Loews (L) 10-Q 30 Apr 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 20, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
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 Common Stock, Shares Outstanding		319,322,226

Consolidated Condensed Balance

Consolidated Condensed Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets:
Fixed maturities, amortized cost of $38,830 and $38,861	$ 41,100	$ 42,133
Equity securities, cost of $1,326 and $1,177	1,333	1,224
Limited partnership investments	3,291	3,278
Other invested assets, primarily mortgage loans	974	945
Short term investments	4,367	4,646
Total investments	51,065	52,226
Cash	451	472
Receivables	7,893	7,613
Property, plant and equipment	15,461	15,427
Goodwill	661	659
Other assets	4,590	2,555
Deferred acquisition costs of insurance subsidiaries	665	634
Total assets	80,786	79,586
Liabilities and Equity:
Claim and claim adjustment expense	22,067	22,004
Future policy benefits	10,783	11,179
Unearned premiums	4,256	4,029
Total insurance reserves	37,106	37,212
Payable to brokers	280	60
Short term debt	213	280
Long term debt	11,255	11,253
Deferred income taxes	734	749
Other liabilities	7,350	5,466
Total liabilities	56,938	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 - 332,646,800 and 332,487,815 shares	3	3
Additional paid-in capital	3,142	3,151
Retained earnings	16,321	16,096
Accumulated other comprehensive loss	(417)	(26)
Shareholders' equity before treasury stock, total	19,049	19,224
Less treasury stock, at cost (10,250,033 and 400,000 shares)	(517)	(20)
Total shareholders' equity	18,532	19,204
Noncontrolling interests	5,316	5,362
Total equity	23,848	24,566
Total liabilities and equity	$ 80,786	$ 79,586

Consolidated Condensed Balance3

Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 38,830	$ 38,861
Equity securities, cost	$ 1,326	$ 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	332,646,800	332,487,815
Treasury stock, shares	10,250,033	400,000

Consolidated Condensed Statemen

Consolidated Condensed Statements of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Insurance premiums	$ 1,785	$ 1,645
Net investment income	506	604
Investment gains (losses):
Other-than-temporary impairment losses	(6)	(2)
Other net investment gains	15	36
Total investment gains	9	34
Operating revenues and other	1,281	1,017
Total	3,581	3,300
Expenses:
Insurance claims and policyholders' benefits	1,339	1,293
Amortization of deferred acquisition costs	296	305
Operating expenses and other	1,400	1,050
Interest	141	142
Total	3,176	2,790
Income before income tax	405	510
Income tax expense	(25)	(119)
Net income	380	391
Amounts attributable to noncontrolling interests	(87)	(96)
Net income attributable to Loews Corporation	$ 293	$ 295
Basic net income per share	$ 0.89	$ 0.88
Diluted net income per share	0.89	0.87
Dividends per share	$ 0.0625	$ 0.0625
Weighted average shares outstanding:
Shares of common stock	327,780	336,880
Dilutive potential shares of common stock	940	800
Total weighted average shares outstanding assuming dilution	328,720	337,680

Consolidated Condensed Stateme5

Consolidated Condensed Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 380	$ 391
Other comprehensive income (loss), after tax Changes in:
Net unrealized losses on investments with other-than-temporary impairments	(9)	(4)
Net other unrealized gains (losses) on investments	(429)	67
Total unrealized gains (losses) on investments	(438)	63
Unrealized gains on cash flow hedges	10
Pension liability	10	8
Foreign currency translation	11	11
Other comprehensive income (loss)	(407)	82
Comprehensive income (loss)	(27)	473
Amounts attributable to noncontrolling interests	(43)	(104)
Total comprehensive income (loss) attributable to Loews Corporation	$ (70)	$ 369

Consolidated Condensed Stateme6

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	391			295			96
Other comprehensive income (loss)	82				74		8
Dividends paid	(97)			(21)
Dividends paid							(76)
Stock-based compensation			(19)				19
Other	(3)			(4)			1
Ending Balance at Mar. 31, 2017	23,734	3	3,168	15,466	(149)		5,246
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	380			293			87
Other comprehensive income (loss)	(407)				(363)		(44)
Dividends paid	(98)			(20)
Dividends paid							(78)
Purchases of Loews treasury stock	(497)					(497)
Stock-based compensation			(7)				7
Other	(5)		(2)	(5)			2
Ending Balance at Mar. 31, 2018	$ 23,848	$ 3	$ 3,142	$ 16,321	$ (417)	$ (517)	$ 5,316

Consolidated Condensed Stateme7

Consolidated Condensed Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities:
Net income	$ 380	$ 391
Adjustments to reconcile net income to net cash provided (used) by operating activities, net	185	318
Changes in operating assets and liabilities, net:
Receivables	(147)	51
Deferred acquisition costs	(29)	(24)
Insurance reserves	311	135
Other assets	(56)	(40)
Other liabilities	(215)	(265)
Trading securities	84	(567)
Net cash flow operating activities	513	(1)
Investing Activities:
Purchases of fixed maturities	(2,690)	(2,097)
Proceeds from sales of fixed maturities	2,576	1,359
Proceeds from maturities of fixed maturities	531	823
Purchases of limited partnership investments	(63)	(18)
Proceeds from sales of limited partnership investments	69	62
Purchases of property, plant and equipment	(230)	(211)
Dispositions	2	2
Change in short term investments	(25)	366
Other, net	(114)	(13)
Net cash flow investing activities	56	273
Financing Activities:
Dividends paid	(20)	(21)
Dividends paid to noncontrolling interests	(78)	(76)
Purchases of Loews treasury stock	(497)
Principal payments on debt	(303)	(776)
Issuance of debt	233	685
Other, net	74
Net cash flow financing activities	(591)	(188)
Effect of foreign exchange rate on cash	1	1
Net change in cash	(21)	85
Cash, beginning of period	472	327
Cash, end of period	$ 451	$ 412

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 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 51% 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 March 31, 2018 and December 31, 2017 and results of operations, comprehensive income and changes in shareholders’ equity and cash flows for the three months ended March 31, 2018 and 2017. Net income for the first quarter 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 0.7 million shares attributable to employee stock-based compensation awards excluded from the diluted weighted average shares outstanding amounts for the three months ended March 31, 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 Recently issued ASUs – 2016-02, 2014-09. In June of 2016, the FASB issued ASU 2016-13, available-for-sale available-for-sale 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

