CNA Financial (CNA) 10-Q 30 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 26, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CNA FINANCIAL CORP
Entity Central Index Key	21,175
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		271,176,870

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Net earned premiums	$ 1,806	$ 1,767	$ 5,185	$ 5,196
Net investment income	509	524	1,529	1,461
Net realized investment (losses) gains:
Other-than-temporary impairment losses	(5)	(18)	(9)	(56)
Other net realized investment (losses) gains	(19)	64	71	82
Net realized investment (losses) gains	(24)	46	62	26
Other revenues	107	96	318	293
Total revenues	2,398	2,433	7,094	6,976
Claims, Benefits and Expenses
Insurance claims and policyholders’ benefits	1,480	1,202	4,053	3,949
Amortization of deferred acquisition costs	309	314	926	926
Other operating expenses	381	403	1,091	1,162
Interest	41	39	124	119
Total claims, benefits and expenses	2,211	1,958	6,194	6,156
Income before income tax	187	475	900	820
Income tax expense	(43)	(132)	(224)	(202)
Net income	$ 144	$ 343	$ 676	$ 618
Basic earnings per share (dollars per share)	$ 0.53	$ 1.27	$ 2.49	$ 2.28
Diluted earnings per share (dollars per share)	0.53	1.26	2.48	2.28
Dividends per share (dollars per share)	$ 0.3	$ 0.25	$ 2.8	$ 2.75
Weighted Average Outstanding Common Stock and Common Stock Equivalents
Basic (in shares)	271.2	270.5	271.1	270.4
Diluted (in shares)	272.1	271.2	272	271

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 144	$ 343	$ 676	$ 618
Other Comprehensive Income, Net of Tax
Net unrealized gains on investments with other-than-temporary impairments	1	3	(3)	7
Net unrealized gains on other investments	23	42	167	586
Net unrealized gains on investments	24	45	164	593
Foreign currency translation adjustment	41	(24)	94	(58)
Pension and postretirement benefits	10	6	22	17
Other comprehensive income, net of tax	75	27	280	552
Total comprehensive income	$ 219	$ 370	$ 956	$ 1,170

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Investments:
Fixed maturity securities at fair value (amortized cost of $38,814 and $38,361)	$ 42,090	$ 40,905
Equity securities at fair value (cost of $118 and $106)	129	110
Limited partnership investments	2,311	2,371
Other invested assets	42	36
Mortgage loans	722	591
Short term investments	1,453	1,407
Total investments	46,747	45,420
Cash	283	271
Reinsurance receivables (less allowance for uncollectible receivables of $37 and $37)	4,332	4,416
Insurance receivables (less allowance for uncollectible receivables of $46 and $46)	2,294	2,209
Accrued investment income	436	405
Deferred acquisition costs	643	600
Deferred income taxes	141	379
Property and equipment at cost (less accumulated depreciation of $275 and $254)	325	310
Goodwill	147	145
Other assets	1,234	1,078
Total assets	56,582	55,233
Insurance reserves:
Claim and claim adjustment expenses	22,209	22,343
Unearned premiums	4,060	3,762
Future policy benefits	11,040	10,326
Short term debt	150	0
Long term debt	2,707	2,710
Other liabilities (includes $25 and $50 due to Loews Corporation)	4,247	4,123
Total liabilities	44,413	43,264
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; 271,176,870 and 270,495,998 shares outstanding)	683	683
Additional paid-in capital	2,167	2,173
Retained earnings	9,273	9,359
Accumulated other comprehensive income (loss)	107	(173)
Treasury stock (1,863,373 and 2,544,245 shares), at cost	(61)	(73)
Total stockholders’ equity	12,169	11,969
Total liabilities and stockholders' equity	$ 56,582	$ 55,233

Condensed Consolidated Balance5

Condensed Consolidated Balance Sheets - (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Amortized cost	$ 38,814	$ 38,361
Cost	118	106
Allowance for uncollectible reinsurance	37	37
Allowance for uncollectible insurance receivables	46	46
Accumulated depreciation	275	254
Due to related parties	$ 25	$ 50
Common stock, par value (dollars 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)	271,176,870	270,495,998
Treasury stock, share (in shares)	1,863,373	2,544,245

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities
Net income	$ 676	$ 618
Adjustments to reconcile net income to net cash flows provided by operating activities:
Deferred income tax expense	125	112
Trading portfolio activity	8	0
Net realized investment gains	(62)	(26)
Equity method investees	89	265
Net amortization of investments	(30)	(17)
Depreciation and amortization	66	57
Changes in:
Receivables, net	18	(311)
Accrued investment income	(31)	(30)
Deferred acquisition costs	(34)	(24)
Insurance reserves	248	464
Other assets	(121)	(96)
Other liabilities	(106)	61
Other, net	48	47
Total adjustments	218	502
Net cash flows provided by operating activities	894	1,120
Dispositions:
Fixed maturity securities - sales	4,167	4,234
Fixed maturity securities - maturities, calls and redemptions	2,635	2,263
Equity securities	22	79
Limited partnerships	160	200
Mortgage loans	22	137
Purchases:
Fixed maturity securities	(6,877)	(7,472)
Equity securities	(18)	(1)
Limited partnerships	(85)	(222)
Mortgage loans	(153)	(88)
Change in other investments	(2)	10
Change in short term investments	(29)	241
Purchases of property and equipment	(80)	(94)
Disposals of property and equipment	0	107
Other, net	20	2
Net cash flows used by investing activities	(218)	(604)
Cash Flows from Financing Activities
Dividends paid to common stockholders	(761)	(746)
Proceeds from the issuance of debt	496	498
Repayment of debt	(391)	(358)
Other, net	(17)	1
Net cash flows used by financing activities	(673)	(605)
Effect of foreign exchange rate changes on cash	9	(8)
Net change in cash	12	(97)
Cash, beginning of year	271	387
Cash, end of period	$ 283	$ 290

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance, beginning of year at Dec. 31, 2015		$ 683	$ 2,153	$ 9,313	$ (315)	$ (78)
Stock-based compensation			10			5
Dividends paid to common stockholders				(746)
Net income	$ 618			618
Other comprehensive income	552				552
Balance, end of period at Sep. 30, 2016	12,195	683	2,163	9,185	237	(73)
Balance, beginning of year at Jun. 30, 2016					210
Net income	343
Other comprehensive income	27
Balance, end of period at Sep. 30, 2016	12,195	683	2,163	9,185	237	(73)
Balance, beginning of year at Dec. 31, 2016	11,969	683	2,173	9,359	(173)	(73)
Stock-based compensation			(6)			12
Dividends paid to common stockholders				(762)
Net income	676			676
Other comprehensive income	280				280
Balance, end of period at Sep. 30, 2017	12,169	683	2,167	9,273	107	(61)
Balance, beginning of year at Jun. 30, 2017					32
Net income	144
Other comprehensive income	75
Balance, end of period at Sep. 30, 2017	$ 12,169	$ 683	$ 2,167	$ 9,273	$ 107	$ (61)

