Loews (L) 10-K 12 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 07, 2020	Jun. 28, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Document Period End Date	Dec. 31, 2019
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0000060086
Entity Registrant Name	LOEWS CORP
Entity Filer Category	Large Accelerated Filer
Trading Symbol	L
Entity Emerging Growth Company	false
Entity Small Business	false
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-2646102
Entity File Number	1-6541
Entity Address, Address Line One	667 Madison Avenue
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10065-8087
City Area Code	212
Local Phone Number	521-2000
Title of 12(b) Security	Common stock
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Address, City or Town	NY
Entity Public Float			$ 14,174,000,000
Entity Common Stock, Shares Outstanding		287,770,405

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets:
Fixed maturities, amortized cost of $38,157 and $38,234	$ 42,240	$ 39,699
Equity securities, cost of $1,244 and $1,479	1,306	1,293
Limited partnership investments	2,004	2,424
Other invested assets, primarily mortgage loans	1,072	901
Short term investments	4,628	3,869
Total investments	51,250	48,186
Cash	336	405
Receivables	7,675	7,960
Property, plant and equipment	15,568	15,511
Goodwill	767	665
Deferred non-insurance warranty acquisition expenses	2,840	2,513
Deferred acquisition costs of insurance subsidiaries	662	633
Other assets	3,145	2,443
Total assets	82,243	78,316
Liabilities and Equity:
Claim and claim adjustment expense	21,720	21,984
Future policy benefits	12,311	10,597
Unearned premiums	4,583	4,183
Total insurance reserves	38,614	36,764
Payable to brokers	108	42
Short term debt	77	17
Long term debt	11,456	11,359
Deferred income taxes	1,168	841
Deferred non-insurance warranty revenue	3,779	3,402
Other liabilities	5,111	4,505
Total liabilities	60,313	56,930
Commitments and contingent liabilities
Shareholders' equity:
Preferred stock, $0.10 par value: Authorized – 100,000,000 shares
Common stock, $0.01 par value: Authorized – 1,800,000,000 shares Issued – 291,210,222 and 312,169,189 shares	3	3
Additional paid-in capital	3,374	3,627
Retained earnings	15,823	15,773
Accumulated other comprehensive loss	(68)	(880)
Shareholders' equity before treasury stock, total	19,132	18,523
Less treasury stock, at cost (240,000 and 100,000 shares)	(13)	(5)
Total shareholders' equity	19,119	18,518
Noncontrolling interests	2,811	2,868
Total equity	21,930	21,386
Total liabilities and equity	$ 82,243	$ 78,316

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 38,157	$ 38,234
Equity securities, cost	$ 1,244	$ 1,479
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	291,210,222	312,169,189
Treasury stock, shares	240,000	100,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Insurance premiums	$ 7,428	$ 7,312	$ 6,988
Net investment income	2,355	1,817	2,182
Investment gains (losses):
Other-than-temporary impairment losses	(44)	(21)	(14)
Other net investment gains (losses)	93	(36)	136
Total investment gains (losses)	49	(57)	122
Non-insurance warranty revenue	1,161	1,007	390
Operating revenues and other	3,938	3,987	4,053
Total	14,931	14,066	13,735
Expenses:
Insurance claims and policyholders' benefits	5,806	5,572	5,310
Amortization of deferred acquisition costs	1,383	1,335	1,233
Non-insurance warranty expense	1,082	923	299
Operating expenses and other	4,950	4,828	4,665
Interest	591	574	646
Total	13,812	13,232	12,153
Income before income tax	1,119	834	1,582
Income tax expense	(248)	(128)	(170)
Net income	871	706	1,412
Amounts attributable to noncontrolling interests	61	(70)	(248)
Net income attributable to Loews Corporation	$ 932	$ 636	$ 1,164
Basic net income per common share	$ 3.08	$ 1.99	$ 3.46
Diluted net income per common share	$ 3.07	$ 1.99	$ 3.45
Basic weighted average number of shares outstanding	302,700	319,060	336,610
Diluted weighted average number of shares outstanding	303,350	319,930	337,500

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 871	$ 706	$ 1,412
Other comprehensive income (loss), after tax Changes in:
Net unrealized losses on investments with other-than-temporary impairments	(1)	(14)	(5)
Net other unrealized gains (losses) on investments	949	(798)	108
Total unrealized gains (losses) on investments	948	(812)	103
Unrealized gains (losses) on cash flow hedges	(11)	6	3
Pension and postretirement benefits	(68)	(2)	12
Foreign currency translation	42	(84)	100
Other comprehensive income (loss)	911	(892)	218
Comprehensive income (loss)	1,782	(186)	1,630
Amounts attributable to noncontrolling interests	(38)	25	(269)
Total comprehensive income (loss) attributable to Loews Corporation	$ 1,744	$ (161)	$ 1,361

Consolidated Statements of Equi

Consolidated 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	1,412			1,164			248
Other comprehensive income (loss)	218				197		21
Dividends paid ($0.25 per share)	(223)			(84)			(139)
Purchases of Loews treasury stock	(237)					$ (237)
Retirement of treasury stock	1		(41)	(175)		217
Stock-based compensation	35		2				33
Other	(1)		3	(5)			1
Ending Balance at Dec. 31, 2017	24,566	3	3,151	16,096	(26)	(20)	5,362
Cumulative effect adjustments 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	706			636			70
Other comprehensive income (loss)	(892)				(797)		(95)
Dividends paid ($0.25 per share)	(201)			(80)			(121)
Purchase of Boardwalk Pipelines common units	(1,718)		658		(29)		(2,347)
Purchases of Loews treasury stock	(1,011)					(1,011)
Retirement of treasury stock			(195)	(831)		1,026
Stock-based compensation	31		19				12
Other	(4)		(6)	(5)			7
Ending Balance at Dec. 31, 2018	21,386	3	3,627	15,773	(880)	(5)	2,868
Net income	871			932			(61)
Other comprehensive income (loss)	911				812		99
Dividends paid ($0.25 per share)	(174)			(76)			(98)
Purchase of subsidiary stock from noncontrolling interests	(23)						(23)
Purchases of Loews treasury stock	(1,059)					(1,059)
Retirement of treasury stock			(248)	(803)		1,051
Stock-based compensation	27		4				23
Other	(9)		(9)	(3)			3
Ending Balance at Dec. 31, 2019	$ 21,930	$ 3	$ 3,374	$ 15,823	$ (68)	$ (13)	$ 2,811

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends paid per share	$ 0.25	$ 0.25	$ 0.25

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities:
Net income	$ 871	$ 706	$ 1,412
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Investment (gains) losses	(49)	57	(122)
Equity method investees	20	572	25
Amortization of investments	(89)	(70)	(40)
Depreciation and amortization	943	912	874
Asset impairments	99	44	106
Provision for deferred income taxes	70	86	(47)
Other non-cash items	87	72	164
Changes in operating assets and liabilities, net:
Receivables	114	(131)	93
Deferred acquisition costs	(26)	(6)	(24)
Insurance reserves	358	482	22
Other assets	(356)	(102)	(95)
Other liabilities	193	(102)	114
Trading securities	(494)	1,702	108
Net cash flow provided by operating activities	1,741	4,222	2,590
Investing Activities:
Purchases of fixed maturities	(8,661)	(10,785)	(9,065)
Proceeds from sales of fixed maturities	5,842	8,408	5,438
Proceeds from maturities of fixed maturities	2,997	2,370	3,641
Purchases of limited partnership investments	(198)	(420)	(171)
Proceeds from sales of limited partnership investments	742	470	212
Purchases of property, plant and equipment	(1,041)	(995)	(1,031)
Acquisitions	(257)	(37)	(1,218)
Dispositions	140	113	79
Change in short term investments	(57)	(339)	(167)
Other, net	(178)	(229)	(373)
Net cash flow used by investing activities	(671)	(1,444)	(2,655)
Financing Activities:
Dividends paid	(76)	(80)	(84)
Dividends paid to noncontrolling interests	(98)	(121)	(139)
Purchase of Boardwalk Pipeline common units		(1,504)
Purchases of Loews treasury stock	(1,051)	(1,026)	(216)
Purchases of subsidiary stock from noncontrolling interests	(23)
Principal payments on debt	(1,956)	(1,043)	(2,411)
Issuance of debt	2,076	865	3,067
Other, net	(16)	74	(16)
Net cash flow (used) provided by financing activities	(1,144)	(2,835)	201
Effect of foreign exchange rate on cash	5	(10)	9
Net change in cash	(69)	(67)	145
Cash, beginning of year	405	472	327
Cash, end of year	$ 336	$ 405	$ 472

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1. Summary of Significant Accounting Policies Basis of presentation – Altium Packaging LLC , Altium Packaging owned subsidiary). Unless the context otherwise requires, (i) the terms “Company” and “Loews” as used herein mean Loews Corporation including its subsidiaries and (ii) the term “Net income (loss) attributable to Loews Corporation” as used herein means Net income (loss) attributable to Loews Corporation shareholders. Principles of consolidation Accounting estimates Investments available-for-sale available-for-sale The cost of fixed maturity securities classified as available-for-sale For asset-backed securities included in fixed maturity securities, the Company recognizes income using an effective yield based on anticipated prepayments and the estimated economic life of the securities. When estimates of prepayments change, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. To the extent that unrealized gains on fixed maturity securities supporting long term care products and structured settlements not funded by annuities would result in a premium deficiency if those gains were realized, a related increase in Insurance reserves is recorded, net of tax and noncontrolling interests, as a reduction of net unrealized gains through Other comprehensive income (“Shadow Adjustments”). Shadow Adjustments increased $1.0 b b Equity securities are carried at fair value. CNA’s non-redeemable non-redeemable as available-for-sale The Company’s carrying value of investments in limited partnerships is its share of the net asset value of each partnership, as determined by the general partner. Certain partnerships for which results are not available on a timely basis are reported on a lag, primarily three months or less. These investments are accounted for under the equity method and changes in net asset values are recorded within Net investment income on the Consolidated Statements of Income. Mortgage loans are commercial in nature, are carried at unpaid principal balance, net of unamortized fees and any valuation allowance, and are recorded once funded. Interest income from mortgage loans is recognized on an accrual basis using the effective yield method. Mortgage loans are considered to be impaired loans when it is probable that contractual principal and interest payments will not be collected. CNA evaluates loans for impairment on an individual loan basis and identifies loans for evaluation of impairment based on the collection experience of each loan and other credit quality indicators such as debt service coverage ratio and the creditworthiness of the borrower or tenants of credit tenant loan properties. Accrual of income is generally suspended for mortgage loans that are impaired and collection of principal and interest payments is unlikely. Mortgage loans are considered past due when full principal or interest payments have not been received according to contractual terms. As of December 31, 2019 and 2018, there were no loans past due or in non-accrual Investments in derivative securities are carried at fair value with changes in fair value reported as a component of Investment gains (losses), Income (loss) from trading portfolio, or Other comprehensive income (loss), depending on their hedge designation. A derivative is typically defined as an instrument whose value is “derived” from an underlying instrument, index or rate, has a notional amount, requires little or no initial investment and can be net settled. Derivatives include, but are not limited to, the following types of investments: interest rate swaps, interest rate caps and floors, put and call options, warrants, futures, forwards, commitments to purchase securities, credit default swaps and combinations of the foregoing. Derivatives embedded within non-derivative An available-for-sale When the decline in value is determined by the Company to be other-than-temporary, losses are recognized within Investment gains (losses) on the Consolidated Statements of Income. Significant judgment is required in the determination of whether an OTTI loss has occurred for a security. CNA follows a consistent and systematic process for determining and recording an OTTI loss including the evaluation of securities in an unrealized loss position on at least a quarterly basis. CNA’s assessment of whether an OTTI loss has occurred incorporates both quantitative and qualitative information. Fixed maturity securities that CNA intends to sell, or it more likely than not will be required to sell before recovery of amortized cost, are considered to be other-than-temporarily impaired and the entire difference between the amortized cost basis and fair value of the security is recognized as an OTTI loss in earnings. The remaining fixed maturity securities in an unrealized loss position are evaluated to determine if a credit loss exists. The factors considered include: (i) the financial condition and near term and long term prospects of the issuer, (ii) whether the debtor is current on interest and principal payments, (iii) credit ratings of the securities and (iv) general market conditions and industry or sector specific outlook. CNA also considers results and analysis of cash flow modeling for asset-backed securities, and when appropriate, other fixed maturity securities. If the present value of the modeled expected cash flows equals or exceeds the amortized cost of a security, no credit loss is judged to exist and the asset-backed security is deemed to be temporarily impaired. If the present value of the expected cash flows is less than amortized cost, the security is judged to be other-than-temporarily impaired for credit reasons and that shortfall, referred to as the credit component, is recognized as an OTTI loss in earnings. The difference between the adjusted amortized cost basis and fair value, referred to as the non-credit non-credit Prior to 2018, CNA applied the same impairment model as described above for the majority of its non-redeemable Joint venture investments Loews Hotels & Co has over which it exercises significant influence, but does not have control over them. Co uses the equity method of accounting for these investments . Loews Hotels & Co’s investment in these entities was $ million and $ million as of December , and and reported in Other assets on the Consolidated Balance Sheets. Equity income for these investments was $ million, $ million and $ million for the years ended December , , and and reported in Operating expenses and other on the Consolidated Statements of Income. These equity method investments are reviewed for impairment when changes in circumstances indicate that the carrying value of the asset may not be recoverable. The following tables present summarized financial information for these joint ventures: Year Ended December 31 2019 2018 (In millions) Total assets $ 2,261 $ 1,924 Total liabilities 1,727 1,451 Year Ended December 31 2019 2018 2017 Revenues $ 804 $ 731 $ 731 Net income 106 114 261 Hedging Securities lending activities Securities lending is typically done on a matched-book basis where the collateral is invested to substantially match the term of the loan. This matching of terms tends to limit risk. In accordance with the Company’s lending agreements, securities on loan are returned immediately to the Company upon notice. Collateral is not reflected as an asset of the Company. There was no collateral held at December 31, 2019 and 2018. Revenue recognition Insurance receivables include balances due currently or in the future, including amounts due from insureds related to paid Property and casualty contracts that are retrospectively rated contain provisions that result in an adjustment to the initial policy premium depending on the contract provisions and loss experience of the insured during the experience period. For such contracts, CNA estimates the amount of ultimate premiums that it may earn upon completion of the experience period and recognizes either an asset or a liability for the difference between the initial policy premium and the estimated ultimate premium. CNA adjusts such estimated ultimate premium amounts during the course of the experience period based on actual results to date. The resulting adjustment is recorded as either a reduction of or an increase to the earned premiums for the period. CNA’s non-insurance N i Non-insurance Non-insurance Prior to 2018, Non-insurance Non-insurance non-insurance non-insurance Contract costs to obtain or fulfill 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 Pipelines 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 Pipelines’ operating subsidiaries are subject to Federal Energy Regulatory Commission (“FERC”) regulations and certain revenues collected, under certain circumstances, may be subject to possible refunds to its customers. An estimated refund liability is recorded considering regulatory proceedings, advice of counsel and estimated total exposure. The majority of Boardwalk Pipelines’ 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. 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 and other expenses as they are incurred on behalf of the owners of joint venture and managed hotel properties. Altium Packaging is a packaging solutions provider and manufacturer in North America, serving a diverse customer base in the pharmaceutical, dairy, household chemicals, food/nutraceuticals, industrial/specialty chemicals, water and beverage/juice segments. Altium Packaging recognizes revenue at the time control is transferred to the customer, there is persuasive evidence of an arrangement, the sales price is fixed and determinable and collection is reasonably assured. Claim and claim adjustment expense reserves Claim and claim adjustment expense reserves are presented net of anticipated amounts due from insureds related to losses under deductible policies of $1.2 billion as of December 31, 2019 and 2018. A significant portion of these amounts are supported by collateral. CNA also has an allowance for uncollectible deductible amounts, which is presented as a component of the allowance for doubtful accounts included in Receivables on the Consolidated Balance Sheets. Structured settlements have been negotiated for certain property and casualty insurance claims. Structured settlements are agreements to provide fixed periodic payments to claimants. CNA’s obligations for structured settlements not funded by annuities are included in claim and claim adjustment expense reserves and carried at present values determined using interest rates ranging from 5.5% to 7.6% and 5.5% to Workers’ compensation lifetime claim reserves are calculated using mortality assumptions determined through statutory regulation and economic factors. At December 31, 2019 and 2018, workers’ compensation lifetime claim reserves are discounted at a 3.5% interest rate. As of December 31, 2019 and 2018, the discounted reserves for workers’ compensation lifetime claim reserves were $293 million and $343 million, net of discount of $135 million and $168 million. For the years ended December 31, 2019, 2018 and 2017, the amount of interest accretion recognized on the discounted reserves of workers’ compensation lifetime claim reserves was $21 million, $16 million and $19 million. This interest accretion is presented as a component of Insurance claims and policyholders’ benefits on the Consolidated Statements of Income, but is excluded from the Company’s disclosure of prior year loss reserve development. Long term care claim reserves are calculated using mortality and morbidity assumptions based on CNA and industry experience. Long term care claim reserves are discounted at a 2019 and Future policy benefit reserves These re locked policy; however if e merges are are increased September 30, 2019 a premium deficiency of $216 million and future policy benefit reserves at that date were increased accordingly. As a result, the carried 2019 represent management’s best estimate assumptions at that date with no margin for adverse deviation. Long term care active life reserves are discounted at a weighted average In circumstances where the cash flow projections supporting future policy benefit reserves are expected to result in profits being recognized in early future years followed by losses in later future years, the future policy benefit reserves are increased in the future profitable years by an amount necessary to offset losses that are projected to be recognized in later future years. The amount of the additional future policy benefit reserves recorded in each period is determined by applying the ratio of the present value of future losses divided by the present value of future profits from the most recently completed GPV to long term care core income in that period. I Reinsurance Reinsurance receivables related to paid losses are presented at unpaid balances. Reinsurance receivables related to unpaid losses are estimated in a manner consistent with claim and claim adjustment expense reserves or future policy benefit reserves. Reinsurance receivables are reported net of an allowance for doubtful accounts on the Consolidated Balance Sheets. The cost of reinsurance is primarily accounted for over the life of the underlying reinsured policies using assumptions consistent with those used to account for the underlying policies or over the reinsurance contract period. The ceding of insurance does not discharge the primary liability of CNA. CNA has established an allowance for doubtful accounts on reinsurance receivables which relates to both amounts already billed on ceded paid losses as well as ceded reserves that will be billed when losses are paid in the future. The allowance for doubtful accounts on reinsurance receivables is estimated on the basis of periodic evaluations of balances due from reinsurers, reinsurer solvency, industry experience and current economic conditions. Reinsurer financial strength ratings are updated and reviewed on an annual basis or sooner if CNA becomes aware of significant changes related to a reinsurer. Because billed receivables generally approximate 5% or less of total reinsurance receivables, the age of the reinsurance receivables related to paid losses is not a significant input into the allowance analysis. Changes in the allowance for doubtful accounts on reinsurance receivables are presented as a component of Insurance claims and policyholders’ benefits on the Consolidated Statements of Income. Amounts are considered past due based on the reinsurance contract terms. Reinsurance receivables related to paid losses and any related allowance are written off after collection efforts have been exhausted or a negotiated settlement is reached with the reinsurer. Reinsurance receivables from insolvent insurers related to paid losses are written off when the settlement due from the estate can be reasonably estimated. At the time reinsurance receivables related to paid losses are written off, any required adjustment to reinsurance receivables related to unpaid losses is recorded as a component of Insurance claims and policyholders’ benefits on the Consolidated Statements of Income. A loss portfolio transfer is a retroactive reinsurance contract. If the cumulative claim and allocated claim adjustment expenses ceded under a loss portfolio transfer exceed the consideration paid, the resulting gain from such excess is deferred and amortized into earnings in future periods in proportion to actual recoveries under the loss portfolio transfer. In any period in which there is a revised estimate of claim and allocated claim adjustment expenses and the loss portfolio transfer is in a gain position, the deferred gain is recalculated as if the revised estimate was available at the inception date of the loss portfolio transfer and the change in the deferred gain is recognized in earnings. Deferred acquisition costs CNA evaluates deferred acquisition costs for recoverability. Anticipated investment income is considered in the determination of the recoverability of deferred acquisition costs. Adjustments, if necessary, are recorded in current period results of operations. Policyholder dividends Goodwill and other intangible assets Other intangible assets are reported within Other assets. Finite-lived intangible assets are amortized over their estimated useful lives. Indefinite-lived other intangible assets are tested for impairment annually or when certain triggering events require such tests. See Note 7 for additional information on the Company’s goodwill and other intangible assets. Property, plant and equipment The principal service lives used in computing provisions for depreciation are as follows: Years Pipeline equipment 30 to 50 Offshore drilling equipment 15 to 30 Other 3 to 40 Impairment of long-lived assets Assets to be disposed of and assets not expected to provide any future service potential to the Company are recorded at the lower of carrying amount or fair value less cost to sell. Income taxes The Company recognizes uncertain tax positions that it has taken or expects to take on a tax return. The tax benefit of a qualifying position is the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. See Note 10 for additional information on the provision for income taxes. Pension and postretirement benefits Stock-based compensation three Net income per share For each of the years ended December 31, 2019, 2018 and 2017, approximately 0.7 million, 0.9 million and 0.9 million potential shares attributable to issuances and exercises under the Loews Corporation 2016 Incentive Compensation Plan and the prior plan were included in the calculation of diluted net income per share. For the years ended December 31, 2019 and 2018, there were no shares and for the year ended December 31, 2017, there were 0.4 million shares attributable to employee stock-based compensation awards excluded from the calculation of diluted net income per share because the effect would have been antidilutive. Foreign currency Regulatory accounting Supplementary cash flow information 190 17 Accounting changes 2016-02, 2016-02”). For leases where we are a lessee we have elected to account for lease and non-lease non-lease At adoption, the cumulative effect adjustment increased Other assets and Other liabilities by $642 million reflecting operating lease right of use assets, lease liabilities and the derecognition of deferred rent related primarily to lease agreements for office space and machinery and equipment. At 2016-02, 9 On January 1, 2018, the Company adopted ASU 2014-09, 2014-09”). non-insurance non-insurance On January 1, 2018 the Company adopted ASU 2016-01, – 825-10): 2016-01”). On January 1, 2018 the Company adopted ASU 2016-16, On January 1, 2018 the Company early adopted ASU 2018-02, 2018-02”). Recently issued ASUs 2016-13, available-for-sale available-for-sale available-for-sale In August of 2018, the FASB issued ASU 2018-12, (“OCI”). This guidance is effective for interim and annual periods beginning after December 15, 2021. The Company will adopt the guidance on January 1, 2022. The guidance requires restatement of prior periods presented. The Company is currently evaluating the method of adoption and the effect the updated guidance will have on its consolidated financial statements, including increased disclosure requirements. The annual updating of cash flow assumptions is expected to increase income statement volatility. The quarterly change in the discount rate is expected to increase volatility in the Company’s Shareholders’ equity, but that will be somewhat mitigated because Shadow Adjustments are eliminated under the new guidance. While the requirements of the new guidance represent a material change from existing accounting guidance, the underlying economics of CNA’s business and related cash flows are unchanged.

Acquisitions and Divestitures

Acquisitions and Divestitures	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisitions and Divestitures	Note 2. Acquisitions and Divestitures Boardwalk Pipelines On June 29, 2018, Boardwalk GP, LP (“General Partner”), the general partner of Boardwalk Pipeline s s s s paid-in 658 213 Following completion of the transaction on July 18, 2018, Boardwalk Pipelines Holding Corp. (“BPHC”), a wholly owned subsidiary of Loews Corporation, holds, directly or indirectly, all of the limited partnership interests of Boardwalk Pipelines. Loews Hotels & Co In 2019, Loews Hotels & Co received proceeds of $118 million for the sale of an owned hotel hotel Altium Packaging In 2019, Altium Packaging paid approximately $260 million to complete three acquisitions of plastic packaging manufacturers located in the U.S. and Canada, including the acquisition on June 14, 2019 of Altium Healthcare Inc. (formerly known as Tri State Distribution, Inc.), a retail pharmaceutical packaging solutions provider. For the year ended December 31, 2019, revenues for the three acquisitions since acquisition were $76 million and net results were not significant. The preliminary allocation of the purchase prices for the three acquisitions resulted in the recognition of approximately $99 million of goodwill and approximately $87 million of intangible assets, primarily related to customer relationships, and are subject to change within the respective measurement periods. The acquisitions were funded with approximately $250 million of debt financing proceeds at Altium Packaging, as discussed in Note 11, and available cash. In 2018, Altium Packaging paid approximately $40 million to complete three acquisitions of plastic packaging manufacturers located in the U.S. and Canada, resulting in recognition of approximately $10 million of goodwill and approximately $15 million of intangible assets, primarily customer relationships. On May 22, 2017, the Company acquired Altium Acquisition Holdings, Inc. (formerly known as ), Altium million of Parent Company cash and debt financing proceeds at Altium Packaging of $ million. The results of Altium Packaging are included in the Consolidated

Investments

Investments	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Investments	N ote 3. Investments Net investment income is as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities $ 1,817 $ 1,795 $ 1,812 Limited partnership investments 204 22 277 Short term investments 52 43 18 Equity securities 85 18 12 Income (loss) from trading portfolio (a) 216 (54 ) 87 Other 56 54 35 Total investment income 2,430 1,878 2,241 Investment expenses (75 ) (61 ) (59 ) Net investment income $ 2,355 $ 1,817 $ 2,182 (a) Net unrealized gains (losses) related to changes in fair value on securities still held were $41, $(121) and $39 for the years ended December 31, 2019, 2018 and 2017. As of December 31, 2019, the Company held less than $1 million of non-income A non-income producing fixed maturity securities. As of December 31, 2019 and 2018, investments in a single issuer exceeded 10% of shareholders’ equity, other than investments in securities issued by the U.S. and obligations of government-sponsored enterprises. Investment gains (losses) are as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities $ (6 ) $ 4 $ 122 Equity securities 66 (74 ) Derivative instruments (11 ) 9 (4 ) Short term investments and other 4 4 Investment gains (losses) (a) $ 49 $ (57 ) $ 122 (a) Gross investment available-for-sale investment available-for-sale $ investment g ains Net investment losses of $73 were recognized due to the change in fair value of non-redeemable preferred stock still held for the year ended December 31, 2018. Net change in unrealized gains (losses) on investments is as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities $ 2,620 $ (1,811 ) $ 728 Equity securities (a) 32 Other (2 ) Total net change in unrealized gains (losses) on investments $ 2,620 $ (1,811 ) $ 758 (a) Due to the adoption of ASU 2016-01 The components of OTTI losses recognized in earnings by asset type are as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 33 $ 12 $ 12 Asset-backed 11 9 1 Total fixed maturity securities available-for-sale 44 21 13 Equity securities available-for-sale 1 Net OTTI losses recognized in earnings $ 44 $ 21 $ 14 The amortized cost and fair values of fixed maturity and equity securities are as follows: December 31, 2019 Cost Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Estimated Fair Value Unrealized OTTI (Gains) (In millions) Fixed maturity securities: Corporate and other bonds $ 19,789 $ 2,292 $ 32 $ 22,049 States, municipalities and political subdivisions 9,093 1,559 10,652 Asset-backed: Residential mortgage-backed 4,387 133 1 4,519 $ ) Commercial mortgage-backed 2,265 86 5 2,346 1 Other asset-backed 1,925 41 4 1,962 (3 ) Total asset-backed 8,577 260 10 8,827 (19) U.S. Treasury and obligations of government- 146 1 2 145 Foreign government 491 14 1 504 Redeemable preferred stock 10 10 Fixed maturities available-for-sale 38,106 4,126 45 42,187 (19) Fixed maturities trading 51 2 53 Total fixed maturities $ 38,157 $ 4,128 $ 45 $ 42,240 $ ) December 31, 2018 Cost or Amortized Cost Gross Unrealized Gains Gross Losses Estimated Fair Value Unrealized OTTI Losses (Gains) (In millions) Fixed maturity securities: Corporate and other bonds $ 18,764 $ 791 $ 395 $ 19,160 States, municipalities and political subdivisions 9,681 1,076 9 10,748 Asset-backed: Residential mortgage-backed 4,815 68 57 4,826 $ (20 ) Commercial mortgage-backed 2,200 28 32 2,196 Other asset-backed 1,975 11 24 1,962 Total asset-backed 8,990 107 113 8,984 (20 ) U.S. Treasury and obligations of government-sponsored enterprises 156 3 159 Foreign government 480 5 4 481 Redeemable preferred stock 10 10 Fixed maturities available-for-sale 38,081 1,982 521 39,542 (20 ) Fixed maturities trading 153 4 157 Total fixed maturities $ 38,234 $ 1,986 $ 521 $ 39,699 $ (20 ) The available-for-sale Less than 12 Months 12 Months or Longer Total December 31, 2019 Estimated Fair V Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (In millions ) Fixed maturity securities: Corporate and other bonds $ 914 $ 21 $ 186 $ 11 $ 1,100 $ 32 States, municipalities and political subdivisions 34 34 Asset-backed: Residential mortgage-backed 249 1 30 279 1 Commercial mortgage-backed 381 3 20 2 401 5 Other asset-backed 449 3 33 1 482 4 Total asset-backed 1,079 7 83 3 1,162 10 U.S. Treasury and obligations of government-sponsored enterprises 62 2 2 64 2 Foreign government 59 1 1 60 1 Total fixed maturity securities $ 2,148 $ 31 $ 272 $ 14 $ 2,420 $ 45 December 31, 2018 Fixed maturity securities: Corporate and other bonds $ 8,543 $ 340 $ 825 $ 55 $ 9,368 $ 395 States, municipalities and political subdivisions 517 8 5 1 522 9 Asset-backed: Residential mortgage-backed 1,932 23 1,119 34 3,051 57 Commercial mortgage-backed 728 10 397 22 1,125 32 Other asset-backed 834 21 125 3 959 24 Total asset-backed 3,494 54 1,641 59 5,135 113 U.S. Treasury and obligations of government-sponsored enterprises 21 19 40 Foreign government 114 2 124 2 238 4 Total fixed maturity securities $ 12,689 $ 404 $ 2,614 $ 117 $ 15,303 $ 521 Based on current facts and circumstances, the Company believes the unrealized losses presented in the December 31, 2019 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 at December 31, 2019. The following table presents the activity related to the pretax credit loss component reflected in Retained earnings on fixed maturity securities still held at December 31, 2019, 2018 and 2017 for which a portion of an OTTI loss was recognized in Other comprehensive income. Year Ended December 31 2019 2018 2017 (In millions) Beginning balance of credit losses on fixed maturity securities $ 18 $ 27 $ 36 Reductions for securities sold during the period (8 ) (9 ) (9 ) Ending balance of credit losses on fixed maturity securities $ 10 $ 18 $ 27 Contractual Maturity The following table presents available-for-sale December 31 2019 2018 Cost Estimated Cost Estimated (In millions) Due in one year or less $ 1,334 $ 1,356 $ 1,350 $ 1,359 Due after one year through five years 9,746 10,186 7,979 8,139 Due after five years through ten years 14,892 15,931 16,859 16,870 Due after ten years 12,134 14,714 11,893 13,174 Total $ 38,106 $ 42,187 $ 38,081 $ 39,542 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. Limited Partnerships The carrying value of limited partnerships as of December 31, 2019 and 2018 was approximately $2.0 billion and $2.4 billion, which includes net undistributed earnings of $297 million and $208 million. Limited partnerships comprising 64.4% of the total carrying value are reported on a current basis through December 31, 2019 with no reporting lag, 9.1% of the total carrying value are reported on a one month lag and the remainder are reported on more than a one month lag. The number of limited partnerships held and the strategies employed provide diversification to the limited partnership portfolio and the overall invested asset portfolio. Limited partnerships comprising 65.7% and 71.3% of the carrying value as of December 31, 2019 and 2018 employ hedge fund strategies. Limited partnerships comprising 29.1% and 24.3% of the carrying value at December 31, 2019 and 2018 were invested in private debt and equity and t ere The ten largest limited partnership positions held totaled $1.1 billion as of December 31, 2019 and 2018. Based on the most recent information available regarding the Company’s percentage ownership of the individual limited partnerships, the carrying value reflected on the Consolidated Balance Sheets represents approximately 2.3% and 2.6% of the aggregate partnership equity at December 31, 2019 and 2018, and the related income reflected on the Consolidated Statements of Income represents approximately 2.5%, 3.3% and 3.0% of the changes in aggregate partnership equity for the years ended December 31, 2019, 2018 and 2017. There are risks inherent in limited partnership investments which may result in losses due to short-selling, derivatives or other speculative investment practices. The use of leverage increases volatility generated by the underlying investment strategies. The Company’s hedge fund limited partnership investments contain withdrawal provisions that generally limit liquidity for a period of thirty days up to one year or longer. Private equity and other non-hedge Derivative Financial Instruments The Company may use derivatives in the normal course of business, primarily in an attempt to reduce exposure to market risk (principally interest rate risk, credit risk, equity price risk, commodity price risk and foreign currency risk) stemming from various assets and liabilities. The principal objective under such strategies is to achieve the desired reduction in economic risk, even if the position does not receive hedge accounting treatment. The Company may enter into interest rate swaps, futures and forward commitments to purchase securities to manage interest rate risk. Credit derivatives such as credit default swaps may be entered into to modify the credit risk inherent in certain investments. Forward contracts, futures, swaps and options may be used to manage foreign currency and commodity price risk. In addition to the derivatives used for risk management purposes described above, the Company may also use derivatives for purposes of income enhancement. Income enhancement transactions include but are not limited to interest rate swaps, call options, put options, credit default swaps, index futures and foreign currency forwards. See Note 4 for information regarding the fair value of derivative instruments. The following tables present the aggregate contractual or notional amount and estimated fair value related to derivative financial instruments. December 31 2019 2018 Contractual/ Contractual/ Notional Estimated Fair Value Notional Estimated Fair Value Amount Asset (Liability) Amount Asset (Liability) (In millions) With hedge designation: Interest rate swaps $ 715 $ (8 ) $ 500 $ 11 Without hedge designation: Equity markets: Options – purchased 57 $ 1 213 18 – written 100 (1) 239 $ (17 ) Commodity futures – long 32 Embedded derivative on funds withheld liability 182 (7) 172 4 Investment Commitments As part of its overall investment strategy, the Company invests in various assets which require future purchase, sale or funding of commitments. These investments are recorded once funded, and the related commitments include future capital calls from various third-party limited partnerships, signed and accepted mortgage loan applications and obligations related to privately placed debt securities. As of December 31, 2019, the Company had commitments to purchase or fund approximately $945 million and sell approximately $85 million under the terms of these investments. Investments on Deposit Securities with carrying values of approximately $2.7 billion and $2.5 billion were deposited by CNA’s insurance subsidiaries under requirements of regulatory authorities and others as of December 31, 2019 and 2018. Cash and securities with carrying values of approximately $1.1 billion and $1.0 billion were deposited with financial institutions in trust accounts or as collateral for letters of credit to secure obligations with various third parties as of December 31, 2019 and 2018.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value	Note 4. Fair Value Fair value is the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The following fair value hierarchy is used in selecting inputs, with the highest priority given to Level 1, as these are the most transparent or reliable: • Level 1 – Quoted prices for identical instruments in active markets. • Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets. • Level 3 – Valuations derived from valuation techniques in which one or more significant inputs are not observable. Prices may fall within Level 1, 2 or 3 depending upon the methodology and inputs used to estimate fair value for each specific security. In general, the Company seeks to price securities using third party pricing services. Securities not priced by pricing services are submitted to independent brokers for valuation and, if those are not available, internally developed pricing models are used to value assets using a methodology and inputs the Company believes market participants would use to value the assets. Prices obtained from third-party pricing services or brokers are not adjusted by the Company. The Company performs control procedures over information obtained from pricing services and brokers to ensure prices received represent a reasonable estimate of fair value and to confirm representations regarding whether inputs are observable or unobservable. Procedures may include: (i) the review of pricing service methodologies or broker pricing qualifications, (ii) back-testing, where past fair value estimates are compared to actual transactions executed in the market on similar dates, (iii) exception reporting, where period-over-period changes in price are reviewed and challenged with the pricing service or broker based on exception criteria and Assets and liabilities measured at fair value on a recurring basis are summarized in the following tables. Corporate bonds and other includes obligations of the U.S. Treasury, government-sponsored enterprises, foreign governments and redeemable preferred stock. December 31, 2019 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 175 $ 22,065 $ 468 $ 22,708 States, municipalities and political subdivisions 10,652 10,652 Asset-backed 8,662 165 8,827 Fixed maturities available-for-sale 175 41,379 633 42,187 Fixed maturities trading 49 4 53 Total fixed maturities $ 175 $ 41,428 $ 637 $ 42,240 Equity securities $ 629 $ 658 $ 19 $ 1,306 Short term and other 3,138 1,383 4,521 Receivables 2 2 Payable to brokers (18 ) (10 ) (28 ) December 31, 2018 Fixed maturity securities: Corporate bonds and other $ 196 $ 19,392 $ 222 $ 19,810 States, municipalities and political subdivisions 10,748 10,748 Asset-backed 8,787 197 8,984 Fixed maturities available-for-sale 196 38,927 419 39,542 Fixed maturities trading 151 6 157 Total fixed maturities $ 196 $ 39,078 $ 425 $ 39,699 Equity securities $ 704 $ 570 $ 19 $ 1,293 Short term and other 2,647 1,111 3,758 Receivables 11 11 Payable to brokers (23 ) (23) The tables below present reconciliations for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2019 and 2018: Unrealized Gains Unrealized (Losses) Gains Recognized in (Losses) Other Recognized in Comprehensive Net Realized Investment Net Income Income (Loss) Gains (Losses) and Net (Loss) on Level on Level 3 Change in Unrealized 3 Assets and Assets and Investment Gains (Losses) Transfers Transfers Liabilities Liabilities Balance, Included in Included in into out of Balance, Held at Held at 2019 January 1 Net Income OCI Purchases Sales Settlements Level 3 Level 3 December 31 December 31 December 31 (In millions) Fixed maturity securities: Corporate bonds and other $ 222 $ 33 $ 256 $ (11) $ (32) $ 468 $ 28 Asset-backed 197 8 48 (16) $ 45 (117) 165 7 Fixed maturities available-for-sale 419 $ - 41 304 $ - (27) 45 (149) 633 $ - 35 Fixed maturities trading 6 (2) 4 (2) Total fixed maturities $ 425 $ (2) $ 41 $ 304 $ - $ (27) $ 45 $ (149) $ 637 $ (2) $ 35 Equity securities $ 19 $ (2) $ 2 $ 19 $ (2) Unrealized Gains Unrealized (Losses) Gains Recognized in (Losses) Other Recognized in Comprehensive Net Realized Investment Net Income Income (Loss) Gains (Losses) and Net (Loss) on Level on Level 3 Change in Unrealized 3 Assets and Assets and Investment Gains (Losses) Transfers Transfers Liabilities Liabilities Balance, Included in Included in into out of Balance, Held at Held at 2018 January 1 Net Income OCI Purchases Sales Settlements Level 3 Level 3 December 31 December 31 December 31 (In millions) Fixed maturity securities: Corporate bonds and other $ 98 $ (1) $ (4) $ 117 $ (5) $ (9) $ 35 $ (9) $ 222 $ (5 ) States, municipalities and political subdivisions 1 (1) - Asset-backed 335 5 (8) 162 (72) (64) 42 (203) 197 $ (2) (4 ) Fixed maturities available-for-sale 434 4 (12) 279 (77) (74) 77 (212) 419 (2) (9 ) Fixed maturities trading 4 3 (1) 6 2 Total fixed maturities $ 438 $ 7 $ (12) $ 279 $ (78) $ (74 ) $ 77 $ (212) $ 425 $ - $ (9 ) Equity securities $ 22 $ (2) $ (1) $ 19 $ (2) Net investment gains and losses are reported in Net income as follows: Major Category of Assets and Liabilities Consolidated 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 Securities may be transferred in or out of levels within the fair value hierarchy based on the availability of observable market information and quoted prices used to determine the fair value of the security. The availability of observable market information and quoted prices varies based on market conditions and trading volume. Valuation Methodologies and Inputs The following section describes the valuation methodologies and relevant inputs used to measure different financial instruments at fair value, including an indication of the level in the fair value hierarchy in which the instruments are generally classified. Fixed Maturity Securities Level 1 securities include highly liquid government securities some 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 some Derivative Financial Instruments E quity option s Over-the-counter currency forwar ds, 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 Significant Unobservable Inputs The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 assets. Valuations for assets and liabilities not presented in the tables below are primarily based on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations. The quantitative detail of unobservable inputs from these broker quotes is neither provided nor reasonably available to the Company. The weighted average rate is calculated based on fair value. Range Estimated Valuation Unobservable (Weighted December 31, 2019 Fair Value Techniques Inputs Average) (In millions) Fixed maturity securities $ 525 Discounted cash Credit 1 % 6 2 ) December 31, 2018 Fixed maturity securities $ Discounted cash 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 Balance Sheets are presented in the following tables. The carrying amounts and estimated fair values of short term debt and long term debt exclude finance Carrying Estimated Fair Value December 31, 2019 Amount Level 1 Level 2 Level 3 Total (In millions) Assets: Other invested assets, primarily mortgage loans $ 994 $ 1,025 $ 1,025 Liabilities: Short term debt 75 $ 9 66 75 Long term debt 11,443 10,884 626 11,510 December 31, 2018 Assets: Other invested assets, primarily mortgage loans $ 839 $ 827 $ 827 Liabilities: Short term debt 15 $ 14 14 Long term debt 11,345 10,111 653 10,764 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. The fair values of debt were based on observable market prices when available. When observable market prices were not available, the fair values of debt were based on observable market prices of comparable instruments adjusted for differences between the observed instruments and the instruments being valued or is estimated using discounted cash flow analyses, based on current incremental borrowing rates for similar types of borrowing arrangements.

