CNA Financial (CNA) 10-Q 7 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	May 05, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-5823
Entity Registrant Name	CNA FINANCIAL CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-6169860
Entity Address, Address Line One	151 N. Franklin
Entity Address, Postal Zip Code	60606
Entity Address, City or Town	Chicago,
Entity Address, State or Province	IL
City Area Code	312
Local Phone Number	822-5000
Title of 12(b) Security	Common Stock, Par value $2.50
Trading Symbol	"CNA"
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		271,656,848
Entity Central Index Key	0000021175
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Amendment Flag	false
New York Stock Exchange
Entity Information [Line Items]
Security Exchange Name	NYSE
Chicago Stock Exchange
Entity Information [Line Items]
Security Exchange Name	CHX

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Net earned premiums	$ 1,962	$ 1,869
Net investment income	504	329
Net investment gains (losses)	57	(216)
Non-insurance warranty revenue	338	301
Other revenues	5	8
Total revenues	2,866	2,291
Claims, Benefits and Expenses
Insurance claims and policyholders’ benefits	1,506	1,425
Amortization of deferred acquisition costs	359	344
Non-insurance warranty expense	311	281
Other operating expenses	284	299
Interest	28	31
Total claims, benefits and expenses	2,488	2,380
Income (loss) before income tax	378	(89)
Income tax (expense) benefit	(66)	28
Net income (loss)	$ 312	$ (61)
Basic earnings (loss) per share
Basic earnings per share (in usd per share)	$ 1.15	$ (0.23)
Diluted earnings (loss) per share
Diluted earnings per share (in usd per share)	$ 1.14	$ (0.23)
Weighted Average Outstanding Common Stock and Common Stock Equivalents
Basic (in shares)	271.9	271.5
Diluted (in shares)	272.9	271.5

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net income (loss)	$ 312	$ (61)
Other Comprehensive Loss, net of tax
Net unrealized gains and losses on investments	(627)	(1,055)
Foreign currency translation adjustment	2	(77)
Pension and postretirement benefits	9	11
Other comprehensive loss, net of tax	(616)	(1,121)
Total comprehensive loss	(304)	(1,182)
Net unrealized gains and losses on investments with an allowance for credit losses
Other Comprehensive Loss, net of tax
Net unrealized gains and losses on investments	0	(11)
Net unrealized gains and losses on other investments
Other Comprehensive Loss, net of tax
Net unrealized gains and losses on investments	$ (627)	$ (1,044)

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Investments:
Fixed maturity securities at fair value (amortized cost of $39,291 and $38,953, less allowance for credit loss of $43 and $40)	$ 43,579	$ 44,631
Equity securities at fair value (cost of $927 and $941)	984	992
Limited partnership investments	1,654	1,619
Other invested assets	77	76
Mortgage loans (less allowance for uncollectible receivables of $26 and $26)	1,043	1,068
Short term investments	1,334	1,907
Total investments	48,671	50,293
Cash	588	419
Reinsurance receivables (less allowance for uncollectible receivables of $22 and $21)	5,111	4,457
Insurance receivables (less allowance for uncollectible receivables of $33 and $33)	2,652	2,607
Accrued investment income	399	380
Deferred acquisition costs	741	708
Deferred income taxes	197	66
Property and equipment at cost (less accumulated depreciation of $243 and $231)	244	252
Goodwill	148	148
Deferred non-insurance warranty acquisition expense	3,149	3,068
Other assets	1,813	1,628
Total assets	63,713	64,026
Insurance reserves:
Claim and claim adjustment expenses	23,056	22,706
Unearned premiums	5,319	5,119
Future policy benefits	12,772	13,318
Long term debt	2,777	2,776
Deferred non-insurance warranty revenue	4,119	4,023
Other liabilities (includes $130 and $89 due to Loews Corporation)	3,581	3,377
Total liabilities	51,624	51,319
Commitments and contingencies (Notes C and F)
Stockholders' Equity
Common stock ($2.50 par value; 500,000,000 shares authorized; 273,040,243 shares issued; 271,644,861 and 271,391,603 shares outstanding)	683	683
Additional paid-in capital	2,194	2,211
Retained earnings	9,084	9,081
Accumulated other comprehensive income	187	803
Treasury stock (1,395,382 and 1,648,640 shares), at cost	(59)	(71)
Total stockholders’ equity	12,089	12,707
Total liabilities and stockholders' equity	$ 63,713	$ 64,026

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets - (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Fixed maturities securities at amortized cost	$ 39,291	$ 38,953
Marketable securities fixed maturities allowance for credit loss	43	40
Equity securities at cost	927	941
Mortgage loans on real estate commercial and consumer allowance for credit loss	26	26
Allowance for uncollectible reinsurance	22	21
Allowance for uncollectible insurance receivables	33	33
Accumulated depreciation on property and equipment	243	231
Due to related parties	$ 130	$ 89
Common stock, par value (in usd per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	273,040,243	273,040,243
Common stock, shares outstanding (in shares)	271,644,861	271,391,603
Treasury stock, shares (in shares)	1,395,382	1,648,640

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flows from Operating Activities
Net income (loss)	$ 312	$ (61)
Adjustments to reconcile net income (loss) to net cash flows provided by operating activities:
Deferred income tax expense (benefit)	30	(37)
Trading portfolio activity	(8)	7
Net investment (gains) losses	(57)	216
Equity method investees	14	98
Net amortization of investments	(24)	(15)
Depreciation and amortization	14	16
Changes in:
Receivables, net	(700)	(229)
Accrued investment income	(19)	(8)
Deferred acquisition costs	(32)	(27)
Insurance reserves	605	510
Other, net	(53)	(258)
Net cash flows provided by operating activities	82	212
Dispositions:
Fixed maturity securities - sales	907	823
Fixed maturity securities - maturities, calls and redemptions	1,084	799
Equity securities	119	98
Limited partnerships	49	204
Mortgage loans	42	15
Purchases:
Fixed maturity securities	(2,203)	(1,818)
Equity securities	(81)	(220)
Limited partnerships	(61)	(32)
Mortgage loans	(16)	(61)
Change in other investments	(2)	(6)
Change in short term investments	573	1,267
Purchases of property and equipment	(3)	(3)
Other, net	0	21
Net cash flows provided by investing activities	408	1,087
Cash Flows from Financing Activities
Dividends paid to common stockholders	(310)	(649)
Purchase of treasury stock	(3)	(18)
Other, net	(8)	(8)
Net cash flows used by financing activities	(321)	(675)
Effect of foreign exchange rate changes on cash	0	(9)
Net change in cash	169	615
Cash, beginning of year	419	242
Cash, end of period	$ 588	$ 857

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained EarningsCumulative effect adjustments from changes in accounting guidance, net of tax	Retained EarningsBalance, beginning of period, as adjusted	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Total stockholder's equity at beginning of period at Dec. 31, 2019		$ 683	$ 2,203	$ 9,348	$ (5)	$ 9,343	$ 51	$ (70)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			(16)					16
Dividends to common stockholders ($1.13 and $2.37 per share)				(648)
Net income (loss)	$ (61)			(61)
Other comprehensive loss	(1,121)						(1,121)
Purchase of treasury stock	(18)							(18)
Total stockholder's equity at end of period at Mar. 31, 2020	10,362	683	2,187	8,634			(1,070)	(72)
Total stockholder's equity at beginning of period at Dec. 31, 2020	12,707	683	2,211	9,081	$ 0	$ 9,081	803	(71)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			(17)					15
Dividends to common stockholders ($1.13 and $2.37 per share)				(309)
Net income (loss)	312			312
Other comprehensive loss	(616)						(616)
Purchase of treasury stock	(3)							(3)
Total stockholder's equity at end of period at Mar. 31, 2021	$ 12,089	$ 683	$ 2,194	$ 9,084			$ 187	$ (59)

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (usd per share)	$ 1.13	$ 2.37

General

General	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
General	General Basis of Presentation The Condensed Consolidated Financial Statements include the accounts of CNA Financial Corporation (CNAF) and its subsidiaries. Collectively, CNAF and its subsidiaries are referred to as CNA or the Company. Loews Corporation (Loews) owned approximately 89.5% of the outstanding common stock of CNAF as of March 31, 2021. The accompanying Condensed Consolidated Financial Statements have been prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). Intercompany amounts have been eliminated. Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, including certain financial statement notes, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the Consolidated Financial Statements and notes thereto included in CNAF's Annual Report on Form 10-K filed with the Securities and Exchange Commission for the year ended December 31, 2020, including the summary of significant accounting policies in Note A. The preparation of Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the Condensed Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. The interim financial data as of March 31, 2021 and for the three months ended March 31, 2021 and 2020 is unaudited. However, in the opinion of management, the interim data includes all adjustments, including normal recurring adjustments, necessary for a fair statement of the Company's results for the interim periods. The results of operations for the interim periods are not necessarily indicative of the results to be expected for the full year. Accounting Standards Pending Adoption In August 2018, the FASB issued ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts . The updated accounting guidance requires changes to the measurement and disclosure of long-duration contracts. The guidance requires entities to annually update cash flow assumptions, including morbidity and persistency, and update discount rate assumptions quarterly using an upper-medium grade fixed-income instrument yield. The effect of changes in cash flow assumptions will be recorded in the Company's results of operations and the effect of changes in discount rate assumptions will be recorded in Other comprehensive income. This guidance is effective for interim and annual periods beginning after December 15, 2022, with early adoption permitted. The guidance may be applied using either a modified retrospective transition method or a full retrospective transition method. The guidance requires restatement of prior periods presented. The Company plans to adopt on the effective date, using the modified retrospective transition method and is currently evaluating the effect the updated guidance will have on its financial statements, including the increased disclosure requirements. The annual updating of cash flow assumptions is expected to increase income statement volatility. While the requirements of the new guidance represent a material change from existing GAAP, the underlying economics of the business and related cash flows will be unchanged.

Earnings (Loss) Per Share

Earnings (Loss) Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	Earnings (Loss) Per Share Earnings (loss) per share is based on weighted average number of outstanding common shares. Basic earnings (loss) per share excludes the impact of dilutive securities and is computed by dividing Net income (loss) by the weighted average number of common shares outstanding for the period. Diluted earnings (loss) per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock. For the three months ended March 31, 2021, approximately 1,020 thousand potential shares attributable to exercises or conversions into common stock under stock-based employee compensation plans were included in the calculation of diluted earnings per share. For the same period, approximately 120 thousand potential shares attributable to exercises or conversions into common stock under stock-based employee compensation plans were not included in the calculation of diluted earnings per share because the effect would have been antidilutive. For the three months ended March 31, 2020, approximately 1,015 thousand potential shares attributable to exercises or conversions into common stock under stock-based employee compensation plans were excluded from the calculation of diluted loss per share because the effect would have been antidilutive due to the net loss position of the Company. The Company repurchased 66,000 and 435,376 shares of CNAF common stock at an aggregate cost of $3 million and $18 million during the three months ended March 31, 2021 and 2020.