General

General	9 Months Ended
	Sep. 30, 2017
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% of the outstanding common stock of CNAF as of September 30, 2017 . 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, 2016 , 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 September 30, 2017 and for the three and nine months ended September 30, 2017 and 2016 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. Recently Adopted Accounting Standards Updates (ASU) In March 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The updated accounting guidance simplifies the accounting for share-based payment award transactions, including income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. As of January 1, 2017, the Company adopted the updated accounting guidance and began recognizing excess tax benefits or deficiencies on vesting or settlement of awards as an income tax benefit or expense within net income, instead of additional paid-in capital as required under previous guidance. The related cash flows are now classified within operating activities. As a result of this change, excess tax benefits are no longer included in assumed proceeds under the treasury stock method of calculating earnings per share. The impact of the accounting change resulted in a decrease of $2 million and $5 million to income tax expense for the three and nine months ended September 30, 2017 . Accounting Standards Pending Adoption In May 2014, the FASB issued ASU No. 2014-09, Revenue Recognition (Topic 606): Revenue from Contracts with Customers . The standard excludes from its scope the accounting for insurance contracts, financial instruments, and certain other agreements that are governed under other GAAP guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in an amount that reflects the consideration the entity is entitled to receive for the transfer of the promised goods or services. The standard is effective for interim and annual reporting periods beginning after December 15, 2017 and may be applied retrospectively or through a cumulative effect adjustment to retained earnings at the date of adoption. While the Company continues to evaluate the impacts of this new guidance on the Consolidated financial statements, including disclosures, the Company expects that revenue on warranty products and services will be recognized more slowly than under the current revenue recognition pattern. For a significant portion of warranty products, the Company also expects Other revenues and Other operating expenses to increase to reflect the gross amount paid by consumers to the auto dealer that acts as the Company's agent. The Company expects to adopt this guidance using the modified retrospective approach. While the cumulative effect of adoption using the modified retrospective approach may be significant, the Company does not expect the impact of the new guidance to be material to its results of operations or financial position. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The updated accounting guidance requires changes to the reporting model for financial instruments. The guidance is effective for interim and annual periods beginning after December 15, 2017. The Company expects the primary change to be the requirement for equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. Upon adoption, the Company will recognize an adjustment for the cumulative amount of unrealized investment gains and losses related to available-for-sale equity securities within the opening balances of Retained earnings and Accumulated other comprehensive income (loss). The Company does not expect the impact of adopting ASU 2016-01 to have a material effect on the Company’s results of operations or financial position. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842): Accounting for Leases. The updated accounting guidance requires lessees to recognize on the balance sheet the assets and liabilities for the rights and obligations created by all leases, including those historically accounted for as operating leases. The guidance is effective for interim and annual periods beginning after December 15, 2018. The Company is currently evaluating the effect the updated guidance will have on the Company's financial statements. It is expected that assets and liabilities will increase based on the present value of remaining lease payments for leases in place at the adoption date; however, this is not expected to be material to the Company's results of operations or financial position. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The updated accounting guidance requires changes to the recognition of credit losses on financial instruments not accounted for at fair value through net income. The guidance is effective for interim and annual periods beginning after December 15, 2019. The Company is currently evaluating the effect the guidance will have on the Company's financial statements, but expects the primary changes to be the use of the expected credit loss model for its mortgage loan portfolio and reinsurance receivables and the presentation of credit losses within the available-for-sale fixed maturities portfolio through an allowance method rather than as a direct write-down. The expected credit loss model will require a financial asset to be presented at the net amount expected to be collected. The allowance method for available-for-sale debt securities will allow the Company to record reversals of credit losses if the estimate of credit losses declines. In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . The updated accounting guidance requires changes to the presentation of the components of net periodic benefit cost on the income statement by requiring service cost to be presented with other employee compensation costs and other components of net periodic pension cost to be presented outside of any subtotal of operating income. The ASU also stipulates that only the service cost component of net benefit cost is eligible for capitalization. The guidance is effective for interim and annual periods beginning after December 15, 2017. The Company is currently evaluating the effect the guidance will have on the Company's financial statements.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Earnings per share is based on the weighted average number of outstanding common shares. Basic earnings (loss) per share excludes the effect 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 and nine months ended September 30, 2017 , approximately 907 thousand and 916 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 those same periods, less than 1 thousand and approximately 4 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 and nine months ended September 30, 2016 , approximately 707 thousand and 549 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 those same periods, approximately 175 thousand and 178 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.

