk Pipeline common units			(28)
Ending Balance	(765)	(622)	(765)	(622)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(125)	(130)	(88)	(178)
Balance, as adjusted			(88)
Other comprehensive income (loss) before reclassifications, after tax		41	(41)	94
Other comprehensive income (loss)		41	(41)	94
Amounts attributable to noncontrolling interests		(4)	4	(9)
Ending Balance	(125)	(93)	(125)	(93)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(625)	(36)	(26)	(223)
Balance, as adjusted			(54)
Other comprehensive income (loss) before reclassifications, after tax	(149)	75	(759)	319
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	(2)	2	2	(34)
Other comprehensive income (loss)	(151)	77	(757)	285
Amounts attributable to noncontrolling interests	18	(9)	82	(30)
Purchase of Boardwalk Pipeline common units			(29)
Ending Balance	$ (758)	$ 32	(758)	$ 32
Accounting Standards Update 2016-01 [Member] | Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards			(25)
Accounting Standards Update 2016-01 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards			(25)
Accounting Standards Update 2018-02 [Member] | OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards			4
Accounting Standards Update 2018-02 [Member] | Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards			123
Accounting Standards Update 2018-02 [Member] | Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards			(130)
Accounting Standards Update 2018-02 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards			$ (3)

Shareholders' Equity - Compon_2

Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	$ 0	$ 0	$ 3	$ 0
Tax on reclassification from accumulated other comprehensive income	0	0	0	1
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	40	(20)	190	(130)
Tax on reclassification from accumulated other comprehensive income	2	4	7	28
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	(2)	0	(4)	0
Tax on reclassification from accumulated other comprehensive income	0	0	0	0
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	0	0	0	0
Tax on reclassification from accumulated other comprehensive income	(1)	(6)	(6)	(13)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	0	0	0	0
Tax on reclassification from accumulated other comprehensive income	0	$ 0	0	$ 0
Accounting Standards Update 2016-01 [Member] | OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on cumulative effect adjustment for adoption of ASU 2016-01	0		0
Accounting Standards Update 2016-01 [Member] | Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on cumulative effect adjustment for adoption of ASU 2016-01	8		8
Accounting Standards Update 2016-01 [Member] | Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on cumulative effect adjustment for adoption of ASU 2016-01	0		0
Accounting Standards Update 2016-01 [Member] | Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on cumulative effect adjustment for adoption of ASU 2016-01	0		0
Accounting Standards Update 2016-01 [Member] | Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on cumulative effect adjustment for adoption of ASU 2016-01	$ 0		$ 0

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Treasury stock repurchased, shares	17.4	0.1
Purchase of Loews treasury stock	$ 876	$ 6

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Schedule of Disaggregation of Revenues (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,209	$ 1,119	$ 3,683	$ 3,176
Other revenues	37	23	71	87
Operating revenues and other	1,246	1,142	3,754	3,263
CNA Financial [Member] | Non-insurance Warranty [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	258	99	744	290
Diamond Offshore [Member] | Drilling Contracts [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	287	366	851	1,139
Boardwalk Pipeline [Member] | Transportation and Storage of Natural Gas and NGLs and Other Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	274	290	886	944
Loews Hotels And Co [Member] | Lodging and Related Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	167	162	550	510
Corporate [Member] | Rigid Plastic Packaging and Recycled Resin [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 223	$ 202	$ 652	$ 293

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Receivables from contracts with customers, included within Receivables	$ 415,000,000	$ 415,000,000	$ 488,000,000
Deferred revenue, included within Other liabilities	3,400,000,000	3,400,000,000	$ 3,000,000,000
Revenue recognized		685,000,000
Contract cost	2,500,000,000	2,500,000,000
Amortization expense, contract cost	202,000,000	552,000,000
Adjustments to deferred costs charges, non-insurance warranty contract		0
Performance obligations	12,400,000,000	12,400,000,000
Remainder of 2018 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations	600,000,000	600,000,000
2019 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations	$ 2,000,000,000	$ 2,000,000,000
Minimum [Member] | CNA Financial [Member]
Disaggregation of Revenue [Line Items]
Non-insurance warranty product term		1 month
Minimum [Member] | Diamond Offshore [Member]
Disaggregation of Revenue [Line Items]
Contract term		2 months
Minimum [Member] | Boardwalk Pipeline [Member]
Disaggregation of Revenue [Line Items]
Contract term		1 year
Maximum [Member] | CNA Financial [Member]
Disaggregation of Revenue [Line Items]
Non-insurance warranty product term		10 years
Maximum [Member] | Diamond Offshore [Member]
Disaggregation of Revenue [Line Items]
Contract term		60 months
Maximum [Member] | Boardwalk Pipeline [Member]
Disaggregation of Revenue [Line Items]
Contract term		20 years