Investments

Investments	3 Months Ended
	Mar. 31, 2021
Investments [Abstract]
Investments	Investments The significant components of Net investment income are presented in the following table. Three months ended March 31 (In millions) 2021 2020 Fixed maturity securities $ 428 $ 438 Equity securities 29 (44) Limited partnership investments 43 (70) Mortgage loans 14 14 Short term investments — 7 Trading portfolio 5 1 Other 2 — Gross investment income 521 346 Investment expense (17) (17) Net investment income $ 504 $ 329 During the three months ended March 31, 2021 and 2020, $13 million and $(45) million of Net i nvestment income was recognized due to the change in fair value of common stock still held as of March 31, 2021 and 2020. Net investment gains (losses) are presented in the following table. Three months ended March 31 (In millions) 2021 2020 Net investment gains (losses): Fixed maturity securities: Gross gains $ 58 $ 29 Gross losses (20) (104) Net investment gains (losses) on fixed maturity securities 38 (75) Equity securities 2 (133) Derivatives 17 5 Mortgage loans — (13) Net investment gains (losses) $ 57 $ (216) During the three months ended March 31, 2021 and 2020 , $2 million of gains and $(133) million of losses were recognized in Net investment gains (losses) due to the change in fair value of non-redeemable preferred stock still held as of March 31, 2021 and 2020 . The following tables present the activity related to the allowance on available-for-sale securities with credit impairments and purchased credit-deteriorated (PCD) assets. Accrued interest receivable on available-for-sale fixed maturity securities totaled $389 million, $371 million and $390 million as of March 31, 2021, December 31, 2020 and March 31, 2020 and is excluded from the estimate of expected credit losses and the amortized cost basis in the tables included within this Note. (In millions) Corporate and other bonds Asset-backed Total Allowance for credit losses: Balance as of January 1, 2021 $ 23 $ 17 $ 40 Additions to the allowance for credit losses: Securities for which credit losses were not previously recorded 14 — 14 Available-for-sale securities accounted for as PCD assets 2 — 2 Reductions to the allowance for credit losses: Securities sold during the period (realized) 6 — 6 Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis — — — Write-offs charged against the allowance — — — Recoveries of amounts previously written off — — — Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period (6) (1) (7) Balance as of March 31, 2021 $ 27 $ 16 $ 43 (In millions) Corporate and other bonds Asset-backed Total Allowance for credit losses: Balance as of January 1, 2020 $ — $ — $ — Additions to the allowance for credit losses: Impact of adopting ASC 326 6 — 6 Securities for which credit losses were not previously recorded 48 — 48 Available-for-sale securities accounted for as PCD assets 1 — 1 Reductions to the allowance for credit losses: Securities sold during the period (realized) 5 — 5 Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis 1 — 1 Write-offs charged against the allowance — — — Recoveries of amounts previously written off — — — Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period — — — Balance as of March 31, 2020 $ 49 $ — $ 49 The components of available-for-sale impairment losses recognized in earnings by asset type are presented in the following table. The table includes losses on securities with an intention to sell and changes in the allowance for credit losses on securities since acquisition date. Three months ended March 31 (In millions) 2021 2020 Fixed maturity securities available-for-sale: Corporate and other bonds $ 7 $ 91 Asset-backed (1) 1 Impairment losses recognized in earnings $ 6 $ 92 There were no losses recognized on mortgage loans during the three months ended March 31, 2021. During the three months ended March 31, 2020, the Company recognized $13 million of losses related to mortgage loans due to changes in expected credit losses. The following tables present a summary of fixed maturity securities. March 31, 2021 Cost or Gross Gross Allowance Estimated (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 21,110 $ 2,644 $ 71 $ 27 $ 23,656 States, municipalities and political subdivisions 10,041 1,590 31 — 11,600 Asset-backed: Residential mortgage-backed 3,215 108 40 — 3,283 Commercial mortgage-backed 1,952 76 24 16 1,988 Other asset-backed 2,281 71 7 — 2,345 Total asset-backed 7,448 255 71 16 7,616 U.S. Treasury and obligations of government-sponsored enterprises 138 1 7 — 132 Foreign government 508 23 2 — 529 Redeemable preferred stock 12 — — — 12 Total fixed maturity securities available-for-sale 39,257 4,513 182 43 43,545 Total fixed maturity securities trading 34 — — — 34 Total fixed maturity securities $ 39,291 $ 4,513 $ 182 $ 43 $ 43,579 December 31, 2020 Cost or Gross Gross Allowance Estimated (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 20,792 $ 3,578 $ 22 $ 23 $ 24,325 States, municipalities and political subdivisions 9,729 1,863 — — 11,592 Asset-backed: Residential mortgage-backed 3,442 146 1 — 3,587 Commercial mortgage-backed 1,933 93 42 17 1,967 Other asset-backed 2,179 81 9 — 2,251 Total asset-backed 7,554 320 52 17 7,805 U.S. Treasury and obligations of government-sponsored enterprises 339 2 3 — 338 Foreign government 512 32 — — 544 Redeemable preferred stock — — — — — Total fixed maturity securities available-for-sale 38,926 5,795 77 40 44,604 Total fixed maturity securities trading 27 — — — 27 Total fixed maturity securities $ 38,953 $ 5,795 $ 77 $ 40 $ 44,631 The net unrealized gains on investments included in the tables above are recorded as a component of Accumulated other comprehensive income (AOCI). When presented in AOCI, these amounts are net of tax and any required Shadow Adjustments. To the extent that unrealized gains on fixed income securities supporting certain products within the Life & Group segment would result in a premium deficiency if realized, a related increase in Insurance reserves is recorded, net of tax, as a reduction of net unrealized gains through Other comprehensive income (loss) (Shadow Adjustments). As of March 31, 2021 and December 31, 2020, the net unrealized gains on investments included in AOCI were correspondingly reduced by Shadow Adjustments of $2,301 million and $2,773 million. The following tables present the estimated fair value and gross unrealized losses of fixed maturity securities in a gross unrealized loss position for which an allowance for credit loss has not been recorded, by the length of time in which the securities have continuously been in that position. Less than 12 Months 12 Months or Longer Total March 31, 2021 Estimated Gross Estimated Gross Estimated Gross (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 1,868 $ 66 $ 82 $ 5 $ 1,950 $ 71 States, municipalities and political subdivisions 866 31 — — 866 31 Asset-backed: Residential mortgage-backed 1,584 40 12 — 1,596 40 Commercial mortgage-backed 320 9 285 15 605 24 Other asset-backed 337 3 97 4 434 7 Total asset-backed 2,241 52 394 19 2,635 71 U.S. Treasury and obligations of government-sponsored enterprises 65 7 — — 65 7 Foreign government 45 2 — — 45 2 Total $ 5,085 $ 158 $ 476 $ 24 $ 5,561 $ 182 Less than 12 Months 12 Months or Longer Total December 31, 2020 Estimated Gross Estimated Gross Estimated Gross (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 609 $ 21 $ 12 $ 1 $ 621 $ 22 States, municipalities and political subdivisions 33 — — — 33 — Asset-backed: Residential mortgage-backed 71 1 11 — 82 1 Commercial mortgage-backed 533 40 28 2 561 42 Other asset-backed 344 9 13 — 357 9 Total asset-backed 948 50 52 2 1,000 52 U.S. Treasury and obligations of government-sponsored enterprises 63 3 — — 63 3 Foreign government 13 — — — 13 — Total $ 1,666 $ 74 $ 64 $ 3 $ 1,730 $ 77 Based on current facts and circumstances, the Company believes the unrealized losses presented in the March 31, 2021 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 impairment losses to be recorded as of March 31, 2021. Contractual Maturity The following table presents available-for-sale fixed maturity securities by contractual maturity. March 31, 2021 December 31, 2020 (In millions) Cost or Estimated Cost or Estimated Due in one year or less $ 1,468 $ 1,473 $ 1,456 $ 1,458 Due after one year through five years 10,837 11,583 12,304 13,098 Due after five years through ten years 13,640 14,685 12,319 13,878 Due after ten years 13,312 15,804 12,847 16,170 Total $ 39,257 $ 43,545 $ 38,926 $ 44,604 Actual maturities may differ from contractual maturities because certain securities may be called or prepaid. Securities not due at a single date are allocated based on weighted average life. Derivative Financial Instruments The Company holds an embedded derivative on a funds withheld liability with a notional value of $256 million and $190 million and a fair value of $(2) million an d $(19) million as of March 31, 2021 and December 31, 2020. The embedded derivative on the funds withheld liability is accounted for separately and reported with the funds withheld liability in Other liabilities on the Condensed Consolidated Balance Sheets. Investment Commitments As part of its overall investment strategy, the Company invests in various assets which require future purchase, sale or funding commitments. These investments are recorded once funded, and the related commitments may include future capital calls from various third-party limited partnerships, signed and accepted mortgage loan applications, and obligations related to private placement securities. As of March 31, 2021, the Company had commitments to purchase or fund approximately $1,365 million and sell approximately $100 million under the terms of these investments. Mortgage Loans The following table presents the amortized cost basis of mortgage loans for each credit quality indicator by year of origination. The primary credit quality indicators utilized are debt service coverage ratios (DSCR) and loan-to-value ratios (LTV). March 31, 2021 Mortgage Loans Amortized Cost Basis by Origination Year (1) (In millions) 2021 2020 2019 2018 2017 Prior Total DSCR ≥1.6x LTV less than 55% $ — $ 75 $ 32 $ 36 $ 114 $ 187 $ 444 LTV 55% to 65% — 14 20 14 15 11 74 LTV greater than 65% 5 — 5 — — 24 34 DSCR 1.2x - 1.6x LTV less than 55% — — 16 — 5 77 98 LTV 55% to 65% — 20 40 53 27 — 140 LTV greater than 65% 10 52 44 — 9 12 127 DSCR ≤1.2 LTV less than 55% — — 50 — 8 10 68 LTV 55% to 65% — — 48 — — — 48 LTV greater than 65% — — 29 — — 7 36 Total $ 15 $ 161 $ 284 $ 103 $ 178 $ 328 $ 1,069 (1) The values in the table above reflect DSCR on a standardized amortization period and LTV based on the most recent appraised values trended forward using changes in a commercial real estate price index. As of March 31, 2021, accrued interest receivable on mortgage loans totaled $4 million and is excluded from the amortized cost basis disclosed in the table above and the estimate of expected credit losses.

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value	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 iv) deep dives, where the Company performs an independent analysis of the inputs and assumptions used to price individual securities. Assets and Liabilities Measured at Fair Value Assets and liabilities measured at fair value on a recurring basis are presented in the following tables. Corporate bonds and other includes obligations of the U.S. Treasury, government-sponsored enterprises, foreign governments and redeemable preferred stock. March 31, 2021 Total (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate bonds and other $ 152 $ 23,444 $ 767 $ 24,363 States, municipalities and political subdivisions — 11,556 44 11,600 Asset-backed — 7,301 315 7,616 Total fixed maturity securities 152 42,301 1,126 43,579 Equity securities: Common stock 177 — 21 198 Non-redeemable preferred stock 67 711 8 786 Total equity securities 244 711 29 984 Short term and other 1,178 25 — 1,203 Total assets $ 1,574 $ 43,037 $ 1,155 $ 45,766 Liabilities Other liabilities $ — $ 2 $ — $ 2 Total liabilities $ — $ 2 $ — $ 2 December 31, 2020 Total (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate bonds and other $ 355 $ 24,109 $ 770 $ 25,234 States, municipalities and political subdivisions — 11,546 46 11,592 Asset-backed — 7,497 308 7,805 Total fixed maturity securities 355 43,152 1,124 44,631 Equity securities: Common stock 175 — 20 195 Non-redeemable preferred stock 68 722 7 797 Total equity securities 243 722 27 992 Short term and other 1,761 28 — 1,789 Total assets $ 2,359 $ 43,902 $ 1,151 $ 47,412 Liabilities Other liabilities $ — $ 19 $ — $ 19 Total liabilities $ — $ 19 $ — $ 19 The tables below present a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3). Level 3 (In millions) Corporate bonds and other States, municipalities and political subdivisions Asset-backed Equity securities Total Balance as of January 1, 2021 $ 770 $ 46 $ 308 $ 27 $ 1,151 Total realized and unrealized investment gains (losses): Reported in Net investment gains (losses) (13) — — 1 (12) Reported in Net investment income — — 2 1 3 Reported in Other comprehensive income (loss) (40) (2) (9) — (51) Total realized and unrealized investment gains (losses) (53) (2) (7) 2 (60) Purchases 42 — 30 — 72 Sales — — — — — Settlements (2) — (17) — (19) Transfers into Level 3 10 — 9 — 19 Transfers out of Level 3 — — (8) — (8) Balance as of March 31, 2021 $ 767 $ 44 $ 315 $ 29 $ 1,155 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2021 recognized in Net income (loss) in the period $ — $ — $ — $ 2 $ 2 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2021 recognized in Other comprehensive income (loss) in the period (40) (2) (9) — (51) Level 3 (In millions) Corporate bonds and other States, municipalities and political subdivisions Asset-backed Equity securities Total Balance as of January 1, 2020 $ 468 $ — $ 165 $ 18 $ 651 Total realized and unrealized investment gains (losses): Reported in Net investment gains (losses) — — — — — Reported in Net investment income — — — (3) (3) Reported in Other comprehensive income (loss) (37) — (9) — (46) Total realized and unrealized investment gains (losses) (37) — (9) (3) (49) Purchases 67 — 45 — 112 Sales — — — — — Settlements (2) — (3) — (5) Transfers into Level 3 — — — — — Transfers out of Level 3 — — (1) — (1) Balance as of March 31, 2020 $ 496 $ — $ 197 $ 15 $ 708 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2020 recognized in Net income (loss) in the period $ — $ — $ — $ (3) $ (3) Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2020 recognized in Other comprehensive income (loss) in the period (35) — (9) — (44) 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 and exchange traded bonds, valued using quoted market prices. Level 2 securities include most other fixed maturity securities as the significant inputs are observable in the marketplace. All classes of Level 2 fixed maturity securities are valued using a methodology based on information generated by market transactions involving identical or comparable assets, a discounted cash flow methodology, or a combination of both when necessary. Common inputs for all classes of fixed maturity securities include prices from recently executed transactions of similar securities, marketplace quotes, benchmark yields, spreads off benchmark yields, interest rates and U.S. Treasury or swap curves. Specifically for asset-backed securities, key inputs include prepayment and default projections based on past performance of the underlying collateral and current market data. Fixed maturity securities are primarily assigned to Level 3 in cases where broker/dealer quotes are significant inputs to the valuation and there is a lack of transparency as to whether these quotes are based on information that is observable in the marketplace. Level 3 securities also include private placement debt securities whose fair value is determined using internal models with some inputs that are not market observable. Equity Securities Level 1 equity 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 inputs that are not market observable. 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 and treasury bills. Level 2 primarily includes commercial paper, for which all inputs are market observable. Fixed maturity securities purchased within one year of maturity are classified consistent with fixed maturity securities discussed above. Short term investments as presented in the tables above differ from the amounts presented on the Condensed Consolidated Balance Sheets because certain short term investments, such as time deposits, are not measured at fair value. As of March 31, 2021 and December 31, 2020, there were $72 million and $71 million of overseas deposits within Other invested assets, which can be redeemed at net asset value in 90 days or less. Overseas deposits are excluded from the fair value hierarchy because their fair value is recorded using the net asset value per share (or equivalent) practical expedient. Derivative Financial Investments The embedded derivative on funds withheld liability is valued using the change in fair value of the assets supporting the funds withheld liability, which are fixed maturity securities primarily valued with observable inputs. Significant Unobservable Inputs The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurements 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 these unobservable inputs is neither provided nor reasonably available to the Company. The weighted average rate is calculated based on fair value. March 31, 2021 Estimated Fair Value Valuation Technique(s) Unobservable Input(s) Range Fixed maturity securities $ 936 Discounted cash flow Credit spread 1% - 8% (2%) December 31, 2020 Estimated Fair Value Valuation Technique(s) Unobservable Input(s) Range Fixed maturity securities $ 966 Discounted cash flow Credit spread 1% - 8% (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 and estimated fair value of the Company's financial assets and liabilities which are not measured at fair value on the Condensed Consolidated Balance Sheets are presented in the following tables. March 31, 2021 Carrying Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 1,043 $ — $ — $ 1,107 $ 1,107 Liabilities Long term debt $ 2,777 $ — $ 3,016 $ — $ 3,016 December 31, 2020 Carrying Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 1,068 $ — $ — $ 1,151 $ 1,151 Liabilities Long term debt $ 2,776 $ — $ 3,148 $ — $ 3,148 The carrying amounts reported on the Condensed Consolidated Balance Sheets for Cash, Short term investments not carried at fair value, Accrued investment income and certain Other assets and Other liabilities approximate fair value due to the short term nature of these items. These assets and liabilities are not listed in the tables above.