Receivables

Receivables	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Receivables	Note 5. Receivables December 31 2019 2018 (In millions) Reinsurance (Note 16) $ 4,204 $ 4,455 Insurance 2,481 2,365 Receivable from brokers 124 296 Accrued investment income 395 394 Federal income taxes 14 52 Other, primarily customer accounts 520 477 Total 7,738 8,039 Less: allowance for doubtful accounts on reinsurance receivables 25 29 allowance for other doubtful accounts 38 50 Receivables $ 7,675 $

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Note 6. Property, Plant and Equipment December 31 2019 2018 (In millions) Pipeline equipment (net of accumulated depreciation of $3,075 and $2,761) $ 8,229 $ Offshore drilling equipment (net of accumulated depreciation of $2,885 and $3,067) 5,119 5,144 Other (net of accumulated depreciation of $1,114 and $1,056 ) 1,625 1,812 Construction in process 595 317 Property, plant and equipment $ 15,568 $ Depreciation expense and capital expenditures are as follows: Year Ended December 31 2019 2018 2017 Depre- Capital Depre- Capital Depre- Capital ciation Expend. ciation Expend. ciation Expend. (In millions) CNA Financial $ 64 $ 26 $ 76 $ 99 $ 80 $ 101 Diamond Offshore 356 345 332 222 349 113 Boardwalk Pipelines 348 418 346 487 325 689 Loews Hotels & Co 60 216 67 139 63 57 Corporate 70 53 59 48 37 30 Total $ 898 $ 1,058 $ 880 $ 995 $ 854 $ 990 Capitalized interest related to the construction and upgrade of qualifying assets amounted to approximately $18 million, $27 million and $37 million for the years ended December 31, 2019, 2018 and 2017. Diamond Offshore Asset Impairments During 2019, Diamond Offshore evaluated three drilling rigs with indicators of impairment. Based on the assumptions and analysis at that time, Diamond Offshore determined that the undiscounted probability-weighted cash flow of each of these rigs was in excess of its carrying value. As a result, Diamond Offshore concluded that no impairment of these rigs had occurred at December 31, 2019. During 2018, Diamond Offshore recorded an asset impairment charge of $27 million ($12 million after tax and noncontrolling interests) to recognize a reduction in fair value of the Ocean Scepter During 2017, Diamond Offshore evaluated ten of its drilling rigs with indicators of impairment and determined that the carrying values of three rigs were impaired. Diamond Offshore estimated the fair value of two of these rigs using an income approach, whereby the fair value of each rig was estimated based on a calculation of the rig’s future net cash flows. These calculations utilized significant unobservable inputs, including estimated proceeds that may be received on ultimate disposition of each rig. The fair value of the remaining rigs was estimated using a market approach, which required Diamond Offshore to estimate the value that would be received for the rig in the principal or most advantageous market for that rig in an orderly transaction between market participants. This estimate was primarily based on an indicative bid to purchase the rig, as well as the evaluation of other market data points. The fair value estimates were representative of Level 3 fair value measurements due to the significant level of estimation involved and the lack of transparency as to the inputs used. Diamond Offshore recorded aggregate asset impairment charges of $100 million ($32 million after tax and noncontrolling interests) for the year ended December 31, 2017. Boardwalk Pipelines Sale of Assets During 2017, Boardwalk Pipelines sold a processing plant and related assets for approximately $64 million, including customary adjustments. The sale resulted in a loss of $47 million ($15 million after tax and noncontrolling interests) and is reported within Operating expenses and other on the Consolidated Statements of Income. Loews Hotels & Co Asset Impairments Loews Hotels & Co evaluat es . It was carrying values of four properties in 2019 and two properties in 2018 were impaired. Loews Hotels & Co recorded aggregate impairment charges of $99 million ($77 million after tax) and $22 million ($15 million after tax) for the years ended December 31, 2019 and 2018 and are reported within Operating expenses and other on the Consolidated Statements of Income. These impairments reduced Property, plant and equipment and Other assets by $62 million and $37 million in 2019 and $16 million and $6 million in 2018. Loews Hotels & Co utilized an undiscounted probability-weighted cash flow analysis in testing the recoverability of long-lived assets for potential impairment. Assumptions and estimates underlying this analysis include (i) occupancy and room rates, (ii) other revenue, including food and beverage, (iii) operating expenses, including management and marketing fees and (iv) maintenance capital expenditures for repairs and refurbishment. Scenarios were developed using multiple assumptions of expected future events which Loews Hotels & Co assigned a probability of occurrence. This provided a projected probability-weighted cash flow of each property and was compared to the carrying value to assess recoverability. The underlying assumptions and assigned probabilities were estimated based on historical data adjusted for known developments, cost projections and future events that were anticipated by management at the time of the assessment. Loews Hotels & Co primarily uses an income approach to estimate the fair value of its properties by discounting future net cash flows. These calculations utilized significant unobservable inputs, including estimating the growth in the hotel’s average daily revenue and operating costs. The fair value of one property was estimated using a market approach which required Loews Hotels & Co to estimate the value that would be received for its property in the principal or most advantageous market in an orderly transaction between market participants. This estimate was informed by a recent independent appraisal. The fair value estimates were representative of Level 3 fair value measurements due to the significant level of estimation involved .

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Note 7. Goodwill and Other Intangible Assets A summary of the changes in the carrying amount of goodwill is as follows: CNA Boardwalk Financial Pipelines Corporate Total (In millions) Balance, December 31, 2017 $ 112 $ 237 $ 310 $ 659 Acquisition 8 8 Other adjustments (2 ) (2) Balance, December 31, 2018 110 237 318 665 Acquisition s 100 100 Other adjustments 2 2 Balance, December 31, 2019 $ 112 $ 237 $ 418 $ 767 The increases as of December 31, 2019 and 2018 reflect the acquisitions made by Altium Pac kagin g A summary of the net carrying amount of other intangible assets is as follows: December 31, 2019 December 31, 2018 Gross Gross Carrying Accumulated Carrying Accumulated Amount Amortization Amount Amortization (In millions) Finite-lived intangible assets: Customer relationships $ 611 76 $ 532 47 Other 71 34 72 20 Total finite-lived intangible assets 682 110 604 67 Indefinite-lived intangible assets 75 74 Total other intangible assets $ 757 110 $ 678 67 The balance as of December 31, 2019 and 2018 includes assets from acquisitions made by Altium Packaging . Amortization expense for the years ended December 31, 2019, 2018 and 2017 of $45 million, $32 million and $20 million is reported in Operating expenses and other on the Consolidated Statements of Income. At December 31, 2019, estimated amortization expense in each of the next five years is approximately $61 million in 2020, $38 million in 2021, $37 million in 2022, $36 million in 2023 and $34 million in 2024.

Claim, Claim Adjustment Expense

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves	12 Months Ended
	Dec. 31, 2019
Insurance [Abstract]
Claim, Claim Adjustment Expense and Future Policy Benefit Reserves	Note 8. Claim, Claim Adjustment Expense and Future Policy Benefit 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 historical patterns such as claim reserving trends and settlement practices, loss payments, pending levels of unpaid claims and product mix, as well as court decisions and 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. CNA’s commercial property and casualty insurance operations (“Property & Casualty Operations”) include its Specialty, Commercial and International lines of business. CNA’s Other Insurance Operations outside of Property & Casualty Operations include its long term care business that is in run-off, run-off, Liability for Unpaid Claim and Claim Adjustment Expenses The table below reconciles the net liability for unpaid claim and claim adjustment expenses to the amount presented o December 31 2019 (In millions) Net liability for unpaid claim and claim adjustment expenses: Property & Casualty Operations $ 14,153 Other Insurance Operations (a) 3,732 Total net claim and claim adjustment expenses 17,885 Reinsurance receivables: (b) Property & Casualty Operations 1,617 Other Insurance Operations (c) 2,218 Total reinsurance receivables 3,835 Total gross liability for unpaid claims and claims adjustment expenses $ 21,720 (a) Other Insurance Operations amounts are primarily related to long term care claim reserves, which are long duration insurance contracts, but also include amounts related to unfunded structured settlements arising from short duration insurance contracts. (b) Reinsurance receivables presented are gross of the allowance for uncollectible reinsurance and do not include reinsurance receivables related to paid losses. (c) The Other Insurance Operations reinsurance receivables are primarily related to A&EP claims covered under the loss portfolio transfer ( “ LPT ” ) 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. Year Ended December 31 2019 2018 2017 (In millions) Reserves, beginning of year: Gross $ 21,984 $ 22,004 $ 22,343 Ceded 4,019 3,934 4,094 Net reserves, beginning of year 17,965 18,070 18,249 Net incurred claim and claim adjustment expenses: Provision for insured events of current year 5,356 5,358 5,201 Decrease in provision for insured events of prior years (127 ) (179 ) (381 ) Amortization of discount 184 176 179 Total net incurred (a) 5,413 5,355 4,999 Net payments attributable to: Current year events (992 ) (1,046 ) (975 ) Prior year events (4,584 ) (4,285 ) (4,366 ) Total net payments (5,576 ) (5,331 ) (5,341 ) Foreign currency translation adjustment and other 83 (129 ) 163 Net reserves, end of year 17,885 17,965 18,070 Ceded reserves, end of year 3,835 4,019 3,934 Gross reserves, end of year $ 21,720 $ 21,984 $ 22,004 (a) Total net incurred above does not agree to Insurance claims and policyholders’ benefits as reflected on the Consolidated Statements of Income due to amounts related to retroactive reinsurance deferred gain accounting, uncollectible reinsurance and benefit expenses related to future policy benefits, which are not reflected in the table above. Reserving Methodology In developing claim and claim adjustment expense (“loss” or “losses”) reserve estimates, CNA’s actuaries perform detailed reserve analyses that are staggered throughout the year. Every reserve group is reviewed at least once during the year, but most are reviewed more frequently. The analyses generally review losses gross of ceded reinsurance and apply the ceded reinsurance terms to the gross estimates to establish estimates net of reinsurance. Factors considered include, but are not limited to, the historical pattern and volatility of the actuarial indications, the sensitivity of the actuarial indications to changes in paid and incurred loss patterns, the consistency of claims handling processes, the consistency of case reserving practices, changes in CNA’s pricing and underwriting, pricing and underwriting trends in the insurance market and legal, judicial, social and economic trends. In addition to the detailed analyses, CNA reviews actual loss emergence for all products each quarter. In developing the loss reserve estimates for property and casualty contracts, CNA generally projects ultimate losses using several common actuarial methods as listed below. CNA reviews the various indications from the various methods and applies judgment to select an actuarial point estimate. The carried reserve may differ from the actuarial point estimate as the result of CNA’s consideration of the factors noted above as well as the potential volatility of the projections associated with the specific product being analyzed and other factors affecting claims costs that may not be quantifiable through traditional actuarial analysis. The indicated required reserve is the difference between the selected ultimate loss and the inception-to-date ● Paid development ● Incurred development ● Loss ratio ● Bornhuetter-Ferguson using premiums and paid loss ● Bornhuetter-Ferguson using premiums and incurred loss ● Frequency times severity ● Stochastic modeling For many exposures, especially those that are considered long-tail, a particular accident or policy year may not have a sufficient volume of paid losses to produce a statistically reliable estimate of ultimate losses. In such a case, CNA’s actuaries typically assign more weight to the incurred development method than to the paid development method. As claims continue to settle and the volume of paid loss increases, the actuaries may assign additional weight to the paid development method. For most of CNA’s products, even the incurred losses for accident or policy years that are early in the claim settlement process will not be of sufficient volume to produce a reliable estimate of ultimate losses. In these cases, CNA may not assign any weight to the paid and incurred development methods. CNA may use the loss ratio, Bornhuetter-Ferguson and frequency times severity methods. For short-tail exposures, the paid and incurred development methods can often be relied on sooner, primarily because CNA’s history includes a sufficient number of years to cover the entire period over which paid and incurred losses are expected to change. However, CNA may also use the loss ratio, Bornhuetter-Ferguson and frequency times severity methods for short-tail exposures. For other more complex reserve groups where the above methods may not produce reliable indications, CNA uses additional methods tailored to the characteristics of the specific situation. CNA’s reserving methodologies for mass tort and A&EP are similar as both are based on detailed reviews of large accounts with estimates of ultimate payments based on the facts in each case and CNA’s view of applicable law and coverage litigation. Gross and Net Carried Reserves The following tables present the gross and net carried reserves: Property Other and Casualty Insurance December 31, 2019 Operations Operations Total (In millions) Gross Case Reserves $ 6,276 $ 4,713 $ 10,989 Gross IBNR Reserves 9,494 1,237 10,731 Total Gross Carried Claim and Claim Adjustment Expense Reserves $ 15,770 $ 5,950 $ 21,720 Net Case Reserves $ 5,645 $ 3,533 $ 9,178 Net IBNR Reserves 8,508 199 8,707 Total Net Carried Claim and Claim Adjustment Expense Reserves $ 14,153 $ 3,732 $ 17,885 December 31, 2018 Gross Case Reserves $ 6,671 $ 4,724 $ 11,395 Gross IBNR Reserves 9,287 1,302 10,589 Total Gross Carried Claim and Claim Adjustment Expense Reserves $ 15,958 $ 6,026 $ 21,984 Net Case Reserves $ 6,063 $ 3,460 $ 9,523 Net IBNR Reserves 8,290 152 8,442 Total Net Carried Claim and Claim Adjustment Expense Reserves $ 14,353 $ 3,612 $ 17,965 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 (“development”). These changes can be favorable or unfavorable. The following table and discussion presents detail of the development in CNA’s Property & Casualty Operations: Year Ended December 31 2019 2018 2017 (In millions) Medical professional liability $ 75 $ 47 $ 30 Other professional liability and management liability (69) (127) (126) Surety (92) (70) (84) Commercial auto (25) 1 (35) General liability 54 32 (24) Workers’ compensation (13) (32) (63) Other (3) (32) (6) Total pretax favorable development $ (73) $ (181) $ (308) Development Tables For CNA’s Property & Casualty Operations, the following tables present further detail and commentary on the development reflected in the financial statements for each of the periods presented. Also presented are loss reserve development tables that illustrate the change over time of reserves established for claim and allocated claim adjustment expenses arising from short duration insurance contracts for certain lines of business within CNA’s Property & Casualty Operations. Not all lines of business are presented based on their context to CNA’s overall loss reserves, calendar year reserve development, or calendar year net earned premiums. Insurance contracts are considered to be short duration contracts when the contracts are not expected to remain in force for an extended period of time. The Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses tables, reading across, show the cumulative net incurred claim and allocated claim adjustment expenses relating to each accident year at the end of the stated calendar year. Changes in the cumulative amount across time are the result of CNA’s expanded awareness of additional facts and circumstances that pertain to the unsettled claims. The Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses tables, reading across, show the cumulative amount paid for claims in each accident year as of the end of the stated calendar year. The Net Strengthening or (Releases) of Prior Accident Year Reserves tables, reading across, show the net increase or decrease in the cumulative net incurred accident year claim and allocated claim adjustment expenses during each stated calendar year and indicates whether the reserves for that accident year were strengthened or released. The information in the tables is reported on a net basis after reinsurance and does not include the effects of discounting. The information contained in calendar years 2018 and prior is unaudited. To the extent CNA enters into a commutation, the transaction is reported on a prospective basis. To the extent that CNA enters into a disposition, the effects of the disposition are reported on a retrospective basis by removing the balances associated with it. The amounts reported for the cumulative number of reported claims include direct and assumed open and closed claims by accident year at the claimant level. The number excludes claim counts for claims within a policy deductible where the insured is responsible for payment of losses in the deductible layer. Claim count data for certain assumed reinsurance contracts is unavailable. In the loss reserve development tables, IBNR includes reserves for incurred but not reported losses and expected development on case reserves. CNA does not establish case reserves for allocated loss adjusted expenses (ALAE), therefore ALAE reserves are also included in the estimate of IBNR. 2019 Unfavorable development in medical professional liability was primarily due to higher than expected severity in accident years 2016 through 2018 in CNA’s aging services business, higher than expected severity in accident year 2013 in the allied healthcare business, unfavorable outcomes on individual claims and higher than expected severity in accident year 2017 in the dentists business. Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency and favorable outcomes on individual claims in accident years 2017 and prior related to financial institutions, lower than expected large claim losses in recent accident years in CNA’s public company directors and officers liability business and lower than expected loss adjustment expenses across accident years 2010 through 2018. Favorable development in surety was due to lower than expected frequency for accident years 2018 and prior. Favorable development in commercial auto was primarily due to continued lower than expected severity across accident years 2015 and prior and a decline in bodily injury frequency in accident year 2018. Unfavorable development in general liability was primarily due to higher than expected emergence in mass tort exposures, primarily from accident years 2016, 2015 and prior to 2010. Favorable development in other coverages was due to lower than expected paid loss emergence on vehicle products in warranty, favorable medical trends driving lower than expected severity in accident years 2012 through 2018 in workers’ compensation, lower than expected claim severity related to catastrophe events in accident years 2017 and 2018 in property and other in Commercial and lower than expected large losses and claim severity in accident years 2018 and prior in Hardy, Europe and Canada in casualty. This was mostly offset by unfavorable development driven by higher than expected claims in Hardy on 2018 accident year Asian catastrophe events in property in International and potential design and construct exposures in professional indemnity within Europe financial lines in accident years 2017 and 2018. 2018 Unfavorable development in medical professional liability was primarily due to higher than expected severity in accident years 2014 and 2017 in CNA’s hospitals business. In addition, there was higher than expected frequency and severity in aging services in accident years 2014 through 2017 combined, partially offset by lower than expected frequency in accident year 2015. Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency in recent accident years related to financial institutions and professional liability errors and omissions (“E&O”), favorable severity in accident years 2015 and prior related to professional liability E&O and favorable outcomes on individual claims in financial institutions in accident years 2013 and prior. Favorable development in surety was due to lower than expected loss emergence for accident years 2017 and prior. Unfavorable development in general liability was driven by higher than expected claim severity in unsupported umbrella in accident years 2013 through 2016. Favorable development in workers’ compensation was driven by lower frequency and severity experience and favorable impacts from California reforms. Favorable development in other coverages was driven by lower than expected claim severity in catastrophes in accident year 2017 for property in Commercial, better than expected frequency in the liability portion of the package business in Canada and general liability in Europe in casualty and better than expected large loss frequency in the energy book in accident year 2017, as well as a reduction in incurred losses within the Europe marine discontinued portfolio in energy and marine and lower than expected frequency in accident years 2015 and prior in Europe in healthcare and technology for International. This was partially offset by unfavorable development primarily driven by higher than expected severity in Canada and higher than expected frequency in Hardy, both in accident year 2017 in property and increased loss severity in the accident year 2017 in Europe professional indemnity in specialty for International. 2017 Unfavorable development in medical professional liability was primarily due to continued higher than expected frequency in aging services and higher than expected severity for hospitals in recent accident years. This was partially offset by favorable development in hospitals in prior accident years as well as favorable development related to unallocated claim adjustment expenses. Favorable development in other professional liability and management liability was primarily due to favorable settlements on closed claims and a lower frequency of large losses for accident years 2011 through 2015 for professional and management liability, lower than expected claim frequency in accident years 2012 through 2015 for professional liability and lower than expected severity in accident years 2014 through 2015 for professional liability. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2015 and prior. Favorable development in commercial auto was primarily due to lower than expected severity in accident years 2013 through 2016, as well as a large favorable recovery on a claim in accident year 2012. Favorable development in general liability was due to lower than expected severity in life sciences. Favorable development in workers’ compensation was primarily related to decreases in frequency and severity in recent accident years, partially attributable to California reforms impacting medical costs. This was partially offset by unfavorable development related to an adverse arbitration ruling on reinsurance recoverables from older accident years as well as the recognition of loss estimates associated with earned premium from a prior exposure year. Unfavorable development for other coverages was primarily due to higher than expected severity in accident year 2015 arising from the management liability business, partially offset by favorable development in accident years 2014 and prior. Additional unfavorable development was related to adverse large claims experience in the CNA Hardy political risks portfolio, relating largely to accident year 2016. This was partially offset by favorable development related to better than expected frequency in accident years 2014 through 2016 in property and in energy and marine. Property & Casualty Operations – Line of Business Composition The table below presents the net liability for unpaid claim and claim adjustment expenses, by line of business for Property & Casualty Operations: December 31 2019 (In millions) Medical professional liability $ 1,429 Other professional liability and management liability 2,739 Surety 369 Commercial auto 404 General liability 3,176 Workers’ compensation 3,932 Other 2,104 Total net liability for unpaid claim and claim adjustment expenses $ 14,153 Medical Professional Liability December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 402 $ 412 $ 423 $ 426 $ 415 $ 395 $ 365 $ 360 $ 356 $ 369 $ 1 14,624 2011 429 437 443 468 439 434 437 437 439 2 16,526 2012 464 469 508 498 493 484 493 499 8 17,724 2013 462 479 500 513 525 535 545 27 19,510 2014 450 489 537 530 535 529 16 19,723 2015 433 499 510 494 488 29 18,029 2016 427 487 485 499 63 15,823 2017 412 449 458 127 14,636 2018 404 429 216 13,760 2019 430 364 10,467 Total $ 4,685 $ 853 Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 10 $ 86 $ 173 $ 257 $ 306 $ 326 $ 337 $ 346 $ 350 $ 353 2011 17 109 208 295 347 375 398 409 414 2012 14 117 221 323 388 427 457 479 2013 17 119 255 355 414 462 495 2014 23 136 258 359 417 472 2015 22 101 230 313 384 2016 18 121 246 339 2017 19 107 235 2018 21 115 2019 17 Total $ 3,303 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 1,382 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 22 Liability for unallocated claim adjustment expenses for accident years presented 25 Total net liability for unpaid claim and claim adjustment expenses $ 1,429 Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 10 $ 11 $ 3 $ (11 ) $ (20 ) $ (30 ) $ (5 ) $ (4 ) $ 13 $ (33 ) 2011 8 6 25 (29 ) (5 ) 3 - 2 10 2012 5 39 (10 ) (5 ) (9 ) 9 6 35 2013 17 21 13 12 10 10 83 2014 39 48 (7 ) 5 (6 ) 79 2015 66 11 (16 ) (6 ) 55 2016 60 (2 ) 14 72 2017 37 9 46 2018 25 25 Total net development for the accident years presented above 65 39 67 Total net development for accident years prior to 2010 (28 ) 9 6 Total unallocated claim adjustment expense development (7 ) (1 ) 2 Total $ 30 $ 47 $ 75 (a) Data presented for these calendar years is required supplemental information, which is unaudited. Other Professional Liability and Management Liability December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 828 $ 828 $ 848 $ 848 $ 847 $ 837 $ 824 $ 827 $ 821 $ 821 $ 9 17,891 2011 880 908 934 949 944 911 899 888 885 21 18,738 2012 923 909 887 878 840 846 833 831 18 18,499 2013 884 894 926 885 866 863 850 45 17,928 2014 878 898 885 831 835 854 74 17,553 2015 888 892 877 832 807 120 17,390 2016 901 900 900 904 188 17,890 2017 847 845 813 308 18,015 2018 850 864 460 19,468 2019 837 714 16,722 Total $ 8,466 $ 1,957 Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 31 $ 204 $ 405 $ 541 $ 630 $ 670 $ 721 $ 752 $ 784 $ 790 2011 71 314 503 605 683 726 781 796 828 2012 56 248 400 573 651 711 755 792 2013 54 249 447 618 702 754 771 2014 51 223 392 515 647 707 2015 60 234 404 542 612 2016 64 248 466 625 2017 57 222 394 2018 54 282 2019 64 Total $ 5,865 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 2,601 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 88 Liability for unallocated claim adjustment expenses for accident years presented 50 Total net liability for unpaid claim and claim adjustment expenses $ 2,739 Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ - $ 20 $ - $ (1 ) $ (10 ) $ (13 ) $ 3 $ (6 ) $ - $ (7 ) 2011 28 26 15 (5 ) (33 ) (12 ) (11 ) (3 ) 5 2012 (14 ) (22 ) (9 ) (38 ) 6 (13 ) (2 ) (92 ) 2013 10 32 (41 ) (19 ) (3 ) (13 ) (34 ) 2014 20 (13 ) (54 ) 4 19 (24 ) 2015 4 (15 ) (45 ) (25 ) (81 ) 2016 (1 ) - 4 3 2017 (2 ) (32 ) (34 ) 2018 14 14 Total net development for the accident years presented above (92 ) (76 ) (38 ) Total net development for accident years prior to 2010 (27 ) (44 ) (17 ) Total unallocated claim adjustment expense development (7 ) (7 ) (14 ) Total $ (126 ) $ (127 ) $ (69 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited. Surety December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 112 $ 112 $ 111 $ 84 $ 76 $ 66 $ 63 $ 59 $ 61 $ 61 $ - 5,982 2011 120 121 116 87 75 70 66 62 62 2 5,813 2012 120 122 98 70 52 45 39 38 1 5,568 2013 120 121 115 106 91 87 83 3 5,062 2014 123 124 94 69 60 45 4 5,078 2015 131 131 104 79 63 11 4,976 2016 124 124 109 84 36 5,379 2017 120 115 103 54 5,496 2018 114 108 76 5,451 2019 119 102 3,549 Total $ 766 $ 289 Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 13 $ 34 $ 50 $ 55 $ 57 $ 58 $ 55 $ 52 $ 52 $ 53 2011 19 42 55 58 60 60 56 57 57 2012 5 32 34 35 35 36 37 37 2013 16 40 69 78 78 78 77 2014 7 30 38 36 38 38 2015 7 26 38 40 42 2016 5 37 45 45 2017 23 37 41 2018 5 25 2019 12 Total $ 427 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 339 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 10 Liability for unallocated claim adjustment expenses for accident years presented 20 Total net liability for unpaid claim and claim adjustment expenses $ 369 Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ - $ (1 ) $ (27 ) $ (8 ) $ (10 ) $ (3 ) $ (4 ) $ 2 $ - $ (51 ) 2011 1 (5 ) (29 ) (12 ) (5 ) (4 ) (4 ) - (58 ) 2012 2 (24 ) (28 ) (18 ) (7 ) (6 ) (1 ) (82 ) 2013 1 (6 ) (9 ) (15 ) (4 ) (4 ) (37 ) 2014 1 (30 ) (25 ) (9 ) (15 ) (78 ) 2015 - (27 ) (25 ) (16 ) (68 ) 2016 - (15 ) (25 ) (40 ) 2017 (5 ) (12 ) (17 ) 2018 (6 ) (6 ) Total net development for the accident years presented above (82 ) (66 ) (79 ) Total net development for accident years prior to 2010 1 (4 ) (3 ) Total unallocated claim adjustment expense development (3 ) - (10 ) Total $ (84 ) $ (70 ) $ (92 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited. Commercial Auto December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 267 $ 283 $ 287 $ 291 $ 298 $ 293 $ 289 $ 288 $ 288 $ 288 $ 1 48,035 2011 268 281 288 302 300 294 294 294 291 - 47,909 2012 275 289 299 303 307 299 299 297 3 46,288 2013 246 265 265 249 245 245 241 2 39,429 2014 234 223 212 205 205 201 3 33,622 2015 201 199 190 190 183 7 30,418 2016 198 186 186 186 7 30,414 2017 199 198 200 9 30,850 2018 229 227 47 33,959 2019 257 128 31,455 Total $ 2,371 $ 207 Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 74 $ 141 $ 203 $ 246 $ 271 $ 281 $ 286 $ 287 $ 287 $ 287 2011 79 145 199 248 274 284 287 289 289 2012 78 160 220 259 282 285 290 291 2013 74 135 168 200 225 234 238 2014 64 102 137 166 187 196 2015 52 96 130 153 172 2016 52 93 126 154 2017 58 107 150 2018 66 128 2019 77 Total $ 1,982 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 389 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 1 Liability for unallocated claim adjustment expenses for accident years presented 14 Total net liability for unpaid claim and claim adjustment expenses $ 404 Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 16 $ 4 $ 4 $ 7 $ (5 ) $ (4 ) $ (1 ) $ - $ - $ 21 2011 13 7 14 (2 ) (6 ) - - (3 ) 23 2012 14 10 4 4 (8 ) - (2 ) 22 2013 19 - (16 ) (4 ) - (4 ) (5 ) 2014 (11 ) (11 ) (7 ) - (4 ) (33 ) 2015 (2 ) (9 ) - (7 ) (18 ) 2016 (12 ) - - (12 ) 2017 (1 ) 2 1 2018 (2 ) (2 ) Total net development for the accident years presented above (41 ) (1 ) (20 ) Total net development for accident years prior to 2010 4 1 (4 ) Total unallocated claim adjustment expense development 2 1 (1 ) Total $ (35 ) $ 1 $ (25 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited. General Liability December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 646 $ 664 $ 658 $ 709 $ 750 $ 726 $ 697 $ 691 $ 691 $ 690 $ 19 44,229 2011 591 589 631 677 676 681 670 669 667 20 39,361 2012 587 611 639 636 619 635 635 630 31 35,219 2013 650 655 650 655 613 623 620 27 33,570 2014 653 658 654 631 635 658 57 27,877 2015 581 576 574 589 600 73 23,834 2016 623 659 667 671 166 23,817 2017 632 632 632 226 21,114 2018 653 644 408 17,889 2019 680 602 12,916 Total $ 6,492 $ 1,629 Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 27 $ 145 $ 280 $ 429 $ 561 $ 611 $ 642 $ 652 $ 656 $ 667 2011 28 148 273 411 517 568 602 622 638 2012 28 132 247 374 454 510 559 579 2013 31 128 240 352 450 510 551 2014 31 119 247 376 481 547 2015 19 110 230 357 446 2016 32 163 279 407 2017 23 118 250 2018 33 107 2019 25 Total $ 4,217 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 2,275 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 836 Liability for unallocated claim adjustment expenses for accident years presented 65 Total net liability for unpaid claim and claim adjustment expenses $ 3,176 Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 18 $ (6 ) $ 51 $ 41 $ (24 ) $ (29 ) $ (6 ) $ - $ (1 ) $ 44 2011 (2 ) 42 46 (1 ) 5 (11 ) (1 ) (2 ) 76 2012 24 28 (3 ) (17 ) 16 - (5 ) 43 2013 5 (5 ) 5 (42 ) 10 (3 ) (30 ) 2014 5 (4 ) (23 ) 4 23 5 2015 (5 ) (2 ) 15 11 19 2016 36 8 4 48 2017 - - - 2018 (9 ) (9 ) Total net development for the accident years presented above (32 ) 36 18 Total net development for accident years prior to 2010 - - 29 Total unallocated claim adjustment expense development 8 (4 ) 7 Total $ (24 ) $ 32 $ 54 (a) Data presented for these calendar years is required supplemental information, which is unaudited. Workers’ Compensation December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 583 $ 632 $ 654 $ 676 $ 698 $ 710 $ 730 $ 733 $ 732 $ 735 $ 55 49,333 2011 607 641 647 659 651 676 676 674 688 40 45,959 2012 601 627 659 669 678 673 671 668 67 42,586 2013 537 572 592 618 593 582 561 93 38,688 2014 467 480 479 452 450 446 99 33,480 2015 422 431 406 408 394 130 31,861 2016 426 405 396 382 144 31,945 2017 440 432 421 138 33,029 2018 450 440 185 34,647 2019 452 257 29,795 Total $ 5,187 $ 1,208 Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 97 $ 251 $ 359 $ 442 $ 510 $ 542 $ 577 $ 615 $ 625 $ 631 2011 99 249 358 438 478 522 564 571 581 2012 87 232 342 416 470 509 524 536 2013 80 213 300 370 417 419 411 2014 61 159 215 258 282 290 2015 51 131 180 212 231 2016 53 129 169 198 2017 63 151 207 2018 68 163 2019 71 Total $ 3,319 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 1,868 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 2,061 Other (b) (22 ) Liability for unallocated claim adjustment expenses for accident years presented 25 Total net liability for unpaid claim and claim adjustment expenses $ 3,932 Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 49 $ 22 $ 22 $ 22 $ 12 $ 20 $ 3 $ (1 ) $ 3 $ 152 2011 34 6 12 (8 ) 25 - (2 ) 14 81 2012 26 32 10 9 (5 ) (2 ) (3 ) 67 2013 35 20 26 (25 ) (1

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Note 9. The Company’s lease agreements primarily cover office facilities and machinery and equipment and expire at various dates. The Company’s leases are predominantly operating leases, which are included in Other assets and Other liabilities on the Consolidated Balance Sheet. The Company’s lease agreements do not contain significant residual value guarantees, restrictions or covenants. Operating lease right of use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The discount rate used to determine the commencement date present value of lease payments is typically the Company’s secured borrowing rate, as most of the Company’s leases do not provide an implicit rate. The Company’s operating lease right of use asset was $573 Total expense $ 146 million for the year ended December 31, 2019, which includes operating lease expense of expense of expense of Prior to the adoption of the new lease standard, lease expense for the years ended December 31, 2018 and 2017 was $120 million and $113 million. Cash paid for amounts included in operating lease liabilities was $117 million for year ended December 31, 2019. Operating lease right of use assets obtained in exchange for lease obligations was $54 million for the year ended December 31, 2019. The table below presents the maturities of lease liabilities: As of December 31, 2019 Operating (In millions) 2020 $ 114 2021 113 2022 102 2023 89 2024 81 Thereafter 361 Total 860 Less: discount 166 Total lease liabilities $ 694 The table below presents the weighted average remaining lease term for operating leases and weighted average discount rate used in calculating the operating lease asset and liability. As of December 31, 2019 Weighted average remaining lease term 9.4 Y Weighted average discount rate 4.7 % The table below presents the future minimum lease payments to be made under non-cancelable Future Minimum Lease Year Ended December 31 Payments Receipts (In millions) 2019 $ 75 $ 6 2020 79 5 2021 79 5 2022 68 4 2023 57 4 Thereafter 344 14 Total $ 702 $ 38