Investments	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Investments	2. Investments Net investment income is as follows: Three Months Ended March 31 2018 2017 (In millions) Fixed maturity securities $ 446 $ 455 Limited partnership investments 48 116 Short term investments 9 4 Equity securities 10 1 Income (loss) from trading portfolio (a) (3 ) 34 Other 11 8 Total investment income 521 618 Investment expenses (15 ) (14 ) Net investment income $ 506 $ 604 (a) Net unrealized (losses) gains related to changes in fair value on securities still held were $(25) and $46 for the three months ended March 31, 2018 and 2017. Investment gains (losses) are as follows: Three Months Ended March 31 2018 2017 (In millions) Fixed maturity securities $ 18 $ 32 Equity securities (15 ) Derivative instruments 5 1 Short term investments and other 1 1 Investment gains (a) $ 9 $ 34 (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 March 31 2018 2017 (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 5 $ 2 Asset-backed 1 Net OTTI losses recognized in earnings $ 6 $ 2 The amortized cost and fair values of fixed maturity and equity securities are as follows: March 31, 2018 Cost or Gross Gross Estimated Unrealized (In millions) Fixed maturity securities: Corporate and other bonds $ 17,538 $ 1,177 $ 115 $ 18,600 States, municipalities and political subdivisions 11,682 1,205 12 12,875 Asset-backed: Residential mortgage-backed 5,050 83 78 5,055 $ (27 ) Commercial mortgage-backed 1,948 29 22 1,955 Other asset-backed 1,185 10 7 1,188 Total asset-backed 8,183 122 107 8,198 (27 ) U.S. Treasury and obligations of government-sponsored enterprises 124 2 7 119 Foreign government 448 7 5 450 Redeemable preferred stock 9 1 10 Fixed maturities available-for-sale 37,984 2,514 246 40,252 (27 ) Fixed maturities trading 846 3 1 848 Total fixed maturity securities $ 38,830 $ 2,517 $ 247 $ 41,100 $ (27 ) December 31, 2017 (In millions) 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 Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized March 31, 2018 Fair Value Losses Fair Value Losses Fair Value Losses (In millions) Fixed maturity securities: Corporate and other bonds $ 4,229 $ 104 $ 146 $ 11 $ 4,375 $ 115 States, municipalities and political subdivisions 962 12 3 965 12 Asset-backed: Residential mortgage-backed 2,570 55 504 23 3,074 78 Commercial mortgage-backed 668 11 200 11 868 22 Other asset-backed 441 5 15 2 456 7 Total asset-backed 3,679 71 719 36 4,398 107 U.S. Treasury and obligations of government- sponsored enterprises 59 4 26 3 85 7 Foreign government 214 5 4 218 5 Total fixed maturity securities $ 9,143 $ 196 $ 898 $ 50 $ 10,041 $ 246 December 31, 2017 (In millions) 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 March 31, 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 March 31, 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 March 31, 2018 and 2017 for which a portion of an OTTI loss was recognized in Other comprehensive income. Three Months Ended March 31 2018 2017 (In millions) Beginning balance of credit losses on fixed maturity securities $ 27 $ 36 Reductions for securities sold during the period (2 ) (4 ) Ending balance of credit losses on fixed maturity securities $ 25 $ 32 Contractual Maturity The following table presents available-for-sale March 31, 2018 December 31, 2017 Cost or Estimated Cost or Estimated Amortized Fair Amortized Fair Cost Value Cost Value (In millions) Due in one year or less $ 1,323 $ 1,343 $ 1,135 $ 1,157 Due after one year through five years 8,277 8,495 8,165 8,501 Due after five years through ten years 15,802 16,093 16,060 16,718 Due after ten years 12,582 14,321 12,852 15,108 Total $ 37,984 $ 40,252 $ 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. March 31, 2018 December 31, 2017 Contractual/ Notional Amount Contractual/ Notional Amount Estimated Fair Value Estimated Fair Value Asset (Liability) Asset (Liability) (In millions) With hedge designation: Interest rate swaps $ 500 $ 15 $ 500 $ 4 Without hedge designation: Equity markets: Options – purchased 144 9 224 12 166 $ (7) 290 $ (7) Futures – short 146 265 1 Commodity futures – long 46 44 Embedded derivative on funds withheld liability 163 1 167 (3)