Claim and Claim Adjustment Expe

Claim and Claim Adjustment Expense Reserves	3 Months Ended
	Mar. 31, 2021
Liability for Claims and Claims Adjustment Expense [Abstract]
Claim and Claim Adjustment Expense Reserves	Claim and Claim Adjustment Expense Reserves 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. The Company's reserve projections are based primarily on detailed analysis of the facts in each case, the Company'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 the Company's ultimate cost for insurance losses will not exceed current estimates. Catastrophes are an inherent risk of the property and casualty insurance business and have contributed to material period-to-period fluctuations in our results of operations and/or equity. The Company reported catastrophe losses, net of reinsurance, of $125 million and $75 million for the three months ended March 31, 2021 and 2020. Net catastrophe losses for the three months ended March 31, 2021 were primarily driven by Winter Storms Uri and Viola. Net catastrophe losses for the three months ended March 31, 2020 included $13 million related to the COVID-19 pandemic, with the remaining $62 million related primarily to U.S. weather related events. Liability for Unpaid Claim and Claim Adjustment Expenses The following table presents a reconciliation between beginning and ending claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves of the Life & Group segment. For the three months ended March 31, 2021 (In millions) 2021 2020 Reserves, beginning of year: Gross $ 22,706 $ 21,720 Ceded 4,005 3,835 Net reserves, beginning of year 18,701 17,885 Reduction of net reserves due to Excess Workers' Compensation Loss Portfolio Transfer (632) — Net incurred claim and claim adjustment expenses: Provision for insured events of current year 1,474 1,355 Increase (decrease) in provision for insured events of prior years (54) (8) Amortization of discount 50 51 Total net incurred (1) 1,470 1,398 Net payments attributable to: Current year events (85) (72) Prior year events (1,067) (1,218) Total net payments (1,152) (1,290) Foreign currency translation adjustment and other (32) (88) Net reserves, end of period 18,355 17,905 Ceded reserves, end of period 4,701 3,967 Gross reserves, end of period $ 23,056 $ 21,872 (1) Total net incurred above does not agree to Insurance claims and policyholders' benefits as reflected on the Condensed Consolidated Statements of Operations due to amounts related to retroactive reinsurance deferred gain accounting, the loss on the Excess Workers' Compensation Loss Portfolio Transfer, uncollectible reinsurance and benefit expenses related to future policy benefits, which are not reflected in the table above. Net Prior Year Development Changes in estimates of claim and claim adjustment expense reserves, net of reinsurance, for prior years are defined as net prior year loss reserve development (development). These changes can be favorable or unfavorable. The following table presents development recorded for the Specialty, Commercial, International and Corporate & Other segments. Three months ended March 31 (In millions) 2021 2020 Pretax (favorable) unfavorable development: Specialty $ (15) $ (11) Commercial — (4) International — — Corporate & Other — — Total pretax (favorable) unfavorable development $ (15) $ (15) Specialty The following table presents further detail of the development recorded for the Specialty segment. Three months ended March 31 (In millions) 2021 2020 Pretax (favorable) unfavorable development: Medical Professional Liability $ 8 $ 10 Other Professional Liability and Management Liability — 3 Surety (15) (30) Warranty (8) — Other — 6 Total pretax (favorable) unfavorable development $ (15) $ (11) 2021 Favorable development in surety was primarily due to lower than expected frequency and lack of systemic activity in recent accident years. 2020 Unfavorable development in medical professional liability was primarily due to unfavorable outcomes on specific claims in accident years 2015 and 2016 in the Company's aging services business. Favorable development in surety was primarily due to lower than expected frequency for accident years 2017 and prior. Commercial The following table presents further detail of the development recorded for the Commercial segment. Three months ended March 31 (In millions) 2021 2020 Pretax (favorable) unfavorable development: Commercial Auto $ — $ 9 General Liability — — Workers' Compensation — (13) Property and Other — — Total pretax (favorable) unfavorable development $ — $ (4) 2020 Favorable development in workers’ compensation was due to favorable medical trends driving lower than expected severity in accident years 2016 through 2018. International There was no development recorded in the International segment for the three months ended March 31, 2021 and 2020. Asbestos & Environmental Pollution (A&EP) Reserves In 2010, Continental Casualty Company (CCC) together with several of the Company’s insurance subsidiaries completed a transaction with National Indemnity Company (NICO), a subsidiary of Berkshire Hathaway Inc., under which substantially all of the Company’s legacy A&EP liabilities were ceded to NICO through a Loss Portfolio Transfer (LPT). At the effective date of the transaction, the Company ceded approximately $1.6 billion of net A&EP claim and allocated claim adjustment expense reserves to NICO under a retroactive reinsurance agreement with an aggregate limit of $4 billion. The $1.6 billion of claim and allocated claim adjustment expense reserves ceded to NICO was net of $1.2 billion of ceded claim and allocated claim adjustment expense reserves under existing third-party reinsurance contracts. The NICO LPT aggregate reinsurance limit also covers credit risk on the existing third-party reinsurance related to these liabilities. The Company paid NICO a reinsurance premium of $2 billion and transferred to NICO billed third-party reinsurance receivables related to A&EP claims with a net book value of $215 million, resulting in total consideration of $2.2 billion. In years subsequent to the effective date of the LPT, the Company recognized adverse prior year development on its A&EP reserves resulting in additional amounts ceded under the LPT. As a result, the cumulative amounts ceded under the LPT have exceeded the $2.2 billion consideration paid, resulting in the NICO LPT moving into a gain position, requiring retroactive reinsurance accounting. Under retroactive reinsurance accounting, this gain is deferred and only recognized in earnings in proportion to actual paid recoveries under the LPT. Over the life of the contract, there is no economic impact as long as any additional losses incurred are within the limit of the LPT. In a period in which the Company recognizes a change in the estimate of A&EP reserves that increases or decreases the amounts ceded under the LPT, the proportion of actual paid recoveries to total ceded losses is affected and the change in the deferred gain is recognized in earnings as if the revised estimate of ceded losses was available at the effective date of the LPT. The effect of the deferred retroactive reinsurance benefit is recorded in Insurance claims and policyholders' benefits on the Condensed Consolidated Statements of Operations. The impact of the LPT on the Condensed Consolidated Statements of Operations was the recognition of a retroactive reinsurance benefit of $10 million and $14 million for the three months ended March 31, 2021 and 2020. As of March 31, 2021 and December 31, 2020, the cumulative amounts ceded under the LPT were $3.3 billion. The unrecognized deferred retroactive reinsurance benefit was $388 million and $398 million as of March 31, 2021 and December 31, 2020 and is included within Other liabilities on the Condensed Consolidated Balance Sheets. NICO established a collateral trust account as security for its obligations to the Company. The fair value of the collateral trust account was $4.6 billion and $4.2 billion as of March 31, 2021 and December 31, 2020. In addition, Berkshire Hathaway Inc. guaranteed the payment obligations of NICO up to the aggregate reinsurance limit as well as certain of NICO’s performance obligations under the trust agreement. NICO is responsible for claims handling and billing and collection from third-party reinsurers related to the majority of the Company’s A&EP claims. Excess Workers' Compensation LPT On February 5, 2021, CCC completed a transaction with Cavello Bay Reinsurance Limited (Cavello), a subsidiary of Enstar Group Limited, under which certain legacy excess workers’ compensation (EWC) liabilities were ceded to Cavello. Under the terms of the transaction, based on reserves in place as of January 1, 2020, the Company ceded approximately $690 million of net EWC claim and allocated claim adjustment expense reserves to Cavello under an LPT with an aggregate limit of $1 billion. The Company paid Cavello a reinsurance premium of $697 million, less claims paid between January 1, 2020 and the closing date of the agreement of $64 million. After transaction costs, the Company recognized an after-tax loss of approximately $12 million in the Corporate & Other segment for the three months ended March 31, 2021 related to the EWC LPT. Cavello established a collateral trust account as security for its obligations to the Company, which will be maintained at 105% of outstanding reserves. As of March 31, 2021, the remaining amount available under the $1 billion aggregate limit of the EWC LPT was $310 million on an incurred basis. Credit Risk for Ceded Reserves The majority of the Company’s outstanding voluntary reinsurance receivables are due from reinsurers with financial strength ratings of A- or higher. Receivables due from reinsurers with lower financial strength ratings are primarily due from captive reinsurers and are backed by collateral arrangements.

Legal Proceedings, Contingencie

Legal Proceedings, Contingencies and Guarantees	3 Months Ended
	Mar. 31, 2021
Legal Proceedings, Commitments and Contingencies, and Guarantees [Abstract]
Legal Proceedings, Contingencies and Guarantees	Legal Proceedings, Contingencies and Guarantees The Company is a party to various claims and litigation incidental to its business, which, based on the facts and circumstances currently known, are not material to the Company's results of operations or financial position. Guarantees As of March 31, 2021 and December 31, 2020, the Company had recorded liabilities of approximately $5 million related to guarantee and indemnification agreements. Management does not believe that any future indemnity claims will be significantly greater than the amounts recorded. The Company has provided guarantees, if the primary obligor fails to perform, to holders of structured settlement annuities issued by a previously owned subsidiary. As of March 31, 2021, the potential amount of future payments the Company could be required to pay under these guarantees was approximately $1.6 billion, which will be paid over the lifetime of the annuitants. The Company does not believe any payment is likely under these guarantees, as the Company is the beneficiary of a trust that must be maintained at a level that approximates the discounted reserves for these annuities.

Benefit Plans

Benefit Plans	3 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The components of net periodic pension cost (benefit) are presented in the following table. Three months ended March 31 (In millions) 2021 2020 Net periodic pension cost (benefit) Interest cost on projected benefit obligation $ 15 $ 20 Expected return on plan assets (38) (39) Amortization of net actuarial (gain) loss 12 11 Settlement loss — 1 Total net periodic pension cost (benefit) $ (11) $ (7) For the three months ended March 31, 2021, the Company recognized $3 million of non-service benefit in Insurance claims and policyholders' benefits and $8 million of non-service benefit in Other operating expenses related to net periodic pension benefit. For the three months ended March 31, 2020, the Company recognized $2 million of non-service benefit in Insurance claims and policyholders' benefits and $5 million of non-service benefit in Other operating expenses related to net periodic pension benefit.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss) by Component	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) by Component	Accumulated Other Comprehensive Income (Loss) by Component The tables below display the changes in Accumulated other comprehensive income (loss) by component. (In millions) Net unrealized gains (losses) on investments with an allowance for credit losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2021 $ — $ 1,745 $ (848) $ (94) $ 803 Other comprehensive income (loss) before reclassifications (3) (593) — 2 (594) Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $1, $(8), $2, $— and $(5) (3) 34 (9) — 22 Other comprehensive income (loss) net of tax (expense) benefit of $—, $162, $(2), $— and $160 — (627) 9 2 (616) Balance as of March 31, 2021 $ — $ 1,118 $ (839) $ (92) $ 187 (In millions) Net unrealized gains (losses) on investments with an allowance for credit losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2020 $ — $ 1,025 $ (833) $ (141) $ 51 Other comprehensive income (loss) before reclassifications (48) (1,066) 1 (77) (1,190) Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $10, $6, $3, $— and $19 (37) (22) (10) — (69) Other comprehensive income (loss) net of tax (expense) benefit of $3, $281, $(3), $— and $281 (11) (1,044) 11 (77) (1,121) Balance as of March 31, 2020 $ (11) $ (19) $ (822) $ (218) $ (1,070) Amounts reclassified from Accumulated other comprehensive income (loss) shown above are reported in Net income (loss) as follows: Component of AOCI Consolidated Statements of Operations Line Item Affected by Reclassifications Net unrealized gains (losses) on investments with an allowance for credit losses and Net unrealized gains (losses) on other investments Net investment gains (losses) Pension and postretirement benefits Other operating expenses and Insurance claims and policyholders' benefits