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Note 10. Income Taxes The Company and its eligible subsidiaries file a consolidated federal income tax return. The Company has entered into a separate tax allocation agreement with CNA, a majority-owned subsidiary in which its ownership exceeds 80%. The agreement provides that the Company will: (i) pay to CNA the amount, if any, by which the Company’s consolidated federal income tax is reduced by virtue of inclusion of CNA in the Company’s return or (ii) be paid by CNA an amount, if any, equal to the federal income tax that would have been payable by CNA if it had filed a separate consolidated return. The agreement may be canceled by either of the parties upon thirty days written notice. For 2017 through 2019, the Internal Revenue Service (“IRS”) has accepted the Company into the Compliance Assurance Process (“CAP”), which is a voluntary program for large corporations. Under CAP, the IRS conducts a real-time audit and works contemporaneously with the Company to resolve any issues prior to the filing of the tax return. The Company believes this approach should reduce tax-related Diamond Offshore, which is not included in the Company’s consolidated federal income tax return, files income tax returns in the U.S. federal and various state and foreign jurisdictions. Tax years that remain subject to examination by these jurisdictions include years 2009 2018 On December 22, 2017, H.R.1, “An Act to Provide for Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018,” previously known as “The Tax Cuts and Jobs Act” was signed into law (the “Tax Act”). The Tax Act provided for a permanent reduction in the U.S. federal corporate income tax rate from 35% to 21% effective January 1, 2018, among other provisions, including the elimination of the corporate alternative minimum tax (“AMT”) and a change to how existing AMT credits can be realized, and a one-time , The Company was required to recognize the effect of the Tax Act in the period the tax rate change was signed into law. Consequently, the Company recorded a one-time non-cash one-time non-U.S. The current and deferred components of income tax expense (benefit) are as follows: Year Ended December 31 2019 2018 2017 (In millions) Income tax expense (benefit): Federal: Current $ 108 $ 6 $ 157 Deferred 47 85 (63 ) State and city: Current 18 15 22 Deferred 22 9 17 Foreign 53 13 37 Total $ 248 $ 128 $ 170 The components of U.S. and foreign income before income tax and a reconciliation between the federal income tax expense at statutory rates and the actual income tax expense (benefit) is as follows: Year Ended December 31 2019 2018 2017 (In millions) Income ( loss U.S. $ 1,145 $ 775 $ 1,322 Foreign (26 ) 59 260 Total $ 1,119 $ 834 $ 1,582 Income tax expense at statutory rate $ 235 $ 175 $ 554 Increase (decrease) in income tax expense resulting from: Effect of the Tax Act (14 ) (6 ) (190 ) Exempt investment income (50 ) (64 ) (134 ) Foreign related tax differential (55 ) 1 (36 ) Taxes related to domestic affiliate (15 ) (7 ) 1 Partnership earnings not subject to taxes (14 ) (51 ) Valuation allowance 12 12 7 Unrecognized tax positions, settlements and adjustments relating to prior years 97 2 (8 ) State taxes 37 20 23 Other 1 9 4 Income tax expense $ 248 $ 128 $ 170 The deferred foreign earnings of certain international subsidiaries were deemed to be repatriated under the Tax Act and consequently the Company will no longer permanently reinvest earnings of its foreign subsidiaries. The Company has not provided income tax on the outside basis difference of its foreign subsidiaries since there is no intention to dispose of these subsidiaries and structuring alternatives exist to mitigate any potential liability. The potential unrecorded liability associated with the outside basis difference is approximately $95 million. A reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding tax carryforwards and interest and penalties, is as follows: Year Ended December 31 2019 2018 2017 (In millions) Balance at January 1 $ 58 $ 84 $ 35 Additions for tax positions related to the current year 86 3 51 Additions for tax positions related to a prior year 2 20 5 Reductions for tax positions related to a prior year (23 ) (48 ) (1 ) Lapse of statute of limitations (2 ) (1 ) (6 ) Balance at December 31 $ 121 $ 58 $ 84 The $86 million 2019 addition to current year tax positions is primarily due to a recent change in Switzerland tax legislation. Due to the uncertainties regarding the application of the Swiss Tax Reform, including the values to be used to measure depreciable property, a liability for uncertain tax positions was recorded. The 2019 reduction for prior year tax is primarily due to the reversal of uncertain tax positions recorded for the mandatory repatriation provision of the Tax Act following the issuance of final regulations. The addition for prior year tax positions in 2018 and the $51 million addition for current year tax positions in 2017, as well as the $49 million reduction for prior year tax positions in 2018 are all primarily due to uncertainty associated with the enactment of the Tax Act and subsequent clarification issued by the IRS. At December 31, 2019, 2018 and 2017, $149 million, $82 million and $102 million of unrecognized tax benefits related to Diamond Offshore would affect the effective tax rate if recognized. At December 31, 2019, the amount of accrued interest and penalties related to uncertain tax positions was $4 million and $17 million, respectively. At December 31, 2018, the amount of accrued interest and penalties related to uncertain tax positions was $3 million and $16 million, respectively. The Company recognizes interest accrued related to unrecognized tax benefits and tax refund claims in Income tax expense (benefit) ( benefit) expense (benefit) Penalty amounts by the Company we re insignificant , and The following table summarizes deferred tax assets and liabilities: December 31 2019 2018 (In millions) Deferred tax assets: Insurance reserves: Property and casualty claim and claim adjustment expense reserves $ 129 $ 108 Unearned premium reserves 153 108 Receivables 11 13 Employee benefits 212 222 Deferred retroactive reinsurance benefit 82 79 Net operating loss carryforwards 275 251 Tax credit carryforwards 47 101 Net unrealized losses 24 Basis differential in investment in subsidiary 8 8 Disallowed interest deduction 41 16 Other 179 181 Total deferred tax assets 1,137 1,111 Valuation allowance (187 ) (175 ) Net deferred tax assets 950 936 Deferred tax liabilities: Deferred acquisition costs (83 ) (78 ) Net unrealized gains (263 ) Property, plant and equipment (848 ) (840 ) Basis differential in investment in subsidiary (679 ) (586 ) Other liabilities (208 ) (236 ) Total deferred tax liabilities (2,081 ) (1,740 ) Net deferred tax liabilities (a) $ (1,131 ) $ (804 ) (a) Includes $ 37 Federal net operating loss carryforwards of $70 million expire between 2034 and 2038 and $88 million can be carried forward indefinitely. Net operating loss carryforwards in foreign tax jurisdictions of $38 million expire between 2021 and 2028, $2 million expire between 2035 and 2039, and $77 million can be carried forward indefinitely. Foreign tax credit carryforwards of $45 million will expire between 2020 and 2030, and $2 million can be carried forward indefinitely. Although realization of deferred tax assets is not assured, management believes it is more likely than not that the recognized deferred tax assets will be realized through recoupment of ordinary and capital taxes paid in prior carryback years and through future earnings, reversal of existing temporary differences and available tax planning strategies. As of December 31, 2019, Diamond Offshore recorded a valuation allowance of $187 million related to net operating losses, foreign tax credits, and other deferred tax assets.

Debt

Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	Note 11. Debt December 31 2019 2018 (In millions) Loews Corporation (Parent Company): Senior: 2.6% notes due 2023 (effective interest rate of 2.8%) (authorized, $ 500 $ 500 $ 500 3.8% notes due 2026 (effective interest rate of 3.9%) (authorized, $ 500 500 500 6.0% notes due 2035 (effective interest rate of 6.2%) (authorized, $ 300 300 300 4.1% notes due 2043 (effective interest rate of 4.3%) (authorized, $ 500 500 500 CNA Financial: Senior: 5.9% notes due 2020 (effective interest rate of 6.0%) (authorized, $ 500 500 5.8% notes due 2021 (effective interest rate of 5.9%) (authorized, $ 400 400 400 7.3% debentures due 2023 (effective interest rate of 7.3%) (authorized, $ 250 243 243 4.0% notes due 2024 (effective interest rate of 4.0%) (authorized, $ 550 550 550 4.5% notes due 2026 (effective interest rate of 4.5%) (authorized, $ 500 500 500 3.5% notes due 2027 (effective interest rate of 3.5%) (authorized, $ 500 500 500 3.9% notes due 2029 (effective interest rate of 3.9%) (authorized, $ 500 500 F 1 Diamond Offshore: Senior: 3.5% notes due 2023 (effective interest rate of 3.5%) (authorized, $ 250 250 250 7.9% notes due 2025 (effective interest rate of 8.0%) (authorized, $ 500 500 500 5.7% notes due 2039 (effective interest rate of 5.8%) (authorized, $ 500 500 500 4.9% notes due 2043 (effective interest rate of 4.9%) (authorized, $ 750 750 750 Boardwalk Pipelines: Senior: Variable rate revolving credit facility due 2022 (effective interest rate of 3.0% and 3.7%) 295 580 5.8% notes due 2019 (effective interest rate of 5.9%) (authorized, $ 350 350 4.5% notes due 2021 (effective interest rate of 5.0%) (authorized, $ 440 440 440 4.0% notes due 2022 (effective interest rate of 4.4%) (authorized, $ 300 300 300 3.4% notes due 2023 (effective interest rate of 3.5%) (authorized, $ 300 300 300 5.0% notes due 2024 (effective interest rate of 5.2%) (authorized, $ 600 600 600 6.0% notes due 2026 (effective interest rate of 6.2%) (authorized, $ 550 550 550 4.5% notes due 2027 (effective interest rate of 4.6%) (authorized, $ 500 500 500 7.3% debentures due 2027 (effective interest rate of 8.1%) (authorized, $ 100 100 100 4.8% notes due 2029 (effective interest rate of 4.9%) (authorized, $ 500 500 Finance 7 8 Loews Hotels & Co: Senior debt, principally mortgages (effective interest rates approximate 4.7% and 4.4% 712 653 Altium Packaging : Senior: Variable rate asset based lending facility due 2022 (effective interest rate of 5.5%) 9 Variable rate term loan due 2024 (effective interest rate of 4.9% and 5.0%) 591 597 Variable rate term loan due 2026 (effective interest rate of 5.3%) 249 Finance 6 7 11,643 11,488 Less unamortized discount and issuance costs 110 112 Debt $ 11,533 $ 11,376 December 31, 2019 Principal Unamortized Net Short Term Long Term (In millions) Loews Corporation $ 1,800 $ 21 $ 1,779 $ 1,779 CNA Financial 2,693 14 2,679 2,679 Diamond Offshore 2,000 24 1,976 1,976 Boardwalk Pipelines 3,592 26 3,566 3,566 Loews Hotels & Co 712 7 705 $ 67 638 Altium Packaging 846 18 828 10 818 Total $ 11,643 $ 110 $ 11,533 $ 77 $ 11,456 At December 31, 2019, the aggregate long term debt maturing in each of the next five years is approximately as follows: $77 million in 2020, $861 million in 2021, $744 million in 2022, $1.3 billion in 2023, $2.0 billion in 2024 and $6.6 billion thereafter. Long term debt is generally redeemable in whole or in part at the greater of the principal amount or the net present value of remaining scheduled payments discounted at the specified treasury rate plus a margin. CNA Financial CNA is a member of the Federal Home Loan Bank of Chicago (“FHLBC”). FHLBC membership provides participants with access to additional sources of liquidity through various programs and services. As a requirement of membership in the FHLBC, CNA held $5 million of FHLBC stock as of December 31, 2019, giving it access to approximately $111 million of additional liquidity. As of December 31, 2019 and 2018, CNA had no In May of 2019, CNA completed a public offering of $500 million aggregate principal amount of its 3.9% senior notes due May 1, 2029 August 15, 2020 500 In the fourth quarter of 2019, CNA amended and restated is existing credit agreement with a syndicate of banks. The amended and restated credit agreement provides a five $ million senior unsecured revolving credit facility which is intended to be used for general corporate purposes. At CNA’s election, the commitments under the amended and restated credit agreement may be increased from time to time up to an additional aggregate amount of $100 million, and two one-year Diamond Offshore As of December 31, 2019, Diamond Offshore had no Boardwalk Pipelines In May of 2019, Boardwalk Pipelines completed a public offering of $500 million aggregate principal amount of its 4.8% senior notes due May 3, 2029. The proceeds were used to retire the outstanding $350 million aggregate principal amount of Boardwalk Pipelines’ 5.8% senior notes at maturity , and for general corporate purposes Boardwalk Pipelines has a revolving credit facility having aggregate lending commitments of $1.5 billion maturing May 26, 2022. As of December 31, 2019, Boardwalk Pipelines had $295 million of outstanding borrowings under its credit agreement and was in compliance with all covenants. Altium Packaging In June of 2019, Altium Packaging June 14, 2026

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Shareholders' Equity	Note 12. Shareholders’ Equity Accumulated other comprehensive income (loss) The tables below present the changes in AOCI by component for the years ended December 31, 2017, 2018 and 2019: Net Unrealized on Investments with OTTI Losses Net Other Unrealized Gains (Losses) on Investments Unrealized Pension and Foreign Total (In millions) Balance, January 1, 2017 $ 27 $ 576 $ (2 ) $ (646 ) $ (178 ) $ (223 ) Other comprehensive income (loss) before reclassifications, after tax of $1, $(106), $(2), $4 and $0 (3 ) 190 1 (18 ) 100 270 Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $1, $38, $0, $(16) and $0 (2 ) (82 ) 2 30 (52 ) Other comprehensive income (loss) (5 ) 108 3 12 100 218 Amounts attributable to noncontrolling interests (11 ) (1 ) 1 (10 ) (21 ) Balance, December 31, 2017 22 673 – (633 ) (88 ) (26 ) Cumulative effect adjustment from changes in accounting standards 4 98 (130 ) (28 ) Balance, January 1, 2018, as adjusted 26 771 – (763 ) (88 ) (54 ) Other comprehensive income (loss) before reclassifications, after tax of $2, $213, $(2), $9 and $0 (7 ) (801 ) 4 (34 ) (84 ) (922 ) Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $2, $(2), $0, $(6) and $0 (7 ) 3 2 32 30 Other comprehensive income (loss) (14 ) (798 ) 6 (2 ) (84 ) (892 ) Amounts attributable to noncontrolling interests 2 84 9 95 Purchase of Boardwalk Pipelines common units (1 ) (28 ) (29 ) Balance, December 31, 2018 14 57 5 (793 ) (163 ) (880 ) Other comprehensive income (loss) before reclassifications, after tax of $3, $(256), $5, $28 and $0 (13 ) 957 (11 ) (102 ) 42 873 Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $(3), $1, $0, $(9) and $0 12 (8 ) 34 38 Other comprehensive income (loss) (1 ) 949 (11 ) (68 ) 42 911 Amounts attributable to noncontrolling interests (101 ) 6 (4 ) (99 ) Balance, December 31, 2019 $ 13 $ 905 $ (6 ) $ (855 ) $ (125 ) $ (68 ) Amounts reclassified from AOCI shown above are reported in Net income as follows: Major Category of AOCI Affected Line Item Net unrealized gains (losses) on investments with OTTI losses Investment gains (losses) Net other unrealized gains (losses) on investments Investment gains (losses) Unrealized gains (losses) on cash flow hedges Operating revenues and other, Interest expense and Operating expenses and other Pension and postretirement benefits Operating expenses and other Common Stock Dividends Dividends of $0.25 per share on the Company’s common stock were declared and paid in 2019, 2018 and 2017. There are no restrictions on the Company’s retained earnings or net income with regard to payment of dividends. However, as a holding company, Loews Corporation relies upon invested cash balances and distributions from its subsidiaries to generate the funds necessary to declare and pay any dividends to holders of its common stock. The ability of the Company’s subsidiaries to pay dividends is subject to, among other things, the availability of sufficient earnings and funds in such subsidiaries, compliance with covenants in their respective credit agreements and applicable state laws, including in the case of the insurance subsidiaries of CNA, laws and rules governing the payment of dividends by regulated insurance companies. See Note 14 for a discussion of the regulatory restrictions on CNA’s availability to pay dividends. Treasury Stock The Company repurchased 21.5 million, 20.3 million and 4.8 million shares of its common stock at aggregate costs of $1.1 billion, $1.0 billion and $237 million during the years ended December 31, 2019, 2018 and 2017. As of December 31, 2019, 21.4 million shares were retired. The remaining shares will be retired in 2020. Upon retirement, treasury stock was eliminated through a reduction to common stock, APIC and retained earnings.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Note 13. Revenue from Contracts with Customers Disaggregation of revenues Non-insurance Year Ended December 31 2019 2018 2017 (a) (In millions) Non-insurance $ 1,161 $ 1,007 $ 390 Contract drilling – Diamond Offshore $ 981 $ 1,083 $ 1,486 Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipelines 1,266 1,206 1,298 Lodging and related services – Loews Hotels & Co 691 730 682 Rigid plastic packaging and recycled resin – Corporate 932 867 498 Total revenues from contracts with customers 3,870 3,886 3,964 Other revenues 68 101 89 Operating revenues and other $ 3,938 $ 3,987 $ 4,053 (a) Prior period amounts have not been adjusted under the modified retrospective method of adoption for ASU 2014-09. Receivables from contracts with customers Deferred revenue non-insurance for the year ended December 31, 2019 was billion Contract costs billion non-insurance non-insurance and 2018, and $744 million Non-insurance and 2018. Performance obligations non-insurance

Statutory Accounting Practices

Statutory Accounting Practices	12 Months Ended
	Dec. 31, 2019
Text Block [Abstract]
Statutory Accounting Practices	Note 14. Statutory Accounting Practices CNA’s insurance subsidiaries are domiciled in various jurisdictions. These subsidiaries prepare statutory financial statements in accordance with accounting practices prescribed or permitted by the respective jurisdictions’ insurance regulators. Domestic prescribed statutory accounting practices are set forth in a variety of publications of the National Association of Insurance Commissioners (“NAIC”) as well as state laws, regulations and general administrative rules. These statutory accounting principles vary in certain respects from GAAP. In converting from statutory accounting principles to GAAP, the more significant adjustments include deferral of policy acquisition costs and the inclusion of net unrealized holding gains or losses in shareholders’ equity relating to certain fixed maturity securities. CNA has a prescribed practice as it relates to the accounting under Statement of Statutory Accounting Principles No. 62R (“SSAP No. 62R”), Property and Casualty Reinsurance The payment of dividends by CNA’s insurance subsidiaries without prior approval of the insurance department of each subsidiary’s domiciliary jurisdiction is generally limited by formula. Dividends in excess of these amounts are subject to prior approval by the respective insurance regulator. Dividends from CCC are subject to the insurance holding company laws of the State of Illinois, the domiciliary state of CCC. Under these laws, ordinary dividends, or dividends that do not require prior approval by the Illinois Department of Insurance (the “Department”) are determined based on the greater of the prior year’s statutory net income or 10% of statutory surplus as of the end of the prior year, as well as the timing and amount of dividends paid in the preceding 12 months. Additionally, ordinary dividends may only be paid from earned surplus, which is calculated by removing unrealized gains from unassigned surplus. As of December 31, 2019, CCC is in a positive earned surplus position. The maximum allowable dividend CCC could pay during 2020 that would not be subject to the Department’s prior approval is $1,078 m m Combined statutory capital and surplus and statutory net income for the Combined Continental Casualty Companies are presented in the table below, determined in accordance with accounting practices prescribed or permitted by insurance and/or other regulatory authorities. Statutory Capital and Surplus Statutory Net Income December 31 Year Ended December 31 2019(a) 2018 2019(a) 2018 2017 (In millions) Combined Continental Casualty Companies $ 10,787 $ 10,411 $ 1,062 $ 1,405 $ 1,029 (a) Information derived from the statutory-basis financial statements to be filed with insurance regulators. CNA’s domestic insurance subsidiaries are subject to risk-based capital (“RBC”) requirements. RBC is a method developed by the NAIC to determine the minimum amount of statutory capital appropriate for an insurance company to support its overall business operations in consideration of its size and risk profile. The formula for determining the amount of RBC specifies various factors, weighted based on the perceived degree of risk, which are applied to certain financial balances and financial activity. The adequacy of a company’s actual capital is evaluated by a comparison to the RBC results, as determined by the formula. Companies below minimum RBC requirements are classified within certain levels, each of which requires specified corrective action. The statutory capital and surplus presented above for CCC was approximately 291% and 266% of company action level RBC at December 31, 2019 and 2018. Company action level RBC is the level of RBC which triggers a heightened level of regulatory supervision. The statutory capital and surplus of C N A

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Benefit Plans	Note 15. Benefit Plans Pension Plans – The Company and its subsidiaries have several non-contributory The Company eliminated future benefit accruals associated with the Loews Corporation Cash Balance Retirement Plan, effective January 1, 2020. However, years of service will continue to count for purposes of vesting. Other Postretirement Benefit Plans – The Company and its subsidiaries have several postretirement benefit plans covering eligible employees and retirees. Participants generally become eligible after reaching age 55 with required years of service. Actual requirements for coverage vary by plan. Benefits for retirees who were covered by bargaining agreements vary by each unit and contract. Benefits for certain retirees are in the form of a Company health care account. Benefits for retirees reaching age 65 The Company and its subsidiaries fund certain of these benefit plans, and accrue postretirement benefits during the active service of those employees who would become eligible for such benefits when they retire. The Company and its subsidiaries use December 31 as the measurement date for their plans. Weighted average assumptions used to determine benefit obligations: Pension Benefits Other Postretirement Benefits December 31 2019 2018 2017 2019 2018 2017 Discount rate 3.0 % 4.1 % 3.5 % 3.0 % 4.1 % 3.4 % Expected long term rate of return on plan assets 7.5 % 7.5 % 7.5 % 3.6 % 5.3 % 5.3 % Interest crediting rate 3.7 % 3.8 % 3.7 % Rate of compensation increase 3.0% to 5.5 % 3.9% to 5.5 % 3.9% to 5.5 % Weighted average assumptions used to determine net periodic benefit cost: Pension Benefits Other Postretirement Benefits Year Ended December 31 2019 2018 2017 2019 2018 2017 Discount rate 4.0 % 3.6 % 3.8 % 4.0 % 3.4 % 3.7 % Expected long term rate of return on plan assets 7.5 % 7.5 % 7.5 % 3.6 % 5.3 % 5.3 % Interest crediting rate 3.7 % 3.7 % 3.7 % Rate of compensation increase 3.0% to 5.5 % 3.9% to 5.5 % 3.9% to 5.5 % In determining the discount rate assumption, current market and liability information is d , including a discounted cash flow analysis of the the The expected long term rate of return for plan assets is determined based on widely-accepted capital market principles, long term return analysis for global fixed income and equity markets as well as the active total return oriented portfolio management style. Long term trends are evaluated relative to market factors such as inflation, interest rates and fiscal and monetary policies, in order to assess the capital market assumptions as applied to the plan. Consideration of diversification needs and rebalancing is maintained. Assumed health care cost trend rates: December 31 2019 2018 2017 Health care cost trend rate assumed for next year 4.0% to 8.0% 4.0% to 6.5 % 4.0% to 7.0 % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.0% to 5.0% 4.0% to 5.0 % 4.0% to 5.0 % Year that the rate reaches the ultimate trend rate 2021-2026 2019-2022 2018-2022 Net periodic benefit cost components: Pension Benefits Other Postretirement Benefits Year Ended December 31 2019 2018 2017 2019 2018 2017 (In millions) Service cost $ 7 $ 8 $ 8 $ 1 $ 1 Interest cost 117 110 119 $ 2 2 2 Expected return on plan assets (159 ) (179 ) (173 ) (3 ) (5 ) (5 ) Amortization of unrecognized net loss 45 42 43 (1 ) (1 ) Amortization of unrecognized prior service benefit (2 ) (2 ) Settlements and curtailments 1 9 11 Net periodic benefit cost $ 11 $ (10 ) $ 8 $ ) $ (5 ) $ (4 ) The following provides a reconciliation of benefit obligations and plan assets: Pension Benefits Other Postretirement Benefits 2019 2018 2019 2018 (In millions) Change in benefit obligation: Benefit obligation at January 1 $ 2,919 $ 3,242 $ 53 $ 62 Acquisitions Service cost 7 8 1 Interest cost 117 110 2 2 Plan participants’ contributions 4 4 Amendments 1 Actuarial (gain) loss 299 (212 ) 3 (6 ) Benefits paid from plan assets (191 ) (187 ) (10 ) (10 ) Settlements and curtailments (19 ) (35 ) Foreign exchange 4 (7 ) Benefit obligation at December 31 3,137 2,919 52 53 Change in plan assets: Fair value of plan assets at January 1 2,304 2,577 85 88 Acquisitions Actual return on plan assets 328 (83 ) 8 Company contributions 146 39 3 3 Plan participants’ contributions 4 4 Benefits paid from plan assets (191 ) (187 ) (10 ) (10 ) Settlements (15 ) (35 ) Foreign exchange 4 (7 ) Fair value of plan assets at December 31 2,576 2,304 90 85 Funded status $ (561 ) $ (615 ) $ 38 $ 32 Pension Other Postretirement Benefits 2019 2018 2019 2018 (In millions) Amounts recognized in the Consolidated Balance Sheets consist of: Other assets $ 5 $ 9 $ 54 $ 49 Other liabilities (566 ) (624 ) (16 ) (17 ) Net amount recognized $ (561 ) $ (615 ) $ 38 $ 32 Amounts recognized in Accumulated other comprehensive income (loss), not yet recognized in net periodic (benefit) cost: Prior service credit $ (2 ) $ (1 ) $ (1 ) Net actuarial loss $ 1,144 1,065 (4 ) (3 ) Net amount recognized $ 1,144 $ 1,063 $ (5 ) $ (4 ) Information for plans with projected and accumulated benefit obligations in excess of plan assets: Projected benefit obligation $ 3,021 $ 2,825 Accumulated benefit obligation 3,014 2,813 $ 16 $ 18 Fair value of plan assets 2,456 2,201 The accumulated benefit obligation for all defined benefit pension plans was $3.1 billion and $2.9 billion at December 31, 2019 and 2018. Changes for the years ended December 31, 2019 and 2018 include actuarial (gains) losses of $300 million and $(212) million primarily driven by changes in the discount rate used to determine the benefit obligations. The Company and its subsidiaries employ a total return approach whereby a mix of equity and fixed maturity securities are used to maximize the long term return of plan assets for a prudent level of risk and to manage cash flows according to plan requirements. The target allocation of plan assets is 40% to 60% invested in equity securities and limited partnerships, with the remainder primarily invested in fixed maturity securities. The intent of this strategy is to minimize expenses by generating investment returns that exceed the growth of the plan liabilities over the long run. Risk tolerance is established after careful consideration of the plan liabilities, plan funded status and corporate financial conditions. The investment portfolio s The table below presents the estimated future minimum benefit payments at December 31, 2019. Expected future benefit payments Pension Other (In millions) 2020 $ 234 $ 5 2021 211 5 2022 215 4 2023 217 4 2024 212 3 2025 – 2029 1,001 14 In 2020, it is expected that contributions of approximately $14 million will be made to pension plans and $2 million to postretirement health care and life insurance benefit plans. Pension plan assets measured at fair value on a recurring basis are summarized below. December 31, 2019 Level 1 Level 2 Level 3 Total (In millions) Plan assets at fair value: Fixed maturity securities: Corporate and other bonds $ 587 $ 10 $ 597 States, municipalities and political subdivisions 51 51 Asset-backed 154 154 Total fixed maturities $ – 792 10 802 Equity securities 541 128 669 Short term investments 74 7 81 Fixed income mutual funds 128 128 Other assets 11 9 20 Total plan assets at fair value $ 754 $ 936 $ 10 $ 1,700 Plan assets at net asset value: (a) Limited partnerships 876 Total plan assets $ 754 $ 936 $ 10 $ 2,576 December 31, 2018 Level 1 Level 2 Level 3 Total Plan assets at fair value: Fixed maturity securities: Corporate and other bonds $ 472 $ 10 $ 482 States, municipalities and political subdivisions 58 58 Asset-backed 165 165 Total fixed maturities $ – 695 10 705 Equity securities 406 110 516 Short term investments 36 54 90 Fixed income mutual funds 120 120 Other assets 9 9 Total plan assets at fair value $ 562 $ 868 $ 10 $ 1,440 Plan assets at net asset value: (a) Limited partnerships 864 Total plan assets $ 562 $ 868 $ 10 $ 2,304 (a) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table for these investments are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statement of financial position. The limited partnership investments held within the plans are recorded at fair value, which represents the plans’ shares of the net asset value of each partnership, as determined by the general partner. Limited partnerships comprising 80% and 82% of the carrying value as of December 31, 2019 and 2018 employ hedge fund strategies that generate returns through investing in marketable securities in the public fixed income and equity markets and the remainder were primarily invested in private debt and equity. Within hedge fund strategies, approximately 62% were equity related, 31% pursued a multi-strategy approach and 7% were focused on distressed investments at December 31, 2019. For a discussion of the valuation methodologies used to measure fixed maturity securities, equities and short term investments, see Note 4. Other postretirement benefits plan assets measured at fair value on a recurring basis are summarized below. December 31, 2019 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate and other bonds $ 22 $ 22 States, municipalities and political subdivisions 16 16 Asset-backed 31 31 Total fixed maturities $ - 69 $ - 69 Short term investments 3 3 Fixed income mutual funds 18 18 Total $ 21 $ 69 $ - $ 90 December 31, 2018 Fixed maturity securities: Corporate and other bonds $ 24 $ 24 States, municipalities and political subdivisions 11 11 Asset-backed 30 30 Total fixed maturities $ - 65 $ - 65 Short term investments 4 4 Fixed income mutual funds 16 16 Total $ 20 $ 65 $ - $ 85 There were no Level 3 assets at December 31, 2019 and 2018. Savings Plans – The Company and its subsidiaries have several contributory savings plans which allow employees to make regular contributions based upon a percentage of their salaries. Matching contributions are made up to specified percentages of employees’ contributions. The contributions by the Company and its subsidiaries to these plans amounted to $102 million, $100 million and $105 million for the years ended December 31, 2019, 2018 and 2017. Stock-based Compensation – In 2016, shareholders approved the Loews Corporation 2016 Incentive Compensation Plan (the “2016 Loews Plan”) which replaced a previously existing plan. The aggregate number of shares of Loews common stock authorized under the 2016 Loews Plan is 6,000,000 shares, plus up to 3,000,000 shares that may be forfeited under the prior plan. The maximum number of shares of Loews common stock with respect to which awards may be granted to any individual in any calendar year is 500,000 shares. In accordance with the 2016 Loews Plan and the Company ’ s prior equ ity plan , the Company’s stock-based compensation consists of the following: SARs: Company ’ s equity four-year Time-based Restricted Stock Units: Performance-based Restricted Stock Units: In 2019, the Company granted an aggregate of 216,802 48.10 3,621 2,469,756 41.11 The Company recognized compensation expense that decreased net income by $37 million, $ 35 33

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2019
Insurance [Abstract]
Reinsurance	Note 16. Reinsurance CNA cedes insurance to reinsurers to limit its maximum loss, provide greater diversification of risk, minimize exposures on larger risks and to exit certain lines of business. The ceding of insurance does not discharge the primary liability of CNA. A credit exposure exists with respect to reinsurance ceded to the extent that any reinsurer is unable to meet its obligations. A collectability exposure also exists to the extent that the reinsurer disputes the liabilities assumed under reinsurance agreements. Property and casualty reinsurance coverages are tailored to the specific risk characteristics of each product line and CNA’s retained amount varies by type of coverage. Reinsurance contracts are purchased to protect specific lines of business such as property and workers’ compensation. Corporate catastrophe reinsurance is also purchased for property and workers’ compensation exposure. CNA also utilizes facultative reinsurance in certain lines. In addition, CNA assumes reinsurance, primarily through Hardy and as a member of various reinsurance pools and associations. The following table presents the amounts receivable from reinsurers: December 31 2019 2018 (In millions) Reinsurance receivables related to insurance reserves: Ceded claim and claim adjustment expenses $ 3,835 $ 4,019 Ceded future policy benefits 226 233 Reinsurance receivables related to paid losses 143 203 Reinsurance receivables 4,204 4,455 Less allowance for doubtful accounts 25 29 Reinsurance receivables, net of allowance for doubtful accounts $ 4,179 $ 4,426 CNA has established an allowance for doubtful accounts on reinsurance receivables related to credit risk. CNA reviews the allowance quarterly and adjusts the allowance as necessary to reflect changes in estimates of uncollectible balances. The allowance may also be reduced by write-offs of reinsurance receivable balances. CNA attempts to mitigate its credit risk related to reinsurance by entering into reinsurance arrangements with reinsurers that have credit ratings above certain levels and by obtaining collateral. On a limited basis, CNA may enter into reinsurance agreements with reinsurers that are not rated, primarily captive reinsurers. The primary methods of obtaining collateral are through reinsurance trusts, letters of credit and funds withheld balances. Such collateral , limited by t he balance of open recoverable s , CNA’s largest recoverables from a single reinsurer, including ceded unearned premium reserves as of December 31, 2019 were approximately $2.0 billion from subsidia ries Palo Verde a y s sidiaries of The effects of reinsurance on earned premiums are presented in the following table: Direct Assumed Ceded Net Assumed/ (In millions) Year Ended December 31, 2019 Property and casualty $ 11,021 $ 288 $ 4,401 $ 6,908 4.2 % Long term care 470 50 520 9.6 Earned premiums $ 11,491 $ 338 $ 4,401 $ 7,428 4.6 % Year Ended December 31, 2018 Property and casualty $ 10,857 $ 305 $ 4,380 $ 6,782 4.5 % Long term care 480 50 530 9.4 Earned premiums $ 11,337 $ 355 $ 4,380 $ 7,312 4.9 % Year Ended December 31, 2017 Property and casualty $ 10,447 $ 317 $ 4,315 $ 6,449 4.9 % Long term care 489 50 539 9.3 Earned premiums $ 10,936 $ 367 $ 4,315 $ 6,988 5.3 % Included in the direct and ceded earned premiums for the years ended December 31, 2019, 2018 and 2017 are $3.6 billion, $3.7 billion and $3.9 billion related to property business that is 100% reinsured under a significant third party captive program. The third party captives that participate in this program are affiliated with the non-insurance Long term care premiums are from long duration contracts; property and casualty premiums are from short duration contracts. Insurance claims and policyholders’ benefits reported on the Consolidated Statements of Income are net of estimated

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Note 17. Quarterly Financial Data (Unaudited) 2019 Quarter Ended Dec. 31 Sept. 30 June 30 March 31 (In millions, except per share data) Total revenues $ 3,876 $ 3,675 $ 3,623 $ 3,757 Net income (a) (b) 217 72 249 394 Per share-basic and diluted 0.73 0.24 0.82 1.27 2018 Quarter Ended Total revenues $ 3,287 $ 3,608 $ 3,590 $ 3,581 Net income (loss) ( c (165 ) 278 230 293 Per share-basic and diluted (0.53 ) 0.88 0.72 0.89 The sum of the quarterly per share amounts may not equal per share amounts reported for year-to-date (a) Net income for the fourth s net i n vestment income of limited partnership s by asset $69 million (after tax). (b) Net income for the third quarter of 2019 included a $151 million (after tax and noncontrolling interests) charge related to the recognition of an active life reserve premium deficiency as a result of the third quarter GPV. ( c Net loss for the fourth quarter of 2018 includes a loss on limited partnership and common stock investments of $97 million (after tax and noncontrolling interests), catastrophe losses of $96 million (after tax and noncontrolling interests) and net investment losses of $57 million (after tax).