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value	3. 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 and foreign governments and redeemable preferred stock. March 31, 2018 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 167 $ 18,912 $ 100 $ 19,179 States, municipalities and political subdivisions 12,874 1 12,875 Asset-backed 7,919 279 8,198 Fixed maturities available-for-sale 167 39,705 380 40,252 Fixed maturities trading 10 831 7 848 Total fixed maturities $ 177 $ 40,536 $ 387 $ 41,100 Equity securities $ 711 $ 602 $ 20 $ 1,333 Short term and other 3,356 978 4,334 Receivables 15 15 Payable to brokers (7) (7) December 31, 2017 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 months ended March 31, 2018 and 2017: Unrealized Gains (Losses) Recognized in Net Realized Gains Net Income (Losses) and Net Change on Level in Unrealized Gains 3 Assets and (Losses) Transfers Transfers Liabilities Balance, Included in Included in into out of Balance, Held at 2018 January 1 Net Income OCI Purchases Sales Settlements Level 3 Level 3 March 31 March 31 (In millions) Fixed maturity securities: Corporate bonds and other $ 98 $ (1) $ (2) $ 5 $ 100 States, municipalities and political subdivisions 1 1 Asset-backed 335 7 $ (5) $ 30 $ (72) (6) $ (10) 279 Fixed maturities available-for-sale 434 6 (5) 30 (72) (8) 5 (10) 380 $ - Fixed maturities trading 4 3 7 3 Total fixed maturities $ 438 $ 9 $ (5) $ 30 $ (72) $ (8) $ 5 $ (10) $ 387 $ 3 Equity securities $ 22 $ (2) $ 20 $ (2) Unrealized (Losses) Net Realized Gains Transfers Transfers Net Income 3 Assets and 2017 Balance, Included in Included in Purchases Sales Settlements into out of Balance, Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 130 $ 1 $ 5 $ (1) $ (14 ) $ 121 States, municipalities and political subdivisions 1 1 Asset-backed 199 2 38 (6 ) $ 28 $ (5) 256 Fixed maturities available-for-sale 330 $ - 3 43 (1) (20 ) 28 (5) 378 $ - Fixed maturities trading 6 (1) 5 Total fixed maturities $ 336 $ (1) $ 3 $ 43 $ (1) $ (20 ) $ 28 $ (5) $ 383 $ - Equity securities available-for-sale $ 19 $ 1 $ 1 $ (2) $ 19 Equity securities trading 1 1 Total equity securities $ 20 $ - $ 1 $ 1 $ (2) $ - $ - $ - $ 20 $ - Life settlement contracts $ 58 $ 6 $ (13) $ (5) $ 46 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. During the three months ended March 31, 2018 there were $29 million of transfers from Level 2 to Level 1 and no transfers from Level 1 to Level 2. During the three months ended March 31, 2017 there were no transfers between Level 1 and Level 2. The Company’s policy is to recognize transfers between levels at the beginning of quarterly reporting periods. 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. March 31, 2018 Estimated Valuation Unobservable Range (In millions) Fixed maturity securities $ 133 Discounted Credit spread 1% – 12% (3%) December 31, 2017 Fixed maturity securities $ 136 Discounted 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 Amount Estimated Fair Value March 31, 2018 Level 1 Level 2 Level 3 Total (In millions) Assets: Other invested assets, primarily mortgage loans $ 864 $ 856 $ 856 Liabilities: Short term debt 210 $ 36 174 210 Long term debt 11,238 10,662 562 11,224 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 following methods and assumptions were used in estimating the fair value of these financial assets and liabilities. 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	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Claim and Claim Adjustment Expense Reserves	4. 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. Three Months Ended March 31 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 1,246 1,207 Decrease in provision for insured events of prior years (34) (82) Amortization of discount 47 48 Total net incurred (a) 1,259 1,173 Net payments attributable to: Current year events (91) (68) Prior year events (1,219) (1,184) Total net payments (1,310) (1,252) Foreign currency translation adjustment and other (9) 14 Net reserves, end of period 18,010 18,184 Ceded reserves, end of period 4,057 4,076 Gross reserves, end of period $ 22,067 $ 22,260 (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 $39 million and $57 million was recorded for CNA’s commercial property and casualty operations (“Property & Casualty Operations”) for the three months ended March 31, 2018 and 2017. 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 March 31 2018 2017 (In millions) Medical professional liability $ 20 $ 20 Other professional liability and management liability (34) (32) Surety (15) Commercial auto (1) (26) General liability (8) (18) Workers’ compensation (6) Other 5 (1) Total pretax (favorable) unfavorable development $ (39) $ (57) 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. Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency in accident years 2013 through 2015 related to financial institutions. Favorable development for surety was due to lower than expected loss emergence for accident years 2015 and prior. Favorable development for general liability was primarily due to lower than expected frequency and severity in accident years 2015 and prior for the middle market construction business. 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 lower than expected frequency of large losses related to professional liability in accident years 2011 through 2016. Favorable development for commercial auto was primarily due to lower than expected severity in accident years 2013 through 2015. Favorable development for general liability was due to lower than expected severity in life sciences. 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. Subsequent to the effective date of the LPT, CNA recognized adverse prior year development on its A&EP reserves which resulted in additional amounts ceded under the LPT. As a result, the cumulative amounts ceded under the LPT 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 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 March 31 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 (57 ) (40) Pretax impact of deferred retroactive reinsurance $ 40 $ 20 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 three months ended March 31, 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. While the unfavorable development was ceded to NICO under the LPT, CNA’s reported earnings in the periods were negatively affected due to the application of retroactive reinsurance accounting. As of March 31, 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 $366 million and $326 million as of March 31, 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 $2.9 billion and $3.1 billion as of March 31, 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	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Shareholders' Equity	5. Shareholders’ Equity Accumulated other comprehensive income (loss) The tables below present the changes in AOCI by component for the three months ended March 31, 2017 and 2018: Total Accumulated OTTI Unrealized Foreign Other Gains Gains (Losses) Cash Flow Pension Currency Comprehensive (Losses) on Investments Hedges Liability Translation Income (Loss) (In millions) Balance, January 1, 2017 $ 27 $ 576 $ (2 ) $ (646 ) $ (178 ) $ (223 ) Other comprehensive income (loss) before reclassifications, after tax of $(1), $(47), $0, $0 and $0 85 (1 ) 11 95 Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $2, $9, $0, $(4) and $0 (4 ) (18 ) 1 8 (13 ) Other comprehensive income (loss) (4 ) 67 - 8 11 82 Amounts attributable to noncontrolling interests (7 ) (1 ) (8 ) Balance, March 31, 2017 $ 23 $ 636 $ (2 ) $ (638 ) $ (168 ) $ (149 ) 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 $2, $105, $(2), $0 and $0 (10 ) (414 ) 8 11 (405 ) Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $0, $4, $0, $(3) and $0 1 (15 ) 2 10 (2 ) Other comprehensive income (loss) (9 ) (429 ) 10 10 11 (407 ) Amounts attributable to noncontrolling interests 1 44 (1 ) 44 Balance, March 31, 2018 $ 18 $ 386 $ 10 $ (753 ) $ (78 ) $ (417 ) (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 9.9 million shares of Loews common stock at an aggregate cost of $497 million during the three months ended March 31, 2018.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	6. Revenue from Contracts with Customers Disaggregation of revenues Three Months Ended March 31 2018 2017 (a) (In millions) Non-insurance $ 245 $ 100 Contract drilling - Diamond Offshore 296 375 Transportation and storage of natural gas and NGLs and other services - Boardwalk Pipeline 331 351 Lodging and related services - Loews Hotels & Co 183 167 Rigid plastic packaging and recycled resin – Corporate 213 Total revenues from contracts with customers 1,268 993 Other revenues 13 24 Operating revenues and other $ 1,281 $ 1,017 (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, accordingly, certain revenues collected 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	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Benefit Plans	7. 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 Other Three Months Ended March 31 2018 2017 2018 2017 (In millions) Service cost $ 2 $ 2 Interest cost 27 30 $ 1 $ 1 Expected return on plan assets (45) (43) (1) (1) Amortization of unrecognized net loss 11 11 Amortization of unrecognized prior service benefit (1) (1) Settlement charge 4 2 Net periodic (benefit) cost $ (1) $ 2 $ (1) $ (1)

Legal Proceedings

Legal Proceedings	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	8. Legal Proceedings CNA Financial In September of 2016, a class action lawsuit was filed against CCC, Continental Assurance Company (“CAC”) (a former subsidiary of CCC), CNA, the Investment Committee of the CNA 401(k) Plus Plan (“Plan”), The Northern Trust Company and John Does 1-10 The plaintiff, Defendants and the Plan’s fiduciary insurance carriers have agreed on terms to settle this matter. Upon execution of final settlement agreements, plaintiff and Defendants will propose a class settlement for court approval. Based on the executed term sheet, management has recorded its best estimate of CNA’s probable loss. The Company does not believe that the ultimate resolution of this matter will have a material impact on its consolidated financial statements. Other Litigation The Company and its subsidiaries are from time to time parties to other 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	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. 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 March 31, 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 March 31, 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 March 31, 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 have been reported net of any impact from the premium rate adjustments. In the first quarter of 2017, CNA recorded a charge which reduced earned premium by $38 million and increased interest expense by $5 million for interest due to policyholders on 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 are expected to be refunded in the second half of 2018, and as such, an additional $1 million of interest expense was recorded in the first quarter of 2018. The estimated refund liability, including interest, for the workers’ compensation policies as of March 31, 2018 was $60 million.

Segments

Segments	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segments	10. 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 months ended March 31, 2018. 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 March 31, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,785 $ 1,785 Net investment income 490 $ 2 $ 14 506 Investment gains 9 9 Operating revenues and other 251 297 $ 337 $ 183 213 1,281 Total 2,535 299 337 183 227 3,581 Expenses: Insurance claims and policyholders’ benefits 1,339 1,339 Amortization of deferred acquisition costs 296 296 Operating expenses and other 518 296 198 156 232 1,400 Interest 35 28 44 7 27 141 Total 2,188 324 242 163 259 3,176 Income (loss) before income tax 347 (25 ) 95 20 (32 ) 405 Income tax (expense) benefit (55 ) 44 (12 ) (7 ) 5 (25 ) Net income (loss) 292 19 83 13 (27 ) 380 Amounts attributable to noncontrolling interests (31 ) (9 ) (47 ) (87 ) Net income (loss) attributable to Loews Corporation $ 261 $ 10 $ 36 $ 13 $ (27 ) $ 293 Three Months Ended March 31, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,645 $ 1,645 Net investment income 545 $ 59 604 Investment gains 34 34 Operating revenues and other 105 $ 377 $ 368 $ 167 1,017 Total 2,329 377 368 167 59 3,300 Expenses: Insurance claims and policyholders’ benefits 1,293 1,293 Amortization of deferred acquisition costs 305 305 Operating expenses and other 343 324 204 141 38 1,050 Interest 43 28 46 7 18 142 Total 1,984 352 250 148 56 2,790 Income before income tax 345 25 118 19 3 510 Income tax expense (84 ) (2 ) (23 ) (9 ) (1 ) (119 ) Net income 261 23 95 10 2 391 Amounts attributable to noncontrolling interests (27 ) (11 ) (58 ) (96 ) Net income attributable to Loews Corporation $ 234 $ 12 $ 37 $ 10 $ 2 $ 295