Business Segments

Business Segments	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Business Segments	Business Segments The Company's property and casualty commercial insurance operations are managed and reported in three business segments: Specialty, Commercial and International. These three segments are collectively referred to as Property & Casualty Operations. The Company's operations outside of Property & Casualty Operations are managed and reported in two segments: Life & Group and Corporate & Other. Effective January 1, 2021, and in connection with the ceding of certain legacy reserves under a retroactive reinsurance agreement executed in February 2021, management changed the segment presentation of a legacy portfolio of excess workers’ compensation policies relating to business written in 2007 and prior. This business, which was previously reported as part of the Commercial business segment, is now reported as part of the Corporate & Other business segment. Further information on this retroactive reinsurance agreement is provided in Note E. In addition, a determination was made to change the segment presentation of certain legacy mass tort reserves. Similar to the aforementioned excess workers’ compensation legacy business, these legacy mass tort reserves were previously reported in the Commercial business segment and are now reported as part of the Corporate & Other business segment. These changes were made to better reflect the manner in which the Company is organized for purposes of making operating decisions and assessing performance. Prior period information has been conformed to the new segment presentation. The accounting policies of the segments are the same as those described in Note A to the Consolidated Financial Statements within CNAF's Annual Report on Form 10-K for the year ended December 31, 2020. The Company manages most of its assets on a legal entity basis, while segment operations are generally conducted across legal entities. As such, only Insurance and Reinsurance receivables, Insurance reserves, Deferred acquisition costs, Goodwill and Deferred non-insurance warranty acquisition expense and revenue are readily identifiable for individual segments. Distinct investment portfolios are not maintained for every individual segment; accordingly, allocation of assets to each segment is not performed. Therefore, a significant portion of Net investment income and Net investment gains or losses are allocated primarily based on each segment's net carried insurance reserves, as adjusted. All significant intersegment income and expense have been eliminated. Income taxes have been allocated on the basis of the taxable income of the segments. In the following tables, certain financial measures are presented to provide information used by management to monitor the Company's operating performance. Management utilizes these financial measures to monitor the Company's insurance operations and investment portfolio. The performance of the Company's insurance operations is monitored by management through core income (loss), which is derived from certain income statement amounts. The Company's investment portfolio is monitored by management through analysis of various factors including unrealized gains and losses on securities, portfolio duration and exposure to market and credit risk. Core income (loss) is calculated by excluding from net income (loss) the after-tax effects of net investment gains or losses and any cumulative effects of changes in accounting guidance. The calculation of core income (loss) excludes net investment gains or losses because net investment gains or losses are generally driven by economic factors that are not necessarily reflective of our primary operations. The Company's results of operations and selected balance sheet items by segment are presented in the following tables. Three months ended March 31, 2021 Specialty Commercial International Life & Corporate (In millions) Eliminations Total Operating revenues Net earned premiums $ 735 $ 855 $ 252 $ 120 $ — $ — $ 1,962 Net investment income 117 148 14 219 6 — 504 Non-insurance warranty revenue 338 — — — — — 338 Other revenues — 5 — 1 1 (2) 5 Total operating revenues 1,190 1,008 266 340 7 (2) 2,809 Claims, benefits and expenses Net incurred claims and benefits 427 639 155 281 (2) — 1,500 Policyholders’ dividends 1 5 — — — — 6 Amortization of deferred acquisition costs 154 153 52 — — — 359 Non-insurance warranty expense 311 — — — — — 311 Other insurance related expenses 70 115 35 25 10 — 255 Other expenses 11 9 (5) 2 42 (2) 57 Total claims, benefits and expenses 974 921 237 308 50 (2) 2,488 Core income (loss) before income tax 216 87 29 32 (43) — 321 Income tax (expense) benefit on core income (loss) (46) (18) (5) 4 7 — (58) Core income (loss) $ 170 $ 69 $ 24 $ 36 $ (36) $ — 263 Net investment gains (losses) 57 Income tax (expense) benefit on net investment gains (losses) (8) Net investment gains (losses), after tax 49 Net income (loss) $ 312 March 31, 2021 (In millions) Reinsurance receivables $ 957 $ 859 $ 300 $ 389 $ 2,628 $ — $ 5,133 Insurance receivables 1,004 1,322 357 2 — — 2,685 Deferred acquisition costs 340 299 102 — — — 741 Goodwill 117 — 31 — — — 148 Deferred non-insurance warranty acquisition expense 3,149 — — — — — 3,149 Insurance reserves Claim and claim adjustment expenses 5,916 8,449 2,142 3,726 2,823 — 23,056 Unearned premiums 2,666 1,930 588 135 — — 5,319 Future policy benefits — — — 12,772 — — 12,772 Deferred non-insurance warranty revenue 4,119 — — — — — 4,119 Three months ended March 31, 2020 Specialty Commercial International Life & Corporate (In millions) Eliminations Total Operating revenues Net earned premiums $ 685 $ 818 $ 239 $ 127 $ — $ — $ 1,869 Net investment income 56 42 15 208 8 — 329 Non-insurance warranty revenue 301 — — — — — 301 Other revenues 1 8 — — 1 (2) 8 Total operating revenues 1,043 868 254 335 9 (2) 2,507 Claims, benefits and expenses Net incurred claims and benefits 405 555 154 316 (11) — 1,419 Policyholders’ dividends 1 5 — — — — 6 Amortization of deferred acquisition costs 151 144 49 — — — 344 Non-insurance warranty expense 281 — — — — — 281 Other insurance related expenses 69 127 36 26 — — 258 Other expenses 13 6 13 3 39 (2) 72 Total claims, benefits and expenses 920 837 252 345 28 (2) 2,380 Core income (loss) before income tax 123 31 2 (10) (19) — 127 Income tax (expense) benefit on core income (loss) (27) (8) — 14 2 — (19) Core income (loss) $ 96 $ 23 $ 2 $ 4 $ (17) $ — 108 Net investment gains (losses) (216) Income tax (expense) benefit on net investment gains (losses) 47 Net investment gains (losses), after tax (169) Net income (loss) $ (61) December 31, 2020 (In millions) Reinsurance receivables $ 886 $ 848 $ 302 $ 390 $ 2,052 $ — $ 4,478 Insurance receivables 1,052 1,254 328 4 2 — 2,640 Deferred acquisition costs 330 281 97 — — — 708 Goodwill 117 — 31 — — — 148 Deferred non-insurance warranty acquisition expense 3,068 — — — — — 3,068 Insurance reserves Claim and claim adjustment expenses 5,748 8,250 2,091 3,743 2,874 — 22,706 Unearned premiums 2,635 1,824 546 114 — — 5,119 Future policy benefits — — — 13,318 — — 13,318 Deferred non-insurance warranty revenue 4,023 — — — — — 4,023 The following table presents operating revenues by line of business for each reportable segment. Three months ended March 31 (In millions) 2021 2020 Specialty Management & Professional Liability $ 667 $ 568 Surety 142 138 Warranty & Alternative Risks 381 337 Specialty revenues 1,190 1,043 Commercial Middle Market 375 335 Construction 309 250 Small Business 126 112 Other Commercial 198 171 Commercial revenues 1,008 868 International Canada 79 73 Europe 111 92 Hardy 76 89 International revenues 266 254 Life & Group revenues 340 335 Corporate & Other revenues 7 9 Eliminations (2) (2) Total operating revenues 2,809 2,507 Net investment gains (losses) 57 (216) Total revenues $ 2,866 $ 2,291

Non-Insurance Revenues from Con

Non-Insurance Revenues from Contracts with Customers	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Non-Insurance Revenues from Contracts with Customers	Non-Insurance Revenues from Contracts with CustomersThe Company had deferred non-insurance warranty revenue balances of $4.1 billion and $4.0 billion reported in Deferred non-insurance warranty revenue as of March 31, 2021 and December 31, 2020. For the three months ended March 31, 2021 and 2020, the Company recognized $0.3 billion of revenues that were included in the deferred revenue balance as of January 1, 2021 and 2020. For the three months ended March 31, 2021 and 2020, Non-insurance warranty revenue recognized from performance obligations related to prior periods due to a change in estimate was not material. The Company expects to recognize approximately $0.9 billion of the deferred revenue in the remainder of 2021, $1.0 billion in 2022, $0.8 billion in 2023 and $1.3 billion thereafter.

General (Policies)

General (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	The Condensed Consolidated Financial Statements include the accounts of CNA Financial Corporation (CNAF) and its subsidiaries. Collectively, CNAF and its subsidiaries are referred to as CNA or the Company. Loews Corporation (Loews) owned approximately 89.5% of the outstanding common stock of CNAF as of March 31, 2021.The accompanying Condensed Consolidated Financial Statements have been prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). Intercompany amounts have been eliminated.
Use of Estimates	The preparation of Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the Condensed Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates.
Accounting Standards Pending Adoption	Accounting Standards Pending Adoption In August 2018, the FASB issued ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts . The updated accounting guidance requires changes to the measurement and disclosure of long-duration contracts. The guidance requires entities to annually update cash flow assumptions, including morbidity and persistency, and update discount rate assumptions quarterly using an upper-medium grade fixed-income instrument yield. The effect of changes in cash flow assumptions will be recorded in the Company's results of operations and the effect of changes in discount rate assumptions will be recorded in Other comprehensive income. This guidance is effective for interim and annual periods beginning after December 15, 2022, with early adoption permitted. The guidance may be applied using either a modified retrospective transition method or a full retrospective transition method. The guidance requires restatement of prior periods presented. The Company plans to adopt on the effective date, using the modified retrospective transition method and is currently evaluating the effect the updated guidance will have on its financial statements, including the increased disclosure requirements. The annual updating of cash flow assumptions is expected to increase income statement volatility. While the requirements of the new guidance represent a material change from existing GAAP, the underlying economics of the business and related cash flows will be unchanged.
Earnings (Loss) Per Share	Earnings (Loss) Per ShareEarnings (loss) per share is based on weighted average number of outstanding common shares. Basic earnings (loss) per share excludes the impact of dilutive securities and is computed by dividing Net income (loss) by the weighted average number of common shares outstanding for the period. Diluted earnings (loss) per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock.

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2021
Investments [Abstract]
Net investment income	The significant components of Net investment income are presented in the following table. Three months ended March 31 (In millions) 2021 2020 Fixed maturity securities $ 428 $ 438 Equity securities 29 (44) Limited partnership investments 43 (70) Mortgage loans 14 14 Short term investments — 7 Trading portfolio 5 1 Other 2 — Gross investment income 521 346 Investment expense (17) (17) Net investment income $ 504 $ 329
Net realized investment gains (losses)	Net investment gains (losses) are presented in the following table. Three months ended March 31 (In millions) 2021 2020 Net investment gains (losses): Fixed maturity securities: Gross gains $ 58 $ 29 Gross losses (20) (104) Net investment gains (losses) on fixed maturity securities 38 (75) Equity securities 2 (133) Derivatives 17 5 Mortgage loans — (13) Net investment gains (losses) $ 57 $ (216)
Debt securities, available-for-sale, allowance for credit loss	Accrued interest receivable on available-for-sale fixed maturity securities totaled $389 million, $371 million and $390 million as of March 31, 2021, December 31, 2020 and March 31, 2020 and is excluded from the estimate of expected credit losses and the amortized cost basis in the tables included within this Note. (In millions) Corporate and other bonds Asset-backed Total Allowance for credit losses: Balance as of January 1, 2021 $ 23 $ 17 $ 40 Additions to the allowance for credit losses: Securities for which credit losses were not previously recorded 14 — 14 Available-for-sale securities accounted for as PCD assets 2 — 2 Reductions to the allowance for credit losses: Securities sold during the period (realized) 6 — 6 Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis — — — Write-offs charged against the allowance — — — Recoveries of amounts previously written off — — — Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period (6) (1) (7) Balance as of March 31, 2021 $ 27 $ 16 $ 43 (In millions) Corporate and other bonds Asset-backed Total Allowance for credit losses: Balance as of January 1, 2020 $ — $ — $ — Additions to the allowance for credit losses: Impact of adopting ASC 326 6 — 6 Securities for which credit losses were not previously recorded 48 — 48 Available-for-sale securities accounted for as PCD assets 1 — 1 Reductions to the allowance for credit losses: Securities sold during the period (realized) 5 — 5 Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis 1 — 1 Write-offs charged against the allowance — — — Recoveries of amounts previously written off — — — Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period — — — Balance as of March 31, 2020 $ 49 $ — $ 49
Components of net other than temporary impairment losses recognized in earnings by asset type	The table includes losses on securities with an intention to sell and changes in the allowance for credit losses on securities since acquisition date. Three months ended March 31 (In millions) 2021 2020 Fixed maturity securities available-for-sale: Corporate and other bonds $ 7 $ 91 Asset-backed (1) 1 Impairment losses recognized in earnings $ 6 $ 92
Summary of fixed maturity securities	The following tables present a summary of fixed maturity securities. March 31, 2021 Cost or Gross Gross Allowance Estimated (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 21,110 $ 2,644 $ 71 $ 27 $ 23,656 States, municipalities and political subdivisions 10,041 1,590 31 — 11,600 Asset-backed: Residential mortgage-backed 3,215 108 40 — 3,283 Commercial mortgage-backed 1,952 76 24 16 1,988 Other asset-backed 2,281 71 7 — 2,345 Total asset-backed 7,448 255 71 16 7,616 U.S. Treasury and obligations of government-sponsored enterprises 138 1 7 — 132 Foreign government 508 23 2 — 529 Redeemable preferred stock 12 — — — 12 Total fixed maturity securities available-for-sale 39,257 4,513 182 43 43,545 Total fixed maturity securities trading 34 — — — 34 Total fixed maturity securities $ 39,291 $ 4,513 $ 182 $ 43 $ 43,579 December 31, 2020 Cost or Gross Gross Allowance Estimated (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 20,792 $ 3,578 $ 22 $ 23 $ 24,325 States, municipalities and political subdivisions 9,729 1,863 — — 11,592 Asset-backed: Residential mortgage-backed 3,442 146 1 — 3,587 Commercial mortgage-backed 1,933 93 42 17 1,967 Other asset-backed 2,179 81 9 — 2,251 Total asset-backed 7,554 320 52 17 7,805 U.S. Treasury and obligations of government-sponsored enterprises 339 2 3 — 338 Foreign government 512 32 — — 544 Redeemable preferred stock — — — — — Total fixed maturity securities available-for-sale 38,926 5,795 77 40 44,604 Total fixed maturity securities trading 27 — — — 27 Total fixed maturity securities $ 38,953 $ 5,795 $ 77 $ 40 $ 44,631
Securities in a gross unrealized loss position	The following tables present the estimated fair value and gross unrealized losses of fixed maturity securities in a gross unrealized loss position for which an allowance for credit loss has not been recorded, by the length of time in which the securities have continuously been in that position. Less than 12 Months 12 Months or Longer Total March 31, 2021 Estimated Gross Estimated Gross Estimated Gross (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 1,868 $ 66 $ 82 $ 5 $ 1,950 $ 71 States, municipalities and political subdivisions 866 31 — — 866 31 Asset-backed: Residential mortgage-backed 1,584 40 12 — 1,596 40 Commercial mortgage-backed 320 9 285 15 605 24 Other asset-backed 337 3 97 4 434 7 Total asset-backed 2,241 52 394 19 2,635 71 U.S. Treasury and obligations of government-sponsored enterprises 65 7 — — 65 7 Foreign government 45 2 — — 45 2 Total $ 5,085 $ 158 $ 476 $ 24 $ 5,561 $ 182 Less than 12 Months 12 Months or Longer Total December 31, 2020 Estimated Gross Estimated Gross Estimated Gross (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 609 $ 21 $ 12 $ 1 $ 621 $ 22 States, municipalities and political subdivisions 33 — — — 33 — Asset-backed: Residential mortgage-backed 71 1 11 — 82 1 Commercial mortgage-backed 533 40 28 2 561 42 Other asset-backed 344 9 13 — 357 9 Total asset-backed 948 50 52 2 1,000 52 U.S. Treasury and obligations of government-sponsored enterprises 63 3 — — 63 3 Foreign government 13 — — — 13 — Total $ 1,666 $ 74 $ 64 $ 3 $ 1,730 $ 77
Contractual maturity	The following table presents available-for-sale fixed maturity securities by contractual maturity. March 31, 2021 December 31, 2020 (In millions) Cost or Estimated Cost or Estimated Due in one year or less $ 1,468 $ 1,473 $ 1,456 $ 1,458 Due after one year through five years 10,837 11,583 12,304 13,098 Due after five years through ten years 13,640 14,685 12,319 13,878 Due after ten years 13,312 15,804 12,847 16,170 Total $ 39,257 $ 43,545 $ 38,926 $ 44,604
Financing receivable credit quality indicators	The following table presents the amortized cost basis of mortgage loans for each credit quality indicator by year of origination. The primary credit quality indicators utilized are debt service coverage ratios (DSCR) and loan-to-value ratios (LTV). March 31, 2021 Mortgage Loans Amortized Cost Basis by Origination Year (1) (In millions) 2021 2020 2019 2018 2017 Prior Total DSCR ≥1.6x LTV less than 55% $ — $ 75 $ 32 $ 36 $ 114 $ 187 $ 444 LTV 55% to 65% — 14 20 14 15 11 74 LTV greater than 65% 5 — 5 — — 24 34 DSCR 1.2x - 1.6x LTV less than 55% — — 16 — 5 77 98 LTV 55% to 65% — 20 40 53 27 — 140 LTV greater than 65% 10 52 44 — 9 12 127 DSCR ≤1.2 LTV less than 55% — — 50 — 8 10 68 LTV 55% to 65% — — 48 — — — 48 LTV greater than 65% — — 29 — — 7 36 Total $ 15 $ 161 $ 284 $ 103 $ 178 $ 328 $ 1,069 (1) The values in the table above reflect DSCR on a standardized amortization period and LTV based on the most recent appraised values trended forward using changes in a commercial real estate price index.