Legal Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	Note 18. Legal Proceedings Boardwalk Pipelines On May 25, 2018, plaintiffs Tsemach Mishal and Paul Berger (on behalf of themselves and the purported class, “Plaintiffs”) initiated a purported class action in the Court of Chancery of the State of Delaware (the “Court”) against the following defendants: Boardwalk Pipelines, Boardwalk GP, LP (“General Partner”), Boardwalk GP, LLC and Boardwalk Pipelines Holding Corp. (“BPHC”) (together, “Defendants”), regarding the potential exercise by the General Partner of its right to purchase all of the issued and outstanding common units representing limited partnership interests in Boardwalk Pipelines not already owned by the General Partner or its affiliates. On June 25, 2018, Plaintiffs and Defendants entered into a Stipulation and Agreement of Compromise and Settlement, subject to the approval of the Court (the “Proposed Settlement”). Under the terms of the Proposed Settlement, the lawsuit would be dismissed, and related claims against the Defendants would be released by the Plaintiffs, if BPHC, the sole member of the General Partner, elected to cause the General Partner to exercise its right to purchase the issued and outstanding common units of Boardwalk Pipelines pursuant to Boardwalk Pipelines’ Third Amended and Restated Agreement of Limited Partnership, as amended (“Limited Partnership Agreement”), within a period specified by the Proposed Settlement. As discussed in Note , on June , , the General Partner elected to exercise its right to purchase all of the issued and outstanding common units representing limited partnership interests in Boardwalk Pipelines not already owned by the General Partner or its affiliates pursuant to the Limited Partnership Agreement within the period specified by the Proposed Settlement. The transaction was completed on July , . On September 28, 2018, the Court denied approval of the Proposed Settlement. On February 11, 2019, a substitute verified class action complaint was filed in this proceeding. The Defendants filed a motion to dismiss, which was heard by the Court in July of 2019. In October of 2019, the Court ruled on the motion and granted a partial dismissal , 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 such 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	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 19. Commitments and Contingencies CNA Guarantees CNA has issued

Segments

Segments	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segments	Note 20. Segments The Company has five reportable segments comprised of four individual operating subsidiaries, CNA, Diamond Offshore, Boardwalk Pipelines and Loews Hotels & Co; and the Corporate segment. The operations of Altium Packaging since the acquisition date are included in the Corporate segment. 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. CNA’s business is the sale of property and casualty insurance coverage primarily through a network of independent agents, brokers and managing general underwriters. CNA’s operations also include its long term care business that is in run-off, run-off, Diamond Offshore provides contract drilling services to the energy industry around the world with a fleet of 15 offshore drilling rigs consisting of four drillships and 11 semisubmersible rigs , t wo of which are cold stacked Boardwalk Pipelines is engaged in the interstate transportation and storage of natural gas and NGLs. This segment consists of interstate natural gas pipeline systems located in the Gulf Coast region, Oklahoma, Arkansas and the midwestern states of Tennessee, Kentucky, Illinois, Indiana and Ohio, natural gas storage facilities in four states and NGL pipelines and storage facilities in Louisiana and Texas, with approximately 14,055 miles of pipeline. Loews Hotels & Co operates a chain of 26 hotels, 24 of which are in the United States and two of which are in Canada. The Corporate segment consists of investment income from the Parent Company’s cash and investments, Parent Company Parent Company Altium Packaging The accounting policies of the segments are the same as those described in the summary of significant accounting policies in Note 1. In the following tables certain financial measures are presented to provide information used by management to monitor the Company’s operating performance. These schedules present the reportable segments of the Company and their contribution to the consolidated financial statements. 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 and Total assets by segment are presented in the following tables. Year Ended December 31, 2019 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 7,428 $ 7,428 Net investment income 2,118 $ 6 $ 1 $ 230 2,355 Investment gains 49 49 Non-insurance 1,161 1,161 Operating revenues and other 32 982 $ 1,300 691 933 3,938 Total 10,788 988 1,300 692 1,163 14,931 Expenses: Insurance claims and policyholders’ benefits 5,806 5,806 Amortization of deferred acquisition costs 1,383 1,383 Non-insurance 1,082 1,082 Operating expenses and other 1,141 1,267 840 698 1,004 4,950 Interest 152 123 179 22 115 591 Total 9,564 1,390 1,019 720 1,119 13,812 Income (loss) before income tax 1,224 (402 ) 281 (28 ) 44 1,119 Income tax (expense) benefit (224 ) 60 (72 ) (3 ) (9 ) (248 ) Net income (loss) 1,000 (342 ) 209 (31 ) 35 871 Amounts attributable to noncontrolling interests (106 ) 167 61 Net income (loss) attributable to Loews Corporation $ 894 $ (175 ) $ 209 $ (31 ) $ 35 $ 932 December 31, 2019 Total assets $ 60,583 $ 5,834 $ 9,248 $ 1,728 $ 4,850 $ 82,243 Year Ended December 31, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 7,312 $ 7,312 Net investment income (loss) 1,817 $ 8 $ 2 $ (10 ) 1,817 Investment losses (57 ) (57 ) Non-insurance 1,007 1,007 Operating revenues and other 55 1,085 $ 1,227 753 867 3,987 Total 10,134 1,093 1,227 755 857 14,066 Expenses: Insurance claims and policyholders’ benefits 5,572 5,572 Amortization of deferred acquisition costs 1,335 1,335 Non-insurance 923 923 Operating expenses and other 1,203 1,196 820 653 956 4,828 Interest 138 123 176 29 108 574 Total 9,171 1,319 996 682 1,064 13,232 Income (loss) before income tax 963 (226 ) 231 73 (207 ) 834 Income tax (expense) benefit (151 ) 30 (28 ) (25 ) 46 (128 ) Net income (loss) 812 (196 ) 203 48 (161 ) 706 Amounts attributable to noncontrolling interests (86 ) 84 (68 ) (70 ) Net income (loss) attributable to Loews Corporation $ 726 $ (112 ) $ 135 $ 48 $ (161 ) $ 636 December 31, 2018 Total assets $ 57,123 $ 6,036 $ 9,131 $ 1,812 $ 4,214 $ 78,316 Year Ended December 31, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 6,988 $ 6,988 Net investment income 2,034 $ 2 $ 146 2,182 Investment gains 122 122 Non-insurance 390 390 Operating revenues and other 49 1,498 $ 1,325 $ 682 499 4,053 Total 9,583 1,500 1,325 682 645 13,735 Expenses: Insurance claims and policyholders’ benefits 5,310 5,310 Amortization of deferred acquisition costs 1,233 1,233 Non-insurance 299 299 Operating expenses and other 1,224 1,373 861 589 618 4,665 Interest 203 149 171 28 95 646 Total 8,269 1,522 1,032 617 713 12,153 Income (loss) before income tax 1,314 (22 ) 293 65 (68 ) 1,582 Income tax (expense) benefit (419 ) 4 232 (1 ) 14 (170 ) Net income (loss) 895 (18 ) 525 64 (54 ) 1,412 Amounts attributable to noncontrolling interests (94 ) (9 ) (145 ) (248 ) Net income (loss) attributable to Loews Corporation $ 801 $ (27 ) $ 380 $ 64 $ (54 ) $ 1,164

Schedule I - Condensed Financia

Schedule I - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule I - Condensed Financial Information of Registrant	SCHEDULE I Condensed Financial Information of Registrant LOEWS CORPORATION BALANCE SHEETS ASSETS December 31 2019 2018 (In millions) Current assets, principally investment in short term instruments $ 2,550 $ 2,050 Investments in securities 734 1,112 Investments in capital stocks of subsidiaries, at equity 18,123 17,556 Other assets 24 402 Total assets $ 21,431 $ 21,120 LIABILITIES AND SHAREHOLDERS’ EQUITY Current liabilities $ 77 $ 109 Long term debt 1,779 1,778 Deferred income tax and other 456 715 Total liabilities 2,312 2,602 Shareholders’ equity 19,119 18,518 Total liabilities and shareholders’ equity $ 21,431 $ 21,120 STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (LOSS) Year Ended December 31 2019 2018 2017 (In millions) Revenues: Equity in income of subsidiaries (a) $ 867 $ 819 $ 1,199 Net investment income (loss), interest and other 239 (11 ) 167 Total 1,106 808 1,366 Expenses: Administrative 83 127 134 Interest 72 72 72 Total 155 199 206 Income before income tax 951 609 1,160 Income tax (expense) benefit (19 ) 27 4 Net income 932 636 1,164 Equity in other comprehensive income (loss) of subsidiaries 812 (797 ) 197 Total comprehensive income (loss) $ 1,744 $ (161 ) $ 1,361 Condensed Financial Information of Registrant LOEWS CORPORATION STATEMENTS OF CASH FLOWS Year Ended December 31 2019 2018 2017 (In millions) Operating Activities: Net income $ 932 $ 636 $ 1,164 Adjustments to reconcile net income to net cash provided (used) by operating activities: Equity method investees 36 401 (405 ) Provision for deferred income taxes 106 113 77 Changes in operating assets and liabilities, net: Receivables 1 3 4 Accounts payable and accrued liabilities (29 ) 92 (20 ) Trading securities (478 ) 1,702 100 Other, net 36 19 (41 ) 604 2,966 879 Investing Activities: Investments in and advances to subsidiaries 183 (135 ) 12 Change in investments, primarily short term 326 (187 ) 30 Purchase of Boardwalk Pipelines common units (1,504 ) Acquisition (620 ) Other (2 ) (1 ) 509 (1,828 ) (579 ) Financing Activities: Dividends paid (76 ) (80 ) (84 ) Purchases of treasury shares (1,051 ) (1,026 ) (216 ) Other (5 ) (3 ) (1,132 ) (1,109 ) (300 ) Net change in cash (19 ) 29 - Cash, beginning of year 29 Cash, end of year $ 10 $ 29 $ - (a) Cash dividends paid to the Company by affiliates amounted to $927, $878 and $804 for the years ended December 31, 2019, 2018 and 2017.

Schedule V - Supplemental Infor

Schedule V - Supplemental Information Concerning Property and Casualty Insurance Operations	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Schedule V - Supplemental Information Concerning Property and Casualty Insurance Operations	SCHEDULE V LOEWS CORPORATION AND SUBSIDIARIES Supplemental Information Concerning Property and Casualty Insurance Operations Consolidated Property and Casualty Operations December 31 2019 2018 (In millions) Deferred acquisition costs $ 662 $ 633 Reserves for unpaid claim and claim adjustment expenses 21,720 21,984 Discount deducted from claim and claim adjustment expense reserves above (based on interest rates ranging from 3.5% to 7.6%) 1,321 1,388 Unearned premiums 4,583 4,183 Year Ended December 31 2019 2018 2017 (In millions) Net written premiums $ 7,656 $ 7,345 $ 7,069 Net earned premiums 7,428 7,312 6,988 Net investment income 2,063 1,751 1,992 Incurred claim and claim adjustment expenses related to current year 5,356 5,358 5,201 Incurred claim and claim adjustment expenses related to prior years (127 ) (179 ) (381 ) Amortization of deferred acquisition costs 1,383 1,335 1,233 Paid claim and claim adjustment expenses 5,576 5,331 5,341

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation – Altium Packaging LLC , Altium Packaging owned subsidiary). Unless the context otherwise requires, (i) the terms “Company” and “Loews” as used herein mean Loews Corporation including its subsidiaries and (ii) the term “Net income (loss) attributable to Loews Corporation” as used herein means Net income (loss) attributable to Loews Corporation shareholders.
Principles of consolidation	Principles of consolidation
Accounting estimates	Accounting estimates
Investments	Investments available-for-sale available-for-sale The cost of fixed maturity securities classified as available-for-sale For asset-backed securities included in fixed maturity securities, the Company recognizes income using an effective yield based on anticipated prepayments and the estimated economic life of the securities. When estimates of prepayments change, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. To the extent that unrealized gains on fixed maturity securities supporting long term care products and structured settlements not funded by annuities would result in a premium deficiency if those gains were realized, a related increase in Insurance reserves is recorded, net of tax and noncontrolling interests, as a reduction of net unrealized gains through Other comprehensive income (“Shadow Adjustments”). Shadow Adjustments increased $1.0 b b Equity securities are carried at fair value. CNA’s non-redeemable non-redeemable as available-for-sale The Company’s carrying value of investments in limited partnerships is its share of the net asset value of each partnership, as determined by the general partner. Certain partnerships for which results are not available on a timely basis are reported on a lag, primarily three months or less. These investments are accounted for under the equity method and changes in net asset values are recorded within Net investment income on the Consolidated Statements of Income. Mortgage loans are commercial in nature, are carried at unpaid principal balance, net of unamortized fees and any valuation allowance, and are recorded once funded. Interest income from mortgage loans is recognized on an accrual basis using the effective yield method. Mortgage loans are considered to be impaired loans when it is probable that contractual principal and interest payments will not be collected. CNA evaluates loans for impairment on an individual loan basis and identifies loans for evaluation of impairment based on the collection experience of each loan and other credit quality indicators such as debt service coverage ratio and the creditworthiness of the borrower or tenants of credit tenant loan properties. Accrual of income is generally suspended for mortgage loans that are impaired and collection of principal and interest payments is unlikely. Mortgage loans are considered past due when full principal or interest payments have not been received according to contractual terms. As of December 31, 2019 and 2018, there were no loans past due or in non-accrual Investments in derivative securities are carried at fair value with changes in fair value reported as a component of Investment gains (losses), Income (loss) from trading portfolio, or Other comprehensive income (loss), depending on their hedge designation. A derivative is typically defined as an instrument whose value is “derived” from an underlying instrument, index or rate, has a notional amount, requires little or no initial investment and can be net settled. Derivatives include, but are not limited to, the following types of investments: interest rate swaps, interest rate caps and floors, put and call options, warrants, futures, forwards, commitments to purchase securities, credit default swaps and combinations of the foregoing. Derivatives embedded within non-derivative An available-for-sale When the decline in value is determined by the Company to be other-than-temporary, losses are recognized within Investment gains (losses) on the Consolidated Statements of Income. Significant judgment is required in the determination of whether an OTTI loss has occurred for a security. CNA follows a consistent and systematic process for determining and recording an OTTI loss including the evaluation of securities in an unrealized loss position on at least a quarterly basis. CNA’s assessment of whether an OTTI loss has occurred incorporates both quantitative and qualitative information. Fixed maturity securities that CNA intends to sell, or it more likely than not will be required to sell before recovery of amortized cost, are considered to be other-than-temporarily impaired and the entire difference between the amortized cost basis and fair value of the security is recognized as an OTTI loss in earnings. The remaining fixed maturity securities in an unrealized loss position are evaluated to determine if a credit loss exists. The factors considered include: (i) the financial condition and near term and long term prospects of the issuer, (ii) whether the debtor is current on interest and principal payments, (iii) credit ratings of the securities and (iv) general market conditions and industry or sector specific outlook. CNA also considers results and analysis of cash flow modeling for asset-backed securities, and when appropriate, other fixed maturity securities. If the present value of the modeled expected cash flows equals or exceeds the amortized cost of a security, no credit loss is judged to exist and the asset-backed security is deemed to be temporarily impaired. If the present value of the expected cash flows is less than amortized cost, the security is judged to be other-than-temporarily impaired for credit reasons and that shortfall, referred to as the credit component, is recognized as an OTTI loss in earnings. The difference between the adjusted amortized cost basis and fair value, referred to as the non-credit non-credit Prior to 2018, CNA applied the same impairment model as described above for the majority of its non-redeemable
Joint venture investments	Joint venture investments Loews Hotels & Co has over which it exercises significant influence, but does not have control over them. Co uses the equity method of accounting for these investments . Loews Hotels & Co’s investment in these entities was $ million and $ million as of December , and and reported in Other assets on the Consolidated Balance Sheets. Equity income for these investments was $ million, $ million and $ million for the years ended December , , and and reported in Operating expenses and other on the Consolidated Statements of Income. These equity method investments are reviewed for impairment when changes in circumstances indicate that the carrying value of the asset may not be recoverable. The following tables present summarized financial information for these joint ventures: Year Ended December 31 2019 2018 (In millions) Total assets $ 2,261 $ 1,924 Total liabilities 1,727 1,451 Year Ended December 31 2019 2018 2017 Revenues $ 804 $ 731 $ 731 Net income 106 114 261
Hedging	Hedging
Securities lending activities	Securities lending activities
Revenue recognition	Securities lending is typically done on a matched-book basis where the collateral is invested to substantially match the term of the loan. This matching of terms tends to limit risk. In accordance with the Company’s lending agreements, securities on loan are returned immediately to the Company upon notice. Collateral is not reflected as an asset of the Company. There was no collateral held at December 31, 2019 and 2018. Revenue recognition Insurance receivables include balances due currently or in the future, including amounts due from insureds related to paid Property and casualty contracts that are retrospectively rated contain provisions that result in an adjustment to the initial policy premium depending on the contract provisions and loss experience of the insured during the experience period. For such contracts, CNA estimates the amount of ultimate premiums that it may earn upon completion of the experience period and recognizes either an asset or a liability for the difference between the initial policy premium and the estimated ultimate premium. CNA adjusts such estimated ultimate premium amounts during the course of the experience period based on actual results to date. The resulting adjustment is recorded as either a reduction of or an increase to the earned premiums for the period. CNA’s non-insurance N i Non-insurance Non-insurance Prior to 2018, Non-insurance Non-insurance non-insurance non-insurance Contract costs to obtain or fulfill 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 Pipelines 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 Pipelines’ operating subsidiaries are subject to Federal Energy Regulatory Commission (“FERC”) regulations and certain revenues collected, under certain circumstances, may be subject to possible refunds to its customers. An estimated refund liability is recorded considering regulatory proceedings, advice of counsel and estimated total exposure. The majority of Boardwalk Pipelines’ 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. 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 and other expenses as they are incurred on behalf of the owners of joint venture and managed hotel properties. Altium Packaging is a packaging solutions provider and manufacturer in North America, serving a diverse customer base in the pharmaceutical, dairy, household chemicals, food/nutraceuticals, industrial/specialty chemicals, water and beverage/juice segments. Altium Packaging recognizes revenue at the time control is transferred to the customer, there is persuasive evidence of an arrangement, the sales price is fixed and determinable and collection is reasonably assured.
Claim and claim adjustment expense reserves	Claim and claim adjustment expense reserves Claim and claim adjustment expense reserves are presented net of anticipated amounts due from insureds related to losses under deductible policies of $1.2 billion as of December 31, 2019 and 2018. A significant portion of these amounts are supported by collateral. CNA also has an allowance for uncollectible deductible amounts, which is presented as a component of the allowance for doubtful accounts included in Receivables on the Consolidated Balance Sheets. Structured settlements have been negotiated for certain property and casualty insurance claims. Structured settlements are agreements to provide fixed periodic payments to claimants. CNA’s obligations for structured settlements not funded by annuities are included in claim and claim adjustment expense reserves and carried at present values determined using interest rates ranging from 5.5% to 7.6% and 5.5% to Workers’ compensation lifetime claim reserves are calculated using mortality assumptions determined through statutory regulation and economic factors. At December 31, 2019 and 2018, workers’ compensation lifetime claim reserves are discounted at a 3.5% interest rate. As of December 31, 2019 and 2018, the discounted reserves for workers’ compensation lifetime claim reserves were $293 million and $343 million, net of discount of $135 million and $168 million. For the years ended December 31, 2019, 2018 and 2017, the amount of interest accretion recognized on the discounted reserves of workers’ compensation lifetime claim reserves was $21 million, $16 million and $19 million. This interest accretion is presented as a component of Insurance claims and policyholders’ benefits on the Consolidated Statements of Income, but is excluded from the Company’s disclosure of prior year loss reserve development. Long term care claim reserves are calculated using mortality and morbidity assumptions based on CNA and industry experience. Long term care claim reserves are discounted at a 2019 and
Future policy benefit reserves	Future policy benefit reserves These re locked policy; however if e merges are are increased September 30, 2019 a premium deficiency of $216 million and future policy benefit reserves at that date were increased accordingly. As a result, the carried 2019 represent management’s best estimate assumptions at that date with no margin for adverse deviation. Long term care active life reserves are discounted at a weighted average In circumstances where the cash flow projections supporting future policy benefit reserves are expected to result in profits being recognized in early future years followed by losses in later future years, the future policy benefit reserves are increased in the future profitable years by an amount necessary to offset losses that are projected to be recognized in later future years. The amount of the additional future policy benefit reserves recorded in each period is determined by applying the ratio of the present value of future losses divided by the present value of future profits from the most recently completed GPV to long term care core income in that period.
Insurance-related assessments	I
Reinsurance	Reinsurance Reinsurance receivables related to paid losses are presented at unpaid balances. Reinsurance receivables related to unpaid losses are estimated in a manner consistent with claim and claim adjustment expense reserves or future policy benefit reserves. Reinsurance receivables are reported net of an allowance for doubtful accounts on the Consolidated Balance Sheets. The cost of reinsurance is primarily accounted for over the life of the underlying reinsured policies using assumptions consistent with those used to account for the underlying policies or over the reinsurance contract period. The ceding of insurance does not discharge the primary liability of CNA. CNA has established an allowance for doubtful accounts on reinsurance receivables which relates to both amounts already billed on ceded paid losses as well as ceded reserves that will be billed when losses are paid in the future. The allowance for doubtful accounts on reinsurance receivables is estimated on the basis of periodic evaluations of balances due from reinsurers, reinsurer solvency, industry experience and current economic conditions. Reinsurer financial strength ratings are updated and reviewed on an annual basis or sooner if CNA becomes aware of significant changes related to a reinsurer. Because billed receivables generally approximate 5% or less of total reinsurance receivables, the age of the reinsurance receivables related to paid losses is not a significant input into the allowance analysis. Changes in the allowance for doubtful accounts on reinsurance receivables are presented as a component of Insurance claims and policyholders’ benefits on the Consolidated Statements of Income. Amounts are considered past due based on the reinsurance contract terms. Reinsurance receivables related to paid losses and any related allowance are written off after collection efforts have been exhausted or a negotiated settlement is reached with the reinsurer. Reinsurance receivables from insolvent insurers related to paid losses are written off when the settlement due from the estate can be reasonably estimated. At the time reinsurance receivables related to paid losses are written off, any required adjustment to reinsurance receivables related to unpaid losses is recorded as a component of Insurance claims and policyholders’ benefits on the Consolidated Statements of Income. A loss portfolio transfer is a retroactive reinsurance contract. If the cumulative claim and allocated claim adjustment expenses ceded under a loss portfolio transfer exceed the consideration paid, the resulting gain from such excess is deferred and amortized into earnings in future periods in proportion to actual recoveries under the loss portfolio transfer. In any period in which there is a revised estimate of claim and allocated claim adjustment expenses and the loss portfolio transfer is in a gain position, the deferred gain is recalculated as if the revised estimate was available at the inception date of the loss portfolio transfer and the change in the deferred gain is recognized in earnings.
Deferred acquisition costs	Deferred acquisition costs CNA evaluates deferred acquisition costs for recoverability. Anticipated investment income is considered in the determination of the recoverability of deferred acquisition costs. Adjustments, if necessary, are recorded in current period results of operations.
Policyholder dividends	Policyholder dividends
Goodwill and other intangible assets	Policyholder dividends Goodwill and other intangible assets Other intangible assets are reported within Other assets. Finite-lived intangible assets are amortized over their estimated useful lives. Indefinite-lived other intangible assets are tested for impairment annually or when certain triggering events require such tests. See Note 7 for additional information on the Company’s goodwill and other intangible assets.
Property, plant and equipment	Property, plant and equipment
Impairment of long-lived assets	Impairment of long-lived assets Assets to be disposed of and assets not expected to provide any future service potential to the Company are recorded at the lower of carrying amount or fair value less cost to sell.
Income taxes	The principal service lives used in computing provisions for depreciation are as follows: Years Pipeline equipment 30 to 50 Offshore drilling equipment 15 to 30 Other 3 to 40 Impairment of long-lived assets Assets to be disposed of and assets not expected to provide any future service potential to the Company are recorded at the lower of carrying amount or fair value less cost to sell. Income taxes The Company recognizes uncertain tax positions that it has taken or expects to take on a tax return. The tax benefit of a qualifying position is the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. See Note 10 for additional information on the provision for income taxes.
Pension and postretirement benefits	Pension and postretirement benefits
Stock-based compensation	Stock-based compensation three
Net income per share	Net income per share For each of the years ended December 31, 2019, 2018 and 2017, approximately 0.7 million, 0.9 million and 0.9 million potential shares attributable to issuances and exercises under the Loews Corporation 2016 Incentive Compensation Plan and the prior plan were included in the calculation of diluted net income per share. For the years ended December 31, 2019 and 2018, there were no shares and for the year ended December 31, 2017, there were 0.4 million shares attributable to employee stock-based compensation awards excluded from the calculation of diluted net income per share because the effect would have been antidilutive.
Regulatory accounting	Foreign currency Regulatory accounting
Supplementary cash flow information	Supplementary cash flow information 190 17
Accounting changes	Accounting changes 2016-02, 2016-02”). For leases where we are a lessee we have elected to account for lease and non-lease non-lease At adoption, the cumulative effect adjustment increased Other assets and Other liabilities by $642 million reflecting operating lease right of use assets, lease liabilities and the derecognition of deferred rent related primarily to lease agreements for office space and machinery and equipment. At 2016-02, 9 On January 1, 2018, the Company adopted ASU 2014-09, 2014-09”). non-insurance non-insurance On January 1, 2018 the Company adopted ASU 2016-01, – 825-10): 2016-01”). On January 1, 2018 the Company adopted ASU 2016-16, On January 1, 2018 the Company early adopted ASU 2018-02, 2018-02”).
Recently issued ASUs	Recently issued ASUs 2016-13, available-for-sale available-for-sale available-for-sale In August of 2018, the FASB issued ASU 2018-12, (“OCI”). This guidance is effective for interim and annual periods beginning after December 15, 2021. The Company will adopt the guidance on January 1, 2022. The guidance requires restatement of prior periods presented. The Company is currently evaluating the method of adoption and the effect the updated guidance will have on its consolidated financial statements, including increased disclosure requirements. The annual updating of cash flow assumptions is expected to increase income statement volatility. The quarterly change in the discount rate is expected to increase volatility in the Company’s Shareholders’ equity, but that will be somewhat mitigated because Shadow Adjustments are eliminated under the new guidance. While the requirements of the new guidance represent a material change from existing accounting guidance, the underlying economics of CNA’s business and related cash flows are unchanged.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Financial Information for Joint Ventures	The following tables present summarized financial information for these joint ventures: Year Ended December 31 2019 2018 (In millions) Total assets $ 2,261 $ 1,924 Total liabilities 1,727 1,451 Year Ended December 31 2019 2018 2017 Revenues $ 804 $ 731 $ 731 Net income 106 114 261
Principal Service Lives

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Summary of Net Investment Income	Net investment income is as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities $ 1,817 $ 1,795 $ 1,812 Limited partnership investments 204 22 277 Short term investments 52 43 18 Equity securities 85 18 12 Income (loss) from trading portfolio (a) 216 (54 ) 87 Other 56 54 35 Total investment income 2,430 1,878 2,241 Investment expenses (75 ) (61 ) (59 ) Net investment income $ 2,355 $ 1,817 $ 2,182 (a) Net unrealized gains (losses) related to changes in fair value on securities still held were $41, $(121) and $39 for the years ended December 31, 2019, 2018 and 2017.
Summary of Investment Gains (Losses)	Investment gains (losses) are as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities $ (6 ) $ 4 $ 122 Equity securities 66 (74 ) Derivative instruments (11 ) 9 (4 ) Short term investments and other 4 4 Investment gains (losses) (a) $ 49 $ (57 ) $ 122 (a) Gross investment available-for-sale investment available-for-sale $ investment g ains Net investment losses of $73 were recognized due to the change in fair value of non-redeemable preferred stock still held for the year ended December 31, 2018.
Schedule of Net Change in Unrealized Gains (Losses) Investments	Net change in unrealized gains (losses) on investments is as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities $ 2,620 $ (1,811 ) $ 728 Equity securities (a) 32 Other (2 ) Total net change in unrealized gains (losses) on investments $ 2,620 $ (1,811 ) $ 758
Components of OTTI Losses Recognized in Earnings by Asset Type	(a) Due to the adoption of ASU 2016-01 The components of OTTI losses recognized in earnings by asset type are as follows: Year Ended December 31 2019 2018 2017 (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 33 $ 12 $ 12 Asset-backed 11 9 1 Total fixed maturity securities available-for-sale 44 21 13 Equity securities available-for-sale 1 Net OTTI losses recognized in earnings $ 44 $ 21 $ 14
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: December 31, 2019 Cost Amortized Cost Gross Unrealized Gains Gross Unrealized Loss Estimated Fair Value Unrealized OTTI (Gains) (In millions) Fixed maturity securities: Corporate and other bonds $ 19,789 $ 2,292 $ 32 $ 22,049 States, municipalities and political subdivisions 9,093 1,559 10,652 Asset-backed: Residential mortgage-backed 4,387 133 1 4,519 $ ) Commercial mortgage-backed 2,265 86 5 2,346 1 Other asset-backed 1,925 41 4 1,962 (3 ) Total asset-backed 8,577 260 10 8,827 (19) U.S. Treasury and obligations of government- 146 1 2 145 Foreign government 491 14 1 504 Redeemable preferred stock 10 10 Fixed maturities available-for-sale 38,106 4,126 45 42,187 (19) Fixed maturities trading 51 2 53 Total fixed maturities $ 38,157 $ 4,128 $ 45 $ 42,240 $ ) December 31, 2018 Cost or Amortized Cost Gross Unrealized Gains Gross Losses Estimated Fair Value Unrealized OTTI Losses (Gains) (In millions) Fixed maturity securities: Corporate and other bonds $ 18,764 $ 791 $ 395 $ 19,160 States, municipalities and political subdivisions 9,681 1,076 9 10,748 Asset-backed: Residential mortgage-backed 4,815 68 57 4,826 $ (20 ) Commercial mortgage-backed 2,200 28 32 2,196 Other asset-backed 1,975 11 24 1,962 Total asset-backed 8,990 107 113 8,984 (20 ) U.S. Treasury and obligations of government-sponsored enterprises 156 3 159 Foreign government 480 5 4 481 Redeemable preferred stock 10 10 Fixed maturities available-for-sale 38,081 1,982 521 39,542 (20 ) Fixed maturities trading 153 4 157 Total fixed maturities $ 38,234 $ 1,986 $ 521 $ 39,699 $ (20 )
Securities Available-for-Sale in Gross Unrealized Loss Position	The available-for-sale Less than 12 Months 12 Months or Longer Total December 31, 2019 Estimated Fair V Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (In millions ) Fixed maturity securities: Corporate and other bonds $ 914 $ 21 $ 186 $ 11 $ 1,100 $ 32 States, municipalities and political subdivisions 34 34 Asset-backed: Residential mortgage-backed 249 1 30 279 1 Commercial mortgage-backed 381 3 20 2 401 5 Other asset-backed 449 3 33 1 482 4 Total asset-backed 1,079 7 83 3 1,162 10 U.S. Treasury and obligations of government-sponsored enterprises 62 2 2 64 2 Foreign government 59 1 1 60 1 Total fixed maturity securities $ 2,148 $ 31 $ 272 $ 14 $ 2,420 $ 45 December 31, 2018 Fixed maturity securities: Corporate and other bonds $ 8,543 $ 340 $ 825 $ 55 $ 9,368 $ 395 States, municipalities and political subdivisions 517 8 5 1 522 9 Asset-backed: Residential mortgage-backed 1,932 23 1,119 34 3,051 57 Commercial mortgage-backed 728 10 397 22 1,125 32 Other asset-backed 834 21 125 3 959 24 Total asset-backed 3,494 54 1,641 59 5,135 113 U.S. Treasury and obligations of government-sponsored enterprises 21 19 40 Foreign government 114 2 124 2 238 4 Total fixed maturity securities $ 12,689 $ 404 $ 2,614 $ 117 $ 15,303 $ 521
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 at December 31, 2019, 2018 and 2017 for which a portion of an OTTI loss was recognized in Other comprehensive income. Year Ended December 31 2019 2018 2017 (In millions) Beginning balance of credit losses on fixed maturity securities $ 18 $ 27 $ 36 Reductions for securities sold during the period (8 ) (9 ) (9 ) Ending balance of credit losses on fixed maturity securities $ 10 $ 18 $ 27
Available-for-Sale Fixed Maturity Securities by Contractual Maturity	The following table presents available-for-sale December 31 2019 2018 Cost Estimated Cost Estimated (In millions) Due in one year or less $ 1,334 $ 1,356 $ 1,350 $ 1,359 Due after one year through five years 9,746 10,186 7,979 8,139 Due after five years through ten years 14,892 15,931 16,859 16,870 Due after ten years 12,134 14,714 11,893 13,174 Total $ 38,106 $ 42,187 $ 38,081 $ 39,542
Summary of Aggregate Contractual or Notional Amount and Estimated Fair Value Related to Derivative Financial Instruments	The following tables present the aggregate contractual or notional amount and estimated fair value related to derivative financial instruments. December 31 2019 2018 Contractual/ Contractual/ Notional Estimated Fair Value Notional Estimated Fair Value Amount Asset (Liability) Amount Asset (Liability) (In millions) With hedge designation: Interest rate swaps $ 715 $ (8 ) $ 500 $ 11 Without hedge designation: Equity markets: Options – purchased 57 $ 1 213 18 – written 100 (1) 239 $ (17 ) Commodity futures – long 32 Embedded derivative on funds withheld liability 182 (7) 172 4

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized in the following tables. Corporate bonds and other includes obligations of the U.S. Treasury, government-sponsored enterprises, foreign governments and redeemable preferred stock. December 31, 2019 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate bonds and other $ 175 $ 22,065 $ 468 $ 22,708 States, municipalities and political subdivisions 10,652 10,652 Asset-backed 8,662 165 8,827 Fixed maturities available-for-sale 175 41,379 633 42,187 Fixed maturities trading 49 4 53 Total fixed maturities $ 175 $ 41,428 $ 637 $ 42,240 Equity securities $ 629 $ 658 $ 19 $ 1,306 Short term and other 3,138 1,383 4,521 Receivables 2 2 Payable to brokers (18 ) (10 ) (28 ) December 31, 2018 Fixed maturity securities: Corporate bonds and other $ 196 $ 19,392 $ 222 $ 19,810 States, municipalities and political subdivisions 10,748 10,748 Asset-backed 8,787 197 8,984 Fixed maturities available-for-sale 196 38,927 419 39,542 Fixed maturities trading 151 6 157 Total fixed maturities $ 196 $ 39,078 $ 425 $ 39,699 Equity securities $ 704 $ 570 $ 19 $ 1,293 Short term and other 2,647 1,111 3,758 Receivables 11 11 Payable to brokers (23 ) (23)
Reconciliations of Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The tables below present reconciliations for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2019 and 2018: Unrealized Gains Unrealized (Losses) Gains Recognized in (Losses) Other Recognized in Comprehensive Net Realized Investment Net Income Income (Loss) Gains (Losses) and Net (Loss) on Level on Level 3 Change in Unrealized 3 Assets and Assets and Investment Gains (Losses) Transfers Transfers Liabilities Liabilities Balance, Included in Included in into out of Balance, Held at Held at 2019 January 1 Net Income OCI Purchases Sales Settlements Level 3 Level 3 December 31 December 31 December 31 (In millions) Fixed maturity securities: Corporate bonds and other $ 222 $ 33 $ 256 $ (11) $ (32) $ 468 $ 28 Asset-backed 197 8 48 (16) $ 45 (117) 165 7 Fixed maturities available-for-sale 419 $ - 41 304 $ - (27) 45 (149) 633 $ - 35 Fixed maturities trading 6 (2) 4 (2) Total fixed maturities $ 425 $ (2) $ 41 $ 304 $ - $ (27) $ 45 $ (149) $ 637 $ (2) $ 35 Equity securities $ 19 $ (2) $ 2 $ 19 $ (2) Unrealized Gains Unrealized (Losses) Gains Recognized in (Losses) Other Recognized in Comprehensive Net Realized Investment Net Income Income (Loss) Gains (Losses) and Net (Loss) on Level on Level 3 Change in Unrealized 3 Assets and Assets and Investment Gains (Losses) Transfers Transfers Liabilities Liabilities Balance, Included in Included in into out of Balance, Held at Held at 2018 January 1 Net Income OCI Purchases Sales Settlements Level 3 Level 3 December 31 December 31 December 31 (In millions) Fixed maturity securities: Corporate bonds and other $ 98 $ (1) $ (4) $ 117 $ (5) $ (9) $ 35 $ (9) $ 222 $ (5 ) States, municipalities and political subdivisions 1 (1) - Asset-backed 335 5 (8) 162 (72) (64) 42 (203) 197 $ (2) (4 ) Fixed maturities available-for-sale 434 4 (12) 279 (77) (74) 77 (212) 419 (2) (9 ) Fixed maturities trading 4 3 (1) 6 2 Total fixed maturities $ 438 $ 7 $ (12) $ 279 $ (78) $ (74 ) $ 77 $ (212) $ 425 $ - $ (9 ) Equity securities $ 22 $ (2) $ (1) $ 19 $ (2) Net investment gains and losses are reported in Net income as follows: Major Category of Assets and Liabilities Consolidated 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
Quantitative Information about Significant Unobservable Inputs Utilized by Company in Fair Value Measurements of Level 3 Assets	The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 assets. Valuations for assets and liabilities not presented in the tables below are primarily based on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations. The quantitative detail of unobservable inputs from these broker quotes is neither provided nor reasonably available to the Company. The weighted average rate is calculated based on fair value. Range Estimated Valuation Unobservable (Weighted December 31, 2019 Fair Value Techniques Inputs Average) (In millions) Fixed maturity securities $ 525 Discounted cash Credit 1 % 6 2 ) December 31, 2018 Fixed maturity securities $ Discounted cash 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 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 Balance Sheets are presented in the following tables. The carrying amounts and estimated fair values of short term debt and long term debt exclude finance Carrying Estimated Fair Value December 31, 2019 Amount Level 1 Level 2 Level 3 Total (In millions) Assets: Other invested assets, primarily mortgage loans $ 994 $ 1,025 $ 1,025 Liabilities: Short term debt 75 $ 9 66 75 Long term debt 11,443 10,884 626 11,510 December 31, 2018 Assets: Other invested assets, primarily mortgage loans $ 839 $ 827 $ 827 Liabilities: Short term debt 15 $ 14 14 Long term debt 11,345 10,111 653 10,764

Receivables (Tables)

Receivables (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Receivables	December 31 2019 2018 (In millions) Reinsurance (Note 16) $ 4,204 $ 4,455 Insurance 2,481 2,365 Receivable from brokers 124 296 Accrued investment income 395 394 Federal income taxes 14 52 Other, primarily customer accounts 520 477 Total 7,738 8,039 Less: allowance for doubtful accounts on reinsurance receivables 25 29 allowance for other doubtful accounts 38 50 Receivables $ 7,675 $

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Components of Property, Plant and Equipment	December 31 2019 2018 (In millions) Pipeline equipment (net of accumulated depreciation of $3,075 and $2,761) $ 8,229 $ Offshore drilling equipment (net of accumulated depreciation of $2,885 and $3,067) 5,119 5,144 Other (net of accumulated depreciation of $1,114 and $1,056 ) 1,625 1,812 Construction in process 595 317 Property, plant and equipment $ 15,568 $
Depreciation Expense and Capital Expenditures	Depreciation expense and capital expenditures are as follows: Year Ended December 31 2019 2018 2017 Depre- Capital Depre- Capital Depre- Capital ciation Expend. ciation Expend. ciation Expend. (In millions) CNA Financial $ 64 $ 26 $ 76 $ 99 $ 80 $ 101 Diamond Offshore 356 345 332 222 349 113 Boardwalk Pipelines 348 418 346 487 325 689 Loews Hotels & Co 60 216 67 139 63 57 Corporate 70 53 59 48 37 30 Total $ 898 $ 1,058 $ 880 $ 995 $ 854 $ 990

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Goodwill	A summary of the changes in the carrying amount of goodwill is as follows: CNA Boardwalk Financial Pipelines Corporate Total (In millions) Balance, December 31, 2017 $ 112 $ 237 $ 310 $ 659 Acquisition 8 8 Other adjustments (2 ) (2) Balance, December 31, 2018 110 237 318 665 Acquisition s 100 100 Other adjustments 2 2 Balance, December 31, 2019 $ 112 $ 237 $ 418 $ 767
Schedule of Carrying Amount of Other Intangible Assets	A summary of the net carrying amount of other intangible assets is as follows: December 31, 2019 December 31, 2018 Gross Gross Carrying Accumulated Carrying Accumulated Amount Amortization Amount Amortization (In millions) Finite-lived intangible assets: Customer relationships $ 611 76 $ 532 47 Other 71 34 72 20 Total finite-lived intangible assets 682 110 604 67 Indefinite-lived intangible assets 75 74 Total other intangible assets $ 757 110 $ 678 67