Investments

Investments	9 Months Ended
	Sep. 30, 2017
Investments [Abstract]
Investments	Investments The significant components of Net investment income are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Fixed maturity securities $ 455 $ 457 $ 1,367 $ 1,352 Equity securities 1 1 4 8 Limited partnership investments 51 65 157 97 Mortgage loans 9 8 24 30 Short term investments 4 2 10 6 Trading portfolio 3 1 9 7 Other 1 4 2 4 Gross investment income 524 538 1,573 1,504 Investment expense (15 ) (14 ) (44 ) (43 ) Net investment income $ 509 $ 524 $ 1,529 $ 1,461 Net realized investment gains (losses) are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Net realized investment gains (losses): Fixed maturity securities: Gross realized gains $ 34 $ 67 $ 139 $ 152 Gross realized losses (18 ) (20 ) (47 ) (106 ) Net realized investment gains (losses) on fixed maturity securities 16 47 92 46 Equity securities: Gross realized gains — 1 1 5 Gross realized losses — (4 ) (1 ) (10 ) Net realized investment gains (losses) on equity securities — (3 ) — (5 ) Derivatives (1 ) 1 (3 ) (12 ) Short term investments and other (39 ) 1 (27 ) (3 ) Net realized investment gains (losses) $ (24 ) $ 46 $ 62 $ 26 Net realized investment gains (losses) for the three and nine months ended September 30, 2017 included a $42 million loss related to the redemption of the Company's $350 million senior notes due November 2019. Net realized investment gains (losses) for the nine months ended September 30, 2016 included a $8 million loss related to the first quarter 2016 redemption of the Company's $350 million senior notes due August 2016. The components of Other-than-temporary impairment (OTTI) losses recognized in earnings by asset type are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Fixed maturity securities available-for-sale: Corporate and other bonds $ 4 $ 14 $ 8 $ 43 Asset-backed: Residential mortgage-backed 1 — 1 1 Other asset-backed — — — 3 Total asset-backed 1 — 1 4 Total fixed maturity securities available-for-sale 5 14 9 47 Equity securities available-for-sale -- Common stock — 4 — 9 OTTI losses recognized in earnings $ 5 $ 18 $ 9 $ 56 The following tables present a summary of fixed maturity and equity securities. September 30, 2017 Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Unrealized OTTI Losses (Gains) (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 17,965 $ 1,645 $ 26 $ 19,584 $ — States, municipalities and political subdivisions 12,462 1,501 7 13,956 (14 ) Asset-backed: Residential mortgage-backed 4,906 127 28 5,005 (28 ) Commercial mortgage-backed 1,858 55 13 1,900 — Other asset-backed 1,047 18 4 1,061 — Total asset-backed 7,811 200 45 7,966 (28 ) U.S. Treasury and obligations of government-sponsored enterprises 115 3 3 115 — Foreign government 439 10 4 445 — Redeemable preferred stock 18 2 — 20 — Total fixed maturity securities available-for-sale 38,810 3,361 85 42,086 $ (42 ) Total fixed maturity securities trading 4 4 Equity securities available-for-sale: Common stock 16 7 1 22 Preferred stock 102 5 — 107 Total equity securities available-for-sale 118 12 1 129 Total $ 38,932 $ 3,373 $ 86 $ 42,219 December 31, 2016 Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Unrealized OTTI Losses (Gains) (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 17,711 $ 1,323 $ 76 $ 18,958 $ (1 ) States, municipalities and political subdivisions 12,060 1,213 33 13,240 (16 ) Asset-backed: Residential mortgage-backed 5,004 120 51 5,073 (28 ) Commercial mortgage-backed 2,016 48 24 2,040 — Other asset-backed 1,022 8 5 1,025 — Total asset-backed 8,042 176 80 8,138 (28 ) U.S. Treasury and obligations of government-sponsored enterprises 83 10 — 93 — Foreign government 435 13 3 445 — Redeemable preferred stock 18 1 — 19 — Total fixed maturity securities available-for-sale 38,349 2,736 192 40,893 $ (45 ) Total fixed maturity securities trading 12 12 Equity securities available-for-sale: Common stock 13 6 — 19 Preferred stock 93 2 4 91 Total equity securities available-for-sale 106 8 4 110 Total $ 38,467 $ 2,744 $ 196 $ 41,015 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 Non-Core 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 September 30, 2017 and December 31, 2016 , the net unrealized gains on investments included in AOCI were correspondingly reduced by Shadow Adjustments of $1,321 million and $1,014 million . The following tables present the estimated fair value and gross unrealized losses of fixed maturity and equity securities in a gross unrealized loss position by the length of time in which the securities have continuously been in that position. Less than 12 Months 12 Months or Longer Total September 30, 2017 Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 1,216 $ 21 $ 91 $ 5 $ 1,307 $ 26 States, municipalities and political subdivisions 583 6 56 1 639 7 Asset-backed: Residential mortgage-backed 1,522 25 106 3 1,628 28 Commercial mortgage-backed 378 6 138 7 516 13 Other asset-backed 129 4 10 — 139 4 Total asset-backed 2,029 35 254 10 2,283 45 U.S. Treasury and obligations of government-sponsored enterprises 67 3 6 — 73 3 Foreign government 191 4 5 — 196 4 Total fixed maturity securities available-for-sale 4,086 69 412 16 4,498 85 Equity securities available-for-sale: Common stock 2 1 — — 2 1 Preferred stock 16 — — — 16 — Total equity securities available-for-sale 18 1 — — 18 1 Total $ 4,104 $ 70 $ 412 $ 16 $ 4,516 $ 86 Less than 12 Months 12 Months or Longer Total December 31, 2016 Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 2,615 $ 61 $ 254 $ 15 $ 2,869 $ 76 States, municipalities and political subdivisions 959 32 23 1 982 33 Asset-backed: Residential mortgage-backed 2,136 44 201 7 2,337 51 Commercial mortgage-backed 756 22 69 2 825 24 Other asset-backed 398 5 24 — 422 5 Total asset-backed 3,290 71 294 9 3,584 80 U.S. Treasury and obligations of government-sponsored enterprises 5 — — — 5 — Foreign government 108 3 — — 108 3 Total fixed maturity securities available-for-sale 6,977 167 571 25 7,548 192 Equity securities available-for-sale -- Preferred stock 12 — 13 4 25 4 Total $ 6,989 $ 167 $ 584 $ 29 $ 7,573 $ 196 Based on current facts and circumstances, the Company believes the unrealized losses presented in the September 30, 2017 securities in a gross unrealized loss position table above are not indicative of the ultimate collectibility of the current amortized cost of the securities, but rather are attributable to changes in interest rates, credit spreads and other factors. The Company has no current intent to sell securities with unrealized losses, nor is it more likely than not that it will be required to sell prior to recovery of amortized cost; accordingly, the Company has determined that there are no additional OTTI losses to be recorded as of September 30, 2017 . The following table presents the activity related to the pretax credit loss component reflected in Retained earnings on fixed maturity securities still held as of September 30, 2017 and 2016 for which a portion of an OTTI loss was recognized in Other comprehensive income (loss). Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Beginning balance of credit losses on fixed maturity securities $ 30 $ 41 $ 36 $ 53 Reductions for securities sold during the period (2 ) (2 ) (8 ) (14 ) Reductions for securities the Company intends to sell or more likely than not will be required to sell — (1 ) — (1 ) Ending balance of credit losses on fixed maturity securities $ 28 $ 38 $ 28 $ 38 Contractual Maturity The following table presents available-for-sale fixed maturity securities by contractual maturity. September 30, 2017 December 31, 2016 (In millions) Cost or Amortized Cost Estimated Fair Value Cost or Amortized Cost Estimated Fair Value Due in one year or less $ 1,374 $ 1,404 $ 1,779 $ 1,828 Due after one year through five years 7,931 8,293 7,566 7,955 Due after five years through ten years 15,853 16,574 15,892 16,332 Due after ten years 13,652 15,815 13,112 14,778 Total $ 38,810 $ 42,086 $ 38,349 $ 40,893 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 $170 million and $174 million as of September 30, 2017 and December 31, 2016 and a fair value of $(1) million and $3 million as of September 30, 2017 and December 31, 2016 . 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 of September 30, 2017 , the Company had committed approximately $405 million to future capital calls from various third-party limited partnership investments in exchange for an ownership interest in the related partnerships. As of September 30, 2017 , the Company had mortgage loan commitments of $68 million representing signed loan applications received and accepted. The Company invests in various privately placed debt securities, including bank loans, as part of its overall investment strategy and has committed to additional future purchases, sales and funding. Purchases and sales of privately placed debt securities are recorded once funded. As of September 30, 2017 , the Company had commitments to purchase or fund additional amounts of $205 million and sell $185 million under the terms of such securities.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2017
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, iv) deep dives, where the Company performs an independent analysis of the inputs and assumptions used to price individual securities and v) pricing validation, where prices received are compared to prices independently estimated by the Company. Assets and Liabilities Measured at Fair Value Assets and liabilities measured at fair value on a recurring basis are presented in the following tables. September 30, 2017 Total Assets/Liabilities at Fair Value (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate and other bonds $ — $ 19,469 $ 119 $ 19,588 States, municipalities and political subdivisions — 13,955 1 13,956 Asset-backed: Residential mortgage-backed — 4,829 176 5,005 Commercial mortgage-backed — 1,876 24 1,900 Other asset-backed — 915 146 1,061 Total asset-backed — 7,620 346 7,966 U.S. Treasury and obligations of government-sponsored enterprises 115 — — 115 Foreign government — 445 — 445 Redeemable preferred stock 20 — — 20 Total fixed maturity securities 135 41,489 466 42,090 Equity securities 110 — 19 129 Other invested assets — 5 — 5 Short term investments 479 876 — 1,355 Total assets $ 724 $ 42,370 $ 485 $ 43,579 Liabilities Other liabilities $ — $ 1 $ — $ 1 Total liabilities $ — $ 1 $ — $ 1 December 31, 2016 Total Assets/Liabilities at Fair Value (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate and other bonds $ — $ 18,840 $ 130 $ 18,970 States, municipalities and political subdivisions — 13,239 1 13,240 Asset-backed: Residential mortgage-backed — 4,944 129 5,073 Commercial mortgage-backed — 2,027 13 2,040 Other asset-backed — 968 57 1,025 Total asset-backed — 7,939 199 8,138 U.S. Treasury and obligations of government-sponsored enterprises 93 — — 93 Foreign government — 445 — 445 Redeemable preferred stock 19 — — 19 Total fixed maturity securities 112 40,463 330 40,905 Equity securities 91 — 19 110 Other invested assets — 5 — 5 Short term investments 475 853 — 1,328 Life settlement contracts, included in Other assets — — 58 58 Total assets $ 678 $ 41,321 $ 407 $ 42,406 Liabilities Other liabilities $ — $ (3 ) $ — $ (3 ) Total liabilities $ — $ (3 ) $ — $ (3 ) 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) Balance as of July 1, 2017 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 100 $ 1 $ 1 $ 13 $ — $ (11 ) $ 15 $ — $ 119 $ — States, municipalities and political subdivisions 1 — — — — — — — 1 — Asset-backed: Residential mortgage-backed 123 1 1 — — (7 ) 58 — 176 — Commercial mortgage-backed 13 — (1 ) 12 — (2 ) 2 — 24 — Other asset-backed 82 (1 ) 1 27 — (4 ) 41 — 146 — Total asset-backed 218 — 1 39 — (13 ) 101 — 346 — Total fixed maturity securities 319 1 2 52 — (24 ) 116 — 466 — Equity securities 19 — — — — — — — 19 — Life settlement contracts 1 — — — (1 ) — — — — — Total $ 339 $ 1 $ 2 $ 52 $ (1 ) $ (24 ) $ 116 $ — $ 485 $ — Level 3 (In millions) Balance as of July 1, 2016 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 242 $ 1 $ 7 $ 16 $ — $ (5 ) $ — $ — $ 261 $ — States, municipalities and political subdivisions 2 — — — — (1 ) — — 1 — Asset-backed: Residential mortgage-backed 134 — (1 ) 5 — (1 ) — (58 ) 79 — Commercial mortgage-backed 11 — — 23 — (8 ) — (2 ) 24 — Other asset-backed 45 — — 34 — — — (36 ) 43 — Total asset-backed 190 — (1 ) 62 — (9 ) — (96 ) 146 — Total fixed maturity securities 434 1 6 78 — (15 ) — (96 ) 408 — Equity securities 19 (1 ) 1 — — — — — 19 (2 ) Life settlement contracts 67 — — — — — — — 67 — Total $ 520 $ — $ 7 $ 78 $ — $ (15 ) $ — $ (96 ) $ 494 $ (2 ) Level 3 (In millions) Balance as of January 1, 2017 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 130 $ 1 $ 2 $ 18 $ (1 ) $ (36 ) $ 15 $ (10 ) $ 119 $ — States, municipalities and political subdivisions 1 — — — — — — — — 1 — Asset-backed: Residential mortgage-backed 129 3 4 — — — (18 ) 58 — 176 — Commercial mortgage-backed 13 — (1 ) — 12 — (2 ) 2 — 24 — Other asset-backed 57 (2 ) 1 — 78 — (6 ) 93 (75 ) 146 — Total asset-backed 199 1 4 90 — (26 ) 153 (75 ) 346 — Total fixed maturity securities 330 2 6 108 (1 ) (62 ) 168 (85 ) 466 — Equity securities 19 — 2 — 1 (3 ) — — — 19 — Derivative financial instruments — 1 — — — (1 ) — — — — — Life settlement contracts 58 6 — — (59 ) (5 ) — — — — Total $ 407 $ 9 $ 8 $ 109 $ (64 ) $ (67 ) $ 168 $ (85 ) $ 485 $ — Level 3 (In millions) Balance as of January 1, 2016 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 168 $ 1 $ 14 $ 163 $ (36 ) $ (15 ) $ — $ (34 ) $ 261 $ — States, municipalities and political subdivisions 2 — — — — (1 ) — — 1 — Asset-backed: Residential mortgage-backed 134 2 (2 ) 15 — (10 ) — (60 ) 79 — Commercial mortgage-backed 22 — — 32 — (17 ) 3 (16 ) 24 — Other asset-backed 53 — 2 69 (25 ) (1 ) 2 (57 ) 43 — Total asset-backed 209 2 — 116 (25 ) (28 ) 5 (133 ) 146 — Total fixed maturity securities 379 3 14 279 (61 ) (44 ) 5 (167 ) 408 — Equity securities 20 (1 ) — — — — — — 19 (2 ) Life settlement contracts 74 10 — — — (17 ) — — 67 2 Total $ 473 $ 12 $ 14 $ 279 $ (61 ) $ (61 ) $ 5 $ (167 ) $ 494 $ — *Net realized and unrealized gains and losses from Level 3 securities and derivatives are reported in Net income (loss) as follows: Major Category of Assets and Liabilities Condensed Consolidated Statements of Operations Line Items Fixed maturity securities available-for-sale (1) Net realized investment gains (losses) Fixed maturity securities trading Net investment income Equity securities (1) Net realized investment gains (losses) Other invested assets - Derivative financial instruments held in a trading portfolio Net investment income Other invested assets - Derivative financial instruments not held in a trading portfolio Net realized investment gains (losses) Life settlement contracts Other revenues Other liabilities - Derivative financial instruments Net realized investment gains (losses) (1) Unrealized gains and losses are reported within AOCI. Securities may be transferred in or out of levels within the fair value hierarchy based on the availability of observable market information and quoted prices used to determine the fair value of the security. The availability of observable market information and quoted prices varies based on market conditions and trading volume. During the three and nine months ended September 30, 2017 and 2016 , there were no transfers between Level 1 and Level 2. The Company's policy is to recognize transfers between levels at the beginning of quarterly reporting periods. Valuation Methodologies and Inputs The following section describes the valuation methodologies and relevant inputs used to measure different financial instruments at fair value, including an indication of the level in the fair value hierarchy in which the instruments are generally classified. Fixed Maturity Securities Level 1 securities include highly liquid and exchange traded bonds and redeemable preferred stock, valued using quoted market prices. Level 2 securities include most other fixed maturity securities as the significant inputs are observable in the marketplace. All classes of Level 2 fixed maturity securities are valued using a methodology based on information generated by market transactions involving identical or comparable assets, a discounted cash flow methodology, or a combination of both when necessary. Common inputs for all classes of fixed maturity securities include prices from recently executed transactions of similar securities, marketplace quotes, benchmark yields, spreads off benchmark yields, interest rates and U.S. Treasury or swap curves. Specifically for asset-backed securities, key inputs include prepayment and default projections based on past performance of the underlying collateral and current market data. Fixed maturity securities are primarily assigned to Level 3 in cases where broker/dealer quotes are significant inputs to the valuation, and there is a lack of transparency as to whether these quotes are based on information that is observable in the marketplace. Level 3 securities also include private placement debt securities whose fair value is determined using internal models with inputs that are not market observable. Equity Securities Level 1 equity securities include publicly traded securities valued using quoted market prices. Level 2 securities are primarily non-redeemable preferred stocks and common stocks valued using pricing for similar securities, recently executed transactions and other pricing models utilizing market observable inputs. Level 3 securities are primarily priced using broker/dealer quotes and internal models with inputs that are not market observable. Other Invested Assets The fair value of Federal Home Loan Bank of Chicago (FHLBC) stock is equal to par because it can only be redeemed by the FHLBC at par or sold to another member of the FHLBC at par and is classified as Level 2. As of September 30, 2017 and December 31, 2016 , there were approximately $37 million and $31 million respectively 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. Short Term Investments 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. Life Settlement Contracts The Company accounts for its investment in life settlement contracts using the fair value method. Historically, the fair value of life settlement contracts was determined as the present value of the anticipated death benefits less anticipated premium payments based on contract terms that are distinct for each insured, as well as the Company's own assumptions for mortality, premium expense and the rate of return that a buyer would require on the contracts. The entire portfolio of life settlement contracts, which is included within the Life and Group Non-Core segment, was determined to be held for sale as of December 31, 2016 as the Company reached an agreement on terms to sell the portfolio. As such, the Company adjusted the fair value to the estimated sales proceeds less cost to sell. The definitive Purchase and Sale Agreement (PSA) related to the portfolio was executed on March 7, 2017 (sale date). In connection therewith, the life settlement contracts and related sale proceeds were placed in escrow until the buyer was recognized as the owner and beneficiary of each individual life settlement contract by the life insurance company that issued the policy. All of the contracts have been released from escrow as of September 30, 2017 . The Company derecognized the released contracts and recorded the consideration, including a note receivable, which is payable over three years and is carried at amortized cost less any valuation allowance. The note receivable of $45 million is included within Other assets on the September 30, 2017 Condensed Consolidated Balance Sheet and interest income is accreted to the principal balance of the note. The fair value of the Company's investments in life settlement contracts were $0 million and $58 million as of September 30, 2017 and December 31, 2016 , and are included in Other assets on the Condensed Consolidated Balance Sheets. Despite the sale, the contracts were classified as Level 3 as there is not an active market for life settlement contracts. The cash receipts and payments related to the life settlement contracts prior to the sale date are included in Cash Flows from operating activities on the Condensed Consolidated Statements of Cash Flows. Cash receipts related to the sale of the life settlement contracts, as well as principal payments on the note receivable, are included in Cash Flows from investing activities. Derivative Financial Investments Level 2 securities primarily include the embedded derivative on the funds withheld liability. 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 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 valuation of life settlement contracts was based on the terms of the sale of the contracts to a third party; therefore, the contracts are not included in the table below. September 30, 2017 Estimated Fair Value (In millions) Valuation Technique(s) Unobservable Input(s) Range (Weighted Average) Fixed maturity securities $ 139 Discounted cash flow Credit spread 1% - 12% (3%) December 31, 2016 Estimated Fair Value Valuation Technique(s) Unobservable Input(s) Range (Weighted Average) Fixed maturity securities $ 106 Discounted cash flow Credit spread 2% - 40% (4%) 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. September 30, 2017 Carrying Amount Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 722 $ — $ — $ 731 $ 731 Note receivable 45 — — — — 46 46 Liabilities Short term debt $ 150 $ — $ 152 $ — $ 152 Long term debt 2,707 — 2,916 — 2,916 December 31, 2016 Carrying Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 591 $ — $ — $ 594 $ 594 Liabilities Long term debt $ 2,710 $ — $ 2,952 $ — $ 2,952 The following methods and assumptions were used to estimate the fair value of these financial assets and liabilities. The fair values of mortgage loans were based on the present value of the expected future cash flows discounted at the current interest rate for origination of similar quality loans, adjusted for specific loan risk. The fair value of the note receivable was based on the present value of the expected future cash flows discounted at the current interest rate for origination of similar notes, adjusted for specific credit risk. The Company's senior notes and debentures were valued based on observable market prices. The fair value for other debt was estimated using discounted cash flows based on current incremental borrowing rates for similar borrowing arrangements. 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	9 Months Ended
	Sep. 30, 2017
Liability for Claims and Claims Adjustment Expense [Abstract]
Claim and Claim Adjustment Expense Reserves	Claim and Claim Adjustment Expense Reserves The Company's property and casualty insurance claim and claim adjustment expense reserves represent the estimated amounts necessary to resolve all outstanding claims, including incurred but not reported (IBNR) claims as of the reporting date. 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 such historical patterns as claim reserving trends and settlement practices, loss payments, pending levels of unpaid claims and product mix, as well as court decisions, economic conditions, including inflation, and public attitudes. All of these factors can affect the estimation of claim and claim adjustment expense reserves. Establishing claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves for catastrophic events that have occurred, is an estimation process. Many factors can ultimately affect the final settlement of a claim and, therefore, the necessary reserve. Changes in the law, results of litigation, medical costs, the cost of repair materials and labor rates can all 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 the Company's results of operations and/or equity. The Company reported catastrophe losses, net of reinsurance, of $269 million and $342 million for the three and nine months ended September 30, 2017 . Net catastrophe losses for the three and nine months ended September 30, 2017 included $149 million related to Hurricane Harvey, $95 million related to Hurricane Irma and $20 million related to Hurricane Maria. The remaining catastrophe losses in 2017 resulted primarily from U.S. weather-related events. Catastrophe-related reinsurance reinstatement premium was $6 million for the three and nine months ended September 30, 2017 . The Company reported catastrophe losses, net of reinsurance, of $16 million and $137 million for the three and nine months ended September 30, 2016 . Catastrophe losses in 2016 resulted primarily from U.S. weather-related events and the Fort McMurray wildfires. Liability for Unpaid Claim and Claim Adjustment Expenses Rollforward The following table presents a reconciliation between beginning and ending claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves of the Life & Group Non-Core segment. For the nine months ended September 30 (In millions) 2017 2016 Reserves, beginning of year: Gross $ 22,343 $ 22,663 Ceded 4,094 4,087 Net reserves, beginning of year 18,249 18,576 Net incurred claim and claim adjustment expenses: Provision for insured events of current year 3,949 3,799 Decrease in provision for insured events of prior years (284 ) (332 ) Amortization of discount 138 134 Total net incurred (1) 3,803 3,601 Net payments attributable to: Current year events (560 ) (591 ) Prior year events (3,401 ) (3,209 ) Total net payments (3,961 ) (3,800 ) Foreign currency translation adjustment and other 110 39 Net reserves, end of period 18,201 18,416 Ceded reserves, end of period 4,008 4,256 Gross reserves, end of period $ 22,209 $ 22,672 (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, uncollectible reinsurance and loss deductible receivables, and benefit expenses related to future policy benefits, which are not reflected in the table above. Net Prior Year Development Changes in estimates of claim and allocated claim adjustment expense reserves and premium accruals, net of reinsurance, for prior years are defined as net prior year development. These changes can be favorable or unfavorable. The following tables and discussion present the net prior year development recorded for Specialty, Commercial, International and Corporate & Other Non-Core segments. Three months ended September 30, 2017 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (109 ) $ (7 ) $ 1 $ — $ (115 ) Pretax (favorable) unfavorable premium development (3 ) (11 ) (5 ) — (19 ) Total pretax (favorable) unfavorable net prior year development $ (112 ) $ (18 ) $ (4 ) $ — $ (134 ) Three months ended September 30, 2016 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (112 ) $ (5 ) $ (15 ) $ — $ (132 ) Pretax (favorable) unfavorable premium development — (3 ) (2 ) — (5 ) Total pretax (favorable) unfavorable net prior year development $ (112 ) $ (8 ) $ (17 ) $ — $ (137 ) Nine months ended September 30, 2017 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (163 ) $ (65 ) $ 1 $ — $ (227 ) Pretax (favorable) unfavorable premium development (13 ) 27 (16 ) — (2 ) Total pretax (favorable) unfavorable net prior year development $ (176 ) $ (38 ) $ (15 ) $ — $ (229 ) Nine months ended September 30, 2016 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (211 ) $ (37 ) $ (34 ) $ — $ (282 ) Pretax (favorable) unfavorable premium development (18 ) (7 ) (2 ) — (27 ) Total pretax (favorable) unfavorable net prior year development $ (229 ) $ (44 ) $ (36 ) $ — $ (309 ) Premium development can occur in the property and casualty business when there is a change in exposure on auditable policies or when premium accruals differ from processed premium. Audits on policies usually occur in a period after the expiration date of the policy. See further information on the premium development in the Commercial segment for the three and nine months ended September 30, 2017 within the Small Business discussion in Note F. Specialty The following table presents further detail of the net prior year claim and allocated claim adjustment expense reserve development (development) recorded for the Specialty segment. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ 1 $ 13 $ 5 $ (17 ) Other Professional Liability and Management Liability (27 ) (48 ) (96 ) (98 ) Surety (82 ) (63 ) (82 ) (63 ) Warranty (1 ) 2 5 7 Other — (16 ) 5 (40 ) Total pretax (favorable) unfavorable development $ (109 ) $ (112 ) $ (163 ) $ (211 ) Three Months 2017 Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency in accident years 2012 through 2015, primarily for professional liability products. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2015 and prior. 2016 Unfavorable development for medical professional liability was largely due to higher than expected frequency in accident years 2014 and 2015 in aging services. Increased claims on a specific hospital policy in accident years 2014 and 2015 was also an unfavorable contributor although more than offset by favorable development relative to expectations in accident years 2013 and prior. Favorable development in other professional liability and management liability was primarily related to lower than expected frequency of claims and favorable outcomes on specific claims for accident years 2010 through 2014. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2014 and prior. Favorable development for other coverages was due to better than expected claim frequency in commercial lines coverages provided to Specialty customers in accident years 2010 through 2015. Nine Months 2017 Favorable development in other professional liability and management liability was primarily due to favorable settlements on closed claims and a lower frequency of large losses for accident years 2011 through 2016 for professional and management liability, lower than expected claim frequency in accident years 2012 through 2015 for professional liability and lower than expected severity in accident years 2014 through 2016 for professional liability. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2015 and prior. 2016 Favorable development for medical professional liability was primarily due to lower than expected severities for individual healthcare professionals, allied facilities and hospitals in accident years 2011 and prior. This was partially offset by unfavorable development in accident years 2012 and 2013 related to higher than expected large loss emergence in hospitals and higher than expected frequency and severity in accident years 2014 and 2015 in our aging services business. Favorable development in other professional liability and management liability was primarily related to favorable settlements on closed claims in accident years 2011 through 2013 in professional services. Additional favorable development related to lower than expected frequency of claims and favorable outcomes on specific claims in accident years 2010 through 2014 in professional services. This was partially offset by unfavorable development related to a specific financial institutions claim in accident year 2014, higher severities in accident year 2015, and deterioration on credit crises-related claims in accident year 2009. Favorable development in surety coverages was primarily due to lower than expected frequency of large losses in accident years 2014 and prior. Favorable development for other coverages provided to Specialty customers was due to better than expected claim frequency in property coverages in accident year 2015 and commercial lines coverages in accident years 2010 through 2015. Commercial The following table presents further detail of the development recorded for the Commercial segment. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Commercial Auto $ (14 ) $ (12 ) $ (40 ) $ (47 ) General Liability 7 14 6 (38 ) Workers' Compensation 7 (6 ) (39 ) 48 Property and Other (7 ) (1 ) 8 — Total pretax (favorable) unfavorable development $ (7 ) $ (5 ) $ (65 ) $ (37 ) Three Months 2017 Favorable development for commercial auto was primarily due to lower than expected severity in accident years 2015 and 2016, as well as a large favorable recovery on a claim in accident year 2012. Unfavorable development in workers' compensation reflects the recognition of loss estimates related to favorable premium development as well as an adverse arbitration ruling related to reinsurance recoverables from older accident years. 2016 Favorable development for commercial auto was primarily due to lower than expected severities in accident years 2012 through 2015. Unfavorable development for general liability was primarily due to an increase in reported claims prior to the closing of the three year window set forth by the Minnesota Child Victims Act in accident years 2006 and prior. Favorable development for workers' compensation was primarily driven by lower than expected frequencies in accident years 2009 through 2014, partially offset by the estimated impact of recent Florida court rulings in accident years 2008 through 2015. Nine Months 2017 Favorable development for commercial auto was primarily due to lower than expected severity in accident years 2013 through 2016, as well as a large favorable recovery on a claim in accident year 2012. Favorable development for workers’ compensation was primarily related to decreases in frequency and severity in recent accident years, partially attributable to California reforms related to decreases in medical costs. This was partially offset by unfavorable development related to an adverse arbitration ruling on reinsurance recoverables from older accident years as well as the recognition of loss estimates associated with favorable premium development. Unfavorable development for property and other was primarily due to higher than expected severity in accident year 2016. 2016 Favorable development for commercial auto was primarily due to favorable settlements on claims in accident years 2010 through 2014 and lower than expected severities in accident years 2012 through 2015. Favorable development for general liability was primarily due to better than expected claim settlements in accident years 2012 through 2014 and better than expected severity on umbrella claims in accident years 2010 through 2013. This was partially offset by unfavorable development related to an increase in reported claims prior to the closing of the three year window set forth by the Minnesota Child Victims Act in accident years 2006 and prior. Unfavorable development for workers' compensation was primarily due to higher than expected severity for Defense Base Act contractors and the estimated impact of recent Florida court rulings in accident years 2008 through 2015. This was partially offset by favorable development related to lower than expected frequencies related to accident years 2009 through 2014. Unfavorable development for property and other was primarily due to higher than expected severity from a 2015 catastrophe event. This was offset by favorable development primarily due to better than expected loss frequency in accident years 2013 through 2015. International The following table presents further detail of the development recorded for the International segment. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ 4 $ (2 ) $ (1 ) $ (3 ) Other Professional Liability (8 ) (1 ) 1 16 Liability 4 (2 ) (1 ) (21 ) Property & Marine (4 ) (9 ) (15 ) (16 ) Other 5 (1 ) 17 (10 ) Total pretax (favorable) unfavorable development $ 1 $ (15 ) $ 1 $ (34 ) Three Months 2017 Favorable development in other professional liability was primarily due to better than expected emergence in the Canadian run-off business in accident years 2014 and prior. 2016 Favorable development for other professional liability was primarily due to favorable settlements on claims in accident years 2013 and prior. This was largely offset by higher than expected unfavorable large loss emergence in accident years 2014 and 2015. Favorable development for property and marine was primarily due to favorable emergence of expected losses on a specific claim relating to the December 2015 United Kingdom (UK) floods. Nine Months 2017 Favorable development for other professional liability was primarily due to better than expected emergence in the Canadian run-off business in accident years 2014 and prior, as well as several favorable settlements relating to large claims in the Europe Professional Indemnity portfolio. This was partially offset by higher than expected severity in accident year 2015 arising from the management liability business. Favorable development for property and marine was due to better than expected frequency in accident years 2014 through 2016. Unfavorable development for other coverages was primarily due to adverse large claims experience in the Hardy Political Risks portfolio, relating largely to accident year 2016. 2016 Unfavorable development for other professional liability was primarily due to higher than expected large loss emergence in accident years 2011 through 2015, partially offset by favorable settlements on claims in accident years 2013 and prior. Favorable development for liability was primarily due to better than expected severity in accident years 2013 and prior. Favorable development for property and marine was primarily due to favorable emergence of expected losses on a specific claim relating to the December 2015 UK floods. Favorable development for other coverages was primarily due to better than expected severity in auto liability in accident years 2011 through 2015. Asbestos and 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 . Subsequent to the effective date of the LPT, the Company recognized adverse prior year development on its A&EP reserves which resulted in additional amounts ceded under the LPT. As a result, the cumulative amounts ceded under the LPT exceeded the $2.2 billion consideration paid, resulting in the NICO LPT moving into a gain position, requiring retroactive reinsurance accounting. Under retroactive reinsurance accounting, this gain is deferred and only recognized in earnings in proportion to actual paid recoveries under the LPT. Over the life of the contract, there is no economic impact as long as any additional losses incurred are within the limit of the LPT. In a period in which the Company recognizes a change in the estimate of A&EP reserves that increases the amounts ceded under the LPT, the proportion of actual paid recoveries to total ceded losses is impacted and the change in the deferred gain is recognized in earnings as if the revised estimate of ceded losses was available at the effective date of the LPT. The effect of the deferred retroactive reinsurance benefit is recorded in Insurance claims and policyholders' benefits in the Condensed Consolidated Statement of Operations. The following table presents the impact of the Loss Portfolio Transfer on the Condensed Consolidated Statements of Operations. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Net A&EP adverse development before consideration of LPT $ — $ — $ 60 $ 200 Retroactive reinsurance benefit recognized (17 ) (12 ) (60 ) (94 ) Pretax impact of A&EP reserve development and the LPT $ (17 ) $ (12 ) $ — $ 106 Based upon the Company's annual A&EP reserve review, net unfavorable prior year development of $60 million and $200 million was recognized before consideration of cessions to the LPT for the nine months ended September 30, 2017 and 2016 . The 2017 unfavorable development was driven by modestly higher anticipated payouts on claims from known sources of asbestos exposure. The 2016 unfavorable development was driven by an increase in anticipated future expenses associated with determination of coverage, higher anticipated payouts associated with a limited number of historical accounts having significant asbestos exposures and higher than expected severity on pollution claims. While this unfavorable development was ceded to NICO under the LPT, the Company’s Net income in both periods was negatively affected due to the application of retroactive reinsurance accounting. As of September 30, 2017 and December 31, 2016 , the cumulative amounts ceded under the LPT were $2.9 billion and $2.8 billion . The unrecognized deferred retroactive reinsurance benefit was $334 million as of September 30, 2017 and December 31, 2016 . NICO established a collateral trust account as security for its obligations to the Company. The fair value of the collateral trust account was $2.9 billion and $2.8 billion as of September 30, 2017 and December 31, 2016 . 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 Company’s A&EP claims.