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	Assets and liabilities measured at fair value on a recurring basis are presented in the following tables. Corporate bonds and other includes obligations of the U.S. Treasury, government-sponsored enterprises, foreign governments and redeemable preferred stock. March 31, 2021 Total (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate bonds and other $ 152 $ 23,444 $ 767 $ 24,363 States, municipalities and political subdivisions — 11,556 44 11,600 Asset-backed — 7,301 315 7,616 Total fixed maturity securities 152 42,301 1,126 43,579 Equity securities: Common stock 177 — 21 198 Non-redeemable preferred stock 67 711 8 786 Total equity securities 244 711 29 984 Short term and other 1,178 25 — 1,203 Total assets $ 1,574 $ 43,037 $ 1,155 $ 45,766 Liabilities Other liabilities $ — $ 2 $ — $ 2 Total liabilities $ — $ 2 $ — $ 2 December 31, 2020 Total (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate bonds and other $ 355 $ 24,109 $ 770 $ 25,234 States, municipalities and political subdivisions — 11,546 46 11,592 Asset-backed — 7,497 308 7,805 Total fixed maturity securities 355 43,152 1,124 44,631 Equity securities: Common stock 175 — 20 195 Non-redeemable preferred stock 68 722 7 797 Total equity securities 243 722 27 992 Short term and other 1,761 28 — 1,789 Total assets $ 2,359 $ 43,902 $ 1,151 $ 47,412 Liabilities Other liabilities $ — $ 19 $ — $ 19 Total liabilities $ — $ 19 $ — $ 19
Table of reconciliation for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs	The tables below present a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3). Level 3 (In millions) Corporate bonds and other States, municipalities and political subdivisions Asset-backed Equity securities Total Balance as of January 1, 2021 $ 770 $ 46 $ 308 $ 27 $ 1,151 Total realized and unrealized investment gains (losses): Reported in Net investment gains (losses) (13) — — 1 (12) Reported in Net investment income — — 2 1 3 Reported in Other comprehensive income (loss) (40) (2) (9) — (51) Total realized and unrealized investment gains (losses) (53) (2) (7) 2 (60) Purchases 42 — 30 — 72 Sales — — — — — Settlements (2) — (17) — (19) Transfers into Level 3 10 — 9 — 19 Transfers out of Level 3 — — (8) — (8) Balance as of March 31, 2021 $ 767 $ 44 $ 315 $ 29 $ 1,155 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2021 recognized in Net income (loss) in the period $ — $ — $ — $ 2 $ 2 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2021 recognized in Other comprehensive income (loss) in the period (40) (2) (9) — (51) Level 3 (In millions) Corporate bonds and other States, municipalities and political subdivisions Asset-backed Equity securities Total Balance as of January 1, 2020 $ 468 $ — $ 165 $ 18 $ 651 Total realized and unrealized investment gains (losses): Reported in Net investment gains (losses) — — — — — Reported in Net investment income — — — (3) (3) Reported in Other comprehensive income (loss) (37) — (9) — (46) Total realized and unrealized investment gains (losses) (37) — (9) (3) (49) Purchases 67 — 45 — 112 Sales — — — — — Settlements (2) — (3) — (5) Transfers into Level 3 — — — — — Transfers out of Level 3 — — (1) — (1) Balance as of March 31, 2020 $ 496 $ — $ 197 $ 15 $ 708 Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2020 recognized in Net income (loss) in the period $ — $ — $ — $ (3) $ (3) Unrealized gains (losses) on Level 3 assets and liabilities held as of March 31, 2020 recognized in Other comprehensive income (loss) in the period (35) — (9) — (44)
Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets	The following tables present quantitative information about the significant unobservable inputs utilized by the Company in the fair value measurements 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 these unobservable inputs is neither provided nor reasonably available to the Company. The weighted average rate is calculated based on fair value. March 31, 2021 Estimated Fair Value Valuation Technique(s) Unobservable Input(s) Range Fixed maturity securities $ 936 Discounted cash flow Credit spread 1% - 8% (2%) December 31, 2020 Estimated Fair Value Valuation Technique(s) Unobservable Input(s) Range Fixed maturity securities $ 966 Discounted cash flow Credit spread 1% - 8% (3%)
Carrying amount and estimated fair value of financial instrument assets and liabilities not measured at fair value	The carrying amount and estimated fair value of the Company's financial assets and liabilities which are not measured at fair value on the Condensed Consolidated Balance Sheets are presented in the following tables. March 31, 2021 Carrying Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 1,043 $ — $ — $ 1,107 $ 1,107 Liabilities Long term debt $ 2,777 $ — $ 3,016 $ — $ 3,016 December 31, 2020 Carrying Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 1,068 $ — $ — $ 1,151 $ 1,151 Liabilities Long term debt $ 2,776 $ — $ 3,148 $ — $ 3,148

Claim and Claim Adjustment Ex_2

Claim and Claim Adjustment Expense Reserves (Tables)	3 Months Ended
	Mar. 31, 2021
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Schedule of liability for unpaid claims and claims adjustment expense	The following table presents a reconciliation between beginning and ending claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves of the Life & Group segment. For the three months ended March 31, 2021 (In millions) 2021 2020 Reserves, beginning of year: Gross $ 22,706 $ 21,720 Ceded 4,005 3,835 Net reserves, beginning of year 18,701 17,885 Reduction of net reserves due to Excess Workers' Compensation Loss Portfolio Transfer (632) — Net incurred claim and claim adjustment expenses: Provision for insured events of current year 1,474 1,355 Increase (decrease) in provision for insured events of prior years (54) (8) Amortization of discount 50 51 Total net incurred (1) 1,470 1,398 Net payments attributable to: Current year events (85) (72) Prior year events (1,067) (1,218) Total net payments (1,152) (1,290) Foreign currency translation adjustment and other (32) (88) Net reserves, end of period 18,355 17,905 Ceded reserves, end of period 4,701 3,967 Gross reserves, end of period $ 23,056 $ 21,872 (1) Total net incurred above does not agree to Insurance claims and policyholders' benefits as reflected on the Condensed Consolidated Statements of Operations due to amounts related to retroactive reinsurance deferred gain accounting, the loss on the Excess Workers' Compensation Loss Portfolio Transfer, uncollectible reinsurance and benefit expenses related to future policy benefits, which are not reflected in the table above.
Net prior year development	The following table presents development recorded for the Specialty, Commercial, International and Corporate & Other segments. Three months ended March 31 (In millions) 2021 2020 Pretax (favorable) unfavorable development: Specialty $ (15) $ (11) Commercial — (4) International — — Corporate & Other — — Total pretax (favorable) unfavorable development $ (15) $ (15)
Specialty
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Net prior year claim and allocated claim adjustment expense reserve development	The following table presents further detail of the development recorded for the Specialty segment. Three months ended March 31 (In millions) 2021 2020 Pretax (favorable) unfavorable development: Medical Professional Liability $ 8 $ 10 Other Professional Liability and Management Liability — 3 Surety (15) (30) Warranty (8) — Other — 6 Total pretax (favorable) unfavorable development $ (15) $ (11)
Commercial
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Net prior year claim and allocated claim adjustment expense reserve development	The following table presents further detail of the development recorded for the Commercial segment. Three months ended March 31 (In millions) 2021 2020 Pretax (favorable) unfavorable development: Commercial Auto $ — $ 9 General Liability — — Workers' Compensation — (13) Property and Other — — Total pretax (favorable) unfavorable development $ — $ (4)
International
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items]
Net prior year claim and allocated claim adjustment expense reserve development

Benefit Plans (Tables)

Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Components of net periodic cost (benefit)	The components of net periodic pension cost (benefit) are presented in the following table. Three months ended March 31 (In millions) 2021 2020 Net periodic pension cost (benefit) Interest cost on projected benefit obligation $ 15 $ 20 Expected return on plan assets (38) (39) Amortization of net actuarial (gain) loss 12 11 Settlement loss — 1 Total net periodic pension cost (benefit) $ (11) $ (7)

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) by Component (Tables)	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) by Component	The tables below display the changes in Accumulated other comprehensive income (loss) by component. (In millions) Net unrealized gains (losses) on investments with an allowance for credit losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2021 $ — $ 1,745 $ (848) $ (94) $ 803 Other comprehensive income (loss) before reclassifications (3) (593) — 2 (594) Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $1, $(8), $2, $— and $(5) (3) 34 (9) — 22 Other comprehensive income (loss) net of tax (expense) benefit of $—, $162, $(2), $— and $160 — (627) 9 2 (616) Balance as of March 31, 2021 $ — $ 1,118 $ (839) $ (92) $ 187 (In millions) Net unrealized gains (losses) on investments with an allowance for credit losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2020 $ — $ 1,025 $ (833) $ (141) $ 51 Other comprehensive income (loss) before reclassifications (48) (1,066) 1 (77) (1,190) Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $10, $6, $3, $— and $19 (37) (22) (10) — (69) Other comprehensive income (loss) net of tax (expense) benefit of $3, $281, $(3), $— and $281 (11) (1,044) 11 (77) (1,121) Balance as of March 31, 2020 $ (11) $ (19) $ (822) $ (218) $ (1,070)
Reclassification out of Accumulated Other Comprehensive Income	Amounts reclassified from Accumulated other comprehensive income (loss) shown above are reported in Net income (loss) as follows: Component of AOCI Consolidated Statements of Operations Line Item Affected by Reclassifications Net unrealized gains (losses) on investments with an allowance for credit losses and Net unrealized gains (losses) on other investments Net investment gains (losses) Pension and postretirement benefits Other operating expenses and Insurance claims and policyholders' benefits