Benefit Plans - Components of N

Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 6	$ 6
Interest cost	27	30	82	89
Expected return on plan assets	(44)	(43)	(134)	(129)
Amortization of unrecognized net (gain) loss	11	10	32	32
Settlement charge		7	7	10
Net periodic (benefit) cost	(4)	6	(7)	8
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of unrecognized prior service benefit	(1)	(1)	(2)	(2)
Amortization of unrecognized net (gain) loss	(1)		(1)
Net periodic (benefit) cost	$ (2)	$ (1)	$ (4)	$ (3)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Commitments [Line Items]
Aggregate amount related to indemnification agreements	$ 252		$ 252
Aggregate amount related to quantifiable guarantees	375		375
Potential amount of future payments under guarantees	1,800		1,800
Increase (decrease) in premium development recognized	$ 6		6	$ (37)
Increase in interest expense		$ 1	$ 1	$ 7

Segments - Additional Informati

Segments - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018Segment
Segment Reporting [Abstract]
Number of reportable segments	5
Number of individual operating subsidiaries	4

Segments - Consolidating Statem

Segments - Consolidating Statement of Income and Total Assets by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Insurance premiums	$ 1,853	$ 1,806	$ 5,453	$ 5,185
Net investment income	494	557	1,551	1,639
Investment gains	15	16	21	93
Operating revenues and other	1,246	1,142	3,754	3,263
Total	3,608	3,521	10,779	10,180
Expenses:
Insurance claims and policyholders' benefits	1,312	1,480	3,978	4,053
Amortization of deferred acquisition costs	337	309	992	926
Operating expenses and other	1,459	1,245	4,313	3,576
Interest	146	223	430	504
Total	3,254	3,257	9,713	9,059
Income (loss) before income tax	354	264	1,066	1,121
Income tax (expense) benefit	(65)	(52)	(149)	(240)
Net income (loss)	289	212	917	881
Amounts attributable to noncontrolling interests	(11)	(55)	(116)	(198)
Net income (loss) attributable to Loews Corporation	278	157	801	683
CNA Financial [Member] | Operating Segments [Member]
Revenues:
Insurance premiums	1,853	1,806	5,453	5,185
Net investment income	487	509	1,483	1,529
Investment gains	15	16	21	93
Operating revenues and other	267	110	774	329
Total	2,622	2,441	7,731	7,136
Expenses:
Insurance claims and policyholders' benefits	1,312	1,480	3,978	4,053
Amortization of deferred acquisition costs	337	309	992	926
Operating expenses and other	538	379	1,580	1,086
Interest	34	83	104	166
Total	2,221	2,251	6,654	6,231
Income (loss) before income tax	401	190	1,077	905
Income tax (expense) benefit	(66)	(44)	(181)	(226)
Net income (loss)	335	146	896	679
Amounts attributable to noncontrolling interests	(35)	(16)	(95)	(71)
Net income (loss) attributable to Loews Corporation	300	130	801	608
Diamond Offshore [Member] | Operating Segments [Member]
Revenues:
Net investment income	2		6	1
Operating revenues and other	287	368	853	1,143
Total	289	368	859	1,144
Expenses:
Operating expenses and other	311	307	927	1,012
Interest	34	64	92	119
Total	345	371	1,019	1,131
Income (loss) before income tax	(56)	(3)	(160)	13
Income tax (expense) benefit	5	14	59	35
Net income (loss)	(51)	11	(101)	48
Amounts attributable to noncontrolling interests	24	(5)	47	(23)
Net income (loss) attributable to Loews Corporation	(27)	6	(54)	25
Boardwalk Pipeline [Member] | Operating Segments [Member]
Revenues:
Operating revenues and other	279	301	901	987
Total	279	301	901	987
Expenses:
Operating expenses and other	197	191	598	646
Interest	44	41	131	131
Total	241	232	729	777
Income (loss) before income tax	38	69	172	210
Income tax (expense) benefit	(10)	(18)	(24)	(46)
Net income (loss)	28	51	148	164
Amounts attributable to noncontrolling interests		(34)	(68)	(104)
Net income (loss) attributable to Loews Corporation	28	17	80	60
Loews Hotels And Co [Member] | Operating Segments [Member]
Revenues:
Net investment income			1
Operating revenues and other	190	162	573	510
Total	190	162	574	510
Expenses:
Operating expenses and other	169	147	494	443
Interest	7	7	22	20
Total	176	154	516	463
Income (loss) before income tax	14	8	58	47
Income tax (expense) benefit	(3)	(4)	(17)	(23)
Net income (loss)	11	4	41	24
Net income (loss) attributable to Loews Corporation	11	4	41	24
Corporate [Member]
Revenues:
Net investment income	5	48	61	109
Operating revenues and other	223	201	653	294
Total	228	249	714	403
Expenses:
Operating expenses and other	244	221	714	389
Interest	27	28	81	68
Total	271	$ 249	795	457
Income (loss) before income tax	(43)		(81)	(54)
Income tax (expense) benefit	9		14	20
Net income (loss)	(34)		(67)	(34)
Net income (loss) attributable to Loews Corporation	$ (34)		$ (67)	$ (34)