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 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 51% 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 March 31, 2018 and December 31, 2017 and results of operations, comprehensive income and changes in shareholders’ equity and cash flows for the three months ended March 31, 2018 and 2017. Net income for the first quarter 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 0.7 million shares attributable to employee stock-based compensation awards excluded from the diluted weighted average shares outstanding amounts for the three months ended March 31, 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
Recently issued ASUs	Recently issued ASUs – 2016-02, 2014-09. In June of 2016, the FASB issued ASU 2016-13, available-for-sale available-for-sale 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)	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Net Investment Income and Investment Gains (Losses)	Net investment income is as follows: Three Months Ended March 31 2018 2017 (In millions) Fixed maturity securities $ 446 $ 455 Limited partnership investments 48 116 Short term investments 9 4 Equity securities 10 1 Income (loss) from trading portfolio (a) (3 ) 34 Other 11 8 Total investment income 521 618 Investment expenses (15 ) (14 ) Net investment income $ 506 $ 604 (a) Net unrealized (losses) gains related to changes in fair value on securities still held were $(25) and $46 for the three months ended March 31, 2018 and 2017. Investment gains (losses) are as follows: Three Months Ended March 31 2018 2017 (In millions) Fixed maturity securities $ 18 $ 32 Equity securities (15 ) Derivative instruments 5 1 Short term investments and other 1 1 Investment gains (a) $ 9 $ 34 (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 March 31 2018 2017 (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 5 $ 2 Asset-backed 1 Net OTTI losses recognized in earnings $ 6 $ 2
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: March 31, 2018 Cost or Gross Gross Estimated Unrealized (In millions) Fixed maturity securities: Corporate and other bonds $ 17,538 $ 1,177 $ 115 $ 18,600 States, municipalities and political subdivisions 11,682 1,205 12 12,875 Asset-backed: Residential mortgage-backed 5,050 83 78 5,055 $ (27 ) Commercial mortgage-backed 1,948 29 22 1,955 Other asset-backed 1,185 10 7 1,188 Total asset-backed 8,183 122 107 8,198 (27 ) U.S. Treasury and obligations of government-sponsored enterprises 124 2 7 119 Foreign government 448 7 5 450 Redeemable preferred stock 9 1 10 Fixed maturities available-for-sale 37,984 2,514 246 40,252 (27 ) Fixed maturities trading 846 3 1 848 Total fixed maturity securities $ 38,830 $ 2,517 $ 247 $ 41,100 $ (27 ) December 31, 2017 (In millions) 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 Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized March 31, 2018 Fair Value Losses Fair Value Losses Fair Value Losses (In millions) Fixed maturity securities: Corporate and other bonds $ 4,229 $ 104 $ 146 $ 11 $ 4,375 $ 115 States, municipalities and political subdivisions 962 12 3 965 12 Asset-backed: Residential mortgage-backed 2,570 55 504 23 3,074 78 Commercial mortgage-backed 668 11 200 11 868 22 Other asset-backed 441 5 15 2 456 7 Total asset-backed 3,679 71 719 36 4,398 107 U.S. Treasury and obligations of government- sponsored enterprises 59 4 26 3 85 7 Foreign government 214 5 4 218 5 Total fixed maturity securities $ 9,143 $ 196 $ 898 $ 50 $ 10,041 $ 246 December 31, 2017 (In millions) 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 March 31, 2018 and 2017 for which a portion of an OTTI loss was recognized in Other comprehensive income. Three Months Ended March 31 2018 2017 (In millions) Beginning balance of credit losses on fixed maturity securities $ 27 $ 36 Reductions for securities sold during the period (2 ) (4 ) Ending balance of credit losses on fixed maturity securities $ 25 $ 32
Available-for-Sale Fixed Maturity Securities by Contractual Maturity	The following table presents available-for-sale March 31, 2018 December 31, 2017 Cost or Estimated Cost or Estimated Amortized Fair Amortized Fair Cost Value Cost Value (In millions) Due in one year or less $ 1,323 $ 1,343 $ 1,135 $ 1,157 Due after one year through five years 8,277 8,495 8,165 8,501 Due after five years through ten years 15,802 16,093 16,060 16,718 Due after ten years 12,582 14,321 12,852 15,108 Total $ 37,984 $ 40,252 $ 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. March 31, 2018 December 31, 2017 Contractual/ Notional Amount Contractual/ Notional Amount Estimated Fair Value Estimated Fair Value Asset (Liability) Asset (Liability) (In millions) With hedge designation: Interest rate swaps $ 500 $ 15 $ 500 $ 4 Without hedge designation: Equity markets: Options – purchased 144 9 224 12 166 $ (7) 290 $ (7) Futures – short 146 265 1 Commodity futures – long 46 44 Embedded derivative on funds withheld liability 163 1 167 (3)

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 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 and foreign governments and redeemable preferred stock. March 31, 2018 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 167 $ 18,912 $ 100 $ 19,179 States, municipalities and political subdivisions 12,874 1 12,875 Asset-backed 7,919 279 8,198 Fixed maturities available-for-sale 167 39,705 380 40,252 Fixed maturities trading 10 831 7 848 Total fixed maturities $ 177 $ 40,536 $ 387 $ 41,100 Equity securities $ 711 $ 602 $ 20 $ 1,333 Short term and other 3,356 978 4,334 Receivables 15 15 Payable to brokers (7) (7) December 31, 2017 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 months ended March 31, 2018 and 2017: Unrealized Gains (Losses) Recognized in Net Realized Gains Net Income (Losses) and Net Change on Level in Unrealized Gains 3 Assets and (Losses) Transfers Transfers Liabilities Balance, Included in Included in into out of Balance, Held at 2018 January 1 Net Income OCI Purchases Sales Settlements Level 3 Level 3 March 31 March 31 (In millions) Fixed maturity securities: Corporate bonds and other $ 98 $ (1) $ (2) $ 5 $ 100 States, municipalities and political subdivisions 1 1 Asset-backed 335 7 $ (5) $ 30 $ (72) (6) $ (10) 279 Fixed maturities available-for-sale 434 6 (5) 30 (72) (8) 5 (10) 380 $ - Fixed maturities trading 4 3 7 3 Total fixed maturities $ 438 $ 9 $ (5) $ 30 $ (72) $ (8) $ 5 $ (10) $ 387 $ 3 Equity securities $ 22 $ (2) $ 20 $ (2) Unrealized (Losses) Net Realized Gains Transfers Transfers Net Income 3 Assets and 2017 Balance, Included in Included in Purchases Sales Settlements into out of Balance, Held at (In millions) Fixed maturity securities: Corporate bonds and other $ 130 $ 1 $ 5 $ (1) $ (14 ) $ 121 States, municipalities and political subdivisions 1 1 Asset-backed 199 2 38 (6 ) $ 28 $ (5) 256 Fixed maturities available-for-sale 330 $ - 3 43 (1) (20 ) 28 (5) 378 $ - Fixed maturities trading 6 (1) 5 Total fixed maturities $ 336 $ (1) $ 3 $ 43 $ (1) $ (20 ) $ 28 $ (5) $ 383 $ - Equity securities available-for-sale $ 19 $ 1 $ 1 $ (2) $ 19 Equity securities trading 1 1 Total equity securities $ 20 $ - $ 1 $ 1 $ (2) $ - $ - $ - $ 20 $ - Life settlement contracts $ 58 $ 6 $ (13) $ (5) $ 46 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. March 31, 2018 Estimated Valuation Unobservable Range (In millions) Fixed maturity securities $ 133 Discounted Credit spread 1% – 12% (3%) December 31, 2017 Fixed maturity securities $ 136 Discounted 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 Amount Estimated Fair Value March 31, 2018 Level 1 Level 2 Level 3 Total (In millions) Assets: Other invested assets, primarily mortgage loans $ 864 $ 856 $ 856 Liabilities: Short term debt 210 $ 36 174 210 Long term debt 11,238 10,662 562 11,224 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 Ex21