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Significant components of the Company's continuing operations and selected balance sheet items	The Company's results of operations and selected balance sheet items by segment are presented in the following tables. Three months ended March 31, 2021 Specialty Commercial International Life & Corporate (In millions) Eliminations Total Operating revenues Net earned premiums $ 735 $ 855 $ 252 $ 120 $ — $ — $ 1,962 Net investment income 117 148 14 219 6 — 504 Non-insurance warranty revenue 338 — — — — — 338 Other revenues — 5 — 1 1 (2) 5 Total operating revenues 1,190 1,008 266 340 7 (2) 2,809 Claims, benefits and expenses Net incurred claims and benefits 427 639 155 281 (2) — 1,500 Policyholders’ dividends 1 5 — — — — 6 Amortization of deferred acquisition costs 154 153 52 — — — 359 Non-insurance warranty expense 311 — — — — — 311 Other insurance related expenses 70 115 35 25 10 — 255 Other expenses 11 9 (5) 2 42 (2) 57 Total claims, benefits and expenses 974 921 237 308 50 (2) 2,488 Core income (loss) before income tax 216 87 29 32 (43) — 321 Income tax (expense) benefit on core income (loss) (46) (18) (5) 4 7 — (58) Core income (loss) $ 170 $ 69 $ 24 $ 36 $ (36) $ — 263 Net investment gains (losses) 57 Income tax (expense) benefit on net investment gains (losses) (8) Net investment gains (losses), after tax 49 Net income (loss) $ 312 March 31, 2021 (In millions) Reinsurance receivables $ 957 $ 859 $ 300 $ 389 $ 2,628 $ — $ 5,133 Insurance receivables 1,004 1,322 357 2 — — 2,685 Deferred acquisition costs 340 299 102 — — — 741 Goodwill 117 — 31 — — — 148 Deferred non-insurance warranty acquisition expense 3,149 — — — — — 3,149 Insurance reserves Claim and claim adjustment expenses 5,916 8,449 2,142 3,726 2,823 — 23,056 Unearned premiums 2,666 1,930 588 135 — — 5,319 Future policy benefits — — — 12,772 — — 12,772 Deferred non-insurance warranty revenue 4,119 — — — — — 4,119 Three months ended March 31, 2020 Specialty Commercial International Life & Corporate (In millions) Eliminations Total Operating revenues Net earned premiums $ 685 $ 818 $ 239 $ 127 $ — $ — $ 1,869 Net investment income 56 42 15 208 8 — 329 Non-insurance warranty revenue 301 — — — — — 301 Other revenues 1 8 — — 1 (2) 8 Total operating revenues 1,043 868 254 335 9 (2) 2,507 Claims, benefits and expenses Net incurred claims and benefits 405 555 154 316 (11) — 1,419 Policyholders’ dividends 1 5 — — — — 6 Amortization of deferred acquisition costs 151 144 49 — — — 344 Non-insurance warranty expense 281 — — — — — 281 Other insurance related expenses 69 127 36 26 — — 258 Other expenses 13 6 13 3 39 (2) 72 Total claims, benefits and expenses 920 837 252 345 28 (2) 2,380 Core income (loss) before income tax 123 31 2 (10) (19) — 127 Income tax (expense) benefit on core income (loss) (27) (8) — 14 2 — (19) Core income (loss) $ 96 $ 23 $ 2 $ 4 $ (17) $ — 108 Net investment gains (losses) (216) Income tax (expense) benefit on net investment gains (losses) 47 Net investment gains (losses), after tax (169) Net income (loss) $ (61) December 31, 2020 (In millions) Reinsurance receivables $ 886 $ 848 $ 302 $ 390 $ 2,052 $ — $ 4,478 Insurance receivables 1,052 1,254 328 4 2 — 2,640 Deferred acquisition costs 330 281 97 — — — 708 Goodwill 117 — 31 — — — 148 Deferred non-insurance warranty acquisition expense 3,068 — — — — — 3,068 Insurance reserves Claim and claim adjustment expenses 5,748 8,250 2,091 3,743 2,874 — 22,706 Unearned premiums 2,635 1,824 546 114 — — 5,119 Future policy benefits — — — 13,318 — — 13,318 Deferred non-insurance warranty revenue 4,023 — — — — — 4,023
Revenues by line of business	The following table presents operating revenues by line of business for each reportable segment. Three months ended March 31 (In millions) 2021 2020 Specialty Management & Professional Liability $ 667 $ 568 Surety 142 138 Warranty & Alternative Risks 381 337 Specialty revenues 1,190 1,043 Commercial Middle Market 375 335 Construction 309 250 Small Business 126 112 Other Commercial 198 171 Commercial revenues 1,008 868 International Canada 79 73 Europe 111 92 Hardy 76 89 International revenues 266 254 Life & Group revenues 340 335 Corporate & Other revenues 7 9 Eliminations (2) (2) Total operating revenues 2,809 2,507 Net investment gains (losses) 57 (216) Total revenues $ 2,866 $ 2,291

General (Narrative) (Details)

General (Narrative) (Details)	Mar. 31, 2021
CNAF Consolidated | Loews
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Noncontrolling interest, ownership percentage by parent	89.50%

Earnings (Loss) Per Share (Narr

Earnings (Loss) Per Share (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in shares)	1,020,000
Antidilutive securities excluded from computation of earnings (in shares)	120,000	1,015,000
Treasury stock, shares, acquired (in shares)	66,000	435,376
Purchase of treasury stock	$ 3	$ 18

Investments (Net investment inc

Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Investment Income [Line Items]
Gross investment income	$ 521	$ 346
Investment expense	(17)	(17)
Net investment income	504	329
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	428	438
Equity securities
Net Investment Income [Line Items]
Gross investment income	29	(44)
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	43	(70)
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	14	14
Short term investments
Net Investment Income [Line Items]
Gross investment income	0	7
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	5	1
Other
Net Investment Income [Line Items]
Gross investment income	$ 2	$ 0

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Gain (Loss) on Securities [Line Items]
Mortgage loan losses due to changes in expected credit losses	$ 0	$ 13,000,000
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments	2,301,000,000		$ 2,773,000,000
Notional value	256,000,000		190,000,000
Derivative liability, fair value, gross liability	(2,000,000)		(19,000,000)
Commitments to purchase or fund privately placed debt securities	1,365,000,000
Commitments to sell various privately placed debt securities	100,000,000
Common Stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	13,000,000	(45,000,000)
Non-redeemable preferred stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	2,000,000	(133,000,000)
Fixed maturity securities
Gain (Loss) on Securities [Line Items]
Interest receivable	389,000,000	$ 390,000,000	$ 371,000,000
Mortgage loans
Gain (Loss) on Securities [Line Items]
Interest receivable	$ 4,000,000

Investments (Net realized inves

Investments (Net realized investment gains (losses)) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fixed maturity securities:
Gross gains	$ 58,000,000	$ 29,000,000
Gross losses	(20,000,000)	(104,000,000)
Net investment gains (losses) on fixed maturity securities	38,000,000	(75,000,000)
Equity securities	2,000,000	(133,000,000)
Derivatives	17,000,000	5,000,000
Mortgage loans	0	(13,000,000)
Net investment gains (losses)	$ 57,000,000	$ (216,000,000)

Investments (Allowance on avail

Investments (Allowance on available-for-sale securities with credit impairments and PCD assets activity) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for credit losses:
Balance at beginning of period	$ 40	$ 0
Additions to the allowance for credit losses:
Securities for which credit losses were not previously recorded	14	48
Available-for-sale securities accounted for as PCD assets	2	1
Reductions to the allowance for credit losses:
Securities sold during the period (realized)	6	5
Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis	0	1
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period	(7)	0
Balance at end of period	43	49
Impact of adopting ASC 326
Allowance for credit losses:
Balance at beginning of period		6
Corporate and other bonds
Allowance for credit losses:
Balance at beginning of period	23	0
Additions to the allowance for credit losses:
Securities for which credit losses were not previously recorded	14	48
Available-for-sale securities accounted for as PCD assets	2	1
Reductions to the allowance for credit losses:
Securities sold during the period (realized)	6	5
Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis	0	1
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period	(6)	0
Balance at end of period	27	49
Corporate and other bonds | Impact of adopting ASC 326
Allowance for credit losses:
Balance at beginning of period		6
Asset-backed
Allowance for credit losses:
Balance at beginning of period	17	0
Additions to the allowance for credit losses:
Securities for which credit losses were not previously recorded	0	0
Available-for-sale securities accounted for as PCD assets	0	0
Reductions to the allowance for credit losses:
Securities sold during the period (realized)	0	0
Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis	0	0
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period	(1)	0
Balance at end of period	$ 16	0
Asset-backed | Impact of adopting ASC 326
Allowance for credit losses:
Balance at beginning of period		$ 0

Investments (Components of othe

Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Impairment losses recognized in earnings	$ 6	$ 92
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Impairment losses recognized in earnings	7	91
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Impairment losses recognized in earnings	$ (1)	$ 1

Investments (Summary of fixed m

Investments (Summary of fixed maturity and equity securities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	$ 39,257	$ 38,926
Gross Unrealized Gains	4,513	5,795
Gross Unrealized Losses	182	77
Allowance for Credit Losses	43	40	$ 49	$ 0
Estimated Fair Value	43,545	44,604
Total fixed maturity securities trading
Debt securities, amortized cost	39,291	38,953
Total fixed maturity securities	43,579	44,631
Corporate and other bonds
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	21,110	20,792
Gross Unrealized Gains	2,644	3,578
Gross Unrealized Losses	71	22
Allowance for Credit Losses	27	23	49	0
Estimated Fair Value	23,656	24,325
Total fixed maturity securities trading
Total fixed maturity securities	24,363	25,234
States, municipalities and political subdivisions
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	10,041	9,729
Gross Unrealized Gains	1,590	1,863
Gross Unrealized Losses	31	0
Allowance for Credit Losses	0	0
Estimated Fair Value	11,600	11,592
Total fixed maturity securities trading
Total fixed maturity securities	11,600	11,592
Residential mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	3,215	3,442
Gross Unrealized Gains	108	146
Gross Unrealized Losses	40	1
Allowance for Credit Losses	0	0
Estimated Fair Value	3,283	3,587
Commercial mortgage-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	1,952	1,933
Gross Unrealized Gains	76	93
Gross Unrealized Losses	24	42
Allowance for Credit Losses	16	17
Estimated Fair Value	1,988	1,967
Other asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	2,281	2,179
Gross Unrealized Gains	71	81
Gross Unrealized Losses	7	9
Allowance for Credit Losses	0	0
Estimated Fair Value	2,345	2,251
Asset-backed
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	7,448	7,554
Gross Unrealized Gains	255	320
Gross Unrealized Losses	71	52
Allowance for Credit Losses	16	17	$ 0	$ 0
Estimated Fair Value	7,616	7,805
Total fixed maturity securities trading
Total fixed maturity securities	7,616	7,805
U.S. Treasury and obligations of government-sponsored enterprises
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	138	339
Gross Unrealized Gains	1	2
Gross Unrealized Losses	7	3
Allowance for Credit Losses	0	0
Estimated Fair Value	132	338
Foreign government
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	508	512
Gross Unrealized Gains	23	32
Gross Unrealized Losses	2	0
Allowance for Credit Losses	0	0
Estimated Fair Value	529	544
Redeemable preferred stock
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	12	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Allowance for Credit Losses	0	0
Estimated Fair Value	12	0
Fixed maturity securities
Fixed maturity securities available-for-sale:
Cost or Amortized Cost	39,257	38,926
Gross Unrealized Gains	4,513	5,795
Gross Unrealized Losses	182	77
Allowance for Credit Losses	43	40
Estimated Fair Value	43,545	44,604
Total fixed maturity securities trading
Total fixed maturity securities trading
Cost or amortized cost, trading securities	34	27
Estimated fair value, trading securities	$ 34	$ 27

Investments (Securities in a gr

Investments (Securities in a gross unrealized loss position) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	$ 5,085	$ 1,666
Gross Unrealized Losses, Less than 12 Months	158	74
Estimated Fair Value, 12 Months or Longer	476	64
Gross Unrealized Losses, 12 Months or Longer	24	3
Estimated Fair Value, Total	5,561	1,730
Gross Unrealized Losses, Total	182	77
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	1,868	609
Gross Unrealized Losses, Less than 12 Months	66	21
Estimated Fair Value, 12 Months or Longer	82	12
Gross Unrealized Losses, 12 Months or Longer	5	1
Estimated Fair Value, Total	1,950	621
Gross Unrealized Losses, Total	71	22
States, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	866	33
Gross Unrealized Losses, Less than 12 Months	31	0
Estimated Fair Value, 12 Months or Longer	0	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Estimated Fair Value, Total	866	33
Gross Unrealized Losses, Total	31
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	1,584	71
Gross Unrealized Losses, Less than 12 Months	40	1
Estimated Fair Value, 12 Months or Longer	12	11
Gross Unrealized Losses, 12 Months or Longer	0	0
Estimated Fair Value, Total	1,596	82
Gross Unrealized Losses, Total	40	1
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	320	533
Gross Unrealized Losses, Less than 12 Months	9	40
Estimated Fair Value, 12 Months or Longer	285	28
Gross Unrealized Losses, 12 Months or Longer	15	2
Estimated Fair Value, Total	605	561
Gross Unrealized Losses, Total	24	42
Other asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	337	344
Gross Unrealized Losses, Less than 12 Months	3	9
Estimated Fair Value, 12 Months or Longer	97	13
Gross Unrealized Losses, 12 Months or Longer	4	0
Estimated Fair Value, Total	434	357
Gross Unrealized Losses, Total	7	9
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	2,241	948
Gross Unrealized Losses, Less than 12 Months	52	50
Estimated Fair Value, 12 Months or Longer	394	52
Gross Unrealized Losses, 12 Months or Longer	19	2
Estimated Fair Value, Total	2,635	1,000
Gross Unrealized Losses, Total	71	52
U.S. Treasury and obligations of government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	65	63
Gross Unrealized Losses, Less than 12 Months	7	3
Estimated Fair Value, 12 Months or Longer	0	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Estimated Fair Value, Total	65	63
Gross Unrealized Losses, Total	7	3
Foreign government
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 months	45	13
Gross Unrealized Losses, Less than 12 Months	2	0
Estimated Fair Value, 12 Months or Longer	0	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Estimated Fair Value, Total	45	13
Gross Unrealized Losses, Total	$ 2	$ 0