Claim, Claim Adjustment Expen_2

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves (Tables)	12 Months Ended
	Dec. 31, 2019
Reconciliation of Net Liability for Unpaid Claim and Claim Adjustment Expenses for Property and Casualty Operations to Amount Presented in Consolidated Balance Sheets	The table below reconciles the net liability for unpaid claim and claim adjustment expenses to the amount presented o December 31 2019 (In millions) Net liability for unpaid claim and claim adjustment expenses: Property & Casualty Operations $ 14,153 Other Insurance Operations (a) 3,732 Total net claim and claim adjustment expenses 17,885 Reinsurance receivables: (b) Property & Casualty Operations 1,617 Other Insurance Operations (c) 2,218 Total reinsurance receivables 3,835 Total gross liability for unpaid claims and claims adjustment expenses $ 21,720 (a) Other Insurance Operations amounts are primarily related to long term care claim reserves, which are long duration insurance contracts, but also include amounts related to unfunded structured settlements arising from short duration insurance contracts. (b) Reinsurance receivables presented are gross of the allowance for uncollectible reinsurance and do not include reinsurance receivables related to paid losses. (c) The Other Insurance Operations reinsurance receivables are primarily related to A&EP claims covered under the loss portfolio transfer ( “ LPT ” )
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. Year Ended December 31 2019 2018 2017 (In millions) Reserves, beginning of year: Gross $ 21,984 $ 22,004 $ 22,343 Ceded 4,019 3,934 4,094 Net reserves, beginning of year 17,965 18,070 18,249 Net incurred claim and claim adjustment expenses: Provision for insured events of current year 5,356 5,358 5,201 Decrease in provision for insured events of prior years (127 ) (179 ) (381 ) Amortization of discount 184 176 179 Total net incurred (a) 5,413 5,355 4,999 Net payments attributable to: Current year events (992 ) (1,046 ) (975 ) Prior year events (4,584 ) (4,285 ) (4,366 ) Total net payments (5,576 ) (5,331 ) (5,341 ) Foreign currency translation adjustment and other 83 (129 ) 163 Net reserves, end of year 17,885 17,965 18,070 Ceded reserves, end of year 3,835 4,019 3,934 Gross reserves, end of year $ 21,720 $ 21,984 $ 22,004 (a) Total net incurred above does not agree to Insurance claims and policyholders’ benefits as reflected on the Consolidated Statements of Income due to amounts related to retroactive reinsurance deferred gain accounting, uncollectible reinsurance and benefit expenses related to future policy benefits, which are not reflected in the table above.
Schedule of Gross and Net Carried Claim and Claim Adjustment Expense ReservesSchedule of Gross and Net Carried Claim and Claim Adjustment Expense Reserves	The following tables present the gross and net carried reserves: Property Other and Casualty Insurance December 31, 2019 Operations Operations Total (In millions) Gross Case Reserves $ 6,276 $ 4,713 $ 10,989 Gross IBNR Reserves 9,494 1,237 10,731 Total Gross Carried Claim and Claim Adjustment Expense Reserves $ 15,770 $ 5,950 $ 21,720 Net Case Reserves $ 5,645 $ 3,533 $ 9,178 Net IBNR Reserves 8,508 199 8,707 Total Net Carried Claim and Claim Adjustment Expense Reserves $ 14,153 $ 3,732 $ 17,885 December 31, 2018 Gross Case Reserves $ 6,671 $ 4,724 $ 11,395 Gross IBNR Reserves 9,287 1,302 10,589 Total Gross Carried Claim and Claim Adjustment Expense Reserves $ 15,958 $ 6,026 $ 21,984 Net Case Reserves $ 6,063 $ 3,460 $ 9,523 Net IBNR Reserves 8,290 152 8,442 Total Net Carried Claim and Claim Adjustment Expense Reserves $ 14,353 $ 3,612 $ 17,965
Details of the Net Prior Year Development in CNA's Property and Casualty Operations	The following table and discussion presents detail of the development in CNA’s Property & Casualty Operations: Year Ended December 31 2019 2018 2017 (In millions) Medical professional liability $ 75 $ 47 $ 30 Other professional liability and management liability (69) (127) (126) Surety (92) (70) (84) Commercial auto (25) 1 (35) General liability 54 32 (24) Workers’ compensation (13) (32) (63) Other (3) (32) (6) Total pretax favorable development $ (73) $ (181) $ (308)
Schedule of Net Prior Year Claim and Allocated Claim Adjustment Expense Reserve Development for Segment	The table below presents the net liability for unpaid claim and claim adjustment expenses, by line of business for Property & Casualty Operations: December 31 2019 (In millions) Medical professional liability $ 1,429 Other professional liability and management liability 2,739 Surety 369 Commercial auto 404 General liability 3,176 Workers’ compensation 3,932 Other 2,104 Total net liability for unpaid claim and claim adjustment expenses $ 14,153
Schedule of Historical Claims Duration	The table below presents information about average historical claims duration as of December 31, 2019 and is presented as required supplementary information, which is unaudited. Average Annual Percentage Payout of Ultimate Net Incurred Claim and Allocated Claim Adjustment Expenses in Year: 1 2 3 4 5 6 7 8 9 10 Total Medical professional liability 3.8 % 20.0 % 24.3 % 19.4 % 12.4 % 7.8 % 5.1 % 3.1 % 1.1 % 0.8 % 97.8 % Other professional liability and management liability 6.6 22.6 21.7 16.9 10.5 6.0 4.9 3.3 3.8 0.7 97.0 Surety (a) 20.0 44.5 21.0 4.4 2.2 0.9 (2.5 ) (1.1 ) 1.6 91.0 Commercial auto 28.6 24.0 18.6 14.3 9.4 3.2 1.5 0.4 100.0 General liability 4.3 15.8 19.0 20.1 15.7 8.7 6.0 2.5 1.5 1.6 95.2 Workers’ compensation 14.1 21.4 13.9 10.3 7.0 3.7 2.9 2.7 1.4 0.8 78.2 (a) Due to the nature of the Surety business, average annual percentage payout of ultimate net incurred claim and allocated claim adjustment expenses has been calculated using only the payouts of mature accident years presented in the loss reserve development tables.
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 Statements of Income. Year Ended December 31 2019 2018 2017 (In millions) Additional amounts ceded under LPT: Net A&EP adverse development before consideration of LPT $ 150 $ 178 $ 60 Provision for uncollectible third-party reinsurance on A&EP (25 ) (16 ) Total additional amounts ceded under LPT 125 162 60 Retroactive reinsurance benefit recognized (107 ) (114 ) (68 ) Pretax impact of deferred retroactive reinsurance $ 18 $ 48 $ (8 )
Medical Professional Liability [Member]
Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses	December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 402 $ 412 $ 423 $ 426 $ 415 $ 395 $ 365 $ 360 $ 356 $ 369 $ 1 14,624 2011 429 437 443 468 439 434 437 437 439 2 16,526 2012 464 469 508 498 493 484 493 499 8 17,724 2013 462 479 500 513 525 535 545 27 19,510 2014 450 489 537 530 535 529 16 19,723 2015 433 499 510 494 488 29 18,029 2016 427 487 485 499 63 15,823 2017 412 449 458 127 14,636 2018 404 429 216 13,760 2019 430 364 10,467 Total $ 4,685 $ 853
Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses	Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 10 $ 86 $ 173 $ 257 $ 306 $ 326 $ 337 $ 346 $ 350 $ 353 2011 17 109 208 295 347 375 398 409 414 2012 14 117 221 323 388 427 457 479 2013 17 119 255 355 414 462 495 2014 23 136 258 359 417 472 2015 22 101 230 313 384 2016 18 121 246 339 2017 19 107 235 2018 21 115 2019 17 Total $ 3,303 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 1,382 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 22 Liability for unallocated claim adjustment expenses for accident years presented 25 Total net liability for unpaid claim and claim adjustment expenses $ 1,429
Schedule of Net Strengthening or (Releases) of Prior Accident Year Reserves	Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 10 $ 11 $ 3 $ (11 ) $ (20 ) $ (30 ) $ (5 ) $ (4 ) $ 13 $ (33 ) 2011 8 6 25 (29 ) (5 ) 3 - 2 10 2012 5 39 (10 ) (5 ) (9 ) 9 6 35 2013 17 21 13 12 10 10 83 2014 39 48 (7 ) 5 (6 ) 79 2015 66 11 (16 ) (6 ) 55 2016 60 (2 ) 14 72 2017 37 9 46 2018 25 25 Total net development for the accident years presented above 65 39 67 Total net development for accident years prior to 2010 (28 ) 9 6 Total unallocated claim adjustment expense development (7 ) (1 ) 2 Total $ 30 $ 47 $ 75 (a) Data presented for these calendar years is required supplemental information, which is unaudited.
Other Professional Liability and Management Liability [Member]
Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses	December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 828 $ 828 $ 848 $ 848 $ 847 $ 837 $ 824 $ 827 $ 821 $ 821 $ 9 17,891 2011 880 908 934 949 944 911 899 888 885 21 18,738 2012 923 909 887 878 840 846 833 831 18 18,499 2013 884 894 926 885 866 863 850 45 17,928 2014 878 898 885 831 835 854 74 17,553 2015 888 892 877 832 807 120 17,390 2016 901 900 900 904 188 17,890 2017 847 845 813 308 18,015 2018 850 864 460 19,468 2019 837 714 16,722 Total $ 8,466 $ 1,957
Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses	Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 31 $ 204 $ 405 $ 541 $ 630 $ 670 $ 721 $ 752 $ 784 $ 790 2011 71 314 503 605 683 726 781 796 828 2012 56 248 400 573 651 711 755 792 2013 54 249 447 618 702 754 771 2014 51 223 392 515 647 707 2015 60 234 404 542 612 2016 64 248 466 625 2017 57 222 394 2018 54 282 2019 64 Total $ 5,865 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 2,601 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 88 Liability for unallocated claim adjustment expenses for accident years presented 50 Total net liability for unpaid claim and claim adjustment expenses $ 2,739
Schedule of Net Strengthening or (Releases) of Prior Accident Year Reserves	Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ - $ 20 $ - $ (1 ) $ (10 ) $ (13 ) $ 3 $ (6 ) $ - $ (7 ) 2011 28 26 15 (5 ) (33 ) (12 ) (11 ) (3 ) 5 2012 (14 ) (22 ) (9 ) (38 ) 6 (13 ) (2 ) (92 ) 2013 10 32 (41 ) (19 ) (3 ) (13 ) (34 ) 2014 20 (13 ) (54 ) 4 19 (24 ) 2015 4 (15 ) (45 ) (25 ) (81 ) 2016 (1 ) - 4 3 2017 (2 ) (32 ) (34 ) 2018 14 14 Total net development for the accident years presented above (92 ) (76 ) (38 ) Total net development for accident years prior to 2010 (27 ) (44 ) (17 ) Total unallocated claim adjustment expense development (7 ) (7 ) (14 ) Total $ (126 ) $ (127 ) $ (69 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited.
Surety [Member]
Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses	December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 112 $ 112 $ 111 $ 84 $ 76 $ 66 $ 63 $ 59 $ 61 $ 61 $ - 5,982 2011 120 121 116 87 75 70 66 62 62 2 5,813 2012 120 122 98 70 52 45 39 38 1 5,568 2013 120 121 115 106 91 87 83 3 5,062 2014 123 124 94 69 60 45 4 5,078 2015 131 131 104 79 63 11 4,976 2016 124 124 109 84 36 5,379 2017 120 115 103 54 5,496 2018 114 108 76 5,451 2019 119 102 3,549 Total $ 766 $ 289
Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses	Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 13 $ 34 $ 50 $ 55 $ 57 $ 58 $ 55 $ 52 $ 52 $ 53 2011 19 42 55 58 60 60 56 57 57 2012 5 32 34 35 35 36 37 37 2013 16 40 69 78 78 78 77 2014 7 30 38 36 38 38 2015 7 26 38 40 42 2016 5 37 45 45 2017 23 37 41 2018 5 25 2019 12 Total $ 427 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 339 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 10 Liability for unallocated claim adjustment expenses for accident years presented 20 Total net liability for unpaid claim and claim adjustment expenses $ 369
Schedule of Net Strengthening or (Releases) of Prior Accident Year Reserves	Years Ended December 31 Total Accident Year 2010 $ - $ (1 ) $ (27 ) $ (8 ) $ (10 ) $ (3 ) $ (4 ) $ 2 $ - $ (51 ) 2011 1 (5 ) (29 ) (12 ) (5 ) (4 ) (4 ) - (58 ) 2012 2 (24 ) (28 ) (18 ) (7 ) (6 ) (1 ) (82 ) 2013 1 (6 ) (9 ) (15 ) (4 ) (4 ) (37 ) 2014 1 (30 ) (25 ) (9 ) (15 ) (78 ) 2015 - (27 ) (25 ) (16 ) (68 ) 2016 - (15 ) (25 ) (40 ) 2017 (5 ) (12 ) (17 ) 2018 (6 ) (6 ) Total net development for the accident years presented above (82 ) (66 ) (79 ) Total net development for accident years prior to 2010 1 (4 ) (3 ) Total unallocated claim adjustment expense development (3 ) - (10 ) Total $ (84 ) $ (70 ) $ (92 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited.
Commercial Auto [Member]
Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses	December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 267 $ 283 $ 287 $ 291 $ 298 $ 293 $ 289 $ 288 $ 288 $ 288 $ 1 48,035 2011 268 281 288 302 300 294 294 294 291 - 47,909 2012 275 289 299 303 307 299 299 297 3 46,288 2013 246 265 265 249 245 245 241 2 39,429 2014 234 223 212 205 205 201 3 33,622 2015 201 199 190 190 183 7 30,418 2016 198 186 186 186 7 30,414 2017 199 198 200 9 30,850 2018 229 227 47 33,959 2019 257 128 31,455 Total $ 2,371 $ 207
Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses	Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 74 $ 141 $ 203 $ 246 $ 271 $ 281 $ 286 $ 287 $ 287 $ 287 2011 79 145 199 248 274 284 287 289 289 2012 78 160 220 259 282 285 290 291 2013 74 135 168 200 225 234 238 2014 64 102 137 166 187 196 2015 52 96 130 153 172 2016 52 93 126 154 2017 58 107 150 2018 66 128 2019 77 Total $ 1,982 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 389 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 1 Liability for unallocated claim adjustment expenses for accident years presented 14 Total net liability for unpaid claim and claim adjustment expenses $ 404
Schedule of Net Strengthening or (Releases) of Prior Accident Year Reserves	Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 16 $ 4 $ 4 $ 7 $ (5 ) $ (4 ) $ (1 ) $ - $ - $ 21 2011 13 7 14 (2 ) (6 ) - - (3 ) 23 2012 14 10 4 4 (8 ) - (2 ) 22 2013 19 - (16 ) (4 ) - (4 ) (5 ) 2014 (11 ) (11 ) (7 ) - (4 ) (33 ) 2015 (2 ) (9 ) - (7 ) (18 ) 2016 (12 ) - - (12 ) 2017 (1 ) 2 1 2018 (2 ) (2 ) Total net development for the accident years presented above (41 ) (1 ) (20 ) Total net development for accident years prior to 2010 4 1 (4 ) Total unallocated claim adjustment expense development 2 1 (1 ) Total $ (35 ) $ 1 $ (25 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited.
General Liability [Member]
Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses	December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 646 $ 664 $ 658 $ 709 $ 750 $ 726 $ 697 $ 691 $ 691 $ 690 $ 19 44,229 2011 591 589 631 677 676 681 670 669 667 20 39,361 2012 587 611 639 636 619 635 635 630 31 35,219 2013 650 655 650 655 613 623 620 27 33,570 2014 653 658 654 631 635 658 57 27,877 2015 581 576 574 589 600 73 23,834 2016 623 659 667 671 166 23,817 2017 632 632 632 226 21,114 2018 653 644 408 17,889 2019 680 602 12,916 Total $ 6,492 $ 1,629
Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses	Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 27 $ 145 $ 280 $ 429 $ 561 $ 611 $ 642 $ 652 $ 656 $ 667 2011 28 148 273 411 517 568 602 622 638 2012 28 132 247 374 454 510 559 579 2013 31 128 240 352 450 510 551 2014 31 119 247 376 481 547 2015 19 110 230 357 446 2016 32 163 279 407 2017 23 118 250 2018 33 107 2019 25 Total $ 4,217 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 2,275 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 836 Liability for unallocated claim adjustment expenses for accident years presented 65 Total net liability for unpaid claim and claim adjustment expenses $ 3,176
Schedule of Net Strengthening or (Releases) of Prior Accident Year Reserves	Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 18 $ (6 ) $ 51 $ 41 $ (24 ) $ (29 ) $ (6 ) $ - $ (1 ) $ 44 2011 (2 ) 42 46 (1 ) 5 (11 ) (1 ) (2 ) 76 2012 24 28 (3 ) (17 ) 16 - (5 ) 43 2013 5 (5 ) 5 (42 ) 10 (3 ) (30 ) 2014 5 (4 ) (23 ) 4 23 5 2015 (5 ) (2 ) 15 11 19 2016 36 8 4 48 2017 - - - 2018 (9 ) (9 ) Total net development for the accident years presented above (32 ) 36 18 Total net development for accident years prior to 2010 - - 29 Total unallocated claim adjustment expense development 8 (4 ) 7 Total $ (24 ) $ 32 $ 54
Workers' Compensation [Member]
Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses	December 31, 2019 Cumulative Net Incurred Claim and Allocated Claim Adjustment Expenses Cumulative Number of December 31 2010 (a) 2011 (a) 2012 (a) 2013 (a) 2014 (a) 2015 (a) 2016 (a) 2017 (a) 2018 (a) 2019 IBNR Claims (In millions, except reported claims data) Accident Year 2010 $ 583 $ 632 $ 654 $ 676 $ 698 $ 710 $ 730 $ 733 $ 732 $ 735 $ 55 49,333 2011 607 641 647 659 651 676 676 674 688 40 45,959 2012 601 627 659 669 678 673 671 668 67 42,586 2013 537 572 592 618 593 582 561 93 38,688 2014 467 480 479 452 450 446 99 33,480 2015 422 431 406 408 394 130 31,861 2016 426 405 396 382 144 31,945 2017 440 432 421 138 33,029 2018 450 440 185 34,647 2019 452 257 29,795 Total $ 5,187 $ 1,208
Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses	Cumulative Net Paid Claim and Allocated Claim Adjustment Expenses Accident Year 2010 $ 97 $ 251 $ 359 $ 442 $ 510 $ 542 $ 577 $ 615 $ 625 $ 631 2011 99 249 358 438 478 522 564 571 581 2012 87 232 342 416 470 509 524 536 2013 80 213 300 370 417 419 411 2014 61 159 215 258 282 290 2015 51 131 180 212 231 2016 53 129 169 198 2017 63 151 207 2018 68 163 2019 71 Total $ 3,319 Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented $ 1,868 Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010 2,061 Other (b) (22 ) Liability for unallocated claim adjustment expenses for accident years presented 25 Total net liability for unpaid claim and claim adjustment expenses $ 3,932
Schedule of Net Strengthening or (Releases) of Prior Accident Year Reserves	Net Strengthening (Releases) of Prior Accident Year Reserves Years Ended December 31 Total Accident Year 2010 $ 49 $ 22 $ 22 $ 22 $ 12 $ 20 $ 3 $ (1 ) $ 3 $ 152 2011 34 6 12 (8 ) 25 - (2 ) 14 81 2012 26 32 10 9 (5 ) (2 ) (3 ) 67 2013 35 20 26 (25 ) (11 ) (21 ) 24 2014 13 (1 ) (27 ) (2 ) (4 ) (21 ) 2015 9 (25 ) 2 (14 ) (28 ) 2016 (21 ) (9 ) (14 ) (44 ) 2017 (8 ) (11 ) (19 ) 2018 (10 ) (10 ) Total net development for the accident years presented above (100 ) (33 ) (60 ) Adjustment for development on a discounted basis (3 ) - 3 Total net development for accident years prior to 2010 39 8 21 Total unallocated claim adjustment expense development 1 (7 ) 23 Total $ (63 ) $ (32 ) $ (13 ) (a) Data presented for these calendar years is required supplemental information, which is unaudited. (b) Other includes the effect of discounting lifetime claim reserves.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lessee Lease Liability Maturity [Table Text Block]	The table below presents the maturities of lease liabilities: As of December 31, 2019 Operating (In millions) 2020 $ 114 2021 113 2022 102 2023 89 2024 81 Thereafter 361 Total 860 Less: discount 166 Total lease liabilities $ 694
Schedule of other information related to leases [Table Text Block]	The table below presents the weighted average remaining lease term for operating leases and weighted average discount rate used in calculating the operating lease asset and liability. As of December 31, 2019 Weighted average remaining lease term 9.4 Y Weighted average discount rate 4.7 %
Future Minimum Lease Payments to be Made Under Non-Cancelable Operating Leases Along with Lease and Sublease Minimum Receipts to be Received on Owned and Leased Properties	The table below presents the future minimum lease payments to be made under non-cancelable Future Minimum Lease Year Ended December 31 Payments Receipts (In millions) 2019 $ 75 $ 6 2020 79 5 2021 79 5 2022 68 4 2023 57 4 Thereafter 344 14 Total $ 702 $ 38

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Current and Deferred Components of Income Tax Expense (Benefit)	The current and deferred components of income tax expense (benefit) are as follows: Year Ended December 31 2019 2018 2017 (In millions) Income tax expense (benefit): Federal: Current $ 108 $ 6 $ 157 Deferred 47 85 (63 ) State and city: Current 18 15 22 Deferred 22 9 17 Foreign 53 13 37 Total $ 248 $ 128 $ 170
Components of U.S. and Foreign Income and Reconciliation between Federal Income Tax Expense at Statutory Rates and Actual Income Tax Expense (Benefit)	The components of U.S. and foreign income before income tax and a reconciliation between the federal income tax expense at statutory rates and the actual income tax expense (benefit) is as follows: Year Ended December 31 2019 2018 2017 (In millions) Income ( loss U.S. $ 1,145 $ 775 $ 1,322 Foreign (26 ) 59 260 Total $ 1,119 $ 834 $ 1,582 Income tax expense at statutory rate $ 235 $ 175 $ 554 Increase (decrease) in income tax expense resulting from: Effect of the Tax Act (14 ) (6 ) (190 ) Exempt investment income (50 ) (64 ) (134 ) Foreign related tax differential (55 ) 1 (36 ) Taxes related to domestic affiliate (15 ) (7 ) 1 Partnership earnings not subject to taxes (14 ) (51 ) Valuation allowance 12 12 7 Unrecognized tax positions, settlements and adjustments relating to prior years 97 2 (8 ) State taxes 37 20 23 Other 1 9 4 Income tax expense $ 248 $ 128 $ 170
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits, Excluding Tax Carryforwards and Interest and Penalties	A reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding tax carryforwards and interest and penalties, is as follows: Year Ended December 31 2019 2018 2017 (In millions) Balance at January 1 $ 58 $ 84 $ 35 Additions for tax positions related to the current year 86 3 51 Additions for tax positions related to a prior year 2 20 5 Reductions for tax positions related to a prior year (23 ) (48 ) (1 ) Lapse of statute of limitations (2 ) (1 ) (6 ) Balance at December 31 $ 121 $ 58 $ 84
Summary of Deferred Tax Assets and Liabilities	The following table summarizes deferred tax assets and liabilities: December 31 2019 2018 (In millions) Deferred tax assets: Insurance reserves: Property and casualty claim and claim adjustment expense reserves $ 129 $ 108 Unearned premium reserves 153 108 Receivables 11 13 Employee benefits 212 222 Deferred retroactive reinsurance benefit 82 79 Net operating loss carryforwards 275 251 Tax credit carryforwards 47 101 Net unrealized losses 24 Basis differential in investment in subsidiary 8 8 Disallowed interest deduction 41 16 Other 179 181 Total deferred tax assets 1,137 1,111 Valuation allowance (187 ) (175 ) Net deferred tax assets 950 936 Deferred tax liabilities: Deferred acquisition costs (83 ) (78 ) Net unrealized gains (263 ) Property, plant and equipment (848 ) (840 ) Basis differential in investment in subsidiary (679 ) (586 ) Other liabilities (208 ) (236 ) Total deferred tax liabilities (2,081 ) (1,740 ) Net deferred tax liabilities (a) $ (1,131 ) $ (804 ) (a) Includes $ 37

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Instruments	December 31 2019 2018 (In millions) Loews Corporation (Parent Company): Senior: 2.6% notes due 2023 (effective interest rate of 2.8%) (authorized, $ 500 $ 500 $ 500 3.8% notes due 2026 (effective interest rate of 3.9%) (authorized, $ 500 500 500 6.0% notes due 2035 (effective interest rate of 6.2%) (authorized, $ 300 300 300 4.1% notes due 2043 (effective interest rate of 4.3%) (authorized, $ 500 500 500 CNA Financial: Senior: 5.9% notes due 2020 (effective interest rate of 6.0%) (authorized, $ 500 500 5.8% notes due 2021 (effective interest rate of 5.9%) (authorized, $ 400 400 400 7.3% debentures due 2023 (effective interest rate of 7.3%) (authorized, $ 250 243 243 4.0% notes due 2024 (effective interest rate of 4.0%) (authorized, $ 550 550 550 4.5% notes due 2026 (effective interest rate of 4.5%) (authorized, $ 500 500 500 3.5% notes due 2027 (effective interest rate of 3.5%) (authorized, $ 500 500 500 3.9% notes due 2029 (effective interest rate of 3.9%) (authorized, $ 500 500 F 1 Diamond Offshore: Senior: 3.5% notes due 2023 (effective interest rate of 3.5%) (authorized, $ 250 250 250 7.9% notes due 2025 (effective interest rate of 8.0%) (authorized, $ 500 500 500 5.7% notes due 2039 (effective interest rate of 5.8%) (authorized, $ 500 500 500 4.9% notes due 2043 (effective interest rate of 4.9%) (authorized, $ 750 750 750 Boardwalk Pipelines: Senior: Variable rate revolving credit facility due 2022 (effective interest rate of 3.0% and 3.7%) 295 580 5.8% notes due 2019 (effective interest rate of 5.9%) (authorized, $ 350 350 4.5% notes due 2021 (effective interest rate of 5.0%) (authorized, $ 440 440 440 4.0% notes due 2022 (effective interest rate of 4.4%) (authorized, $ 300 300 300 3.4% notes due 2023 (effective interest rate of 3.5%) (authorized, $ 300 300 300 5.0% notes due 2024 (effective interest rate of 5.2%) (authorized, $ 600 600 600 6.0% notes due 2026 (effective interest rate of 6.2%) (authorized, $ 550 550 550 4.5% notes due 2027 (effective interest rate of 4.6%) (authorized, $ 500 500 500 7.3% debentures due 2027 (effective interest rate of 8.1%) (authorized, $ 100 100 100 4.8% notes due 2029 (effective interest rate of 4.9%) (authorized, $ 500 500 Finance 7 8 Loews Hotels & Co: Senior debt, principally mortgages (effective interest rates approximate 4.7% and 4.4% 712 653 Altium Packaging : Senior: Variable rate asset based lending facility due 2022 (effective interest rate of 5.5%) 9 Variable rate term loan due 2024 (effective interest rate of 4.9% and 5.0%) 591 597 Variable rate term loan due 2026 (effective interest rate of 5.3%) 249 Finance 6 7 11,643 11,488 Less unamortized discount and issuance costs 110 112 Debt $ 11,533 $ 11,376
Schedule of Debt by Subsidiary	December 31, 2019 Principal Unamortized Net Short Term Long Term (In millions) Loews Corporation $ 1,800 $ 21 $ 1,779 $ 1,779 CNA Financial 2,693 14 2,679 2,679 Diamond Offshore 2,000 24 1,976 1,976 Boardwalk Pipelines 3,592 26 3,566 3,566 Loews Hotels & Co 712 7 705 $ 67 638 Altium Packaging 846 18 828 10 818 Total $ 11,643 $ 110 $ 11,533 $ 77 $ 11,456

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Components of Accumulated Other Comprehensive Income	The tables below present the changes in AOCI by component for the years ended December 31, 2017, 2018 and 2019: Net Unrealized on Investments with OTTI Losses Net Other Unrealized Gains (Losses) on Investments Unrealized Pension and Foreign Total (In millions) Balance, January 1, 2017 $ 27 $ 576 $ (2 ) $ (646 ) $ (178 ) $ (223 ) Other comprehensive income (loss) before reclassifications, after tax of $1, $(106), $(2), $4 and $0 (3 ) 190 1 (18 ) 100 270 Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $1, $38, $0, $(16) and $0 (2 ) (82 ) 2 30 (52 ) Other comprehensive income (loss) (5 ) 108 3 12 100 218 Amounts attributable to noncontrolling interests (11 ) (1 ) 1 (10 ) (21 ) Balance, December 31, 2017 22 673 – (633 ) (88 ) (26 ) Cumulative effect adjustment from changes in accounting standards 4 98 (130 ) (28 ) Balance, January 1, 2018, as adjusted 26 771 – (763 ) (88 ) (54 ) Other comprehensive income (loss) before reclassifications, after tax of $2, $213, $(2), $9 and $0 (7 ) (801 ) 4 (34 ) (84 ) (922 ) Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $2, $(2), $0, $(6) and $0 (7 ) 3 2 32 30 Other comprehensive income (loss) (14 ) (798 ) 6 (2 ) (84 ) (892 ) Amounts attributable to noncontrolling interests 2 84 9 95 Purchase of Boardwalk Pipelines common units (1 ) (28 ) (29 ) Balance, December 31, 2018 14 57 5 (793 ) (163 ) (880 ) Other comprehensive income (loss) before reclassifications, after tax of $3, $(256), $5, $28 and $0 (13 ) 957 (11 ) (102 ) 42 873 Reclassification of (gains) losses from accumulated other comprehensive loss, after tax of $(3), $1, $0, $(9) and $0 12 (8 ) 34 38 Other comprehensive income (loss) (1 ) 949 (11 ) (68 ) 42 911 Amounts attributable to noncontrolling interests (101 ) 6 (4 ) (99 ) Balance, December 31, 2019 $ 13 $ 905 $ (6 ) $ (855 ) $ (125 ) $ (68 )

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2019
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 20: Year Ended December 31 2019 2018 2017 (a) (In millions) Non-insurance $ 1,161 $ 1,007 $ 390 Contract drilling – Diamond Offshore $ 981 $ 1,083 $ 1,486 Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipelines 1,266 1,206 1,298 Lodging and related services – Loews Hotels & Co 691 730 682 Rigid plastic packaging and recycled resin – Corporate 932 867 498 Total revenues from contracts with customers 3,870 3,886 3,964 Other revenues 68 101 89 Operating revenues and other $ 3,938 $ 3,987 $ 4,053 (a) Prior period amounts have not been adjusted under the modified retrospective method of adoption for ASU 2014-09.

Statutory Accounting Practices

Statutory Accounting Practices (Tables)	12 Months Ended
	Dec. 31, 2019
Text Block [Abstract]
Combined Statutory Capital and Surplus and Net Income	Combined statutory capital and surplus and statutory net income for the Combined Continental Casualty Companies are presented in the table below, determined in accordance with accounting practices prescribed or permitted by insurance and/or other regulatory authorities. Statutory Capital and Surplus Statutory Net Income December 31 Year Ended December 31 2019(a) 2018 2019(a) 2018 2017 (In millions) Combined Continental Casualty Companies $ 10,787 $ 10,411 $ 1,062 $ 1,405 $ 1,029 (a) Information derived from the statutory-basis financial statements to be filed with insurance regulators.

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost	Weighted average assumptions used to determine benefit obligations: Pension Benefits Other Postretirement Benefits December 31 2019 2018 2017 2019 2018 2017 Discount rate 3.0 % 4.1 % 3.5 % 3.0 % 4.1 % 3.4 % Expected long term rate of return on plan assets 7.5 % 7.5 % 7.5 % 3.6 % 5.3 % 5.3 % Interest crediting rate 3.7 % 3.8 % 3.7 % Rate of compensation increase 3.0% to 5.5 % 3.9% to 5.5 % 3.9% to 5.5 % Weighted average assumptions used to determine net periodic benefit cost: Pension Benefits Other Postretirement Benefits Year Ended December 31 2019 2018 2017 2019 2018 2017 Discount rate 4.0 % 3.6 % 3.8 % 4.0 % 3.4 % 3.7 % Expected long term rate of return on plan assets 7.5 % 7.5 % 7.5 % 3.6 % 5.3 % 5.3 % Interest crediting rate 3.7 % 3.7 % 3.7 % Rate of compensation increase 3.0% to 5.5 % 3.9% to 5.5 % 3.9% to 5.5 %
Assumed Health Care Cost Trend Rates	Assumed health care cost trend rates: December 31 2019 2018 2017 Health care cost trend rate assumed for next year 4.0% to 8.0% 4.0% to 6.5 % 4.0% to 7.0 % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.0% to 5.0% 4.0% to 5.0 % 4.0% to 5.0 % Year that the rate reaches the ultimate trend rate 2021-2026 2019-2022 2018-2022
Components of Net Periodic Benefit Cost	Net periodic benefit cost components: Pension Benefits Other Postretirement Benefits Year Ended December 31 2019 2018 2017 2019 2018 2017 (In millions) Service cost $ 7 $ 8 $ 8 $ 1 $ 1 Interest cost 117 110 119 $ 2 2 2 Expected return on plan assets (159 ) (179 ) (173 ) (3 ) (5 ) (5 ) Amortization of unrecognized net loss 45 42 43 (1 ) (1 ) Amortization of unrecognized prior service benefit (2 ) (2 ) Settlements and curtailments 1 9 11 Net periodic benefit cost $ 11 $ (10 ) $ 8 $ ) $ (5 ) $ (4 )
Reconciliation of Benefit Obligations and Plan Assets	The following provides a reconciliation of benefit obligations and plan assets: Pension Benefits Other Postretirement Benefits 2019 2018 2019 2018 (In millions) Change in benefit obligation: Benefit obligation at January 1 $ 2,919 $ 3,242 $ 53 $ 62 Acquisitions Service cost 7 8 1 Interest cost 117 110 2 2 Plan participants’ contributions 4 4 Amendments 1 Actuarial (gain) loss 299 (212 ) 3 (6 ) Benefits paid from plan assets (191 ) (187 ) (10 ) (10 ) Settlements and curtailments (19 ) (35 ) Foreign exchange 4 (7 ) Benefit obligation at December 31 3,137 2,919 52 53 Change in plan assets: Fair value of plan assets at January 1 2,304 2,577 85 88 Acquisitions Actual return on plan assets 328 (83 ) 8 Company contributions 146 39 3 3 Plan participants’ contributions 4 4 Benefits paid from plan assets (191 ) (187 ) (10 ) (10 ) Settlements (15 ) (35 ) Foreign exchange 4 (7 ) Fair value of plan assets at December 31 2,576 2,304 90 85 Funded status $ (561 ) $ (615 ) $ 38 $ 32
Amounts Recognized in the Consolidated Balance Sheets	Pension Other Postretirement Benefits 2019 2018 2019 2018 (In millions) Amounts recognized in the Consolidated Balance Sheets consist of: Other assets $ 5 $ 9 $ 54 $ 49 Other liabilities (566 ) (624 ) (16 ) (17 ) Net amount recognized $ (561 ) $ (615 ) $ 38 $ 32
Amounts Recognized in Accumulated Other Comprehensive Income (Loss), Not Yet Recognized in Net Periodic (Benefit) Cost	Amounts recognized in Accumulated other comprehensive income (loss), not yet recognized in net periodic (benefit) cost: Prior service credit $ (2 ) $ (1 ) $ (1 ) Net actuarial loss $ 1,144 1,065 (4 ) (3 ) Net amount recognized $ 1,144 $ 1,063 $ (5 ) $ (4 )
Plans With Projected and Accumulated Benefit Obligations in Excess of Plan Assets	Information for plans with projected and accumulated benefit obligations in excess of plan assets: Projected benefit obligation $ 3,021 $ 2,825 Accumulated benefit obligation 3,014 2,813 $ 16 $ 18 Fair value of plan assets 2,456 2,201
Estimated Future Minimum Benefit Payments	The table below presents the estimated future minimum benefit payments at December 31, 2019. Expected future benefit payments Pension Other (In millions) 2020 $ 234 $ 5 2021 211 5 2022 215 4 2023 217 4 2024 212 3 2025 – 2029 1,001 14
Pension Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets Measured on Recurring Basis	Pension plan assets measured at fair value on a recurring basis are summarized below. December 31, 2019 Level 1 Level 2 Level 3 Total (In millions) Plan assets at fair value: Fixed maturity securities: Corporate and other bonds $ 587 $ 10 $ 597 States, municipalities and political subdivisions 51 51 Asset-backed 154 154 Total fixed maturities $ – 792 10 802 Equity securities 541 128 669 Short term investments 74 7 81 Fixed income mutual funds 128 128 Other assets 11 9 20 Total plan assets at fair value $ 754 $ 936 $ 10 $ 1,700 Plan assets at net asset value: (a) Limited partnerships 876 Total plan assets $ 754 $ 936 $ 10 $ 2,576 December 31, 2018 Level 1 Level 2 Level 3 Total Plan assets at fair value: Fixed maturity securities: Corporate and other bonds $ 472 $ 10 $ 482 States, municipalities and political subdivisions 58 58 Asset-backed 165 165 Total fixed maturities $ – 695 10 705 Equity securities 406 110 516 Short term investments 36 54 90 Fixed income mutual funds 120 120 Other assets 9 9 Total plan assets at fair value $ 562 $ 868 $ 10 $ 1,440 Plan assets at net asset value: (a) Limited partnerships 864 Total plan assets $ 562 $ 868 $ 10 $ 2,304 (a) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table for these investments are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statement of financial position.
Other Postretirement Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets Measured on Recurring Basis	Other postretirement benefits plan assets measured at fair value on a recurring basis are summarized below. December 31, 2019 Level 1 Level 2 Level 3 Total (In millions) Fixed maturity securities: Corporate and other bonds $ 22 $ 22 States, municipalities and political subdivisions 16 16 Asset-backed 31 31 Total fixed maturities $ - 69 $ - 69 Short term investments 3 3 Fixed income mutual funds 18 18 Total $ 21 $ 69 $ - $ 90 December 31, 2018 Fixed maturity securities: Corporate and other bonds $ 24 $ 24 States, municipalities and political subdivisions 11 11 Asset-backed 30 30 Total fixed maturities $ - 65 $ - 65 Short term investments 4 4 Fixed income mutual funds 16 16 Total $ 20 $ 65 $ - $ 85

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2019
Insurance [Abstract]
Summary of Amounts Receivable from Reinsurers	The following table presents the amounts receivable from reinsurers: December 31 2019 2018 (In millions) Reinsurance receivables related to insurance reserves: Ceded claim and claim adjustment expenses $ 3,835 $ 4,019 Ceded future policy benefits 226 233 Reinsurance receivables related to paid losses 143 203 Reinsurance receivables 4,204 4,455 Less allowance for doubtful accounts 25 29 Reinsurance receivables, net of allowance for doubtful accounts $ 4,179 $ 4,426
Summary of Effects of Reinsurance on Earned Premiums	The effects of reinsurance on earned premiums are presented in the following table: Direct Assumed Ceded Net Assumed/ (In millions) Year Ended December 31, 2019 Property and casualty $ 11,021 $ 288 $ 4,401 $ 6,908 4.2 % Long term care 470 50 520 9.6 Earned premiums $ 11,491 $ 338 $ 4,401 $ 7,428 4.6 % Year Ended December 31, 2018 Property and casualty $ 10,857 $ 305 $ 4,380 $ 6,782 4.5 % Long term care 480 50 530 9.4 Earned premiums $ 11,337 $ 355 $ 4,380 $ 7,312 4.9 % Year Ended December 31, 2017 Property and casualty $ 10,447 $ 317 $ 4,315 $ 6,449 4.9 % Long term care 489 50 539 9.3 Earned premiums $ 10,936 $ 367 $ 4,315 $ 6,988 5.3 %

Quarterly Financial Data (Una_2

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	2019 Quarter Ended Dec. 31 Sept. 30 June 30 March 31 (In millions, except per share data) Total revenues $ 3,876 $ 3,675 $ 3,623 $ 3,757 Net income (a) (b) 217 72 249 394 Per share-basic and diluted 0.73 0.24 0.82 1.27 2018 Quarter Ended Total revenues $ 3,287 $ 3,608 $ 3,590 $ 3,581 Net income (loss) ( c (165 ) 278 230 293 Per share-basic and diluted (0.53 ) 0.88 0.72 0.89 The sum of the quarterly per share amounts may not equal per share amounts reported for year-to-date (a) Net income for the fourth s net i n vestment income of limited partnership s by asset $69 million (after tax). (b) Net income for the third quarter of 2019 included a $151 million (after tax and noncontrolling interests) charge related to the recognition of an active life reserve premium deficiency as a result of the third quarter GPV. ( c Net loss for the fourth quarter of 2018 includes a loss on limited partnership and common stock investments of $97 million (after tax and noncontrolling interests), catastrophe losses of $96 million (after tax and noncontrolling interests) and net investment losses of $57 million (after tax).