Claim and Claim Adjustment Expense Reserves (Tables)	3 Months Ended
	Mar. 31, 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. Three Months Ended March 31 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 1,246 1,207 Decrease in provision for insured events of prior years (34) (82) Amortization of discount 47 48 Total net incurred (a) 1,259 1,173 Net payments attributable to: Current year events (91) (68) Prior year events (1,219) (1,184) Total net payments (1,310) (1,252) Foreign currency translation adjustment and other (9) 14 Net reserves, end of period 18,010 18,184 Ceded reserves, end of period 4,057 4,076 Gross reserves, end of period $ 22,067 $ 22,260 (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 Casulaity 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 March 31 2018 2017 (In millions) Medical professional liability $ 20 $ 20 Other professional liability and management liability (34) (32) Surety (15) Commercial auto (1) (26) General liability (8) (18) Workers’ compensation (6) Other 5 (1) Total pretax (favorable) unfavorable development $ (39) $ (57)
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 March 31 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 (57 ) (40) Pretax impact of deferred retroactive reinsurance $ 40 $ 20

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Components of Accumulated Other Comprehensive Income	The tables below present the changes in AOCI by component for the three months ended March 31, 2017 and 2018: Total Accumulated OTTI Unrealized Foreign Other Gains Gains (Losses) Cash Flow Pension Currency Comprehensive (Losses) on Investments Hedges Liability Translation Income (Loss) (In millions) Balance, January 1, 2017 $ 27 $ 576 $ (2 ) $ (646 ) $ (178 ) $ (223 ) Other comprehensive income (loss) before reclassifications, after tax of $(1), $(47), $0, $0 and $0 85 (1 ) 11 95 Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $2, $9, $0, $(4) and $0 (4 ) (18 ) 1 8 (13 ) Other comprehensive income (loss) (4 ) 67 - 8 11 82 Amounts attributable to noncontrolling interests (7 ) (1 ) (8 ) Balance, March 31, 2017 $ 23 $ 636 $ (2 ) $ (638 ) $ (168 ) $ (149 ) 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 $2, $105, $(2), $0 and $0 (10 ) (414 ) 8 11 (405 ) Reclassification of (gains) losses from accumulated other comprehensive income, after tax of $0, $4, $0, $(3) and $0 1 (15 ) 2 10 (2 ) Other comprehensive income (loss) (9 ) (429 ) 10 10 11 (407 ) Amounts attributable to noncontrolling interests 1 44 (1 ) 44 Balance, March 31, 2018 $ 18 $ 386 $ 10 $ (753 ) $ (78 ) $ (417 ) (a) For information regarding this accounting standard see Note 1.

Revenue from Contracts with C23

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 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 10: Three Months Ended March 31 2018 2017 (a) (In millions) Non-insurance $ 245 $ 100 Contract drilling - Diamond Offshore 296 375 Transportation and storage of natural gas and NGLs and other services - Boardwalk Pipeline 331 351 Lodging and related services - Loews Hotels & Co 183 167 Rigid plastic packaging and recycled resin – Corporate 213 Total revenues from contracts with customers 1,268 993 Other revenues 13 24 Operating revenues and other $ 1,281 $ 1,017 (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)	3 Months Ended
	Mar. 31, 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 Other Three Months Ended March 31 2018 2017 2018 2017 (In millions) Service cost $ 2 $ 2 Interest cost 27 30 $ 1 $ 1 Expected return on plan assets (45) (43) (1) (1) Amortization of unrecognized net loss 11 11 Amortization of unrecognized prior service benefit (1) (1) Settlement charge 4 2 Net periodic (benefit) cost $ (1) $ 2 $ (1) $ (1)

Segments (Tables)

Segments (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,785 $ 1,785 Net investment income 490 $ 2 $ 14 506 Investment gains 9 9 Operating revenues and other 251 297 $ 337 $ 183 213 1,281 Total 2,535 299 337 183 227 3,581 Expenses: Insurance claims and policyholders’ benefits 1,339 1,339 Amortization of deferred acquisition costs 296 296 Operating expenses and other 518 296 198 156 232 1,400 Interest 35 28 44 7 27 141 Total 2,188 324 242 163 259 3,176 Income (loss) before income tax 347 (25 ) 95 20 (32 ) 405 Income tax (expense) benefit (55 ) 44 (12 ) (7 ) 5 (25 ) Net income (loss) 292 19 83 13 (27 ) 380 Amounts attributable to noncontrolling interests (31 ) (9 ) (47 ) (87 ) Net income (loss) attributable to Loews Corporation $ 261 $ 10 $ 36 $ 13 $ (27 ) $ 293 Three Months Ended March 31, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 1,645 $ 1,645 Net investment income 545 $ 59 604 Investment gains 34 34 Operating revenues and other 105 $ 377 $ 368 $ 167 1,017 Total 2,329 377 368 167 59 3,300 Expenses: Insurance claims and policyholders’ benefits 1,293 1,293 Amortization of deferred acquisition costs 305 305 Operating expenses and other 343 324 204 141 38 1,050 Interest 43 28 46 7 18 142 Total 1,984 352 250 148 56 2,790 Income before income tax 345 25 118 19 3 510 Income tax expense (84 ) (2 ) (23 ) (9 ) (1 ) (119 ) Net income 261 23 95 10 2 391 Amounts attributable to noncontrolling interests (27 ) (11 ) (58 ) (96 ) Net income attributable to Loews Corporation $ 234 $ 12 $ 37 $ 10 $ 2 $ 295

Basis of presentation - Additio

Basis of presentation - Additional Information (Detail) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Shares excluded from diluted EPS calculation			0	700,000
Other assets		$ 2,555	$ 4,590
Other liabilities		$ 5,466	7,350
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%
Boardwalk Pipeline Partners, LP [Member]
Summary Of Significant Accounting Policies [Line Items]
Subsidiary ownership percentage			51.00%
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			$ (15)
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				$ 4
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			131
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			133
Prior to Adoption of Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Other assets		$ 2,600	2,600
Other liabilities		$ 5,500	$ 5,300