Investments (Contractual maturi

Investments (Contractual maturity) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Investments [Abstract]
Due in one year or less, cost or amortized cost	$ 1,468	$ 1,456
Due after one year through five years, cost or amortized cost	10,837	12,304
Due after five years through ten years, cost or amortized cost	13,640	12,319
Due after ten years, cost or amortized cost	13,312	12,847
Cost or Amortized Cost	39,257	38,926
Due in one year or less, estimated fair value	1,473	1,458
Due after one year through five years, estimated fair value	11,583	13,098
Due after five years through ten years, estimated fair value	14,685	13,878
Due after ten years, estimated fair value	15,804	16,170
Total Estimated Fair Value	$ 43,545	$ 44,604

Investments (Credit quality ind

Investments (Credit quality indicator) (Details) - Mortgage loans $ in Millions	Mar. 31, 2021USD ($)
Debt Securities, Available-for-sale [Line Items]
2021	$ 15
2020	161
2019	284
2018	103
2017	178
Prior	328
Total	1,069
DSCR ≥1.6x | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	75
2019	32
2018	36
2017	114
Prior	187
Total	444
DSCR ≥1.6x | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	14
2019	20
2018	14
2017	15
Prior	11
Total	74
DSCR ≥1.6x | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	5
2020	0
2019	5
2018	0
2017	0
Prior	24
Total	34
DSCR 1.2x - 1.6x | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	16
2018	0
2017	5
Prior	77
Total	98
DSCR 1.2x - 1.6x | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	20
2019	40
2018	53
2017	27
Prior	0
Total	140
DSCR 1.2x - 1.6x | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	10
2020	52
2019	44
2018	0
2017	9
Prior	12
Total	127
DSCR ≤1.2 | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	50
2018	0
2017	8
Prior	10
Total	68
DSCR ≤1.2 | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	48
2018	0
2017	0
Prior	0
Total	48
DSCR ≤1.2 | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	29
2018	0
2017	0
Prior	7
Total	$ 36

Fair Value (Assets and liabilit

Fair Value (Assets and liabilities measured at fair value on a recurring basis) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fixed maturity securities:
Total fixed maturity securities	$ 43,579	$ 44,631
Equity securities:
Equity securities	984	992
Short term and other	1,203	1,789
Total assets	45,766	47,412
Other liabilities	2	19
Total liabilities	2	19
Corporate and other bonds
Fixed maturity securities:
Total fixed maturity securities	24,363	25,234
States, municipalities and political subdivisions
Fixed maturity securities:
Total fixed maturity securities	11,600	11,592
Asset-backed
Fixed maturity securities:
Total fixed maturity securities	7,616	7,805
Common Stock
Equity securities:
Equity securities	198	195
Non-redeemable preferred stock
Equity securities:
Equity securities	786	797
Level 1
Fixed maturity securities:
Total fixed maturity securities	152	355
Equity securities:
Equity securities	244	243
Short term and other	1,178	1,761
Total assets	1,574	2,359
Other liabilities	0	0
Total liabilities	0	0
Level 1 | Corporate and other bonds
Fixed maturity securities:
Total fixed maturity securities	152	355
Level 1 | States, municipalities and political subdivisions
Fixed maturity securities:
Total fixed maturity securities	0	0
Level 1 | Asset-backed
Fixed maturity securities:
Total fixed maturity securities	0	0
Level 1 | Common Stock
Equity securities:
Equity securities	177	175
Level 1 | Non-redeemable preferred stock
Equity securities:
Equity securities	67	68
Level 2
Fixed maturity securities:
Total fixed maturity securities	42,301	43,152
Equity securities:
Equity securities	711	722
Short term and other	25	28
Total assets	43,037	43,902
Other liabilities	2	19
Total liabilities	2	19
Level 2 | Corporate and other bonds
Fixed maturity securities:
Total fixed maturity securities	23,444	24,109
Level 2 | States, municipalities and political subdivisions
Fixed maturity securities:
Total fixed maturity securities	11,556	11,546
Level 2 | Asset-backed
Fixed maturity securities:
Total fixed maturity securities	7,301	7,497
Level 2 | Common Stock
Equity securities:
Equity securities	0	0
Level 2 | Non-redeemable preferred stock
Equity securities:
Equity securities	711	722
Level 3
Fixed maturity securities:
Total fixed maturity securities	1,126	1,124
Equity securities:
Equity securities	29	27
Short term and other	0	0
Total assets	1,155	1,151
Other liabilities	0	0
Total liabilities	0	0
Level 3 | Corporate and other bonds
Fixed maturity securities:
Total fixed maturity securities	767	770
Level 3 | States, municipalities and political subdivisions
Fixed maturity securities:
Total fixed maturity securities	44	46
Level 3 | Asset-backed
Fixed maturity securities:
Total fixed maturity securities	315	308
Level 3 | Common Stock
Equity securities:
Equity securities	21	20
Level 3 | Non-redeemable preferred stock
Equity securities:
Equity securities	$ 8	$ 7

Fair Value (Table of reconcilia

Fair Value (Table of reconciliation for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,151	$ 651
Reported in Other comprehensive income (loss)	(51)	(46)
Total realized and unrealized investment gains (losses)	(60)	(49)
Purchases	72	112
Sales	0	0
Settlements	(19)	(5)
Transfers into Level 3	19	0
Transfers out of Level 3	(8)	(1)
Balance, Ending, Assets	1,155	708
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Net income (loss) in the period	2	(3)
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Other comprehensive income (loss) in the period	(51)	(44)
Corporate and other bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	770	468
Reported in Other comprehensive income (loss)	(40)	(37)
Total realized and unrealized investment gains (losses)	(53)	(37)
Purchases	42	67
Sales	0	0
Settlements	(2)	(2)
Transfers into Level 3	10	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	767	496
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Net income (loss) in the period	0	0
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Other comprehensive income (loss) in the period	(40)	(35)
States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	46	0
Reported in Other comprehensive income (loss)	(2)	0
Total realized and unrealized investment gains (losses)	(2)	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	44	0
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Net income (loss) in the period	0	0
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Other comprehensive income (loss) in the period	(2)	0
Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	308	165
Reported in Other comprehensive income (loss)	(9)	(9)
Total realized and unrealized investment gains (losses)	(7)	(9)
Purchases	30	45
Sales	0	0
Settlements	(17)	(3)
Transfers into Level 3	9	0
Transfers out of Level 3	(8)	(1)
Balance, Ending, Assets	315	197
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Net income (loss) in the period	0	0
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Other comprehensive income (loss) in the period	(9)	(9)
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	27	18
Reported in Other comprehensive income (loss)	0	0
Total realized and unrealized investment gains (losses)	2	(3)
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	29	15
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Net income (loss) in the period	2	(3)
Unrealized gains (losses) on Level 3 assets and liabilities recognized in Other comprehensive income (loss) in the period	0	0
Reported in Net investment gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment gains (losses)	(12)	0
Reported in Net investment gains (losses) | Corporate and other bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment gains (losses)	(13)	0
Reported in Net investment gains (losses) | States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment gains (losses)	0	0
Reported in Net investment gains (losses) | Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment gains (losses)	0	0
Reported in Net investment gains (losses) | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment gains (losses)	1	0
Reported in Net investment income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment income	3	(3)
Reported in Net investment income | Corporate and other bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment income	0	0
Reported in Net investment income | States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment income	0	0
Reported in Net investment income | Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment income	2	0
Reported in Net investment income | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Reported in Net investment income	$ 1	$ (3)

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Other invested assets overseas deposit	$ 72	$ 71

Fair Value (Quantitative inform

Fair Value (Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets) (Details) $ in Millions	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated fair value	$ 45,766	$ 47,412
Fixed maturity securities | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated fair value	$ 936	$ 966
Measurement Input, Credit Spread | Income Approach Valuation Technique | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt securities, available-for-sale, measurement Input	0.01	0.01
Measurement Input, Credit Spread | Income Approach Valuation Technique | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt securities, available-for-sale, measurement Input	0.08	0.08
Measurement Input, Credit Spread | Income Approach Valuation Technique | Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt securities, available-for-sale, measurement Input	0.02	0.03

Fair Value (Carrying amount and

Fair Value (Carrying amount and estimated fair value of financial instrument assets and liabilities which are not measured at fair value) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets
Mortgage loans	$ 1,043	$ 1,068
Liabilities
Long term debt	2,777	2,776
Carrying Amount
Assets
Mortgage loans	1,043	1,068
Liabilities
Long term debt	2,777	2,776
Estimated Fair Value
Assets
Mortgage loans	1,107	1,151
Liabilities
Long term debt	3,016	3,148
Level 1 | Estimated Fair Value
Assets
Mortgage loans	0	0
Liabilities
Long term debt	0	0
Level 2 | Estimated Fair Value
Assets
Mortgage loans	0	0
Liabilities
Long term debt	3,016	3,148
Level 3 | Estimated Fair Value
Assets
Mortgage loans	1,107	1,151
Liabilities
Long term debt	$ 0	$ 0

Claim and Claim Adjustment Ex_3

Claim and Claim Adjustment Expense Reserves (Narrative) (Details) - USD ($)	Feb. 05, 2021	Mar. 31, 2021	Mar. 31, 2020	Feb. 05, 2021	Dec. 31, 2020	Dec. 31, 2010
Liability for Claims and Claims Adjustment Expense [Line Items]
Unusual or infrequent item, or both, net of insurance proceeds		$ 125,000,000	$ 75,000,000
Retroactive reinsurance benefit recognized		10,000,000	14,000,000
Funds held under reinsurance agreements, liability	$ 690,000,000			$ 690,000,000
Retroactive reinsurance agreement, maximum	1,000,000,000			1,000,000,000
Reinsurance premiums paid	$ 697,000,000			$ 64,000,000
Reinsurance, loss on uncollectible accounts in period, amount		12,000,000
Percentage of outstanding reserves	105.00%			105.00%
Retroactive reinsurance agreement, amount remaining		310,000,000
Weather Related Events
Liability for Claims and Claims Adjustment Expense [Line Items]
Unusual or infrequent item, or both, net of insurance proceeds			62,000,000
COVID-19
Liability for Claims and Claims Adjustment Expense [Line Items]
Unusual or infrequent item, or both, net of insurance proceeds			$ 13,000,000
Asbestos and Environmental Reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Net A&EP claim and allocated claim adjustment expense reserves ceded to NICO						$ 1,600,000,000
Aggregate limit under A&EP Loss Portfolio Transfer						4,000,000,000
A&EP claim and allocated claim adjustment expense reserves ceded under existing third party reinsurance contracts transferred to NICO under A&EP Loss Portfolio Transfer						1,200,000,000
Reinsurance premium paid to NICO under A&EP Loss Portfolio Transfer						2,000,000,000
Net reinsurance receivables transferred to NICO under A&EP Loss Portfolio Transfer						215,000,000
Total consideration paid to NICO under AEP Loss Portfolio Transfer						$ 2,200,000,000
Cumulative amounts ceded under AEP Loss Portfolio Transfer		3,300,000,000			$ 3,300,000,000
Deferred reinsurance benefit yet to be recognized		388,000,000			398,000,000
Fair value of collateral trust account established by NICO under A&EP Loss Portfolio Transfer		$ 4,600,000,000			$ 4,200,000,000

Claim and Claim Adjustment Ex_4

Claim and Claim Adjustment Expense Reserves (Reconciliation of claim and claim adjustment expense reserves) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Reserves, beginning of year:
Gross	$ 22,706	$ 21,720
Ceded	4,005	3,835
Net reserves, beginning of year	18,701	17,885
Reduction of net reserves due to Excess Workers' Compensation Loss Portfolio Transfer			$ (632)	$ 0
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	1,474	1,355
Increase (decrease) in provision for insured events of prior years	(54)	(8)
Amortization of discount	50	51
Total net incurred	1,470	1,398
Net payments attributable to:
Current year events	(85)	(72)
Prior year events	(1,067)	(1,218)
Total net payments	(1,152)	(1,290)
Foreign currency translation adjustment and other	(32)	(88)
Net reserves, end of period	18,355	17,905
Ceded reserves, end of period	4,701	3,967
Gross reserves, end of period	$ 23,056	$ 21,872

Claim and Claim Adjustment Ex_5

Claim and Claim Adjustment Expense Reserves (Net prior year development) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable premium development, excluding Life & Group	$ (15)	$ (15)
Specialty
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable premium development, excluding Life & Group	(15)	(11)
Commercial
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable premium development, excluding Life & Group	0	(4)
International
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable premium development, excluding Life & Group	0	0
Corporate & Other
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable premium development, excluding Life & Group	$ 0	$ 0