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Consolidating Statement of Income and Total Assets by Segment	Statements of Income and Total assets by segment are presented in the following tables. Year Ended December 31, 2019 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 7,428 $ 7,428 Net investment income 2,118 $ 6 $ 1 $ 230 2,355 Investment gains 49 49 Non-insurance 1,161 1,161 Operating revenues and other 32 982 $ 1,300 691 933 3,938 Total 10,788 988 1,300 692 1,163 14,931 Expenses: Insurance claims and policyholders’ benefits 5,806 5,806 Amortization of deferred acquisition costs 1,383 1,383 Non-insurance 1,082 1,082 Operating expenses and other 1,141 1,267 840 698 1,004 4,950 Interest 152 123 179 22 115 591 Total 9,564 1,390 1,019 720 1,119 13,812 Income (loss) before income tax 1,224 (402 ) 281 (28 ) 44 1,119 Income tax (expense) benefit (224 ) 60 (72 ) (3 ) (9 ) (248 ) Net income (loss) 1,000 (342 ) 209 (31 ) 35 871 Amounts attributable to noncontrolling interests (106 ) 167 61 Net income (loss) attributable to Loews Corporation $ 894 $ (175 ) $ 209 $ (31 ) $ 35 $ 932 December 31, 2019 Total assets $ 60,583 $ 5,834 $ 9,248 $ 1,728 $ 4,850 $ 82,243 Year Ended December 31, 2018 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 7,312 $ 7,312 Net investment income (loss) 1,817 $ 8 $ 2 $ (10 ) 1,817 Investment losses (57 ) (57 ) Non-insurance 1,007 1,007 Operating revenues and other 55 1,085 $ 1,227 753 867 3,987 Total 10,134 1,093 1,227 755 857 14,066 Expenses: Insurance claims and policyholders’ benefits 5,572 5,572 Amortization of deferred acquisition costs 1,335 1,335 Non-insurance 923 923 Operating expenses and other 1,203 1,196 820 653 956 4,828 Interest 138 123 176 29 108 574 Total 9,171 1,319 996 682 1,064 13,232 Income (loss) before income tax 963 (226 ) 231 73 (207 ) 834 Income tax (expense) benefit (151 ) 30 (28 ) (25 ) 46 (128 ) Net income (loss) 812 (196 ) 203 48 (161 ) 706 Amounts attributable to noncontrolling interests (86 ) 84 (68 ) (70 ) Net income (loss) attributable to Loews Corporation $ 726 $ (112 ) $ 135 $ 48 $ (161 ) $ 636 December 31, 2018 Total assets $ 57,123 $ 6,036 $ 9,131 $ 1,812 $ 4,214 $ 78,316 Year Ended December 31, 2017 CNA Diamond Boardwalk Loews Corporate Total (In millions) Revenues: Insurance premiums $ 6,988 $ 6,988 Net investment income 2,034 $ 2 $ 146 2,182 Investment gains 122 122 Non-insurance 390 390 Operating revenues and other 49 1,498 $ 1,325 $ 682 499 4,053 Total 9,583 1,500 1,325 682 645 13,735 Expenses: Insurance claims and policyholders’ benefits 5,310 5,310 Amortization of deferred acquisition costs 1,233 1,233 Non-insurance 299 299 Operating expenses and other 1,224 1,373 861 589 618 4,665 Interest 203 149 171 28 95 646 Total 8,269 1,522 1,032 617 713 12,153 Income (loss) before income tax 1,314 (22 ) 293 65 (68 ) 1,582 Income tax (expense) benefit (419 ) 4 232 (1 ) 14 (170 ) Net income (loss) 895 (18 ) 525 64 (54 ) 1,412 Amounts attributable to noncontrolling interests (94 ) (9 ) (145 ) (248 ) Net income (loss) attributable to Loews Corporation $ 801 $ (27 ) $ 380 $ 64 $ (54 ) $ 1,164

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) in Shadow Adjustments		$ 1,000	$ (298)
Net unrealized gains on investments included in "AOCI"		2,000	964
Investment in joint venture entities		356	312
Equity income (loss) for the investments		$ 69	$ 73	$ 81
Initial collateral deposit as a percentage of the fair value of the securities loaned		100.00%
Interest rate used to discount workers' compensation lifetime claim reserves		3.50%	3.50%
Discounted reserves for workers' compensation lifetime claim reserves		$ 293	$ 343
Discounted reserves for workers' compensation lifetime claims reserves, discount amount		135	168
Interest recognized on discounted reserves for workers' compensation lifetime claim reserves		21	$ 16	$ 19
Premium deficiency		$ 216
Long term care active life reserves, interest rate		5.70%	6.90%
Liability balance for guaranty fund		$ 84	$ 108
Billed receivables percentage of total reinsurance receivables		5.00%
Tax benefit of a qualifying position is the largest amount of tax benefit threshold		50.00%
Potential shares attributable to exercises included in diluted EPS calculation		0.7	0.9	0.9
Shares excluded from diluted EPS calculation		0	0	0.4
Foreign currency transaction gain (loss)		$ (3)	$ 0	$ 26
Cash payments made for interest on long term debt, net of capitalized interest		560	558	533
Cash payments for federal, foreign, state and local income taxes amount		190	101	166
Accrued capital expenditures not included in investing activities		17	15
Accrued capital expenditures included in investing activities				$ 87
Cumulative effect adjustment on other assets and other liabilities					$ 642
Other assets		3,145	2,443
Other liabilities		$ 5,111	$ 4,505
Percentage of net written premium		1.00%	1.00%	1.00%
CNA Financial [Member]
Summary Of Significant Accounting Policies [Line Items]
Anticipated amounts due from insureds related to losses under deductible policies		$ 1,200	$ 1,200
Discounted reserves for unfunded structured settlements		497	512
Discounted reserves for unfunded structured settlements, discount amount		724	760
Interest recognized on discounted reserves for unfunded structured settlements		$ 36	$ 40	$ 41
Interest rate used to discount long term care claim reserves		5.90%	6.00%
Discounted reserves for long term care claim reserves		$ 2,700	$ 2,600
Discounted reserves for long term care claim reserves, discount amount		$ 462
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage equity method investments in associated companies		20.00%
Share-based payment awards requisite service period		0 years
Minimum [Member] | CNA Financial [Member] | Structured Settlement Annuity [Member]
Summary Of Significant Accounting Policies [Line Items]
Interest rate used in determining present value of obligations of structured settlements unfunded by annuities		5.50%	5.50%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage equity method investments in associated companies		50.00%
Share-based payment awards requisite service period		4 years
Maximum [Member] | CNA Financial [Member] | Structured Settlement Annuity [Member]
Summary Of Significant Accounting Policies [Line Items]
Interest rate used in determining present value of obligations of structured settlements unfunded by annuities		7.60%	8.00%
CNA Financial Corporation [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%
CNA Financial [Member]
Summary Of Significant Accounting Policies [Line Items]
Subsidiary ownership percentage		99.00%
Discounted reserves for long term care claim reserves, discount amount			$ 460
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
Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	(62)
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)
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
Deferred Non-Insurance Warranty Acquisition Expenses [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
Deferred Non-Insurance Warranty Revenue [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
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
Subsequent to Adoption of Accounting Standards Update 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Other assets			2,400		3,100
Other liabilities			$ 4,500		$ 5,100
Accounting Standards Update 2016-01 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	$ 25

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Financial Information for Joint Ventures (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Total assets	$ 2,261	$ 1,924
Total liabilities	1,727	1,451
Revenues	804	731	$ 731
Net income	$ 106	$ 114	$ 261

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Principal Service Lives (Detail)	12 Months Ended
	Dec. 31, 2019
Minimum [Member] | Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	30 years
Minimum [Member] | Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	15 years
Minimum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Principal service life	3 years
Maximum [Member] | Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	50 years
Maximum [Member] | Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	30 years
Maximum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Principal service life	40 years

Acquisitions and Divestitures -

Acquisitions and Divestitures - Additional Information (Detail) $ / shares in Units, $ in Millions	Jun. 29, 2018USD ($)$ / shares	May 22, 2017USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)HotelAcquisition	Dec. 31, 2018USD ($)HotelAcquisition	Dec. 31, 2017USD ($)Hotel
Business Acquisition [Line Items]
Purchase of Boardwalk Pipelines common units												$ (1,718)
Revenues			$ 3,876	$ 3,675	$ 3,623	$ 3,757	$ 3,287	$ 3,608	$ 3,590	$ 3,581	$ 14,931	14,066	$ 13,735
Estimated goodwill recognized			767				665				767	665	659
Additional Paid-in Capital [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipelines common units												658
Accumulated Other Comprehensive Income (Loss) [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipelines common units												(29)
Altium Packing [Member]
Business Acquisition [Line Items]
Debt financing proceeds											250
Corporate [Member]
Business Acquisition [Line Items]
Revenues											1,163	857	645
Corporate [Member] | Altium Packing [Member]
Business Acquisition [Line Items]
Revenues											76
Boardwalk Pipeline [Member]
Business Acquisition [Line Items]
Increase to deferred income tax liabilities											213
Boardwalk Pipeline [Member] | Additional Paid-in Capital [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipelines common units											658
Boardwalk Pipeline [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Business Acquisition [Line Items]
Purchase of Boardwalk Pipelines common units											(29)
Altium Acquisition Holdings, Inc. [Member]
Business Acquisition [Line Items]
Payments for acquisition		$ 1,200
Cash payments funding acquisition		$ 620
Altium Acquisition Holdings, Inc. [Member] | Altium Packing [Member]
Business Acquisition [Line Items]
Revenues											933	868	498
Plastic Packaging Manufacturers Business Acquisition [Member] | Altium Packing [Member]
Business Acquisition [Line Items]
Payments for acquisition											260	40
Estimated goodwill recognized			99				10				$ 99	$ 10
Number of businesses acquired | Acquisition											3	3
Plastic Packaging Manufacturers Business Acquisition [Member] | Altium Packing [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Estimated intangible assets recognized			$ 87				$ 15				$ 87	$ 15
Boardwalk Gp Lp [Member] | Boardwalk Pipeline [Member] | Subsidiaries [Member]
Business Acquisition [Line Items]
Payments for acquisition	$ 1,500
Purchase price, per unit | $ / shares	$ 12.06
Loews Hotels And Co [Member]
Business Acquisition [Line Items]
Proceeds from sale of hotels											$ 118	$ 40	$ 31
Number of hotel properties sold | Hotel											1	1	2

Investments - Net Investment In

Investments - Net Investment Income and Investment Gains (Losses) (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Investment Income [Line Items]
Total investment income		$ 2,430	$ 1,878	$ 2,241
Investment expenses		(75)	(61)	(59)
Investment gains (losses)		49	(57)	122
Net investment income	$ 116	2,355	1,817	2,182
Fixed Maturity Securities [Member]
Net Investment Income [Line Items]
Total investment income		1,817	1,795	1,812
Investment gains (losses)		(6)	4	122
Limited Partnership Investments [Member]
Net Investment Income [Line Items]
Total investment income		204	22	277
Short term investments and other [Member]
Net Investment Income [Line Items]
Total investment income		52	43	18
Investment gains (losses)			4	4
Equity Securities [Member]
Net Investment Income [Line Items]
Total investment income		85	18	12
Investment gains (losses)		66	(74)
Income (loss) From Trading Portfolio [Member]
Net Investment Income [Line Items]
Total investment income		216	(54)	87
Other [Member]
Net Investment Income [Line Items]
Total investment income		56	54	35
Derivative Instruments [Member]
Net Investment Income [Line Items]
Investment gains (losses)		$ (11)	$ 9	$ (4)

Investments - Net Investment _2

Investments - Net Investment Income and Investment Gains (Losses) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Investment Income [Line Items]
Net unrealized gains (losses) on trading securities	$ 41	$ (121)	$ 39
Fixed Maturity Securities [Member]
Net Investment Income [Line Items]
Gross investment gains on available-for-sale securities	125	168	187
Gross investment losses on available-for-sale securities	131	164	$ 65
Fixed Maturity Securities [Member] | Nonredeemable Preferred Stock [Member]
Net Investment Income [Line Items]
Net investment gains (losses) on trading securities	$ 66	$ (73)

Investments - Additional Inform

Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)Investment	Dec. 31, 2017
Schedule of Investments [Line Items]
Number of Investments not exceeds 10% of shareholders equity | Investment		0
Additional other than temporary impairment losses	$ 0
Carrying value of limited partnerships	2,000,000,000	$ 2,400,000,000
Net undistributed earnings of limited partnerships	$ 297,000,000	$ 208,000,000
Percentage of carrying value reported on a current basis	64.40%
Percentage of carrying value reported on one month lag	9.10%
Percentage of limited partnerships comprising of the carrying value that employ hedge fund strategies	65.70%	71.30%
Percentage of limited partnerships comprising of the carrying value that invested in private debt and equity	29.10%	24.30%
Percentage of limited partnerships employing hedge fund strategies focused on equity investments	44.00%
Percentage of limited partnerships employing hedge fund strategies with a multi-strategy approach	32.30%
Percentage of limited partnerships employing hedge fund strategies focused on distressed investments	18.80%
Percentage of limited partnerships employing hedge fund strategies focused on fixed income investments	4.90%
Ownership percentage of aggregate partnership equity	2.30%	2.60%
Changes in ownership percentage of aggregate partnership equity	2.50%	3.30%	3.00%
Withdrawal provisions limited partnership investments, description	The Company’s hedge fund limited partnership investments contain withdrawal provisions that generally limit liquidity for a period of thirty days up to one year or longer. Private equity and other non-hedge funds generally do not permit voluntary withdrawals. Typically, hedge fund withdrawals require advance written notice of up to 90 days.
Commitments to purchase various privately placed debt securities, including bank loans	$ 945,000,000
Commitments to sell various privately placed debt securities, including bank loans	85,000,000
Securities deposited	2,700,000,000	$ 2,500,000,000
Cash and securities with carrying values deposited as collateral for letters of credit	1,100,000,000	1,000,000,000
Fixed Maturity Securities [Member]
Schedule of Investments [Line Items]
Non-income producing fixed maturity securities	1,000,000	0
Ten Largest Limited Partnership Holdings
Schedule of Investments [Line Items]
Carrying value of limited partnerships	$ 1,100,000,000	$ 1,100,000,000

Investments - Schedule of Net C

Investments - Schedule of Net Change in Unrealized Gains (Losses) Investments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Total net change in unrealized gains (losses) on investments	$ 2,620	$ (1,811)	$ 758
Fixed Maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Total net change in unrealized gains (losses) on investments	$ 2,620	$ (1,811)	728
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Total net change in unrealized gains (losses) on investments			32
Other [Member]
Debt Securities, Available-for-sale [Line Items]
Total net change in unrealized gains (losses) on investments			$ (2)

Investments - Components of OTT

Investments - Components of OTTI Losses Recognized in Earnings by Asset Type (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	$ 44	$ 21	$ 14
Corporate Bonds and Other [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	33	12	12
Total Asset-Backed [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	11	9	1
Total Fixed Maturities Available-for-Sale [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net OTTI losses recognized in earnings	$ 44	$ 21	13
Equity Securities Available-for-Sale [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	Dec. 31, 2019	Dec. 31, 2018
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	$ 38,157	$ 38,234
Gross Unrealized Gains	4,128	1,986
Gross Unrealized Losses	45	521
Estimated Fair Value	42,240	39,699
Unrealized OTTI Losses (Gains)	(19)	(20)
Corporate Bonds and Other [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	19,789	18,764
Gross Unrealized Gains	2,292	791
Gross Unrealized Losses	32	395
Estimated Fair Value	22,049	19,160
States, Municipalities and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	9,093	9,681
Gross Unrealized Gains	1,559	1,076
Gross Unrealized Losses		9
Estimated Fair Value	10,652	10,748
Residential Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	4,387	4,815
Gross Unrealized Gains	133	68
Gross Unrealized Losses	1	57
Estimated Fair Value	4,519	4,826
Unrealized OTTI Losses (Gains)	(17)	(20)
Commercial Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	2,265	2,200
Gross Unrealized Gains	86	28
Gross Unrealized Losses	5	32
Estimated Fair Value	2,346	2,196
Unrealized OTTI Losses (Gains)	1
Other Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	1,925	1,975
Gross Unrealized Gains	41	11
Gross Unrealized Losses	4	24
Estimated Fair Value	1,962	1,962
Unrealized OTTI Losses (Gains)	(3)
Total Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	8,577	8,990
Gross Unrealized Gains	260	107
Gross Unrealized Losses	10	113
Estimated Fair Value	8,827	8,984
Unrealized OTTI Losses (Gains)	(19)	(20)
U.S. Treasury and obligations of government-sponsored enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	146	156
Gross Unrealized Gains	1	3
Gross Unrealized Losses	2
Estimated Fair Value	145	159
Foreign Government [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	491	480
Gross Unrealized Gains	14	5
Gross Unrealized Losses	1	4
Estimated Fair Value	504	481
Redeemable Preferred Stock [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	10	10
Estimated Fair Value	10	10
Total Fixed Maturities Available-for-Sale [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	38,106	38,081
Gross Unrealized Gains	4,126	1,982
Gross Unrealized Losses	45	521
Estimated Fair Value	42,187	39,542
Unrealized OTTI Losses (Gains)	(19)	(20)
Fixed Maturities Trading [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Cost or Amortized Cost	51	153
Gross Unrealized Gains	2	4
Estimated Fair Value	$ 53	$ 157

Investments - Securities Availa

Investments - Securities Available-for-Sale in Gross Unrealized Loss Position (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	$ 2,148	$ 12,689
Gross Unrealized Losses, Less than 12 Months	31	404
Estimated Fair Value, 12 Months or Longer	272	2,614
Gross Unrealized Losses, 12 Months or Longer	14	117
Total Estimated Fair Value	2,420	15,303
Total Gross Unrealized Losses	45	521
Corporate Bonds and Other [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	914	8,543
Gross Unrealized Losses, Less than 12 Months	21	340
Estimated Fair Value, 12 Months or Longer	186	825
Gross Unrealized Losses, 12 Months or Longer	11	55
Total Estimated Fair Value	1,100	9,368
Total Gross Unrealized Losses	32	395
States, Municipalities and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	34	517
Gross Unrealized Losses, Less than 12 Months		8
Estimated Fair Value, 12 Months or Longer		5
Gross Unrealized Losses, 12 Months or Longer		1
Total Estimated Fair Value	34	522
Total Gross Unrealized Losses		9
Residential Mortgage-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	249	1,932
Gross Unrealized Losses, Less than 12 Months	1	23
Estimated Fair Value, 12 Months or Longer	30	1,119
Gross Unrealized Losses, 12 Months or Longer		34
Total Estimated Fair Value	279	3,051
Total Gross Unrealized Losses	1	57
Commercial Mortgage-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	381	728
Gross Unrealized Losses, Less than 12 Months	3	10
Estimated Fair Value, 12 Months or Longer	20	397
Gross Unrealized Losses, 12 Months or Longer	2	22
Total Estimated Fair Value	401	1,125
Total Gross Unrealized Losses	5	32
Other Asset-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	449	834
Gross Unrealized Losses, Less than 12 Months	3	21
Estimated Fair Value, 12 Months or Longer	33	125
Gross Unrealized Losses, 12 Months or Longer	1	3
Total Estimated Fair Value	482	959
Total Gross Unrealized Losses	4	24
Total Asset-Backed [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	1,079	3,494
Gross Unrealized Losses, Less than 12 Months	7	54
Estimated Fair Value, 12 Months or Longer	83	1,641
Gross Unrealized Losses, 12 Months or Longer	3	59
Total Estimated Fair Value	1,162	5,135
Total Gross Unrealized Losses	10	113
U.S. Treasury and obligations of government-sponsored enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	62	21
Gross Unrealized Losses, Less than 12 Months	2
Estimated Fair Value, 12 Months or Longer	2	19
Total Estimated Fair Value	64	40
Total Gross Unrealized Losses	2
Foreign Government [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	59	114
Gross Unrealized Losses, Less than 12 Months	1	2
Estimated Fair Value, 12 Months or Longer	1	124
Gross Unrealized Losses, 12 Months or Longer		2
Total Estimated Fair Value	60	238
Total Gross Unrealized Losses	$ 1	$ 4

Investments - Pretax Credit Los

Investments - Pretax Credit Loss Component Reflected in Retained Earnings on Fixed Maturity Securities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Beginning balance of credit losses on fixed maturity securities	$ 18	$ 27	$ 36
Reductions for securities sold during the period	(8)	(9)	(9)
Ending balance of credit losses on fixed maturity securities	$ 10	$ 18	$ 27

Investments - Available-for-Sal

Investments - Available-for-Sale Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Cost or Amortized Cost, Due in one year or less	$ 1,334	$ 1,350
Cost or Amortized Cost, Due after one year through five years	9,746	7,979
Cost or Amortized Cost, Due after five years through ten years	14,892	16,859
Cost or Amortized Cost, Due after ten years	12,134	11,893
Cost or Amortized Cost, Total	38,106	38,081
Estimated Fair Value, Due in one year or less	1,356	1,359
Estimated Fair Value, Due after one year through five years	10,186	8,139
Estimated Fair Value, Due after five years through ten years	15,931	16,870
Estimated Fair Value, Due after ten years	14,714	13,174
Estimated Fair Value, Total	$ 42,187	$ 39,542

Investments - Summary of Aggreg

Investments - Summary of Aggregate Contractual or Notional Amounts and Estimated Fair Values Related to Derivative Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Embedded Derivative on Funds Withheld Liability [Member]
Derivative [Line Items]
Contractual/Notional Amount	$ 182	$ 172
Estimated Fair Value, Asset		4
With Hedge Designation [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Contractual/Notional Amount	715	500
Estimated Fair Value, Asset		11
Estimated Fair Value, (Liability)	(8)
Without Hedge Designation [Member] | Equity Markets, Options - Purchased [Member]
Derivative [Line Items]
Contractual/Notional Amount	57	213
Estimated Fair Value, Asset	1	18
Without Hedge Designation [Member] | Equity Markets, Options - Written [Member]
Derivative [Line Items]
Contractual/Notional Amount	100	239
Estimated Fair Value, (Liability)	(1)	(17)
Without Hedge Designation [Member] | Commodity Futures [Member] | Long [Member]
Derivative [Line Items]
Contractual/Notional Amount		$ 32
Without Hedge Designation [Member] | Embedded Derivative on Funds Withheld Liability [Member]
Derivative [Line Items]
Estimated Fair Value, (Liability)	$ (7)

Fair Value - Assets and Liabili

Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
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	$ (28)	$ (23)
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	22,708	19,810
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	10,652	10,748
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	8,827	8,984
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	42,187	39,542
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	53	157
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	42,240	39,699
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	1,306	1,293
Receivables [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets, measured on a recurring basis	2	11
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	4,521	3,758
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	(18)	(23)
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	175	196
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	175	196
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	175	196
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	629	704
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	3,138	2,647
Level 2 [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	(10)
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	22,065	19,392
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	10,652	10,748
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	8,662	8,787
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	41,379	38,927
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	49	151
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	41,428	39,078
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	658	570
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	2	11
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	1,383	1,111
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	468	222
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	165	197
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	633	419
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	4	6
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	637	425
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	$ 19	$ 19

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	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Corporate Bonds and Other [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 222	$ 98
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in Net Income (Loss)		(1)
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in OCI	33	(4)
Purchases	256	117
Sales		(5)
Settlements	(11)	(9)
Transfers into Level 3		35
Transfers out of Level 3	(32)	(9)
Ending balance	468	222
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	28	(5)
States, Municipalities and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		1
Settlements		(1)
Total Asset-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	197	335
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in Net Income (Loss)		5
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in OCI	8	(8)
Purchases	48	162
Sales		(72)
Settlements	(16)	(64)
Transfers into Level 3	45	42
Transfers out of Level 3	(117)	(203)
Ending balance	165	197
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities		(2)
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	7	(4)
Total Fixed Maturities Available-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	419	434
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in Net Income (Loss)		4
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in OCI	41	(12)
Purchases	304	279
Sales		(77)
Settlements	(27)	(74)
Transfers into Level 3	45	77
Transfers out of Level 3	(149)	(212)
Ending balance	633	419
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities		(2)
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	35	(9)
Fixed Maturities Trading [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	6	4
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in Net Income (Loss)	(2)	3
Sales		(1)
Ending balance	4	6
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	(2)	2
Fixed Maturity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	425	438
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in Net Income (Loss)	(2)	7
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in OCI	41	(12)
Purchases	304	279
Sales		(78)
Settlements	(27)	(74)
Transfers into Level 3	45	77
Transfers out of Level 3	(149)	(212)
Ending balance	637	425
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	(2)
Unrealized Gains (Losses) Recognized in other Comprehensive Income (Loss) on Level 3 Assets and Liabilities	35	(9)
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	19	22
Net Realized Investment Gains (Losses) and Net Change in Unrealized Investment Gains (Losses), Included in Net Income (Loss)	(2)	(2)
Purchases	2
Sales		(1)
Ending balance	19	19
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities	$ (2)	$ (2)

Fair Value - Quantitative Infor

Fair Value - Quantitative Information about Significant Unobservable Inputs Utilized by Company in Fair Value Measurements of Level 3 Assets (Detail) $ in Millions	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair value	$ 42,187	$ 39,542
Level 3 [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair value	$ 525	$ 228
Minimum [Member] | Level 3 [Member] | Credit Spread [Member] | Discounted Cash Flow [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input	0.01	0.01
Maximum [Member] | Level 3 [Member] | Credit Spread [Member] | Discounted Cash Flow [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input	0.06	0.12
Weighted Average [Member] | Level 3 [Member] | Credit Spread [Member] | Discounted Cash Flow [Member] | Fixed Maturity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input	0.02	0.03

Fair Value - Carrying Amount, E

Fair Value - Carrying Amount, Estimated Fair Value and Level of Fair Value Hierarchy of Company's Financial Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Estimate Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	$ 1,025	$ 827
Short term debt	75	14
Long term debt	11,510	10,764
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	994	839
Short term debt	75	15
Long term debt	11,443	11,345
Level 2 [Member] | Estimate Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short term debt	9	14
Long term debt	10,884	10,111
Level 3 [Member] | Estimate Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other invested assets, primarily mortgage loans	1,025	827
Short term debt	66
Long term debt	$ 626	$ 653

Receivables - Receivables (Deta

Receivables - Receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Reinsurance (Note 16)	$ 4,204	$ 4,455
Insurance	2,481	2,365
Receivable from brokers	124	296
Accrued investment income	395	394
Federal income taxes	14	52
Other, primarily customer accounts	520	477
Total	7,738	8,039
Less: allowance for doubtful accounts on reinsurance receivables	25	29
allowance for other doubtful accounts	38	50
Receivables	$ 7,675	$ 7,960

Property, Plant and Equipment -

Property, Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Construction in process	$ 595	$ 317
Property, plant and equipment	15,568	15,511
Pipeline equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	8,229	8,238
Offshore drilling equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,119	5,144
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,625	$ 1,812

Property, Plant and Equipment_2

Property, Plant and Equipment - Components of Property, Plant and Equipment (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pipeline equipment [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 3,075	$ 2,761
Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	2,885	3,067
Other [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 1,114	$ 1,056

Property, Plant and Equipment_3

Property, Plant and Equipment - Additional Information (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)Acquisition	Dec. 31, 2018USD ($)Acquisition	Dec. 31, 2017USD ($)Rig
Property, Plant and Equipment [Line Items]
Capitalized interest related to the construction and upgrade of qualifying assets		$ 18	$ 27	$ 37
Asset impairment loss, before tax and noncontrolling interests		99	44	106
Impairment charges net of tax	$ 69
Impairment loss on plant property equipment		62	16
Impairment loss on other assets		37	6
Diamond Offshore [Member]
Property, Plant and Equipment [Line Items]
Asset impairment loss, before tax and noncontrolling interests			27	100
Asset impairment loss, net of tax and noncontrolling interests			12	$ 32
Diamond Offshore [Member] | Drilling Rigs [Member]
Property, Plant and Equipment [Line Items]
Number rigs evaluated for impairment | Rig				10
Number of rigs impaired | Rig				3
Number of rigs fair value using income approach | Rig				2
Boardwalk Pipeline [Member]
Property, Plant and Equipment [Line Items]
Proceed from sale of plant and equipment				$ 64
Gain (loss) on sale of plant and equipment				47
Gain (loss) on sale of plant and equipment,net of tax and noncontrolling interests				$ 15
Loews Hotels And Co [Member]
Property, Plant and Equipment [Line Items]
Asset impairment loss, before tax and noncontrolling interests		99	22
Impairment charges net of tax		$ 77	$ 15
Number of hotels impaired | Acquisition		4	2

Property, Plant and Equipment_4

Property, Plant and Equipment - Depreciation Expense and Capital Expenditures (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation	$ 898	$ 880	$ 854
Capital Expend.	1,058	995	990
Corporate [Member]
Property, Plant and Equipment [Line Items]
Depreciation	70	59	37
Capital Expend.	53	48	30
CNA Financial [Member]
Property, Plant and Equipment [Line Items]
Depreciation	64	76	80
Capital Expend.	26	99	101
Diamond Offshore [Member]
Property, Plant and Equipment [Line Items]
Depreciation	356	332	349
Capital Expend.	345	222	113
Boardwalk Pipelines [Member]
Property, Plant and Equipment [Line Items]
Depreciation	348	346	325
Capital Expend.	418	487	689
Loews Hotels And Co [Member]
Property, Plant and Equipment [Line Items]
Depreciation	60	67	63
Capital Expend.	$ 216	$ 139	$ 57

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Schedule of Changes in Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill, beginning balance	$ 665	$ 659
Acquisitions	100	8
Other adjustments	2	(2)
Goodwill, ending balance	767	665
CNA Financial [Member]
Goodwill [Line Items]
Goodwill, beginning balance	110	112
Other adjustments	2	(2)
Goodwill, ending balance	112	110
Boardwalk Pipeline [Member]
Goodwill [Line Items]
Goodwill, beginning balance	237	237
Goodwill, ending balance	237	237
Corporate [Member]
Goodwill [Line Items]
Goodwill, beginning balance	318	310
Acquisitions	100	8
Goodwill, ending balance	$ 418	$ 318

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Schedule of Carrying Amount of Other Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	$ 682	$ 604
Finite-lived intangible assets, Accumulated amortization	110	67
Indefinite-lived intangible assets, Gross carrying amount	75	74
Total other intangible assets, Gross carrying amount	757	678
Total other intangible assets, Accumulated amortization	110	67
Customer Relationships [Member]
Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	611	532
Finite-lived intangible assets, Accumulated amortization	76	47
Other [Member]
Intangible Assets [Line Items]
Finite-lived intangible assets, Gross carrying amount	71	72
Finite-lived intangible assets, Accumulated amortization	$ 34	$ 20

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 45	$ 32	$ 20
Estimated amortization expense in 2020	61
Estimated amortization expense in 2021	38
Estimated amortization expense in 2022	37
Estimated amortization expense in 2023	36
Estimated amortization expense in 2024	$ 34

Claim, Claim Adjustment Expen_3

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Reconciliation of Net Liability for Unpaid Claim and Claim Adjustment Expenses to Amount Presented in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Total reinsurance receivables	$ 3,835	$ 4,019
Total gross liability for unpaid claims and claims adjustment expenses	21,720	21,984
CNA Financial Corporation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	$ 18,070	$ 18,249
Total reinsurance receivables	3,835
Total gross liability for unpaid claims and claims adjustment expenses	21,720
Property and Casualty Operations [Member] | CNA Financial Corporation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	$ 14,353
Total reinsurance receivables	1,617
Other Insurance Operations [Member] | CNA Financial Corporation [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	3,732
Total reinsurance receivables	$ 2,218

Claim, Claim Adjustment Expen_4

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Reconciliation of Claim and Claim Adjustment Expense Reserves (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	$ 5,356	$ 5,358	$ 5,201
Decrease in provision for insured events of prior years	(127)	(179)	(381)
CNA Financial Corporation [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross reserves, beginning of year	21,984	22,004	22,343
Ceded reserves, beginning of year	4,019	3,934	4,094
Net reserves, beginning of year	17,965	18,070	18,249
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	5,356	5,358	5,201
Decrease in provision for insured events of prior years	(127)	(179)	(381)
Amortization of discount	184	176	179
Total net incurred	5,413	5,355	4,999
Net payments attributable to:
Current year events	(992)	(1,046)	(975)
Prior year events	(4,584)	(4,285)	(4,366)
Total net payments	(5,576)	(5,331)	(5,341)
Foreign currency translation adjustment and other	83	(129)	163
Net reserves, end of year	17,885	17,965	18,070
Ceded reserves, end of year	3,835	4,019	3,934
Gross reserves, end of year	$ 21,720	$ 21,984	$ 22,004

Claim, Claim Adjustment Expen_5

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Gross and Net Carried Claim and Claim Adjustment Expense Reserves (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Gross Case Reserves	$ 10,989	$ 11,395
Gross IBNR Reserves	10,731	10,589
Total Gross Carried Claim and Claim Adjustment Expense Reserves	21,720	21,984	$ 22,004	$ 22,343
Net Case Reserves	9,178	9,523
Net IBNR Reserves	8,707	8,442
Total Net Carried Claim and Claim Adjustment Expense Reserves	17,885	17,965	$ 18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Gross Case Reserves	6,276	6,671
Gross IBNR Reserves	9,494	9,287
Total Gross Carried Claim and Claim Adjustment Expense Reserves	15,770	15,958
Net Case Reserves	5,645	6,063
Net IBNR Reserves	8,508	8,290
Total Net Carried Claim and Claim Adjustment Expense Reserves	14,153	14,353
Other Insurance Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Gross Case Reserves	4,713	4,724
Gross IBNR Reserves	1,237	1,302
Total Gross Carried Claim and Claim Adjustment Expense Reserves	5,950	6,026
Net Case Reserves	3,533	3,460
Net IBNR Reserves	199	152
Total Net Carried Claim and Claim Adjustment Expense Reserves	$ 3,732	$ 3,612

Claim, Claim Adjustment Expen_6

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Net Prior Year Development in CNA's Property and Casualty Operations (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Medical professional liability	$ 75	$ 47	$ 30
Other professional liability and management liability	(69)	(127)	(126)
Surety	(92)	(70)	(84)
Commercial auto	(25)	1	(35)
General liability	54	32	(24)
Workers' compensation	(13)	(32)	(63)
Other	(3)	(32)	(6)
Total pretax favorable development	$ (73)	$ (181)	$ (308)

Claim, Claim Adjustment Expen_7

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Additional Information (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2010
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net A&EP adverse development before consideration of LPT	$ 150	$ 178	$ 60
Fair value of the collateral trust account	3,700	2,700
Changes In Claims And Claims Adjustment Reserve	56	31
Additions To Long-Duration Insurance at Original Discount Rate	216
Provision for uncollectible third-party reinsurance on A&EP	(25)	(16)
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
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	3,200	3,100
Remaining unrecognized retroactive reinsurance benefit	$ 392	$ 374

Claim, Claim Adjustment Expen_8

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Prior Year Claim and Allocated Claim Adjustment Expense Reserve Development for Segment (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	$ 17,885	$ 17,965	$ 18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	$ 14,353
Property and Casualty Operations [Member] | Medical Professional Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	1,429
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	2,739
Property and Casualty Operations [Member] | Surety [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	369
Property and Casualty Operations [Member] | Commercial Auto [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	404
Property and Casualty Operations [Member] | General Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	3,176
Property and Casualty Operations [Member] | Workers' Compensation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	3,932
Property and Casualty Operations [Member] | Other [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	$ 2,104

Claim, Claim Adjustment Expen_9

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses (Medical Professional Liability) (Detail) - Property and Casualty Operations [Member] - Medical Professional Liability [Member] - CNA Financial Corporation [Member] Claim in Millions, $ in Millions	Dec. 31, 2019USD ($)Claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 4,685
IBNR	853
2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	369	$ 356	$ 360	$ 365	$ 395	$ 415	$ 426	$ 423	$ 412	$ 402
IBNR	$ 1
Cumulative number of claims | Claim	14,624
2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 439	437	437	434	439	468	443	437	$ 429
IBNR	$ 2
Cumulative number of claims | Claim	16,526
2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 499	493	484	493	498	508	469	$ 464
IBNR	$ 8
Cumulative number of claims | Claim	17,724
2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 545	535	525	513	500	479	$ 462
IBNR	$ 27
Cumulative number of claims | Claim	19,510
2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 529	535	530	537	489	$ 450
IBNR	$ 16
Cumulative number of claims | Claim	19,723
2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 488	494	510	499	$ 433
IBNR	$ 29
Cumulative number of claims | Claim	18,029
2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 499	485	487	$ 427
IBNR	$ 63
Cumulative number of claims | Claim	15,823
2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 458	449	$ 412
IBNR	$ 127
Cumulative number of claims | Claim	14,636
2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 429	$ 404
IBNR	$ 216
Cumulative number of claims | Claim	13,760
2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 430
IBNR	$ 364
Cumulative number of claims | Claim	10,467