Investments - Net Investment In

Investments - Net Investment Income and Investment Gains (Losses) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net Investment Income [Line Items]
Total investment income	$ 521	$ 618
Investment expenses	(15)	(14)
Investment gains (losses)	9	34
Net investment income	506	604
Fixed Maturity Securities [Member]
Net Investment Income [Line Items]
Total investment income	446	455
Investment gains (losses)	18	32
Equity Securities [Member]
Net Investment Income [Line Items]
Total investment income	10	1
Investment gains (losses)	(15)
Derivative Instruments [Member]
Net Investment Income [Line Items]
Investment gains (losses)	5	1
Short Term and Other [Member]
Net Investment Income [Line Items]
Total investment income	9	4
Investment gains (losses)	1	1
Limited Partnership Investments [Member]
Net Investment Income [Line Items]
Total investment income	48	116
Income (Loss) from Trading Portfolio [Member]
Net Investment Income [Line Items]
Total investment income	(3)	34
Other [Member]
Net Investment Income [Line Items]
Total investment income	$ 11	$ 8

Investments - Net Investment 28

Investments - Net Investment Income and Investment Gains (Losses) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net Investment Income [Line Items]
Net unrealized gains (losses) on trading securities	$ (25)	$ 46
Fixed Maturity Securities [Member]
Net Investment Income [Line Items]
Gross realized gains on available-for-sale securities	69	49
Gross realized losses on available-for-sale securities	51	$ 17
Fixed Maturity Securities [Member] | Nonredeemable Preferred Stock [Member]
Net Investment Income [Line Items]
Net unrealized gains (losses) on trading securities	$ 15

Investments - Components of OTT

Investments - Components of OTTI Losses Recognized in Earnings by Asset Type (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	$ 6	$ 2
Corporate Bonds and Other [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	5	$ 2
Total Asset-Backed [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	$ 1

Investments - Amortized Cost an

Investments - Amortized Cost and Fair Values of Fixed Maturity and Equity Securities (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	$ 38,830	$ 40,038
Gross Unrealized Gains	2,517	3,491
Gross Unrealized Losses	247	172
Estimated Fair Value	41,100	43,357
Unrealized OTTI Losses (Gains)	(27)	(38)
Corporate Bonds and Other [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	17,538	17,210
Gross Unrealized Gains	1,177	1,625
Gross Unrealized Losses	115	28
Estimated Fair Value	18,600	18,807
States, Municipalities and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	11,682	12,478
Gross Unrealized Gains	1,205	1,551
Gross Unrealized Losses	12	2
Estimated Fair Value	12,875	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	5,050	5,043
Gross Unrealized Gains	83	109
Gross Unrealized Losses	78	32
Estimated Fair Value	5,055	5,120
Unrealized OTTI Losses (Gains)	(27)	(27)
Commercial Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	1,948	1,840
Gross Unrealized Gains	29	46
Gross Unrealized Losses	22	14
Estimated Fair Value	1,955	1,872
Other Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	1,185	1,083
Gross Unrealized Gains	10	16
Gross Unrealized Losses	7	5
Estimated Fair Value	1,188	1,094
Total Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	8,183	7,966
Gross Unrealized Gains	122	171
Gross Unrealized Losses	107	51
Estimated Fair Value	8,198	8,086
Unrealized OTTI Losses (Gains)	(27)	(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	124	111
Gross Unrealized Gains	2	2
Gross Unrealized Losses	7	4
Estimated Fair Value	119	109
Foreign Government [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	448	437
Gross Unrealized Gains	7	9
Gross Unrealized Losses	5	2
Estimated Fair Value	450	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	37,984	38,212
Gross Unrealized Gains	2,514	3,359
Gross Unrealized Losses	246	87
Estimated Fair Value	40,252	41,484
Unrealized OTTI Losses (Gains)	(27)	(38)
Fixed Maturities Trading [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	846	649
Gross Unrealized Gains	3	2
Gross Unrealized Losses	1	2
Estimated Fair Value	$ 848	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 ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Shadow Adjustments	$ 1,200,000,000	$ 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	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [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]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 4,229	1,354
Gross Unrealized Losses, Less than 12 Months	104	21
Estimated Fair Value, 12 Months or Longer	146	168
Gross Unrealized Losses, 12 Months or Longer	11	7
Total Estimated Fair Value	4,375	1,522
Total Gross Unrealized Losses	115	28
States, Municipalities and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	962	72
Gross Unrealized Losses, Less than 12 Months	12	1
Estimated Fair Value, 12 Months or Longer	3	85
Gross Unrealized Losses, 12 Months or Longer		1
Total Estimated Fair Value	965	157
Total Gross Unrealized Losses	12	2
Residential Mortgage-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	2,570	1,228
Gross Unrealized Losses, Less than 12 Months	55	5
Estimated Fair Value, 12 Months or Longer	504	947
Gross Unrealized Losses, 12 Months or Longer	23	27
Total Estimated Fair Value	3,074	2,175
Total Gross Unrealized Losses	78	32
Commercial Mortgage-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	668	403
Gross Unrealized Losses, Less than 12 Months	11	4
Estimated Fair Value, 12 Months or Longer	200	212
Gross Unrealized Losses, 12 Months or Longer	11	10
Total Estimated Fair Value	868	615
Total Gross Unrealized Losses	22	14
Other Asset-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	441	248
Gross Unrealized Losses, Less than 12 Months	5	3
Estimated Fair Value, 12 Months or Longer	15	18
Gross Unrealized Losses, 12 Months or Longer	2	2
Total Estimated Fair Value	456	266
Total Gross Unrealized Losses	7	5
Total Asset-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	3,679	1,879
Gross Unrealized Losses, Less than 12 Months	71	12
Estimated Fair Value, 12 Months or Longer	719	1,177
Gross Unrealized Losses, 12 Months or Longer	36	39
Total Estimated Fair Value	4,398	3,056
Total Gross Unrealized Losses	107	51
U.S. Treasury and Obligations of Government-Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	59	49
Gross Unrealized Losses, Less than 12 Months	4	2
Estimated Fair Value, 12 Months or Longer	26	21
Gross Unrealized Losses, 12 Months or Longer	3	2
Total Estimated Fair Value	85	70
Total Gross Unrealized Losses	7	4
Foreign Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	214	166
Gross Unrealized Losses, Less than 12 Months	5	2
Estimated Fair Value, 12 Months or Longer	4	4
Total Estimated Fair Value	218	170
Total Gross Unrealized Losses	5	2
Total Fixed Maturities Available-for-Sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value, Less than 12 Months	9,143	3,520
Gross Unrealized Losses, Less than 12 Months	196	38
Estimated Fair Value, 12 Months or Longer	898	1,455
Gross Unrealized Losses, 12 Months or Longer	50	49
Total Estimated Fair Value	10,041	4,975
Total Gross Unrealized Losses	$ 246	87
Common Stock [Member]
Schedule of Available-for-sale Securities [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]
Schedule of Available-for-sale Securities [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]
Schedule of Available-for-sale Securities [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
	Mar. 31, 2018	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Beginning balance of credit losses on fixed maturity securities	$ 27	$ 36
Reductions for securities sold during the period	(2)	(4)
Ending balance of credit losses on fixed maturity securities	$ 25	$ 32