Legal Proceedings and Guarantee

Legal Proceedings and Guarantees	9 Months Ended
	Sep. 30, 2017
Legal Proceedings, Commitments and Contingencies, and Guarantees [Abstract]
Legal Proceedings and Guarantees	Legal Proceedings and Guarantees CNA 401(k) Plus Plan Litigation In September 2016, a class action lawsuit was filed against CCC, Continental Assurance Company (CAC) (a former subsidiary of CCC), CNAF, the Investment Committee of the CNA 401(k) Plus Plan (Plan), The Northern Trust Company and John Does 1-10 (collectively Defendants) related to the Plan. The complaint alleges that Defendants breached fiduciary duties to the Plan and caused prohibited transactions in violation of the Employee Retirement Income Security Act of 1974 when the Plan's Fixed Income Fund’s annuity contract with CAC was canceled. The plaintiff alleges he and a proposed class of Plan participants who had invested in the Fixed Income Fund suffered lower returns in their Plan investments as a consequence of these alleged violations and seeks relief on behalf of the putative class. CCC and the other defendants are contesting the case, and no class has been certified. The Plan trustees have provided notice to their fiduciary coverage insurance carriers. Progress on the litigation has been limited as the parties are currently in mediation. Based on information currently available and our assessment of the mediation, management has recorded its best estimate of probable loss; however, it is reasonably possible that the ultimate liability may differ from that amount given the inherent uncertainty involved in this matter. After consideration of available insurance coverage, management does not believe that the ultimate resolution of this matter will have a material impact on the Company’s results of operations or financial position though the timing of recognition of any additional loss, if any, and insurance recovery, if any, may differ. Small Business Premium Rate Adjustment In prior quarters, the Company identified rating errors related to its multi-peril package product and workers' compensation policies within its Small Business unit, and the Company determined that it would voluntarily issue premium refunds along with interest on affected policies. After the rating errors were identified, written and earned premium have been reported net of any impact from the premium rate adjustments. There was no premium development impact for the three months ended September 30, 2017 and $37 million of adverse premium development was recognized as a result of the rating errors for the nine months ended September 30, 2017 . Pretax operating income was reduced by $1 million and $7 million for the three and nine months ended September 30, 2017 for interest due to policyholders on the premium rate adjustments. The policyholder refunds for the multi-package product were issued in the current quarter. The estimated refund liability for the workers' compensation policies as of September 30, 2017 was $61 million including interest. Any fines or penalties related to the foregoing are reasonably possible, but are not expected to be material to the Company's results of operations or financial position. Other Litigation The Company is a party to other routine litigation incidental to its business, which, based on the facts and circumstances currently known, is not material to the Company's results of operations or financial position. Guarantees As of September 30, 2017 and December 31, 2016 , the Company had recorded liabilities of approximately $5 million related to guarantee and indemnification agreements. Management believes that it is not likely that any future indemnity claims will be significantly greater than the amounts recorded. In the course of selling business entities and assets to third parties, the Company agreed to guarantee the performance of certain obligations of previously owned subsidiaries and to indemnify purchasers for losses arising out of breaches of representations and warranties with respect to the business entities or assets sold, including, in certain cases, losses arising from undisclosed liabilities or certain named litigation. Such guarantee and indemnification agreements in effect for sales of business entities, assets and third-party loans may include provisions that survive indefinitely. As of September 30, 2017 , the aggregate amount related to quantifiable guarantees was $375 million and the aggregate amount related to quantifiable indemnification agreements was $254 million . In certain cases, should the Company be required to make payments under any such guarantee, it would have the right to seek reimbursement from an affiliate of a previously owned subsidiary. In addition, the Company has agreed to provide indemnification to third-party purchasers for certain losses associated with sold business entities or assets that are not limited by a contractual monetary amount. As of September 30, 2017 , the Company had outstanding unlimited indemnifications in connection with the sales of certain of its business entities or assets that included tax liabilities arising prior to a purchaser's ownership of an entity or asset, defects in title at the time of sale, employee claims arising prior to closing and in some cases losses arising from certain litigation and undisclosed liabilities. Certain provisions of the indemnification agreements survive indefinitely, while others survive until the applicable statutes of limitation expire, or until the agreed-upon contract terms expire. The Company also provided guarantees, if the primary obligor fails to perform, to holders of structured settlement annuities provided by a previously owned subsidiary. As of September 30, 2017 , the potential amount of future payments the Company could be required to pay under these guarantees was approximately $1.8 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	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The components of net periodic cost (benefit) are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pension cost (benefit) Interest cost on projected benefit obligation $ 25 $ 29 $ 77 $ 85 Expected return on plan assets (38 ) (41 ) (116 ) (121 ) Amortization of net actuarial loss 9 9 27 28 Settlement loss 6 — 8 — Net periodic pension cost (benefit) $ 2 $ (3 ) $ (4 ) $ (8 ) The Company contributed $26 million to its pension plans for the nine months ended September 30, 2017 and expects to contribute an additional $2 million to its pension plans before December 31, 2017 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss) by Component	9 Months Ended
	Sep. 30, 2017
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 OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of July 1, 2017 $ 26 $ 786 $ (635 ) $ (145 ) $ 32 Other comprehensive income (loss) before reclassifications 1 35 — 41 77 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $-, $(4), $5, $- and $1 — 12 (10 ) — 2 Other comprehensive income (loss) net of tax (expense) benefit of $-, $(16), $(5), $- and $(21) 1 23 10 41 75 Balance as of September 30, 2017 $ 27 $ 809 $ (625 ) $ (104 ) $ 107 (In millions) Net unrealized gains (losses) on investments with OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of July 1, 2016 $ 31 $ 934 $ (637 ) $ (118 ) $ 210 Other comprehensive income (loss) before reclassifications 7 69 — (24 ) 52 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(2), $(13), $3, $- and $(12) 4 27 (6 ) — 25 Other comprehensive income (loss) net of tax (expense) benefit of $(2), $(19), $(3), $- and $(24) 3 42 6 (24 ) 27 Balance as of September 30, 2016 $ 34 $ 976 $ (631 ) $ (142 ) $ 237 (In millions) Net unrealized gains (losses) on investments with OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2017 $ 30 $ 642 $ (647 ) $ (198 ) $ (173 ) Other comprehensive income (loss) before reclassifications — 228 — 94 322 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(1), $(28), $12, $- and $(17) 3 61 (22 ) — 42 Other comprehensive income (loss) net of tax (expense) benefit of $1, $(102), $(12), $- and $(113) (3 ) 167 22 94 280 Balance as of September 30, 2017 $ 27 $ 809 $ (625 ) $ (104 ) $ 107 (In millions) Net unrealized gains (losses) on investments with OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2016 $ 27 $ 390 $ (648 ) $ (84 ) $ (315 ) Other comprehensive income (loss) before reclassifications 9 615 — (58 ) 566 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(1), $(12), $9, $- and $(4) 2 29 (17 ) — 14 Other comprehensive income (loss) net of tax (expense) benefit of $(4), $(292), $(9), $- and $(305) 7 586 17 (58 ) 552 Balance as of September 30, 2016 $ 34 $ 976 $ (631 ) $ (142 ) $ 237 Amounts reclassified from Accumulated other comprehensive income (loss) shown above are reported in Net income (loss) as follows: Component of AOCI Condensed Consolidated Statements of Operations Line Item Affected by Reclassifications Net unrealized gains (losses) on investments with OTTI losses Net realized investment gains (losses) Net unrealized gains (losses) on other investments Net realized investment gains (losses) Pension and postretirement benefits Other operating expenses