Claim, Claim Adjustment Expe_10

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses (Medical Professional Liability) (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	$ 4,584	$ 4,285	$ 4,366
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	14,353
Property and Casualty Operations [Member] | Medical Professional Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	3,303
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	1,382
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	22
Liability for unallocated claim adjustment expenses for accident years presented	25
Total net liability for unpaid claim and claim adjustment expenses	1,429
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	353	350	346	337	$ 326	$ 306	$ 257	$ 173	$ 86	$ 10
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	414	409	398	375	347	295	208	109	$ 17
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	479	457	427	388	323	221	117	$ 14
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	495	462	414	355	255	119	$ 17
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	472	417	359	258	136	$ 23
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	384	313	230	101	$ 22
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	339	246	121	$ 18
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	235	107	$ 19
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	115	$ 21
Property and Casualty Operations [Member] | Medical Professional Liability [Member] | 2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 17

Claim, Claim Adjustment Expe_11

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Strengthening or Releasing of Prior Accident Year Reserves (Medical Professional Liability) (Detail) - Property and Casualty Operations [Member] - Medical Professional Liability [Member] - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ 75	$ 47	$ 30
2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	13	(4)	(5)	$ (30)	$ (20)	$ (11)	$ 3	$ 11	$ 10
Net Strengthening or (Releases) of Prior Accident Year Reserves	(33)
2011 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	2		3	(5)	(29)	25	6	$ 8
Net Strengthening or (Releases) of Prior Accident Year Reserves	10
2012 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	6	9	(9)	(5)	(10)	39	$ 5
Net Strengthening or (Releases) of Prior Accident Year Reserves	35
2013 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	10	10	12	13	21	$ 17
Net Strengthening or (Releases) of Prior Accident Year Reserves	83
2014 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(6)	5	(7)	48	$ 39
Net Strengthening or (Releases) of Prior Accident Year Reserves	79
2015 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(6)	(16)	11	$ 66
Net Strengthening or (Releases) of Prior Accident Year Reserves	55
2016 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	14	(2)	60
Net Strengthening or (Releases) of Prior Accident Year Reserves	72
2017 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	9	37
Net Strengthening or (Releases) of Prior Accident Year Reserves	46
Short-duration Insurance Contracts, Accident Year 2018 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	25
Net Strengthening or (Releases) of Prior Accident Year Reserves	25
Total net development for the accident years presented above [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	67	39	65
Total net development for the accident years prior to 2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	6	9	(28)
Unallocated Claim Adjustment Expense Development [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ 2	$ (1)	$ (7)

Claim, Claim Adjustment Expe_12

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses (Other Professional Liability and Management Liability) (Detail) - Property and Casualty Operations [Member] - Other Professional Liability and Management Liability [Member] - CNA Financial Corporation [Member] $ in Millions	Dec. 31, 2019USD ($)Claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 8,466
IBNR	1,957
2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	821	$ 821	$ 827	$ 824	$ 837	$ 847	$ 848	$ 848	$ 828	$ 828
IBNR	$ 9
Cumulative number of claims | Claim	17,891
2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 885	888	899	911	944	949	934	908	$ 880
IBNR	$ 21
Cumulative number of claims | Claim	18,738
2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 831	833	846	840	878	887	909	$ 923
IBNR	$ 18
Cumulative number of claims | Claim	18,499
2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 850	863	866	885	926	894	$ 884
IBNR	$ 45
Cumulative number of claims | Claim	17,928
2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 854	835	831	885	898	$ 878
IBNR	$ 74
Cumulative number of claims | Claim	17,553
2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 807	832	877	892	$ 888
IBNR	$ 120
Cumulative number of claims | Claim	17,390
2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 904	900	900	$ 901
IBNR	$ 188
Cumulative number of claims | Claim	17,890
2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 813	845	$ 847
IBNR	$ 308
Cumulative number of claims | Claim	18,015
2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 864	$ 850
IBNR	$ 460
Cumulative number of claims | Claim	19,468
2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 837
IBNR	$ 714
Cumulative number of claims | Claim	16,722

Claim, Claim Adjustment Expe_13

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses (Other Professional Liability and Management Liability) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	$ 4,584	$ 4,285	$ 4,366
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	18,070	$ 18,249
Property and Casualty Operations [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	14,353
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	5,865
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	2,601
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	88
Liability for unallocated claim adjustment expenses for accident years presented	50
Total net liability for unpaid claim and claim adjustment expenses	2,739
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2010 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	790	784	752	721	$ 670	$ 630	$ 541	$ 405	$ 204	$ 31
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2011 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	828	796	781	726	683	605	503	314	$ 71
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2012 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	792	755	711	651	573	400	248	$ 56
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2013 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	771	754	702	618	447	249	$ 54
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2014 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	707	647	515	392	223	$ 51
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2015 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	612	542	404	234	$ 60
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2016 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	625	466	248	$ 64
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2017 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	394	222	$ 57
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2018 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	282	$ 54
Property and Casualty Operations [Member] | Other Professional Liability and Management Liability [Member] | 2019 [Member] | CNA Financial Corporation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 64

Claim, Claim Adjustment Expe_14

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Strengthening or Releasing of Prior Accident Year Reserves (Other Professional Liability and Management Liability) (Detail) - Property and Casualty Operations [Member] - CNA Financial Corporation [Member] - Other Professional Liability and Management Liability [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (69)	$ (127)	$ (126)
2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves		(6)	3	$ (13)	$ (10)	$ (1)		$ 20
Net Strengthening or (Releases) of Prior Accident Year Reserves	(7)
2011 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(3)	(11)	(12)	(33)	(5)	15	$ 26	$ 28
Net Strengthening or (Releases) of Prior Accident Year Reserves	5
2012 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(2)	(13)	6	(38)	(9)	(22)	$ (14)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(92)
2013 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(13)	(3)	(19)	(41)	32	$ 10
Net Strengthening or (Releases) of Prior Accident Year Reserves	(34)
2014 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	19	4	(54)	(13)	$ 20
Net Strengthening or (Releases) of Prior Accident Year Reserves	(24)
2015 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(25)	(45)	(15)	$ 4
Net Strengthening or (Releases) of Prior Accident Year Reserves	(81)
2016 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	4		(1)
Net Strengthening or (Releases) of Prior Accident Year Reserves	3
2017 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(32)	(2)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(34)
2018 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	14
Net Strengthening or (Releases) of Prior Accident Year Reserves	14
Total net development for the accident years presented above [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(38)	(76)	(92)
Total net development for the accident years prior to 2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(17)	(44)	(27)
Unallocated Claim Adjustment Expense Development [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (14)	$ (7)	$ (7)

Claim, Claim Adjustment Expe_15

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses (Surety) (Detail) - Property and Casualty Operations [Member] - Surety [Member] - CNA Financial Corporation [Member] Claim in Millions, $ in Millions	Dec. 31, 2019USD ($)Claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 766
IBNR	289
2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 61	$ 61	$ 59	$ 63	$ 66	$ 76	$ 84	$ 111	$ 112	$ 112
Cumulative number of claims | Claim	5,982
2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 62	62	66	70	75	87	116	121	$ 120
IBNR	$ 2
Cumulative number of claims | Claim	5,813
2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 38	39	45	52	70	98	122	$ 120
IBNR	$ 1
Cumulative number of claims | Claim	5,568
2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 83	87	91	106	115	121	$ 120
IBNR	$ 3
Cumulative number of claims | Claim	5,062
2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 45	60	69	94	124	$ 123
IBNR	$ 4
Cumulative number of claims | Claim	5,078
2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 63	79	104	131	$ 131
IBNR	$ 11
Cumulative number of claims | Claim	4,976
2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 84	109	124	$ 124
IBNR	$ 36
Cumulative number of claims | Claim	5,379
2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 103	115	$ 120
IBNR	$ 54
Cumulative number of claims | Claim	5,496
2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 108	$ 114
IBNR	$ 76
Cumulative number of claims | Claim	5,451
2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 119
IBNR	$ 102
Cumulative number of claims | Claim	3,549

Claim, Claim Adjustment Expe_16

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses (Surety) (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	$ 4,584	$ 4,285	$ 4,366
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	14,353
Property and Casualty Operations [Member] | Surety [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	427
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	339
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	10
Liability for unallocated claim adjustment expenses for accident years presented	20
Total net liability for unpaid claim and claim adjustment expenses	369
Property and Casualty Operations [Member] | Surety [Member] | 2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	53	52	52	55	$ 58	$ 57	$ 55	$ 50	$ 34	$ 13
Property and Casualty Operations [Member] | Surety [Member] | 2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	57	57	56	60	60	58	55	42	$ 19
Property and Casualty Operations [Member] | Surety [Member] | 2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	37	37	36	35	35	34	32	$ 5
Property and Casualty Operations [Member] | Surety [Member] | 2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	77	78	78	78	69	40	$ 16
Property and Casualty Operations [Member] | Surety [Member] | 2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	38	38	36	38	30	$ 7
Property and Casualty Operations [Member] | Surety [Member] | 2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	42	40	38	26	$ 7
Property and Casualty Operations [Member] | Surety [Member] | 2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	45	45	37	$ 5
Property and Casualty Operations [Member] | Surety [Member] | 2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	41	37	$ 23
Property and Casualty Operations [Member] | Surety [Member] | 2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	25	$ 5
Property and Casualty Operations [Member] | Surety [Member] | 2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 12

Claim, Claim Adjustment Expe_17

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Strengthening or Releasing of Prior Accident Year Reserves (Surety) (Detail) - Property and Casualty Operations [Member] - Surety [Member] - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (92)	$ (70)	$ (84)
2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves		2	(4)	$ (3)	$ (10)	$ (8)	$ (27)	$ (1)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(51)
2011 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves		(4)	(4)	(5)	(12)	(29)	(5)	$ 1
Net Strengthening or (Releases) of Prior Accident Year Reserves	(58)
2012 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(1)	(6)	(7)	(18)	(28)	(24)	$ 2
Net Strengthening or (Releases) of Prior Accident Year Reserves	(82)
2013 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(4)	(4)	(15)	(9)	(6)	$ 1
Net Strengthening or (Releases) of Prior Accident Year Reserves	(37)
2014 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(15)	(9)	(25)	$ (30)	$ 1
Net Strengthening or (Releases) of Prior Accident Year Reserves	(78)
2015 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(16)	(25)	(27)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(68)
2016 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(25)	(15)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(40)
2017 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(12)	(5)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(17)
2018 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(6)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(6)
Total net development for the accident years presented above [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(79)	(66)	(82)
Total net development for the accident years prior to 2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(3)	$ (4)	1
Unallocated Claim Adjustment Expense Development [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (10)		$ (3)

Claim, Claim Adjustment Expe_18

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses (Commercial Auto) (Detail) - Property and Casualty Operations [Member] - Commercial Auto [Member] - CNA Financial Corporation [Member] $ in Millions	Dec. 31, 2019USD ($)Claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 2,371
IBNR	207
2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	288	$ 288	$ 288	$ 289	$ 293	$ 298	$ 291	$ 287	$ 283	$ 267
IBNR	$ 1
Cumulative number of claims | Claim	48,035
2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 291	294	294	294	300	302	288	281	$ 268
Cumulative number of claims | Claim	47,909
2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 297	299	299	307	303	299	289	$ 275
IBNR	$ 3
Cumulative number of claims | Claim	46,288
2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 241	245	245	249	265	265	$ 246
IBNR	$ 2
Cumulative number of claims | Claim	39,429
2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 201	205	205	212	223	$ 234
IBNR	$ 3
Cumulative number of claims | Claim	33,622
2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 183	190	190	199	$ 201
IBNR	$ 7
Cumulative number of claims | Claim	30,418
2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 186	186	186	$ 198
IBNR	$ 7
Cumulative number of claims | Claim	30,414
2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 200	198	$ 199
IBNR	$ 9
Cumulative number of claims | Claim	30,850
2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 227	$ 229
IBNR	$ 47
Cumulative number of claims | Claim	33,959
2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 257
IBNR	$ 128
Cumulative number of claims | Claim	31,455

Claim, Claim Adjustment Expe_19

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses (Commercial Auto) (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	$ 4,584	$ 4,285	$ 4,366
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	14,353
Property and Casualty Operations [Member] | Commercial Auto [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	1,982
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	389
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	1
Liability for unallocated claim adjustment expenses for accident years presented	14
Total net liability for unpaid claim and claim adjustment expenses	404
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	287	287	287	286	$ 281	$ 271	$ 246	$ 203	$ 141	$ 74
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	289	289	287	284	274	248	199	145	$ 79
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	291	290	285	282	259	220	160	$ 78
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	238	234	225	200	168	135	$ 74
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	196	187	166	137	102	$ 64
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	172	153	130	96	$ 52
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	154	126	93	$ 52
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	150	107	$ 58
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	128	$ 66
Property and Casualty Operations [Member] | Commercial Auto [Member] | 2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 77

Claim, Claim Adjustment Expe_20

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Strengthening or Releasing of Prior Accident Year Reserves (Commercial Auto) (Detail) - Property and Casualty Operations [Member] - Commercial Auto [Member] - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (25)	$ 1	$ (35)
2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves			(1)	$ (4)	$ (5)	$ 7	$ 4	$ 4	$ 16
Net Strengthening or (Releases) of Prior Accident Year Reserves	21
2011 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(3)			(6)	(2)	14	7	$ 13
Net Strengthening or (Releases) of Prior Accident Year Reserves	23
2012 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(2)		(8)	4	4	10	$ 14
Net Strengthening or (Releases) of Prior Accident Year Reserves	22
2013 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(4)		(4)	(16)		$ 19
Net Strengthening or (Releases) of Prior Accident Year Reserves	(5)
2014 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(4)		(7)	(11)	$ (11)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(33)
2015 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(7)		(9)	$ (2)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(18)
2016 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves			(12)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(12)
2017 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	2	(1)
Net Strengthening or (Releases) of Prior Accident Year Reserves	1
2018 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(2)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(2)
Total net development for the accident years presented above [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(20)	(1)	(41)
Total net development for the accident years prior to 2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(4)	1	4
Unallocated Claim Adjustment Expense Development [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (1)	$ 1	$ 2

Claim, Claim Adjustment Expe_21

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses (General Liability) (Detail) - Property and Casualty Operations [Member] - General Liability [Member] - CNA Financial Corporation [Member] Claim in Millions, $ in Millions	Dec. 31, 2019USD ($)Claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 6,492
IBNR	1,629
2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	690	$ 691	$ 691	$ 697	$ 726	$ 750	$ 709	$ 658	$ 664	$ 646
IBNR	$ 19
Cumulative number of claims | Claim	44,229
2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 667	669	670	681	676	677	631	589	$ 591
IBNR	$ 20
Cumulative number of claims | Claim	39,361
2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 630	635	635	619	636	639	611	$ 587
IBNR	$ 31
Cumulative number of claims | Claim	35,219
2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 620	623	613	655	650	655	$ 650
IBNR	$ 27
Cumulative number of claims | Claim	33,570
2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 658	635	631	654	658	$ 653
IBNR	$ 57
Cumulative number of claims | Claim	27,877
2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 600	589	574	576	$ 581
IBNR	$ 73
Cumulative number of claims | Claim	23,834
2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 671	667	659	$ 623
IBNR	$ 166
Cumulative number of claims | Claim	23,817
2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 632	632	$ 632
IBNR	$ 226
Cumulative number of claims | Claim	21,114
2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 644	$ 653
IBNR	$ 408
Cumulative number of claims | Claim	17,889
2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 680
IBNR	$ 602
Cumulative number of claims | Claim	12,916

Claim, Claim Adjustment Expe_22

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses (General Liability) (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	$ 4,584	$ 4,285	$ 4,366
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	14,353
Property and Casualty Operations [Member] | General Liability [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	4,217
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	2,275
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	836
Liability for unallocated claim adjustment expenses for accident years presented	65
Total net liability for unpaid claim and claim adjustment expenses	3,176
Property and Casualty Operations [Member] | General Liability [Member] | 2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	667	656	652	642	$ 611	$ 561	$ 429	$ 280	$ 145	$ 27
Property and Casualty Operations [Member] | General Liability [Member] | 2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	638	622	602	568	517	411	273	148	$ 28
Property and Casualty Operations [Member] | General Liability [Member] | 2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	579	559	510	454	374	247	132	$ 28
Property and Casualty Operations [Member] | General Liability [Member] | 2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	551	510	450	352	240	128	$ 31
Property and Casualty Operations [Member] | General Liability [Member] | 2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	547	481	376	247	119	$ 31
Property and Casualty Operations [Member] | General Liability [Member] | 2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	446	357	230	110	$ 19
Property and Casualty Operations [Member] | General Liability [Member] | 2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	407	279	163	$ 32
Property and Casualty Operations [Member] | General Liability [Member] | 2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	250	118	$ 23
Property and Casualty Operations [Member] | General Liability [Member] | 2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	107	$ 33
Property and Casualty Operations [Member] | General Liability [Member] | 2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 25

Claim, Claim Adjustment Expe_23

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Strengthening or Releasing of Prior Accident Year Reserves (General Liability) (Detail) - Property and Casualty Operations [Member] - General Liability [Member] - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ 54	$ 32	$ (24)
2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(1)		(6)	$ (29)	$ (24)	$ 41	$ 51	$ (6)	$ 18
Net Strengthening or (Releases) of Prior Accident Year Reserves	44
2011 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(2)	(1)	(11)	5	(1)	46	42	$ (2)
Net Strengthening or (Releases) of Prior Accident Year Reserves	76
2012 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(5)		16	(17)	(3)	28	$ 24
Net Strengthening or (Releases) of Prior Accident Year Reserves	43
2013 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(3)	10	(42)	5	(5)	$ 5
Net Strengthening or (Releases) of Prior Accident Year Reserves	(30)
2014 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	23	4	(23)	(4)	$ 5
Net Strengthening or (Releases) of Prior Accident Year Reserves	5
2015 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	11	15	(2)	$ (5)
Net Strengthening or (Releases) of Prior Accident Year Reserves	19
2016 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	4	8	36
Net Strengthening or (Releases) of Prior Accident Year Reserves	48
2018 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(9)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(9)
Total net development for the accident years presented above [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	18	36	(32)
Total net development for the accident years prior to 2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	29
Unallocated Claim Adjustment Expense Development [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ 7	$ (4)	$ 8

Claim, Claim Adjustment Expe_24

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Incurred Claims and Allocated Claim Adjustment Expenses (Workers' Compensation) (Detail) - Property and Casualty Operations [Member] - Workers' Compensation [Member] - CNA Financial Corporation [Member] $ in Millions	Dec. 31, 2019USD ($)Claim	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 5,187
IBNR	1,208
2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	735	$ 732	$ 733	$ 730	$ 710	$ 698	$ 676	$ 654	$ 632	$ 583
IBNR	$ 55
Cumulative number of claims | Claim	49,333
2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 688	674	676	676	651	659	647	641	$ 607
IBNR	$ 40
Cumulative number of claims | Claim	45,959
2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 668	671	673	678	669	659	627	$ 601
IBNR	$ 67
Cumulative number of claims | Claim	42,586
2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 561	582	593	618	592	572	$ 537
IBNR	$ 93
Cumulative number of claims | Claim	38,688
2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 446	450	452	479	480	$ 467
IBNR	$ 99
Cumulative number of claims | Claim	33,480
2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 394	408	406	431	$ 422
IBNR	$ 130
Cumulative number of claims | Claim	31,861
2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 382	396	405	$ 426
IBNR	$ 144
Cumulative number of claims | Claim	31,945
2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 421	432	$ 440
IBNR	$ 138
Cumulative number of claims | Claim	33,029
2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 440	$ 450
IBNR	$ 185
Cumulative number of claims | Claim	34,647
2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 452
IBNR	$ 257
Cumulative number of claims | Claim	29,795

Claim, Claim Adjustment Expe_25

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Cumulative Paid Claim and Claim Adjustment Expenses (Workers' Compensation) (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	$ 4,584	$ 4,285	$ 4,366
Total net liability for unpaid claim and claim adjustment expenses	17,885	17,965	18,070	$ 18,249
Property and Casualty Operations [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total net liability for unpaid claim and claim adjustment expenses	14,153	14,353
Property and Casualty Operations [Member] | Workers' Compensation [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	3,319
Net liability for unpaid claim and allocated claim adjustment expenses for the accident years presented	1,868
Net liability for unpaid claim and claim adjustment expenses for accident years prior to 2010	2,061
Other	(22)
Liability for unallocated claim adjustment expenses for accident years presented	25
Total net liability for unpaid claim and claim adjustment expenses	3,932
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2010 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	631	625	615	577	$ 542	$ 510	$ 442	$ 359	$ 251	$ 97
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2011 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	581	571	564	522	478	438	358	249	$ 99
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2012 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	536	524	509	470	416	342	232	$ 87
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2013 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	411	419	417	370	300	213	$ 80
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2014 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	290	282	258	215	159	$ 61
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2015 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	231	212	180	131	$ 51
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2016 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	198	169	129	$ 53
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2017 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	207	151	$ 63
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2018 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	163	$ 68
Property and Casualty Operations [Member] | Workers' Compensation [Member] | 2019 [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Total	$ 71

Claim, Claim Adjustment Expe_26

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Net Strengthening or Releasing of Prior Accident Year Reserves (Workers' Compensation) (Detail) - Property and Casualty Operations [Member] - Workers' Compensation [Member] - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ (13)	$ (32)	$ (63)
2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	3	(1)	3	$ 20	$ 12	$ 22	$ 22	$ 22	$ 49
Net Strengthening or (Releases) of Prior Accident Year Reserves	152
2011 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	14	(2)		25	(8)	12	6	$ 34
Net Strengthening or (Releases) of Prior Accident Year Reserves	81
2012 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(3)	(2)	(5)	9	10	32	$ 26
Net Strengthening or (Releases) of Prior Accident Year Reserves	67
2013 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(21)	(11)	(25)	26	20	$ 35
Net Strengthening or (Releases) of Prior Accident Year Reserves	24
2014 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(4)	(2)	(27)	(1)	$ 13
Net Strengthening or (Releases) of Prior Accident Year Reserves	(21)
2015 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(14)	2	(25)	$ 9
Net Strengthening or (Releases) of Prior Accident Year Reserves	(28)
2016 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(14)	(9)	(21)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(44)
2017 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(11)	(8)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(19)
2018 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(10)
Net Strengthening or (Releases) of Prior Accident Year Reserves	(10)
Total net development for the accident years presented above [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	(60)	(33)	(100)
Adjustment for Development on a Discounted Basis [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	3		(3)
Total net development for the accident years prior to 2010 [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	21	8	39
Unallocated Claim Adjustment Expense Development [Member]
Claims Development [Line Items]
Strengthening or (Releases) of Prior Accident Year Reserves	$ 23	$ (7)	$ 1

Claim, Claim Adjustment Expe_27

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Historical Claims Duration (Detail) - CNA Financial Corporation [Member]	Dec. 31, 2019
Medical Professional Liability [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Claims in Year 1	3.80%
Average Annual Percentage Payout of Claims in Year 2	20.00%
Average Annual Percentage Payout of Claims in Year 3	24.30%
Average Annual Percentage Payout of Claims in Year 4	19.40%
Average Annual Percentage Payout of Claims in Year 5	12.40%
Average Annual Percentage Payout of Claims in Year 6	7.80%
Average Annual Percentage Payout of Claims in Year 7	5.10%
Average Annual Percentage Payout of Claims in Year 8	3.10%
Average Annual Percentage Payout of Claims in Year 9	1.10%
Average Annual Percentage Payout of Claims in Year 10	0.80%
Total	97.80%
Other Professional Liability and Management Liability [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Claims in Year 1	6.60%
Average Annual Percentage Payout of Claims in Year 2	22.60%
Average Annual Percentage Payout of Claims in Year 3	21.70%
Average Annual Percentage Payout of Claims in Year 4	16.90%
Average Annual Percentage Payout of Claims in Year 5	10.50%
Average Annual Percentage Payout of Claims in Year 6	6.00%
Average Annual Percentage Payout of Claims in Year 7	4.90%
Average Annual Percentage Payout of Claims in Year 8	3.30%
Average Annual Percentage Payout of Claims in Year 9	3.80%
Average Annual Percentage Payout of Claims in Year 10	0.70%
Total	97.00%
Surety [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Claims in Year 1	20.00%
Average Annual Percentage Payout of Claims in Year 2	44.50%
Average Annual Percentage Payout of Claims in Year 3	21.00%
Average Annual Percentage Payout of Claims in Year 4	4.40%
Average Annual Percentage Payout of Claims in Year 5	2.20%
Average Annual Percentage Payout of Claims in Year 6	0.90%
Average Annual Percentage Payout of Claims in Year 7	(2.50%)
Average Annual Percentage Payout of Claims in Year 8	(1.10%)
Average Annual Percentage Payout of Claims in Year 10	1.60%
Total	91.00%
Commercial Auto [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Claims in Year 1	28.60%
Average Annual Percentage Payout of Claims in Year 2	24.00%
Average Annual Percentage Payout of Claims in Year 3	18.60%
Average Annual Percentage Payout of Claims in Year 4	14.30%
Average Annual Percentage Payout of Claims in Year 5	9.40%
Average Annual Percentage Payout of Claims in Year 6	3.20%
Average Annual Percentage Payout of Claims in Year 7	1.50%
Average Annual Percentage Payout of Claims in Year 8	0.40%
Total	100.00%
General Liability [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Claims in Year 1	4.30%
Average Annual Percentage Payout of Claims in Year 2	15.80%
Average Annual Percentage Payout of Claims in Year 3	19.00%
Average Annual Percentage Payout of Claims in Year 4	20.10%
Average Annual Percentage Payout of Claims in Year 5	15.70%
Average Annual Percentage Payout of Claims in Year 6	8.70%
Average Annual Percentage Payout of Claims in Year 7	6.00%
Average Annual Percentage Payout of Claims in Year 8	2.50%
Average Annual Percentage Payout of Claims in Year 9	1.50%
Average Annual Percentage Payout of Claims in Year 10	1.60%
Total	95.20%
Workers' Compensation [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Claims in Year 1	14.10%
Average Annual Percentage Payout of Claims in Year 2	21.40%
Average Annual Percentage Payout of Claims in Year 3	13.90%
Average Annual Percentage Payout of Claims in Year 4	10.30%
Average Annual Percentage Payout of Claims in Year 5	7.00%
Average Annual Percentage Payout of Claims in Year 6	3.70%
Average Annual Percentage Payout of Claims in Year 7	2.90%
Average Annual Percentage Payout of Claims in Year 8	2.70%
Average Annual Percentage Payout of Claims in Year 9	1.40%
Average Annual Percentage Payout of Claims in Year 10	0.80%
Total	78.20%

Claim, Claim Adjustment Expe_28

Claim, Claim Adjustment Expense and Future Policy Benefit Reserves - Schedule of Impact of Loss Portfolio Transfer on the Consolidated Statement of Operations (Detail) - CNA Financial Corporation [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Additional amounts ceded under LPT:
Net A&EP adverse development before consideration of LPT	$ 150	$ 178	$ 60
Provision for uncollectible third-party reinsurance on A&EP	(25)	(16)
Total additional amounts ceded under LPT	125	162	60
Retroactive reinsurance benefit recognized	(107)	(114)	(68)
Pretax impact of deferred retroactive reinsurance	$ 18	$ 48	$ (8)

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Operating lease asset	$ 573
Operating lease liability	694
Operating lease cost	121
Variable lease cost	19
Short term lease cost	6
Lease Expense	146	$ 120	$ 113
Lease liability cash payments	117
Operating lease right of use assets obtained in exchange for lease obligations	$ 54

Leases - Future Minimum Lease P

Leases - Future Minimum Lease Payments to be Made Under Non-Cancelable Operating Leases Along with Lease and Sublease Minimum Receipts to be Received on Owned and Leased Properties (Detail) $ in Millions	Dec. 31, 2018USD ($)
Leases [Abstract]
Operating leases, Future Minimum Lease Payments, 2019	$ 75
Operating leases, Future Minimum Lease Payments, 2020	79
Operating leases, Future Minimum Lease Payments, 2021	79
Operating leases, Future Minimum Lease Payments, 2022	68
Operating leases, Future Minimum Lease Payments, 2023	57
Operating leases, Future Minimum Lease Payments, Thereafter	344
Operating leases, Future Minimum Lease Payments, Total	702
Operating leases, Future Minimum Lease Receipts, 2019	6
Operating leases, Future Minimum Lease Receipts, 2020	5
Operating leases, Future Minimum Lease Receipts, 2021	5
Operating leases, Future Minimum Lease Receipts, 2022	4
Operating leases, Future Minimum Lease Receipts, 2023	4
Operating leases, Future Minimum Lease Receipts, Thereafter	14
Operating leases, Future Minimum Lease Receipts, Total	$ 38

Leases - Presents the maturitie

Leases - Presents the maturities of lease liabilities (Detail) $ in Millions	Dec. 31, 2019USD ($)
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, 2020	$ 114
Lessee, Operating Lease, Liability, Payments, 2021	113
Lessee, Operating Lease, Liability, Payments, 2022	102
Lessee, Operating Lease, Liability, Payments, 2023	89
Lessee, Operating Lease, Liability, Payments, 2024	81
Lessee, Operating Lease, Liability, Payments, Thereafter	361
Lessee, Operating Lease, Liability, Payments, Lessee, Operating Lease, Total	860
Discount on Operating Less: discount	166
Operating Lease, Total lease liabilities	$ 694

Leases - other information rela

Leases - other information related to leases (Detail)	Dec. 31, 2019
Weighted Average Remaining Lease Term [Abstract]
Operating leases	9 years 4 months 24 days
Weighted Average Discount Rate [Abstract]
Operating leases	4.70%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
U.S corporate income tax rate	35.00%	21.00%	35.00%
Non-cash increase in net income	$ 14	$ 6	$ 200
Increase in income tax benefit			268
Net deferred tax liabilities partially offset by provisional charge			78
Uncertain income tax positions	95
Reductions for tax positions related to a prior year	23	48	1
Additions for tax positions related to the current year	86	3	51
Net operating loss carryforwards	275	251
Uncertain tax position penalties	17	16
Uncertain tax position interest	4	3
Federal [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	70
Net operating loss carryforwards indefinitely	$ 88
Net operating loss carryforwards expiration year	2034 and 2038
Foreign [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 2
Net operating loss carryforwards indefinitely	$ 77
Net operating loss carryforwards expiration year	2035 and 2039
Net operating loss carryforwards in foreign tax jurisdictions	$ 38
Tax credit carryforwards	$ 45
Tax credit carryforwards expiration year	2020 and 2030
Tax credit carryforwards indefinitely	$ 2
CNA Financial Corporation [Member]
Income Tax Contingency [Line Items]
Equity ownership percentage	80.00%
Diamond Offshore [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would affect effective tax rate upon recognition	$ 149	$ 82	$ 102

Income Taxes - Schedule of Curr

Income Taxes - Schedule of Current and Deferred Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income tax expense (benefit):
Federal income tax expense (benefit), Current	$ 108	$ 6	$ 157
Federal income tax expense (benefit), Deferred	47	85	(63)
State and city income tax expense (benefit), Current	18	15	22
State and city income tax expense (benefit), Deferred	22	9	17
Foreign income tax expense (benefit)	53	13	37
Income tax expense (benefit)	$ 248	$ 128	$ 170

Income Taxes - Components of U.

Income Taxes - Components of U.S. and Foreign Income and Reconciliation between Federal Income Tax Expense at Statutory Rates and Actual Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income before income tax:
Income before income tax, U.S.	$ 1,145	$ 775	$ 1,322
Income before income tax, Foreign	(26)	59	260
Income before income tax	1,119	834	1,582
Income tax expense at statutory rate	235	175	554
Increase (decrease) in income tax expense resulting from:
Effect of the Tax Act	(14)	(6)	(190)
Exempt investment income	(50)	(64)	(134)
Foreign related tax differential	(55)	1	(36)
Taxes related to domestic affiliate	(15)	(7)	1
Partnership earnings not subject to taxes		(14)	(51)
Valuation allowance	12	12	7
Unrecognized tax positions, settlements and adjustments relating to prior years	97	2	(8)
State taxes	37	20	23
Other	1	9	4
Income tax expense (benefit)	$ 248	$ 128	$ 170

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits, Excluding Tax Carryforwards and Interest and Penalties (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Balance at January 1	$ 58	$ 84	$ 35
Additions for tax positions related to the current year	86	3	51
Additions for tax positions related to a prior year	2	20	5
Reductions for tax positions related to a prior year	(23)	(48)	(1)
Lapse of statute of limitations	(2)	(1)	(6)
Balance at December 31	$ 121	$ 58	$ 84

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Property and casualty claim and claim adjustment expense reserves	$ 129	$ 108
Unearned premium reserves	153	108
Receivables	11	13
Employee benefits	212	222
Deferred retroactive reinsurance benefit	82	79
Net operating loss carryforwards	275	251
Tax credit carryforwards	47	101
Net unrealized losses		24
Basis differential in investment in subsidiary	8	8
Disallowed interest deduction	41	16
Other	179	181
Total deferred tax assets	1,137	1,111
Valuation allowance	(187)	(175)
Net deferred tax assets	950	936
Deferred tax liabilities:
Deferred acquisition costs	(83)	(78)
Net unrealized gains	(263)
Property, plant and equipment	(848)	(840)
Basis differential in investment in subsidiary	(679)	(586)
Other liabilities	(208)	(236)
Total deferred tax liabilities	(2,081)	(1,740)
Net deferred tax liabilities	$ (1,131)	$ (804)

Income Taxes - Summary of Def_2

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Parenthetical) (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Deferred Tax Assets And Liabilities [Line Items]
Deferred tax assets	$ 1,137,000,000	$ 1,111,000,000
Other Assets [Member]
Schedule Of Deferred Tax Assets And Liabilities [Line Items]
Deferred tax assets	$ 37	$ 37

Debt - Schedule of Long-Term De

Debt - Schedule of Long-Term Debt Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt, Gross	$ 11,643	$ 11,488
Less unamortized discount and issuance costs	110	112
Net	11,533	11,376
Loews Corporation [Member]
Debt Instrument [Line Items]
Debt, Gross	1,800
Less unamortized discount and issuance costs	21
Net	1,779
CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	2,693
Less unamortized discount and issuance costs	14
Finance lease obligation		1
Net	2,679
Diamond Offshore [Member]
Debt Instrument [Line Items]
Debt, Gross	2,000
Less unamortized discount and issuance costs	24
Net	1,976
Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	3,592
Less unamortized discount and issuance costs	26
Finance lease obligation	7	8
Net	3,566
Loews Hotels [Member]
Debt Instrument [Line Items]
Debt, Gross	712	653
Less unamortized discount and issuance costs	7
Net	705
Altium Packaging Company [Member]
Debt Instrument [Line Items]
Debt, Gross	846
Less unamortized discount and issuance costs	18
Finance lease obligation	6	7
Net	828
Altium Packaging Company [Member] | Variable Rate Term Loan Due Two Zero Two Four [Member]
Debt Instrument [Line Items]
Debt, Gross	591	597
Altium Packaging Company [Member] | Variable Rate Term Loan Due Two zero Two Six [Member]
Debt Instrument [Line Items]
Debt, Gross	249
2.6% Notes Due 2023 [Member] | Loews Corporation [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
3.8% Notes Due 2026 [Member] | Loews Corporation [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
6.0% Notes Due 2035 [Member] | Loews Corporation [Member]
Debt Instrument [Line Items]
Debt, Gross	300	300
4.1% Notes Due 2043 [Member] | Loews Corporation [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
5.9% Notes Due 2020 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross		500
5.8% Notes Due 2021 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	400	400
7.3% Debentures Due 2023 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	243	243
4.0% Notes Due 2024 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	550	550
4.5% Notes Due 2026 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
3.5% Notes Due 2027 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
3.9% notes due 2029 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Debt, Gross	500
3.5% notes due 2023 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Debt, Gross	250	250
7.9% Notes Due 2025 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
5.7% Notes Due 2039 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
4.9% Notes Due 2043 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Debt, Gross	750	750
Variable Rate Revolving Credit Facility Due 2022 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	295	580
Variable Rate Revolving Credit Facility Due 2022 [Member] | Altium Packaging Company [Member]
Debt Instrument [Line Items]
Debt, Gross		9
5.8% Notes Due 2019 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross		350
4.5% Notes Due 2021 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	440	440
4.0% Notes Due 2022 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	300	300
3.4% Notes Due 2023 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	300	300
5.0% Notes Due 2024 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	600	600
6.0% Notes Due 2026 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	550	550
4.5% Notes Due 2027 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	500	500
7.3% Debentures Due 2027 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	100	$ 100
4.8% notes due 2029 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Debt, Gross	$ 500