Investments - Available-for-Sal

Investments - Available-for-Sale Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Cost or Amortized Cost, Due in one year or less	$ 1,323	$ 1,135
Cost or Amortized Cost, Due after one year through five years	8,277	8,165
Cost or Amortized Cost, Due after five years through ten years	15,802	16,060
Cost or Amortized Cost, Due after ten years	12,582	12,852
Cost or Amortized Cost, Total	37,984	38,212
Estimated Fair Value, Due in one year or less	1,343	1,157
Estimated Fair Value, Due after one year through five years	8,495	8,501
Estimated Fair Value, Due after five years through ten years	16,093	16,718
Estimated Fair Value, Due after ten years	14,321	15,108
Estimated Fair Value, Total	$ 40,252	$ 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 ($)	Mar. 31, 2018	Dec. 31, 2017
Embedded Derivative on Funds Withheld Liability [Member]
Derivative [Line Items]
Contractual/Notional Amount	$ 163,000,000	$ 167,000,000
Estimated Fair Value, Asset	1,000,000
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	15,000,000	4,000,000
Without Hedge Designation [Member] | Equity Markets, Options - Purchased [Member]
Derivative [Line Items]
Contractual/Notional Amount	144,000,000	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	166,000,000	290,000,000
Estimated Fair Value, (Liability)	(7,000,000)	(7,000,000)
Without Hedge Designation [Member] | Equity Futures [Member] | Short [Member]
Derivative [Line Items]
Contractual/Notional Amount	146,000,000	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	$ 46,000,000	$ 44,000,000

Fair Value - Assets and Liabili

Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 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	$ (7)	$ (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	19,179	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	12,875	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	8,198	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	40,252	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	848	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	41,100	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	1,333	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	15	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	4,334	4,627
Level 1 [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	(7)	(12)
Level 1 [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	167	128
Level 1 [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	167	128
Level 1 [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	10
Level 1 [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	177	138
Level 1 [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] | 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] | 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	711	618
Level 1 [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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	3,356	3,669
Level 2 [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	18,912	19,145
Level 2 [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	12,874	14,026
Level 2 [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	7,919	7,751
Level 2 [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	39,705	40,922
Level 2 [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	831	635
Level 2 [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	40,536	41,557
Level 2 [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] | 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	602	584
Level 2 [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	15	4
Level 2 [Member] | 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	978	958
Level 3 [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	100	98
Level 3 [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	1
Level 3 [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	279	335
Level 3 [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	380	434
Level 3 [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	7	4
Level 3 [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	387	438
Level 3 [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] | 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] | 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	$ 20	$ 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
	Mar. 31, 2018	Mar. 31, 2017
Corporate Bonds and Other [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 98	$ 130
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income	(1)
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		1
Purchases		5
Sales		(1)
Settlements	(2)	(14)
Transfers into Level 3	5
Ending balance	100	121
States, Municipalities and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	1	1
Ending balance	1	1
Total Asset-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	335	199
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income	7
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI	(5)	2
Purchases	30	38
Sales	(72)
Settlements	(6)	(6)
Transfers into Level 3		28
Transfers out of Level 3	(10)	(5)
Ending balance	279	256
Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	434	330
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income	6
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI	(5)	3
Purchases	30	43
Sales	(72)	(1)
Settlements	(8)	(20)
Transfers into Level 3	5	28
Transfers out of Level 3	(10)	(5)
Ending balance	380	378
Fixed Maturities Trading [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	4	6
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income	3	(1)
Ending balance	7	5
Unrealized Gains (Losses) Recognized in Net Income on Level 3 Assets Held at December 31	3
Fixed Maturity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	438	336
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income	9	(1)
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI	(5)	3
Purchases	30	43
Sales	(72)	(1)
Settlements	(8)	(20)
Transfers into Level 3	5	28
Transfers out of Level 3	(10)	(5)
Ending balance	387	383
Unrealized Gains (Losses) Recognized in Net Income on Level 3 Assets Held at December 31	3
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	22	20
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income	(2)
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		1
Purchases		1
Sales		(2)
Ending balance	20	20
Unrealized Gains (Losses) Recognized in Net Income on Level 3 Assets Held at December 31	$ (2)
Equity Securities Available-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		19
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in OCI		1
Purchases		1
Sales		(2)
Ending balance		19
Equity Securities Trading [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		1
Ending balance		1
Life Settlement Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		58
Net Realized Gains (Losses) and Net Change in Unrealized Gains (Losses), Included in Net Income		6
Sales		(13)
Settlements		(5)
Ending balance		46
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		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
Unrealized Gains (Losses) Recognized in Net Income on Level 3 Liabilities Held at December 31		$ 0

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Transfers out of Level 2 to Level 1, Assets	$ 29,000,000	$ 0
Transfers out of Level 1 to Level 2, Assets	$ 0	$ 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) - Fixed Maturity Securities [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Discounted Cash Flow [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	$ 133	$ 136
Valuation Techniques	Discounted cash flow
Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit spread adjustment	1.00%	1.00%
Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit spread adjustment	12.00%	12.00%
Weighted Average [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit spread adjustment	3.00%	3.00%

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	Mar. 31, 2018	Dec. 31, 2017
Estimate Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	$ 856	$ 844
Short term debt	210	278
Long term debt	11,224	11,491
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	864	839
Short term debt	210	278
Long term debt	11,238	11,236
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short term debt	36	156
Long term debt	10,662	10,966
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	856	844
Short term debt	174	122
Long term debt	$ 562	$ 525

Claim and Claim Adjustment Ex41

Claim and Claim Adjustment Expense Reserves - Additional Information (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 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	$ 34	$ 34
Net A&EP adverse development before consideration of LPT	113	60
Fair value of the collateral trust account	2,900			$ 3,100
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			2,900
Remaining unrecognized retroactive reinsurance benefit	366			$ 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	$ 39	$ 57

Claim and Claim Adjustment Ex42

Claim and Claim Adjustment Expense Reserves - Reconciliation of Claim and Claim Adjustment Expense Reserves (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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	1,246	1,207
Decrease in provision for insured events of prior years	(34)	(82)
Amortization of discount	47	48
Total net incurred	1,259	1,173
Net payments attributable to:
Current year events	(91)	(68)
Prior year events	(1,219)	(1,184)
Total net payments	(1,310)	(1,252)
Foreign currency translation adjustment and other	(9)	14
Net reserves, end of period	18,010	18,184
Ceded reserves, end of period	4,057	4,076
Gross reserves, end of period	$ 22,067	$ 22,260

Claim and Claim Adjustment Ex43

Claim and Claim Adjustment Expense Reserves - Net Prior Year Development in CNA's Property and Casulaity Operations (Detail) - CNA Financial [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Medical professional liability	$ 20	$ 20
Other professional liability and management liability	(34)	(32)
Surety	(15)
Commercial auto	(1)	(26)
General liability	(8)	(18)
Workers' compensation	(6)
Other	5	(1)
Total pretax (favorable) unfavorable development	$ (39)	$ (57)

Claim and Claim Adjustment Ex44

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
	Mar. 31, 2018	Mar. 31, 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	(57)	(40)
Pretax impact of deferred retroactive reinsurance	$ 40	$ 20