Business Segments

Business Segments	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Business Segments	Business Segments The Company's core property and casualty commercial insurance operations are managed and reported in three business segments: Specialty, Commercial and International. The Company's non-core operations are managed and reported in two segments: Life & Group Non-Core and Corporate & Other Non-Core. 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, 2016 . 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 and Goodwill are readily identifiable for all 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 Realized investment gains or losses are allocated primarily based on each segment's net carried insurance reserves, as adjusted. All significant intersegment income and expense has 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. Net operating income (loss), which is derived from certain income statement amounts, is used by management to monitor performance of the Company's insurance operations. 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. Based on such analyses, the Company may recognize an OTTI loss on an investment security in accordance with its policy, or sell a security, which may produce realized gains and losses. Net operating income (loss) is calculated by excluding from net income (loss) the after-tax effects of i) net realized investment gains (losses) ii) income or loss from discontinued operations and iii) any cumulative effects of changes in accounting guidance. The calculation of net operating income excludes net realized investment gains (losses) because net realized investment gains (losses) are largely discretionary, except for some losses related to OTTI, and are generally driven by economic factors that are not necessarily consistent with key drivers of underwriting performance, and are therefore not considered an indication of trends in insurance operations. The Company's results of operations and selected balance sheet items by segment are presented in the following tables. Three months ended September 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 703 $ 741 $ 226 $ 136 $ — $ — $ 1,806 Net investment income 134 161 13 195 6 — 509 Other revenues 99 7 1 — — — 107 Total operating revenues 936 909 240 331 6 — 2,422 Claims, Benefits and Expenses Net incurred claims and benefits 357 611 200 322 (15 ) — 1,475 Policyholders’ dividends 1 4 — — — — 5 Amortization of deferred acquisition costs 153 120 36 — — — 309 Other insurance related expenses 68 133 48 32 — — 281 Other expenses 85 6 (4 ) 2 52 — 141 Total claims, benefits and expenses 664 874 280 356 37 — 2,211 Operating income (loss) before income tax 272 35 (40 ) (25 ) (31 ) — 211 Income tax (expense) benefit on operating income (loss) (92 ) (10 ) 2 35 13 — (52 ) Net operating income (loss) 180 25 (38 ) 10 (18 ) — 159 Net realized investment gains (losses) 4 6 4 3 (41 ) — (24 ) Income tax (expense) benefit on net realized investment gains (losses) (1 ) (3 ) (1 ) (1 ) 15 — 9 Net realized investment gains (losses), after tax 3 3 3 2 (26 ) — (15 ) Net income (loss) $ 183 $ 28 $ (35 ) $ 12 $ (44 ) $ — $ 144 Three months ended September 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 704 $ 719 $ 210 $ 134 $ — $ — $ 1,767 Net investment income 140 175 13 192 4 — 524 Other revenues 93 7 — (4 ) — — 96 Total operating revenues 937 901 223 322 4 — 2,387 Claims, Benefits and Expenses Net incurred claims and benefits 330 446 117 313 (11 ) — 1,195 Policyholders’ dividends 4 3 — — — — 7 Amortization of deferred acquisition costs 151 118 45 — — — 314 Other insurance related expenses 77 151 33 37 (3 ) — 295 Other expenses 78 9 1 2 57 — 147 Total claims, benefits and expenses 640 727 196 352 43 — 1,958 Operating income (loss) before income tax 297 174 27 (30 ) (39 ) — 429 Income tax (expense) benefit on operating income (loss) (102 ) (60 ) (7 ) 36 15 — (118 ) Net operating income (loss) 195 114 20 6 (24 ) — 311 Net realized investment gains (losses) 9 12 6 17 2 — 46 Income tax (expense) benefit on net realized investment gains (losses) (3 ) (3 ) (1 ) (6 ) (1 ) — (14 ) Net realized investment gains (losses), after tax 6 9 5 11 1 — 32 Net income (loss) $ 201 $ 123 $ 25 $ 17 $ (23 ) $ — $ 343 Nine months ended September 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 2,056 $ 2,097 $ 629 $ 404 $ — $ (1 ) $ 5,185 Net investment income 407 482 38 587 15 — 1,529 Other revenues 291 25 — 1 1 — 318 Total operating revenues 2,754 2,604 667 992 16 (1 ) 7,032 Claims, Benefits and Expenses Net incurred claims and benefits 1,141 1,470 444 980 4 — 4,039 Policyholders’ dividends 3 11 — — — — 14 Amortization of deferred acquisition costs 445 354 127 — — — 926 Other insurance related expenses 209 387 106 96 (1 ) (1 ) 796 Other expenses 248 31 (11 ) 5 146 — 419 Total claims, benefits and expenses 2,046 2,253 666 1,081 149 (1 ) 6,194 Operating income (loss) before income tax 708 351 1 (89 ) (133 ) — 838 Income tax (expense) benefit on operating income (loss) (238 ) (117 ) (9 ) 108 51 — (205 ) Net operating income (loss) 470 234 (8 ) 19 (82 ) — 633 Net realized investment gains (losses) 25 36 17 20 (36 ) — 62 Income tax (expense) benefit on net realized investment gains (losses) (9 ) (12 ) (3 ) (8 ) 13 — (19 ) Net realized investment gains (losses), after tax 16 24 14 12 (23 ) — 43 Net income (loss) $ 486 $ 258 $ 6 $ 31 $ (105 ) $ — $ 676 September 30, 2017 (In millions) Reinsurance receivables $ 819 $ 590 $ 227 $ 453 $ 2,280 $ — $ 4,369 Insurance receivables 984 1,087 256 11 2 — 2,340 Deferred acquisition costs 318 230 95 — — — 643 Goodwill 117 — 30 — — — 147 Insurance reserves Claim and claim adjustment expenses 6,063 8,630 1,640 3,468 2,408 — 22,209 Unearned premiums 2,010 1,426 490 134 — — 4,060 Future policy benefits — — — 11,040 — — 11,040 Nine months ended September 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 2,088 $ 2,103 $ 605 $ 401 $ — $ (1 ) $ 5,196 Net investment income 380 465 38 567 11 — 1,461 Other revenues 269 21 1 (1 ) 3 — 293 Total operating revenues 2,737 2,589 644 967 14 (1 ) 6,950 Claims, Benefits and Expenses Net incurred claims and benefits 1,097 1,357 395 976 109 — 3,934 Policyholders’ dividends 6 9 — — — — 15 Amortization of deferred acquisition costs 443 351 132 — — — 926 Other insurance related expenses 225 422 98 101 (3 ) (1 ) 842 Other expenses 232 25 17 7 158 — 439 Total claims, benefits and expenses 2,003 2,164 642 1,084 264 (1 ) 6,156 Operating income (loss) before income tax 734 425 2 (117 ) (250 ) — 794 Income tax (expense) benefit on operating income (loss) (248 ) (145 ) (3 ) 117 88 — (191 ) Net operating income (loss) 486 280 (1 ) — (162 ) — 603 Net realized investment gains (losses) 2 2 14 12 (4 ) — 26 Income tax (expense) benefit on net realized investment gains (losses) (1 ) — (3 ) (9 ) 2 — (11 ) Net realized investment gains (losses), after tax 1 2 11 3 (2 ) — 15 Net income (loss) $ 487 $ 282 $ 10 $ 3 $ (164 ) $ — $ 618 December 31, 2016 (In millions) Reinsurance receivables $ 760 $ 621 $ 131 $ 462 $ 2,479 $ — $ 4,453 Insurance receivables 982 1,021 233 17 2 — 2,255 Deferred acquisition costs 310 214 76 — — — 600 Goodwill 117 — 28 — — — 145 Insurance reserves Claim and claim adjustment expenses 6,149 8,894 1,328 3,358 2,614 — 22,343 Unearned premiums 1,911 1,323 396 132 — — 3,762 Future policy benefits — — — 10,326 — — 10,326 The following table presents revenue by line of business for each reportable segment. Revenues are comprised of operating revenues and net realized investment gains and losses. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Specialty Management & Professional Liability $ 656 $ 677 $ 1,963 $ 1,954 Surety 144 139 404 399 Warranty & Alternative Risks 140 130 412 386 Specialty revenues 940 946 2,779 2,739 Commercial Middle Market 501 463 1,421 1,298 Small Business 131 154 357 448 Other Commercial Insurance 283 296 862 845 Commercial revenues 915 913 2,640 2,591 International Canada 60 51 164 152 CNA Europe 87 82 239 241 Hardy 97 96 281 265 International revenues 244 229 684 658 Life & Group Non-Core revenues 334 339 1,012 979 Corporate & Other Non-Core revenues (35 ) 6 (20 ) 10 Eliminations — — (1 ) (1 ) Total revenues $ 2,398 $ 2,433 $ 7,094 $ 6,976