Claim and Claim Adjustment Ex_6

Claim and Claim Adjustment Expense Reserves (Specialty - Net prior year claim and allocated claim adjustment expense reserve development) (Details) - Specialty - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Medical Professional Liability	$ 8	$ 10
Other Professional Liability and Management Liability	0	3
Surety	(15)	(30)
Warranty	(8)	0
Other	0	6
Total pretax (favorable) unfavorable development	$ (15)	$ (11)

Claim and Claim Adjustment Ex_7

Claim and Claim Adjustment Expense Reserves (Commercial - Net prior year claim and allocated claim adjustment expense reserve development) (Details) - Commercial - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial Auto	$ 0	$ 9
General Liability	0	0
Workers' Compensation	0	(13)
Property and Other	0	0
Total pretax (favorable) unfavorable development	$ 0	$ (4)

Legal Proceedings, Contingenc_2

Legal Proceedings, Contingencies and Guarantees (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Guarantee Obligations
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 1,600
Guarantee and Indemnification
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, current carrying value	$ 5	$ 5

Benefit Plans (Components of ne

Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 15	$ 20
Expected return on plan assets	(38)	(39)
Amortization of net actuarial (gain) loss	12	11
Settlement loss	0	1
Total net periodic pension cost (benefit)	$ (11)	$ (7)

Benefit Plans (Narrative) (Deta

Benefit Plans (Narrative) (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Insurance Claims and Policyholder's Benefits, Including Policyholder's Dividends
Net periodic defined benefits expense (reversal of expense), excluding service cost component	$ 3	$ 2
Other Expense
Net periodic defined benefits expense (reversal of expense), excluding service cost component	$ 8	$ 5

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) by Component Schedule of Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	$ 12,707
Other comprehensive income (loss) before reclassifications	(594)	$ (1,190)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit	22	(69)
Other comprehensive income (loss) net of tax (expense) benefit	(616)	(1,121)
Total stockholder's equity at end of period	12,089	10,362
Reclassification from AOCI, tax	(5)	19
Tax (expense) benefit on other comprehensive income (loss)	160	281
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	803	51
Total stockholder's equity at end of period	187	(1,070)
Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, tax		6
Tax (expense) benefit on other comprehensive income (loss)		281
Net unrealized gains (losses) on other investments | Net unrealized gains (losses) on investments with an allowance for credit losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	0	0
Other comprehensive income (loss) before reclassifications	(3)	(48)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit	(3)	(37)
Other comprehensive income (loss) net of tax (expense) benefit	0	(11)
Total stockholder's equity at end of period	0	(11)
Reclassification from AOCI, tax	1	10
Tax (expense) benefit on other comprehensive income (loss)	0	3
Net unrealized gains (losses) on other investments | Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	1,745	1,025
Other comprehensive income (loss) before reclassifications	(593)	(1,066)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit	34	(22)
Other comprehensive income (loss) net of tax (expense) benefit	(627)	(1,044)
Total stockholder's equity at end of period	1,118	(19)
Reclassification from AOCI, tax	(8)
Tax (expense) benefit on other comprehensive income (loss)	162
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(848)	(833)
Other comprehensive income (loss) before reclassifications	0	1
Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit	(9)	(10)
Other comprehensive income (loss) net of tax (expense) benefit	9	11
Total stockholder's equity at end of period	(839)	(822)
Reclassification from AOCI, tax	2	3
Tax (expense) benefit on other comprehensive income (loss)	(2)	(3)
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	(94)	(141)
Other comprehensive income (loss) before reclassifications	2	(77)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit	0	0
Other comprehensive income (loss) net of tax (expense) benefit	2	(77)
Total stockholder's equity at end of period	(92)	(218)
Reclassification from AOCI, tax	0	0
Tax (expense) benefit on other comprehensive income (loss)	$ 0	$ 0

Business Segments (Narrative) (

Business Segments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2021segment
Core Segments - Specialty, Commercial and International
Segment Reporting Information [Line Items]
Number of operating segments	3

Business Segments (Income State

Business Segments (Income Statement Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating revenues
Net earned premiums	$ 1,962	$ 1,869
Net investment income	504	329
Non-insurance warranty revenue	338	301
Other revenues	5	8
Total operating revenues	2,809	2,507
Claims, Benefits and Expenses
Net incurred claims and benefits	1,500	1,419
Policyholders’ dividends	6	6
Amortization of deferred acquisition costs	359	344
Non-insurance warranty expense	311	281
Other insurance related expenses	255	258
Other expenses	57	72
Total claims, benefits and expenses	2,488	2,380
Core income (loss) before income tax	321	127
Income tax (expense) benefit on core income (loss)	(58)	(19)
Core income (loss)	263	108
Net investment gains (losses)	57	(216)
Income tax (expense) benefit on net investment gains (losses)	(8)	47
Net investment gains (losses), after tax	49	(169)
Net income (loss)	312	(61)
Operating Segments | Specialty
Operating revenues
Net earned premiums	735	685
Net investment income	117	56
Non-insurance warranty revenue	338	301
Other revenues	0	1
Total operating revenues	1,190	1,043
Claims, Benefits and Expenses
Net incurred claims and benefits	427	405
Policyholders’ dividends	1	1
Amortization of deferred acquisition costs	154	151
Non-insurance warranty expense	311	281
Other insurance related expenses	70	69
Other expenses	11	13
Total claims, benefits and expenses	974	920
Core income (loss) before income tax	216	123
Income tax (expense) benefit on core income (loss)	(46)	(27)
Core income (loss)	170	96
Operating Segments | Commercial
Operating revenues
Net earned premiums	855	818
Net investment income	148	42
Non-insurance warranty revenue	0	0
Other revenues	5	8
Total operating revenues	1,008	868
Claims, Benefits and Expenses
Net incurred claims and benefits	639	555
Policyholders’ dividends	5	5
Amortization of deferred acquisition costs	153	144
Non-insurance warranty expense	0	0
Other insurance related expenses	115	127
Other expenses	9	6
Total claims, benefits and expenses	921	837
Core income (loss) before income tax	87	31
Income tax (expense) benefit on core income (loss)	(18)	(8)
Core income (loss)	69	23
Operating Segments | International
Operating revenues
Net earned premiums	252	239
Net investment income	14	15
Non-insurance warranty revenue	0	0
Other revenues	0	0
Total operating revenues	266	254
Claims, Benefits and Expenses
Net incurred claims and benefits	155	154
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	52	49
Non-insurance warranty expense	0	0
Other insurance related expenses	35	36
Other expenses	(5)	13
Total claims, benefits and expenses	237	252
Core income (loss) before income tax	29	2
Income tax (expense) benefit on core income (loss)	(5)	0
Core income (loss)	24	2
Operating Segments | Life & Group
Operating revenues
Net earned premiums	120	127
Net investment income	219	208
Non-insurance warranty revenue	0	0
Other revenues	1	0
Total operating revenues	340	335
Claims, Benefits and Expenses
Net incurred claims and benefits	281	316
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	0	0
Non-insurance warranty expense	0	0
Other insurance related expenses	25	26
Other expenses	2	3
Total claims, benefits and expenses	308	345
Core income (loss) before income tax	32	(10)
Income tax (expense) benefit on core income (loss)	4	14
Core income (loss)	36	4
Operating Segments | Corporate & Other
Operating revenues
Net earned premiums	0	0
Net investment income	6	8
Non-insurance warranty revenue	0	0
Other revenues	1	1
Total operating revenues	7	9
Claims, Benefits and Expenses
Net incurred claims and benefits	(2)	(11)
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	0	0
Non-insurance warranty expense	0	0
Other insurance related expenses	10	0
Other expenses	42	39
Total claims, benefits and expenses	50	28
Core income (loss) before income tax	(43)	(19)
Income tax (expense) benefit on core income (loss)	7	2
Core income (loss)	(36)	(17)
Eliminations
Operating revenues
Net earned premiums	0	0
Net investment income	0	0
Non-insurance warranty revenue	0	0
Other revenues	(2)	(2)
Total operating revenues	(2)	(2)
Claims, Benefits and Expenses
Net incurred claims and benefits	0	0
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	0	0
Non-insurance warranty expense	0	0
Other insurance related expenses	0	0
Other expenses	(2)	(2)
Total claims, benefits and expenses	(2)	(2)
Core income (loss) before income tax	0	0
Income tax (expense) benefit on core income (loss)	0	0
Core income (loss)	$ 0	$ 0

Business Segments (Balance Shee

Business Segments (Balance Sheet Information) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Reinsurance receivables	$ 5,133	$ 4,478
Insurance receivables	2,685	2,640
Deferred acquisition costs	741	708
Goodwill	148	148
Deferred non-insurance warranty acquisition expense	3,149	3,068
Insurance reserves
Claim and claim adjustment expenses	23,056	22,706
Unearned premiums	5,319	5,119
Future policy benefits	12,772	13,318
Deferred non-insurance warranty revenue	4,119	4,023
Operating Segments | Specialty
Segment Reporting Information [Line Items]
Reinsurance receivables	957	886
Insurance receivables	1,004	1,052
Deferred acquisition costs	340	330
Goodwill	117	117
Deferred non-insurance warranty acquisition expense	3,149	3,068
Insurance reserves
Claim and claim adjustment expenses	5,916	5,748
Unearned premiums	2,666	2,635
Future policy benefits	0	0
Deferred non-insurance warranty revenue	4,119	4,023
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Reinsurance receivables	859	848
Insurance receivables	1,322	1,254
Deferred acquisition costs	299	281
Goodwill	0	0
Deferred non-insurance warranty acquisition expense	0	0
Insurance reserves
Claim and claim adjustment expenses	8,449	8,250
Unearned premiums	1,930	1,824
Future policy benefits	0	0
Deferred non-insurance warranty revenue	0	0
Operating Segments | International
Segment Reporting Information [Line Items]
Reinsurance receivables	300	302
Insurance receivables	357	328
Deferred acquisition costs	102	97
Goodwill	31	31
Deferred non-insurance warranty acquisition expense	0	0
Insurance reserves
Claim and claim adjustment expenses	2,142	2,091
Unearned premiums	588	546
Future policy benefits	0	0
Deferred non-insurance warranty revenue	0	0
Operating Segments | Life & Group
Segment Reporting Information [Line Items]
Reinsurance receivables	389	390
Insurance receivables	2	4
Deferred acquisition costs	0	0
Goodwill	0	0
Deferred non-insurance warranty acquisition expense	0	0
Insurance reserves
Claim and claim adjustment expenses	3,726	3,743
Unearned premiums	135	114
Future policy benefits	12,772	13,318
Deferred non-insurance warranty revenue	0	0
Operating Segments | Corporate & Other
Segment Reporting Information [Line Items]
Reinsurance receivables	2,628	2,052
Insurance receivables	0	2
Deferred acquisition costs	0	0
Goodwill	0	0
Deferred non-insurance warranty acquisition expense	0	0
Insurance reserves
Claim and claim adjustment expenses	2,823	2,874
Unearned premiums	0	0
Future policy benefits	0	0
Deferred non-insurance warranty revenue	0	0
Eliminations
Segment Reporting Information [Line Items]
Reinsurance receivables	0	0
Insurance receivables	0	0
Deferred acquisition costs	0	0
Goodwill	0	0
Deferred non-insurance warranty acquisition expense	0	0
Insurance reserves
Claim and claim adjustment expenses	0	0
Unearned premiums	0	0
Future policy benefits	0	0
Deferred non-insurance warranty revenue	$ 0	$ 0

Business Segments (Revenues by

Business Segments (Revenues by Line of Business) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total revenues	$ 2,866	$ 2,291
Total operating revenues	2,809	2,507
Net investment gains (losses)	57	(216)
Operating Segments | Specialty
Total revenues	1,190	1,043
Operating Segments | Commercial
Total revenues	1,008	868
Operating Segments | International
Total revenues	266	254
Operating Segments | Life & Group
Total revenues	340	335
Operating Segments | Corporate & Other
Total revenues	7	9
Eliminations
Total revenues	(2)	(2)
Management & Professional Liability | Operating Segments | Specialty
Total revenues	667	568
Surety | Operating Segments | Specialty
Total revenues	142	138
Warranty & Alternative Risks | Operating Segments | Specialty
Total revenues	381	337
Middle Market | Operating Segments | Commercial
Total revenues	375	335
Construction | Operating Segments | Commercial
Total revenues	309	250
Small Business | Operating Segments | Commercial
Total revenues	126	112
Other Commercial | Operating Segments | Commercial
Total revenues	198	171
Canada | Operating Segments | International
Total revenues	79	73
Europe | Operating Segments | International
Total revenues	111	92
Hardy | Operating Segments | International
Total revenues	$ 76	$ 89

Non-Insurance Revenues from C_2

Non-Insurance Revenues from Contracts with Customers (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Deferred non-insurance warranty revenue	$ 4,119		$ 4,023
Contract with customer, liability, revenue recognized	$ 300	$ 300

Non-Insurance Revenues from C_3

Non-Insurance Revenues from Contracts with Customers (Performance Obligation) (Details) $ in Billions	Mar. 31, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligation, expected timing of satisfaction, period	9 months
Remaining performance obligation, amount	$ 0.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligation, expected timing of satisfaction, period	1 year
Remaining performance obligation, amount	$ 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligation, expected timing of satisfaction, period	1 year
Remaining performance obligation, amount	$ 0.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligation, expected timing of satisfaction, period
Remaining performance obligation, amount	$ 1.3