Debt - Schedule of Long-Term _2

Debt - Schedule of Long-Term Debt Instruments (Parenthetical) (Detail) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Loews Hotels And Co [Member]
Debt Instrument [Line Items]
Effective interest rate		4.70%	4.40%
5.9% Notes Due 2020 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate	5.90%	5.90%
Maturity year		2020
Effective interest rate		6.00%
Debt authorized		$ 500,000,000
5.8% Notes Due 2021 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate		5.80%
Maturity year		2021
Effective interest rate		5.90%
Debt authorized		$ 400,000,000
7.3% Debentures Due 2023 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate		7.30%
Maturity year		2023
Effective interest rate		7.30%
Debt authorized		$ 250,000,000
4.0% Notes Due 2024 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate		4.00%
Maturity year		2024
Effective interest rate		4.00%
Debt authorized		$ 550,000,000
4.5% Notes Due 2026 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate		4.50%
Maturity year		2026
Effective interest rate		4.50%
Debt authorized		$ 500,000,000
3.5% Notes Due 2027 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate		3.50%
Maturity year		2027
Effective interest rate		3.50%
Debt authorized		$ 500,000,000
3.9% Notes Due 2029 [Member] | CNA Financial [Member]
Debt Instrument [Line Items]
Stated interest rate		3.90%
Maturity year		2029
Effective interest rate		3.90%
Debt authorized		$ 500,000,000
3.5% notes due 2023 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Stated interest rate		3.50%
Maturity year		2023
Effective interest rate		3.50%
Debt authorized		$ 250,000,000
7.9% Notes Due 2025 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Stated interest rate		7.90%
Maturity year		2025
Effective interest rate		8.00%
Debt authorized		$ 500,000,000
5.7% Notes Due 2039 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Stated interest rate		5.70%
Maturity year		2039
Effective interest rate		5.80%
Debt authorized		$ 500,000,000
4.9% Notes Due 2043 [Member] | Diamond Offshore [Member]
Debt Instrument [Line Items]
Stated interest rate		4.90%
Maturity year		2043
Effective interest rate		4.90%
Debt authorized		$ 750,000,000
Variable Rate Revolving Credit Facility Due 2022 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Maturity year		2022
Effective interest rate		3.00%	3.70%
5.8% Notes Due 2019 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate	5.80%	5.80%
Maturity year	2019	2019
Effective interest rate		5.90%
Debt authorized		$ 350,000,000
4.5% Notes Due 2021 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		4.50%
Maturity year		2021
Effective interest rate		5.00%
Debt authorized		$ 440,000,000
4.0% Notes Due 2022 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		4.00%
Maturity year		2022
Effective interest rate		4.40%
Debt authorized		$ 300,000,000
3.4% Notes Due 2023 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		3.40%
Maturity year		2023
Effective interest rate		3.50%
Debt authorized		$ 300,000,000
5.0% Notes Due 2024 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		5.00%
Maturity year		2024
Effective interest rate		5.20%
Debt authorized		$ 600,000,000
6.0% Notes Due 2026 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		6.00%
Maturity year		2026
Effective interest rate		6.20%
Debt authorized		$ 550,000,000
4.5% Notes Due 2027 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		4.50%
Maturity year		2027
Effective interest rate		4.60%
Debt authorized		$ 500,000,000
7.3% Debentures Due 2027 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate		7.30%
Maturity year		2027
Effective interest rate		8.10%
Debt authorized		$ 100,000,000
4.8% Notes Due 2029 [Member] | Boardwalk Pipelines [Member]
Debt Instrument [Line Items]
Stated interest rate	4.80%	4.80%
Maturity year		2029
Effective interest rate		4.90%
Debt authorized	$ 500,000,000	$ 500,000,000
Variable Rate Asset Based Lending Facility Due Two Thousand Twenty Two [Member] | Altium Packaging [Member]
Debt Instrument [Line Items]
Maturity year		2022
Effective interest rate		5.50%	5.50%
Variable Rate Term Loan Due Two Zero Two Four [Member] | Altium Packaging [Member]
Debt Instrument [Line Items]
Maturity year		2024
Effective interest rate		4.90%	5.00%
Variable Rate Term Loan Due Two zero Two Six [Member] | Altium Packaging [Member]
Debt Instrument [Line Items]
Maturity year		2026
Effective interest rate		5.30%	5.30%
Loews Corporation [Member] | 2.6% Notes Due 2023 [Member]
Debt Instrument [Line Items]
Stated interest rate		2.60%
Maturity year		2023
Effective interest rate		2.80%
Debt authorized		$ 500,000,000
Loews Corporation [Member] | 3.8% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Stated interest rate		3.80%
Maturity year		2026
Effective interest rate		3.90%
Debt authorized		$ 500,000,000
Loews Corporation [Member] | 6.0% Notes Due 2035 [Member]
Debt Instrument [Line Items]
Stated interest rate		6.00%
Maturity year		2035
Effective interest rate		6.20%
Debt authorized		$ 300,000,000
Loews Corporation [Member] | 4.1% Notes Due 2043 [Member]
Debt Instrument [Line Items]
Stated interest rate		4.10%
Maturity year		2043
Effective interest rate		4.30%
Debt authorized		$ 500,000,000

Debt - Schedule of Debt by Subs

Debt - Schedule of Debt by Subsidiary (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal	$ 11,643	$ 11,488
Unamortized Discount and Issuance Costs	110	112
Net	11,533	11,376
Short Term Debt	77	17
Long term debt	11,456	11,359
Loews Corporation [Member]
Debt Instrument [Line Items]
Principal	1,800
Unamortized Discount and Issuance Costs	21
Net	1,779
Long term debt	1,779
CNA Financial [Member]
Debt Instrument [Line Items]
Principal	2,693
Unamortized Discount and Issuance Costs	14
Net	2,679
Long term debt	2,679
Diamond Offshore [Member]
Debt Instrument [Line Items]
Principal	2,000
Unamortized Discount and Issuance Costs	24
Net	1,976
Long term debt	1,976
Boardwalk Pipeline [Member]
Debt Instrument [Line Items]
Principal	3,592
Unamortized Discount and Issuance Costs	26
Net	3,566
Long term debt	3,566
Loews Hotels And Co [Member]
Debt Instrument [Line Items]
Principal	712	$ 653
Unamortized Discount and Issuance Costs	7
Net	705
Short Term Debt	67
Long term debt	638
Altium Packaging [Member]
Debt Instrument [Line Items]
Principal	846
Unamortized Discount and Issuance Costs	18
Net	828
Short Term Debt	10
Long term debt	$ 818

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Jun. 30, 2019	May 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Aggregate of long term debt maturing, 2020			$ 77,000,000
Aggregate of long term debt maturing, 2021			861,000,000
Aggregate of long term debt maturing, 2022			744,000,000
Aggregate of long term debt maturing, 2023			1,300,000,000
Aggregate of long term debt maturing, 2024			2,000,000,000
Aggregate of long term debt maturing, Thereafter			6,600,000,000
Additional borrowings credit facility			100,000,000
Revolving Credit Facility [Member] | Diamond Offshore [Member]
Borrowings outstanding amount			0
CNA Financial [Member]
Acquisition of FHLBC stock			5,000,000
Additional liquidity			111,000,000
Outstanding borrowings			0	$ 0
CNA Financial [Member] | Senior Unsecured Revolving Credit Facility [Member]
Credit agreement term loan			$ 250,000,000
Senior unsecured revolving credit facility, term			0 years
CNA Financial [Member] | Three Point Nine Percentage Notes Due Two Thousand Twenty Nine [Member]
Aggregate principal amount		$ 500,000,000
Percentage of senior notes		3.90%
Senior notes due date		May 1, 2029
CNA Financial [Member] | Five Point Nine Percentage Notes Due Two Zero Two Zero [Member]
Aggregate principal amount			$ 500,000,000
Percentage of senior notes		5.90%	5.90%
Senior notes due date		Aug. 15, 2020
Aggregate outstanding principal amount		$ 500,000,000	$ 500,000,000
Senior notes due year			2020
Gain (Loss) on Extinguishment of Debt			$ (21,000,000)
Extinguishment of Debt, Gain (Loss), Net of Tax			(15,000,000)
Boardwalk Pipeline [Member] | Revolving Credit Facility [Member]
Credit agreement term loan			1,500,000,000
Borrowings outstanding amount			295,000,000
Boardwalk Pipeline [Member] | Five Point Eight Percentage Notes Due Two Zero One Nine [Member]
Aggregate principal amount			$ 350,000,000
Percentage of senior notes		5.80%	5.80%
Aggregate outstanding principal amount		$ 350,000,000
Senior notes due year		2019	2019
Boardwalk Pipeline [Member] | Four Point Eight Percentage Due Two Thousand Twenty Nine [Member]
Aggregate principal amount		$ 500,000,000	$ 500,000,000
Percentage of senior notes		4.80%	4.80%
Senior notes due year			2029
Altium Packaging [Member] | Term Loan [Member]
Senior notes due date	Jun. 14, 2026
Credit agreement term loan	$ 250,000,000
Debt Instrument, Description of Variable Rate Basis	London Interbank Offered Rate (“LIBOR”) plus an applicable margin of 3.5%
Debt Instrument, Basis Spread on Variable Rate	3.50%

Shareholders' Equity - Componen

Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 21,386	$ 24,566	$ 23,361
Cumulative effect adjustment from changes in accounting standards		(91)
Balance, as adjusted		24,475
Other comprehensive income (loss)	911	(892)	218
Purchase of Boardwalk Pipelines common units		(1,718)
Ending Balance	21,930	21,386	24,566
Net Unrealized Gains (Losses) on Investments with OTTI Losses [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	14	22	27
Balance, as adjusted		26
Other comprehensive income (loss) before reclassifications, after tax	(13)	(7)	(3)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	12	(7)	(2)
Other comprehensive income (loss)	(1)	(14)	(5)
Amounts attributable to noncontrolling interests		2
Ending Balance	13	14	22
Net Other Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	57	673	576
Balance, as adjusted		771
Other comprehensive income (loss) before reclassifications, after tax	957	(801)	190
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	(8)	3	(82)
Other comprehensive income (loss)	949	(798)	108
Amounts attributable to noncontrolling interests	(101)	84	(11)
Ending Balance	905	57	673
Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	5		(2)
Other comprehensive income (loss) before reclassifications, after tax	(11)	4	1
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax		2	2
Other comprehensive income (loss)	(11)	6	3
Amounts attributable to noncontrolling interests			(1)
Purchase of Boardwalk Pipelines common units		(1)
Ending Balance	(6)	5
Pension and Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(793)	(633)	(646)
Balance, as adjusted		(763)
Other comprehensive income (loss) before reclassifications, after tax	(102)	(34)	(18)
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	34	32	30
Other comprehensive income (loss)	(68)	(2)	12
Amounts attributable to noncontrolling interests	6		1
Purchase of Boardwalk Pipelines common units		(28)
Ending Balance	(855)	(793)	(633)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(163)	(88)	(178)
Balance, as adjusted		(88)
Other comprehensive income (loss) before reclassifications, after tax	42	(84)	100
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax
Other comprehensive income (loss)	42	(84)	100
Amounts attributable to noncontrolling interests	(4)	9	(10)
Ending Balance	(125)	(163)	(88)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(880)	(26)	(223)
Balance, as adjusted		(54)
Other comprehensive income (loss) before reclassifications, after tax	873	(922)	270
Reclassification of (gains) losses from accumulated other comprehensive loss, after tax	38	30	(52)
Other comprehensive income (loss)	911	(892)	218
Amounts attributable to noncontrolling interests	(99)	95	(21)
Purchase of Boardwalk Pipelines common units		(29)
Ending Balance	$ (68)	(880)	$ (26)
Accounting Standards Update 2016-01 [Member] | Net Unrealized Gains (Losses) on Investments with OTTI Losses [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards		4
Accounting Standards Update 2016-01 [Member] | Net Other Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards		98
Accounting Standards Update 2016-01 [Member] | Pension and Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect adjustment from changes in accounting standards		(130)
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		$ (28)

Shareholders' Equity - Compon_2

Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Unrealized Gains (Losses) on Investments with OTTI Losses [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	$ 3	$ 2	$ 1
Tax on reclassification from accumulated other comprehensive income	(3)	2	1
Net Other Unrealized Gains (Losses) on Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	(256)	213	(106)
Tax on reclassification from accumulated other comprehensive income	1	(2)	38
Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	5	(2)	(2)
Tax on reclassification from accumulated other comprehensive income	0	0	0
Pension and Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	28	9	4
Tax on reclassification from accumulated other comprehensive income	(9)	(6)	(16)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax on change in other comprehensive income (loss) before reclassifications	0	0	0
Tax on reclassification from accumulated other comprehensive income	$ 0	0	$ 0
Accounting Standards Update 2016-01 [Member] | Net Unrealized Gains (Losses) on Investments with OTTI 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] | Net Other 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] | Unrealized Gains (Losses) on 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 and Postretirement Benefits [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) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Common stock dividend declared	$ 0.25	$ 0.25	$ 0.25
Common stock dividend paid	$ 0.25	$ 0.25	$ 0.25
Treasury stock repurchased, shares	21.5	20.3	4.8
Purchase of Loews treasury stock	$ 1,059	$ 1,011	$ 237
Treasury stock retired, shares	21.4

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Schedule of Disaggregation of Revenues (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Operating revenues and other	$ 3,938	$ 3,987	$ 4,053
Total revenues from contracts with customers	3,870	3,886	3,964
Other revenues	68	101	89
CNA Financial Corporation [Member] | Non-insurance Warranty [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,161	1,007	390
Diamond Offshore [Member] | Drilling Contracts [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	981	1,083	1,486
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	1,266	1,206	1,298
Loews Hotels And Co [Member] | Lodging and Related Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	691	730	682
Corporate [Member] | Rigid Plastic Packaging and Recycled Resin [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 932	$ 867	$ 498

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Receivables from contracts with customers, included within Receivables	$ 458	$ 434
Deferred revenue, included within Other liabilities	3,779	3,402
Revenue recognized	1,000	886
Contract cost	2,900	2,600
Amortization expense, contract cost	912	744
Performance obligations	13,000
Deferred NonInsurance Warranty Revenue and Other Liabilities [Member]
Disaggregation of Revenue [Line Items]
Deferred revenue, included within Other liabilities	3,900	$ 3,500
2020 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations	2,200
2021 [Member]
Disaggregation of Revenue [Line Items]
Performance obligations	$ 1,900

Statutory Accounting Practice_2

Statutory Accounting Practices - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statutory Accounting Practices [Line Items]
Increase in statutory capital and surplus	$ 91	$ 88
Combined Continental Casualty Companies [Member]
Statutory Accounting Practices [Line Items]
Increase in statutory capital and surplus	10,787	$ 10,411
Dividends payable without prior supervisory approval	1,078
Dividends paid	$ 1,065
Statutory capital and surplus percentage	291.00%	266.00%

Statutory Accounting Practice_3

Statutory Accounting Practices - Combined Statutory Capital and Surplus and Net Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statutory Accounting Practices [Line Items]
Statutory Capital and Surplus	$ 91	$ 88
Combined Continental Casualty Companies [Member]
Statutory Accounting Practices [Line Items]
Statutory Capital and Surplus	10,787	10,411
Statutory Net Income	$ 1,062	$ 1,405	$ 1,029

Benefit Plans - Additional Info

Benefit Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Eligible age for several postretirement benefit plans	55 years
Eligible age for Medicare benefits	65 years
Accumulated benefit obligation for all defined benefit pension plans	$ 3,100	$ 2,900
Actuarial (gain) loss	300	$ (212)
Future capital calls from various third party limited partnership investments	$ 111
Percentage of limited partnerships comprising of the carrying value that employ hedge fund strategies	65.70%	71.30%
Amount contributed to the savings plans	$ 102	$ 100	$ 105
Stock-based Compensation, vesting period	4 years
Stock-based Compensation, expiration period	10 years
Recognized compensation expense	$ 37	35	33
Time-based Restricted Stock Units (RSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
Terms of Award	right to receive one share of the Company’s common stock for each vested RSU
Forfeited during the year	3,621
Performance-based Restricted Stock Units (PSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
Terms of Award	receive one share of the Company’s common stock for each vested PSU
Restricted Stock Units (RSUs) and Performance Stock Units (PSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
Grants In Period	216,802
Weighted average grant date fair value	$ 48.10
Stock Appreciation Rights (SARs) [Member]
Defined Benefit Plan Disclosure [Line Items]
SARs outstanding	2,469,756
Weighted average grant date fair value	$ 41.11
2016 Loews Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Stock-based Compensation, number of shares authorized				6,000,000
Stock-based Compensation, maximum number of shares to be granted to each individual				500,000
Maximum [Member] | 2016 Loews Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Stock-based Compensation, number of shares to be forfeited under prior plan				3,000,000
Second Anniversary [Member] | Time-based Restricted Stock Units (RSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
vesting percentage				50.00%
Second Anniversary [Member] | Performance-based Restricted Stock Units (PSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
vesting percentage				50.00%
Third Anniversary [Member] | Time-based Restricted Stock Units (RSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
vesting percentage				50.00%
Third Anniversary [Member] | Performance-based Restricted Stock Units (PSUs) [Member]
Defined Benefit Plan Disclosure [Line Items]
vesting percentage				50.00%
Defined Benefit Plan, Equity Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets invested in equity securities and limited partnerships, Maximum	40.00%
Defined Benefit Plan, Equity Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets invested in equity securities and limited partnerships, Maximum	60.00%
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of hedge fund strategies	62.00%
Hedge Funds, Multi-strategy [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of hedge fund strategies	31.00%
Distressed Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of hedge fund strategies	7.00%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss	$ 299	(212)
Expected contribution to plan(s), next fiscal year	14
Fair value of plan assets	2,576	2,304	2,577
Pension Benefits [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	$ 10
Postretirement Healthcare and Life Insurance Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to plan(s), next fiscal year	$ 2
Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of limited partnerships comprising of the carrying value that employ hedge fund strategies	80.00%	82.00%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss	$ 3	$ (6)
Fair value of plan assets	90	85	$ 88
Other Postretirement Benefits [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0

Benefit Plans - Weighted Averag

Benefit Plans - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.00%	4.10%	3.50%
Expected long term rate of return on plan assets	7.50%	7.50%	7.50%
Interest crediting rate	3.70%	3.80%	3.70%
Pension Benefits [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.00%	3.90%	3.90%
Pension Benefits [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	5.50%	5.50%	5.50%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.00%	4.10%	3.40%
Expected long term rate of return on plan assets	3.60%	5.30%	5.30%

Benefit Plans - Weighted Aver_2

Benefit Plans - Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.00%	3.60%	3.80%
Expected long term rate of return on plan assets	7.50%	7.50%	7.50%
Interest crediting rate	3.70%	3.70%	3.70%
Pension Benefits [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.00%	3.90%	3.90%
Pension Benefits [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	5.50%	5.50%	5.50%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.00%	3.40%	3.70%
Expected long term rate of return on plan assets	3.60%	5.30%	5.30%

Benefit Plans - Assumed Health

Benefit Plans - Assumed Health Care Cost Trend Rates (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	4.00%	4.00%	4.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.00%	4.00%	4.00%
Year that the rate reaches the ultimate trend rate	2021	2019	2018
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	8.00%	6.50%	7.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2026	2022	2022

Benefit Plans - Components of N

Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7	$ 8	$ 8
Interest cost	117	110	119
Expected return on plan assets	(159)	(179)	(173)
Amortization of unrecognized net loss	45	42	43
Settlements and curtailments	1	9	11
Net periodic benefit cost	11	(10)	8
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	1
Interest cost	2	2	2
Expected return on plan assets	(3)	(5)	(5)
Amortization of unrecognized net loss	(1)	(1)
Amortization of unrecognized prior service benefit		(2)	(2)
Net periodic benefit cost	$ (2)	$ (5)	$ (4)

Benefit Plans - Reconciliation

Benefit Plans - Reconciliation of Benefit Obligations and Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Actuarial (gain) loss	$ 300	$ (212)
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	2,919	3,242
Service cost	7	8	$ 8
Interest cost	117	110	119
Amendments	1
Actuarial (gain) loss	299	(212)
Benefits paid from plan assets	(191)	(187)
Settlements and curtailments	(19)	(35)
Foreign exchange	4	(7)
Benefit obligation, ending balance	3,137	2,919	3,242
Change in plan assets:
Fair value of plan assets, ending balance	2,304	2,577
Actual return on plan assets	328	(83)
Company contributions	146	39
Benefits paid from plan assets	(191)	(187)
Settlements	(15)	(35)
Foreign exchange	4	(7)
Fair value of plan assets, ending balance	2,576	2,304	2,577
Funded status	(561)	(615)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	53	62
Service cost		1	1
Interest cost	2	2	2
Plan participants' contributions	4	4
Actuarial (gain) loss	3	(6)
Benefits paid from plan assets	(10)	(10)
Benefit obligation, ending balance	52	53	62
Change in plan assets:
Fair value of plan assets, ending balance	85	88
Actual return on plan assets	8
Company contributions	3	3
Plan participants' contributions	4	4
Benefits paid from plan assets	(10)	(10)
Fair value of plan assets, ending balance	90	85	$ 88
Funded status	$ 38	$ 32

Benefit Plans - Amounts Recogni

Benefit Plans - Amounts Recognized in the Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Amounts recognized in the Consolidated Balance Sheets consist of:
Other assets	$ 5	$ 9
Other liabilities	(566)	(624)
Net amount recognized	(561)	(615)
Other Postretirement Benefits [Member]
Amounts recognized in the Consolidated Balance Sheets consist of:
Other assets	54	49
Other liabilities	(16)	(17)
Net amount recognized	$ 38	$ 32

Benefit Plans - Amounts Recog_2

Benefit Plans - Amounts Recognized in Accumulated Other Comprehensive Income (Loss), Not Yet Recognized in Net Periodic (Benefit) Cost (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service credit		$ (2)
Net actuarial loss	$ 1,144	1,065
Net amount recognized	1,144	1,063
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service credit	(1)	(1)
Net actuarial loss	(4)	(3)
Net amount recognized	$ (5)	$ (4)

Benefit Plans - Information for

Benefit Plans - Information for Plans With Projected and Accumulated Benefit Obligations in Excess of Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 3,021	$ 2,825
Accumulated benefit obligation	3,014	2,813
Fair value of plan assets	2,456	2,201
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 16	$ 18

Benefit Plans - Estimated Futur

Benefit Plans - Estimated Future Minimum Benefit Payments (Detail) $ in Millions	Dec. 31, 2019USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected future benefit payments 2020	$ 234
Expected future benefit payments 2021	211
Expected future benefit payments 2022	215
Expected future benefit payments 2023	217
Expected future benefit payments 2024	212
Expected future benefit payments 2025 - 2029	1,001
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected future benefit payments 2020	5
Expected future benefit payments 2021	5
Expected future benefit payments 2022	4
Expected future benefit payments 2023	4
Expected future benefit payments 2024	3
Expected future benefit payments 2025 - 2029	$ 14

Benefit Plans - Pension Plan As

Benefit Plans - Pension Plan Assets Measured at Fair Value on Recurring Basis (Detail) - Pension Benefits [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	$ 2,576	$ 2,304	$ 2,577
Corporate Bonds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	597	482
States, Municipalities and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	51	58
Total Asset-Backed [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	154	165
Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	802	705
Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	669	516
Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	81	90
Fixed Income Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	128	120
Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	20	9
Fair Value of Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	1,700	1,440
Limited Partnership Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	876	864
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	754	562
Level 1 [Member] | Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	541	406
Level 1 [Member] | Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	74	36
Level 1 [Member] | Fixed Income Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	128	120
Level 1 [Member] | Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	11
Level 1 [Member] | Fair Value of Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	754	562
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	936	868
Level 2 [Member] | Corporate Bonds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	587	472
Level 2 [Member] | States, Municipalities and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	51	58
Level 2 [Member] | Total Asset-Backed [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	154	165
Level 2 [Member] | Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	792	695
Level 2 [Member] | Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	128	110
Level 2 [Member] | Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	7	54
Level 2 [Member] | Other Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	9	9
Level 2 [Member] | Fair Value of Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	936	868
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	10	10
Level 3 [Member] | Corporate Bonds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	10	10
Level 3 [Member] | Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	10	10
Level 3 [Member] | Fair Value of Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total plan assets	$ 10	$ 10

Benefit Plans - Other Postretir

Benefit Plans - Other Postretirement Benefit Plan Assets Measured at Fair Value on Recurring Basis (Detail) - Other Postretirement Benefits [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 90	$ 85	$ 88
Corporate Bonds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22	24
States, Municipalities and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	11
Total Asset-Backed [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31	30
Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69	65
Short Term and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	4
Fixed Income Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	16
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	20
Level 1 [Member] | Short Term and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	4
Level 1 [Member] | Fixed Income Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	16
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69	65
Level 2 [Member] | Corporate Bonds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22	24
Level 2 [Member] | States, Municipalities and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	11
Level 2 [Member] | Total Asset-Backed [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31	30
Level 2 [Member] | Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 69	$ 65

Reinsurance - Summary of Amount

Reinsurance - Summary of Amounts Receivable from Reinsurers (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Reinsurance Disclosures [Abstract]
Ceded claim and claim adjustment expenses	$ 3,835	$ 4,019
Ceded future policy benefits	226	233
Reinsurance receivables related to paid losses	143	203
Reinsurance receivables	4,204	4,455
Less allowance for doubtful accounts	25	29
Reinsurance receivables, net of allowance for doubtful accounts	$ 4,179	$ 4,426

Reinsurance - Additional Inform

Reinsurance - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Reinsurance collateral	$ 3,200	$ 3,200
Reinsurance recoveries	2,700	2,800	$ 3,100
Berkshire Hathaway Group [Member]
Effects of Reinsurance [Line Items]
Largest recoverables from a single reinsurer	2
Palo Verde Insurance Company [Member]
Effects of Reinsurance [Line Items]
Largest recoverables from a single reinsurer	289
Wilton Re [Member]
Effects of Reinsurance [Line Items]
Largest recoverables from a single reinsurer	226
Significant Captive Program [Member]
Effects of Reinsurance [Line Items]
Direct and ceded earned premiums	$ 3,600	3,700	3,900
Percentage reinsured of direct and ceded earned premiums	100.00%
Reinsurance recoveries	$ 2,100	$ 1,900	$ 2,500

Reinsurance - Summary of Effect

Reinsurance - Summary of Effects of Reinsurance on Earned Premiums (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Earned premiums, Direct	$ 11,491	$ 11,337	$ 10,936
Earned premiums, Assumed	338	355	367
Earned premiums, Ceded	4,401	4,380	4,315
Earned premiums, Net	$ 7,428	$ 7,312	$ 6,988
Percentage of amount assumed to net	4.60%	4.90%	5.30%
Property and Casualty Operations [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Earned premiums, Direct	$ 11,021	$ 10,857	$ 10,447
Earned premiums, Assumed	288	305	317
Earned premiums, Ceded	4,401	4,380	4,315
Earned premiums, Net	$ 6,908	$ 6,782	$ 6,449
Percentage of amount assumed to net	4.20%	4.50%	4.90%
Long Term Care [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Earned premiums, Direct	$ 470	$ 480	$ 489
Earned premiums, Assumed	50	50	50
Earned premiums, Ceded
Earned premiums, Net	$ 520	$ 530	$ 539
Percentage of amount assumed to net	9.60%	9.40%	9.30%

Quarterly Financial Data - Sche

Quarterly Financial Data - Schedule of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Total revenues	$ 3,876	$ 3,675	$ 3,623	$ 3,757	$ 3,287	$ 3,608	$ 3,590	$ 3,581	$ 14,931	$ 14,066	$ 13,735
Net income (loss)	$ 217	$ 72	$ 249	$ 394	$ (165)	$ 278	$ 230	$ 293	$ 932	$ 636	$ 1,164
Per share-basic and diluted	$ 0.73	$ 0.24	$ 0.82	$ 1.27	$ (0.53)	$ 0.88	$ 0.72	$ 0.89

Quarterly Financial Data - Sc_2

Quarterly Financial Data - Schedule of Quarterly Financial Information (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data [Line Items]
Net investment income	$ 116								$ 2,355	$ 1,817	$ 2,182
Asset impairment charges	69
Net loss	$ 217	$ 72	$ 249	$ 394	$ (165)	$ 278	$ 230	$ 293	932	636	1,164
Net investment losses									$ 49	$ (57)	$ 122
Active life reserve premium deficiency [Member]
Quarterly Financial Data [Line Items]
Net loss		$ 151
CNA Financial Corporation [Member] | Catastrophe [Member]
Quarterly Financial Data [Line Items]
Net loss					96
Loews [Member]
Quarterly Financial Data [Line Items]
Net investment losses					57
Limited Partnership and Common Stock Investments [Member ]
Quarterly Financial Data [Line Items]
Net loss					$ 97

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Billions	Dec. 31, 2019USD ($)
CNA Financial Corporation [Member]
Commitments [Line Items]
Potential amount of future payments under guarantees	$ 1.7

Segments - Additional Informati

Segments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019miRigHotelSegmentState
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	5
Number of individual operating subsidiaries | Segment	4
Diamond Offshore [Member]
Segment Reporting Information [Line Items]
Number of offshore rigs owned | Rig	15
Diamond Offshore [Member] | Drillship [Member]
Segment Reporting Information [Line Items]
Number of offshore rigs owned | Rig	4
Diamond Offshore [Member] | Semisubmersible [Member]
Segment Reporting Information [Line Items]
Number of offshore rigs owned | Rig	11
Boardwalk Pipeline [Member]
Segment Reporting Information [Line Items]
Miles of natural gas and NGL pipeline | mi	14,055
Number of states having natural gas storage facilities | State	4
Loews Hotels And Co [Member]
Segment Reporting Information [Line Items]
Total number of hotels owned and/or operated | Hotel	26
Loews Hotels And Co [Member] | United States [Member]
Segment Reporting Information [Line Items]
Total number of hotels owned and/or operated | Hotel	24
Number of hotels | Hotel	2

Segments - Consolidating Statem

Segments - Consolidating Statement of Income and Total Assets by Segment (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Insurance premiums									$ 7,428	$ 7,312	$ 6,988
Net investment income (loss)	$ 116								2,355	1,817	2,182
Investment gains (losses)									49	(57)	122
Non-insurance warranty revenue									1,161	1,007	390
Operating revenues and other									3,938	3,987	4,053
Total	3,876	$ 3,675	$ 3,623	$ 3,757	$ 3,287	$ 3,608	$ 3,590	$ 3,581	14,931	14,066	13,735
Expenses:
Insurance claims and policyholders' benefits									5,806	5,572	5,310
Amortization of deferred acquisition costs									1,383	1,335	1,233
Non-insurance warranty expense									1,082	923	299
Operating expenses and other									4,950	4,828	4,665
Interest									591	574	646
Total									13,812	13,232	12,153
Income (loss) before income tax									1,119	834	1,582
Income tax (expense) benefit									(248)	(128)	(170)
Net income (loss)									871	706	1,412
Amounts attributable to noncontrolling interests									61	(70)	(248)
Net income (loss) attributable to Loews Corporation	217	$ 72	$ 249	$ 394	(165)	$ 278	$ 230	$ 293	932	636	1,164
Total assets	82,243				78,316				82,243	78,316
CNA Financial Corporation [Member] | Operating Segments [Member]
Revenues:
Insurance premiums									7,428	7,312	6,988
Net investment income (loss)									2,118	1,817	2,034
Investment gains (losses)									49	(57)	122
Non-insurance warranty revenue									1,161	1,007	390
Operating revenues and other									32	55	49
Total									10,788	10,134	9,583
Expenses:
Insurance claims and policyholders' benefits									5,806	5,572	5,310
Amortization of deferred acquisition costs									1,383	1,335	1,233
Non-insurance warranty expense									1,082	923	299
Operating expenses and other									1,141	1,203	1,224
Interest									152	138	203
Total									9,564	9,171	8,269
Income (loss) before income tax									1,224	963	1,314
Income tax (expense) benefit									(224)	(151)	(419)
Net income (loss)									1,000	812	895
Amounts attributable to noncontrolling interests									(106)	(86)	(94)
Net income (loss) attributable to Loews Corporation									894	726	801
Total assets	60,583				57,123				60,583	57,123
Diamond Offshore [Member] | Operating Segments [Member]
Revenues:
Net investment income (loss)									6	8	2
Operating revenues and other									982	1,085	1,498
Total									988	1,093	1,500
Expenses:
Operating expenses and other									1,267	1,196	1,373
Interest									123	123	149
Total									1,390	1,319	1,522
Income (loss) before income tax									(402)	(226)	(22)
Income tax (expense) benefit									60	30	4
Net income (loss)									(342)	(196)	(18)
Amounts attributable to noncontrolling interests									167	84	(9)
Net income (loss) attributable to Loews Corporation									(175)	(112)	(27)
Total assets	5,834				6,036				5,834	6,036
Boardwalk Pipeline [Member] | Operating Segments [Member]
Revenues:
Operating revenues and other									1,300	1,227	1,325
Total									1,300	1,227	1,325
Expenses:
Operating expenses and other									840	820	861
Interest									179	176	171
Total									1,019	996	1,032
Income (loss) before income tax									281	231	293
Income tax (expense) benefit									(72)	(28)	232
Net income (loss)									209	203	525
Amounts attributable to noncontrolling interests										(68)	(145)
Net income (loss) attributable to Loews Corporation									209	135	380
Total assets	9,248				9,131				9,248	9,131
Loews Hotels And Co [Member] | Operating Segments [Member]
Revenues:
Net investment income (loss)									1	2
Operating revenues and other									691	753	682
Total									692	755	682
Expenses:
Operating expenses and other									698	653	589
Interest									22	29	28
Total									720	682	617
Income (loss) before income tax									(28)	73	65
Income tax (expense) benefit									(3)	(25)	(1)
Net income (loss)									(31)	48	64
Net income (loss) attributable to Loews Corporation									(31)	48	64
Total assets	1,728				1,812				1,728	1,812
Corporate [Member]
Revenues:
Net investment income (loss)									230	(10)	146
Operating revenues and other									933	867	499
Total									1,163	857	645
Expenses:
Operating expenses and other									1,004	956	618
Interest									115	108	95
Total									1,119	1,064	713
Income (loss) before income tax									44	(207)	(68)
Income tax (expense) benefit									(9)	46	14
Net income (loss)									35	(161)	(54)
Net income (loss) attributable to Loews Corporation									35	(161)	$ (54)
Total assets	$ 4,850				$ 4,214				$ 4,850	$ 4,214

Schedule I - Condensed Financ_2

Schedule I - Condensed Financial Information of Registrant - Parent Company Only, Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Other assets	$ 3,145	$ 2,443
Total assets	82,243	78,316
LIABILITIES AND SHAREHOLDERS' EQUITY
Total liabilities	60,313	56,930
Shareholders' equity	19,119	18,518
Total liabilities and equity	82,243	78,316
Loews Corporation [Member]
ASSETS
Current assets, principally investment in short term instruments	2,550	2,050
Investments in securities	734	1,112
Investments in capital stocks of subsidiaries, at equity	18,123	17,556
Other assets	24	402
Total assets	21,431	21,120
LIABILITIES AND SHAREHOLDERS' EQUITY
Current liabilities	77	109
Long term debt	1,779	1,778
Deferred income tax and other	456	715
Total liabilities	2,312	2,602
Shareholders' equity	19,119	18,518
Total liabilities and equity	$ 21,431	$ 21,120

Schedule I - Condensed Financ_3

Schedule I - Condensed Financial Information of Registrant - Parent Company Only, Statements of Income and Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Equity in income of subsidiaries									$ 69	$ 73	$ 81
Total	$ 3,876	$ 3,675	$ 3,623	$ 3,757	$ 3,287	$ 3,608	$ 3,590	$ 3,581	14,931	14,066	13,735
Expenses:
Interest									591	574	646
Total									13,812	13,232	12,153
Income before income tax									1,119	834	1,582
Income tax (expense) benefit									248	128	170
Net income									871	706	1,412
Total comprehensive income (loss) attributable to Loews Corporation									1,744	(161)	1,361
Loews Corporation [Member]
Revenues:
Equity in income of subsidiaries									867	819	1,199
Net investment income (loss), interest and other									239	(11)	167
Total									1,106	808	1,366
Expenses:
Administrative									83	127	134
Interest									72	72	72
Total									155	199	206
Income before income tax									951	609	1,160
Income tax (expense) benefit									(19)	27	4
Net income									932	636	1,164
Equity in other comprehensive income (loss) of subsidiaries									812	(797)	197
Total comprehensive income (loss) attributable to Loews Corporation									$ 1,744	$ (161)	$ 1,361

Schedule I - Condensed Financ_4

Schedule I - Condensed Financial Information of Registrant - Parent Company Only, Statements of Income and Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loews Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash dividends paid to the Company by affiliates	$ 927	$ 878	$ 804

Schedule I - Condensed Financ_5

Schedule I - Condensed Financial Information of Registrant - Parent Company Only, Statements of Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities:
Net income	$ 871	$ 706	$ 1,412
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Equity method investees	20	572	25
Provision for deferred income taxes	70	86	(47)
Changes in operating assets and liabilities, net:
Receivables	114	(131)	93
Trading securities	(494)	1,702	108
Net cash flow provided by operating activities	1,741	4,222	2,590
Investing Activities:
Change in investments, primarily short term	(57)	(339)	(167)
Acquisition	(257)	(37)	(1,218)
Other	(178)	(229)	(373)
Net cash flow used by investing activities	(671)	(1,444)	(2,655)
Financing Activities:
Dividends paid	(76)	(80)	(84)
Purchases of treasury shares	(1,051)	(1,026)	(216)
Other	(16)	74	(16)
Net cash flow (used) provided by financing activities	(1,144)	(2,835)	201
Net change in cash	(69)	(67)	145
Cash, beginning of year	405	472	327
Cash, end of year	336	405	472
Loews Corporation [Member]
Operating Activities:
Net income	932	636	1,164
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Equity method investees	36	401	(405)
Provision for deferred income taxes	106	113	77
Changes in operating assets and liabilities, net:
Receivables	1	3	4
Accounts payable and accrued liabilities	(29)	92	(20)
Trading securities	(478)	1,702	100
Other, net	36	19	(41)
Net cash flow provided by operating activities	604	2,966	879
Investing Activities:
Investments in and advances to subsidiaries	183	(135)	12
Change in investments, primarily short term	326	(187)	30
Purchase of Boardwalk Pipelines common units		(1,504)
Acquisition			(620)
Other		(2)	(1)
Net cash flow used by investing activities	509	(1,828)	(579)
Financing Activities:
Dividends paid	(76)	(80)	(84)
Purchases of treasury shares	(1,051)	(1,026)	(216)
Other	(5)	(3)
Net cash flow (used) provided by financing activities	(1,132)	(1,109)	$ (300)
Net change in cash	(19)	29
Cash, beginning of year	29
Cash, end of year	$ 10	$ 29

Schedule V - Supplemental Inf_2

Schedule V - Supplemental Information Concerning Property and Casualty Insurance Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Deferred acquisition costs	$ 662	$ 633
Reserves for unpaid claim and claim adjustment expenses	21,720	21,984
Discount deducted from claim and claim adjustment expense reserves above (based on interest rates ranging from 3.5% to 7.6%)	1,321	1,388
Unearned premiums	4,583	4,183
Net written premiums	7,656	7,345	$ 7,069
Net earned premiums	7,428	7,312	6,988
Net investment income	2,063	1,751	1,992
Incurred claim and claim adjustment expenses related to current year	5,356	5,358	5,201
Incurred claim and claim adjustment expenses related to prior years	(127)	(179)	(381)
Amortization of deferred acquisition costs	1,383	1,335	1,233
Paid claim and claim adjustment expenses	$ 5,576	$ 5,331	$ 5,341

Schedule V - Supplemental Inf_3

Schedule V - Supplemental Information Concerning Property and Casualty Insurance Operations (Parenthetical) (Detail)	Dec. 31, 2019	Dec. 31, 2018
Minimum [Member]
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Discount deducted from claim and claim adjustment expense reserves interest rates	7.60%	7.60%
Maximum [Member]
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items]
Discount deducted from claim and claim adjustment expense reserves interest rates	3.50%	3.50%