Shareholders' Equity - Componen

Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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)	(407)	82
Ending Balance	23,848	23,734
OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	22	27
Balance, as adjusted	26
Other comprehensive income (loss) before reclassifications, after tax	(10)
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	1	(4)
Other comprehensive income (loss)	(9)	(4)
Amounts attributable to noncontrolling interests	1
Ending Balance	18	23
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	673	576
Balance, as adjusted	771
Other comprehensive income (loss) before reclassifications, after tax	(414)	85
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	(15)	(18)
Other comprehensive income (loss)	(429)	67
Amounts attributable to noncontrolling interests	44	(7)
Ending Balance	386	636
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(2)
Other comprehensive income (loss) before reclassifications, after tax	8	(1)
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	2	1
Other comprehensive income (loss)	10
Ending Balance	10	(2)
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(633)	(646)
Balance, as adjusted	(763)
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	10	8
Other comprehensive income (loss)	10	8
Ending Balance	(753)	(638)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(88)	(178)
Balance, as adjusted	(88)
Other comprehensive income (loss) before reclassifications, after tax	11	11
Other comprehensive income (loss)	11	11
Amounts attributable to noncontrolling interests	(1)	(1)
Ending Balance	(78)	(168)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(26)	(223)
Balance, as adjusted	(54)
Other comprehensive income (loss) before reclassifications, after tax	(405)	95
Reclassification of (gains) losses from accumulated other comprehensive income, after tax	(2)	(13)
Other comprehensive income (loss)	(407)	82
Amounts attributable to noncontrolling interests	44	(8)
Ending Balance	(417)	$ (149)
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 - Compon46

Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OTTI Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	$ 2	$ (1)
Tax on reclassification from accumulated other comprehensive income	0	2
Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	105	(47)
Tax on reclassification from accumulated other comprehensive income	4	9
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	(2)	0
Tax on reclassification from accumulated other comprehensive income	0	0
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	0	0
Tax on reclassification from accumulated other comprehensive income	(3)	(4)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	0	0
Tax on reclassification from accumulated other comprehensive income	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
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
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
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
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

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)shares
Equity [Abstract]
Treasury stock repurchased, shares | shares	9.9
Purchase of Loews treasury stock | $	$ 497

Revenue from Contracts with C48

Revenue from Contracts with Customers - Schedule of Disaggregation of Revenues (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,268	$ 993
Other revenues	13	24
Operating revenues and other	1,281	1,017
CNA Financial [Member] | Non-insurance Warranty And Other Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	245	100
Diamond Offshore [Member] | Drilling Contracts [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	296	375
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	331	351
Loews Hotels And Co [Member] | Lodging and Related Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	183	$ 167
Corporate [Member] | Rigid Plastic Packaging and Recycled Resin [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 213

Revenue from Contracts with C49

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Receivables from contracts with customers, included within Receivables	$ 424,000,000	$ 488,000,000
Deferred revenue, included within Other liabilities	3,100,000,000	$ 3,000,000,000
Revenue recognized	268,000,000
Contract cost	2,300,000,000
Amortization expense, contract cost	171,000,000
Premium deficiency charges, non-insurance warranty contract	0
Performance obligations, total	11,900,000,000
2018 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations, total	1,500,000,000
2019 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations, total	$ 1,800,000,000
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
	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2
Interest cost	27	30
Expected return on plan assets	(45)	(43)
Amortization of unrecognized net loss	11	11
Settlement charge	4	2
Net periodic (benefit) cost	(1)	2
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1
Expected return on plan assets	(1)	(1)
Amortization of unrecognized prior service benefit	(1)	(1)
Net periodic (benefit) cost	$ (1)	$ (1)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Commitments [Line Items]
Future policy benefits	$ 10,783		$ 11,179
Interest expense	141	$ 142
CNA Financial [Member]
Commitments [Line Items]
Aggregate amount related to indemnification agreements	375
Aggregate amount related to quantifiable guarantees	252
Potential amount of future payments under guarantees	1,800
Charges recorded to reduce earned premium		38
Increase in interest expense		$ 5
CNA Financial [Member] | Workers Compensation Policy [Member]
Commitments [Line Items]
Future policy benefits	60
Interest expense	$ 1

Segments - Additional Informati

Segments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 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
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Insurance premiums	$ 1,785	$ 1,645
Net investment income	506	604
Investment gains	9	34
Operating revenues and other	1,281	1,017
Total	3,581	3,300
Expenses:
Insurance claims and policyholders' benefits	1,339	1,293
Amortization of deferred acquisition costs	296	305
Operating expenses and other	1,400	1,050
Interest	141	142
Total	3,176	2,790
Income (loss) before income tax	405	510
Income tax (expense) benefit	(25)	(119)
Net income	380	391
Amounts attributable to noncontrolling interests	(87)	(96)
Net income (loss) attributable to Loews Corporation	293	295
CNA Financial [Member] | Operating Segments [Member]
Revenues:
Insurance premiums	1,785	1,645
Net investment income	490	545
Investment gains	9	34
Operating revenues and other	251	105
Total	2,535	2,329
Expenses:
Insurance claims and policyholders' benefits	1,339	1,293
Amortization of deferred acquisition costs	296	305
Operating expenses and other	518	343
Interest	35	43
Total	2,188	1,984
Income (loss) before income tax	347	345
Income tax (expense) benefit	(55)	(84)
Net income	292	261
Amounts attributable to noncontrolling interests	(31)	(27)
Net income (loss) attributable to Loews Corporation	261	234
Diamond Offshore [Member] | Operating Segments [Member]
Revenues:
Net investment income	2
Operating revenues and other	297	377
Total	299	377
Expenses:
Operating expenses and other	296	324
Interest	28	28
Total	324	352
Income (loss) before income tax	(25)	25
Income tax (expense) benefit	44	(2)
Net income	19	23
Amounts attributable to noncontrolling interests	(9)	(11)
Net income (loss) attributable to Loews Corporation	10	12
Boardwalk Pipeline [Member] | Operating Segments [Member]
Revenues:
Operating revenues and other	337	368
Total	337	368
Expenses:
Operating expenses and other	198	204
Interest	44	46
Total	242	250
Income (loss) before income tax	95	118
Income tax (expense) benefit	(12)	(23)
Net income	83	95
Amounts attributable to noncontrolling interests	(47)	(58)
Net income (loss) attributable to Loews Corporation	36	37
Loews Hotels And Co [Member] | Operating Segments [Member]
Revenues:
Operating revenues and other	183	167
Total	183	167
Expenses:
Operating expenses and other	156	141
Interest	7	7
Total	163	148
Income (loss) before income tax	20	19
Income tax (expense) benefit	(7)	(9)
Net income	13	10
Net income (loss) attributable to Loews Corporation	13	10
Corporate [Member]
Revenues:
Net investment income	14	59
Operating revenues and other	213
Total	227	59
Expenses:
Operating expenses and other	232	38
Interest	27	18
Total	259	56
Income (loss) before income tax	(32)	3
Income tax (expense) benefit	5	(1)
Net income	(27)	2
Net income (loss) attributable to Loews Corporation	$ (27)	$ 2