General (Policies)

General (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Consolidation	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, 2016 , including the summary of significant accounting policies in Note A.
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.
Recently Adopted Accounting Standards Updates and Accounting Standards Pending Adoption	Recently Adopted Accounting Standards Updates (ASU) In March 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The updated accounting guidance simplifies the accounting for share-based payment award transactions, including income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. As of January 1, 2017, the Company adopted the updated accounting guidance and began recognizing excess tax benefits or deficiencies on vesting or settlement of awards as an income tax benefit or expense within net income, instead of additional paid-in capital as required under previous guidance. The related cash flows are now classified within operating activities. As a result of this change, excess tax benefits are no longer included in assumed proceeds under the treasury stock method of calculating earnings per share. The impact of the accounting change resulted in a decrease of $2 million and $5 million to income tax expense for the three and nine months ended September 30, 2017 . Accounting Standards Pending Adoption In May 2014, the FASB issued ASU No. 2014-09, Revenue Recognition (Topic 606): Revenue from Contracts with Customers . The standard excludes from its scope the accounting for insurance contracts, financial instruments, and certain other agreements that are governed under other GAAP guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in an amount that reflects the consideration the entity is entitled to receive for the transfer of the promised goods or services. The standard is effective for interim and annual reporting periods beginning after December 15, 2017 and may be applied retrospectively or through a cumulative effect adjustment to retained earnings at the date of adoption. While the Company continues to evaluate the impacts of this new guidance on the Consolidated financial statements, including disclosures, the Company expects that revenue on warranty products and services will be recognized more slowly than under the current revenue recognition pattern. For a significant portion of warranty products, the Company also expects Other revenues and Other operating expenses to increase to reflect the gross amount paid by consumers to the auto dealer that acts as the Company's agent. The Company expects to adopt this guidance using the modified retrospective approach. While the cumulative effect of adoption using the modified retrospective approach may be significant, the Company does not expect the impact of the new guidance to be material to its results of operations or financial position. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The updated accounting guidance requires changes to the reporting model for financial instruments. The guidance is effective for interim and annual periods beginning after December 15, 2017. The Company expects the primary change to be the requirement for equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. Upon adoption, the Company will recognize an adjustment for the cumulative amount of unrealized investment gains and losses related to available-for-sale equity securities within the opening balances of Retained earnings and Accumulated other comprehensive income (loss). The Company does not expect the impact of adopting ASU 2016-01 to have a material effect on the Company’s results of operations or financial position. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842): Accounting for Leases. The updated accounting guidance requires lessees to recognize on the balance sheet the assets and liabilities for the rights and obligations created by all leases, including those historically accounted for as operating leases. The guidance is effective for interim and annual periods beginning after December 15, 2018. The Company is currently evaluating the effect the updated guidance will have on the Company's financial statements. It is expected that assets and liabilities will increase based on the present value of remaining lease payments for leases in place at the adoption date; however, this is not expected to be material to the Company's results of operations or financial position. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The updated accounting guidance requires changes to the recognition of credit losses on financial instruments not accounted for at fair value through net income. The guidance is effective for interim and annual periods beginning after December 15, 2019. The Company is currently evaluating the effect the guidance will have on the Company's financial statements, but expects the primary changes to be the use of the expected credit loss model for its mortgage loan portfolio and reinsurance receivables and the presentation of credit losses within the available-for-sale fixed maturities portfolio through an allowance method rather than as a direct write-down. The expected credit loss model will require a financial asset to be presented at the net amount expected to be collected. The allowance method for available-for-sale debt securities will allow the Company to record reversals of credit losses if the estimate of credit losses declines. In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . The updated accounting guidance requires changes to the presentation of the components of net periodic benefit cost on the income statement by requiring service cost to be presented with other employee compensation costs and other components of net periodic pension cost to be presented outside of any subtotal of operating income. The ASU also stipulates that only the service cost component of net benefit cost is eligible for capitalization. The guidance is effective for interim and annual periods beginning after December 15, 2017. The Company is currently evaluating the effect the guidance will have on the Company's financial statements.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments [Abstract]
Net investment income	The significant components of Net investment income are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Fixed maturity securities $ 455 $ 457 $ 1,367 $ 1,352 Equity securities 1 1 4 8 Limited partnership investments 51 65 157 97 Mortgage loans 9 8 24 30 Short term investments 4 2 10 6 Trading portfolio 3 1 9 7 Other 1 4 2 4 Gross investment income 524 538 1,573 1,504 Investment expense (15 ) (14 ) (44 ) (43 ) Net investment income $ 509 $ 524 $ 1,529 $ 1,461
Net realized investment gains (losses)	Net realized investment gains (losses) are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Net realized investment gains (losses): Fixed maturity securities: Gross realized gains $ 34 $ 67 $ 139 $ 152 Gross realized losses (18 ) (20 ) (47 ) (106 ) Net realized investment gains (losses) on fixed maturity securities 16 47 92 46 Equity securities: Gross realized gains — 1 1 5 Gross realized losses — (4 ) (1 ) (10 ) Net realized investment gains (losses) on equity securities — (3 ) — (5 ) Derivatives (1 ) 1 (3 ) (12 ) Short term investments and other (39 ) 1 (27 ) (3 ) Net realized investment gains (losses) $ (24 ) $ 46 $ 62 $ 26
Components of net other than temporary impairment losses recognized in earnings by asset type	The components of Other-than-temporary impairment (OTTI) losses recognized in earnings by asset type are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Fixed maturity securities available-for-sale: Corporate and other bonds $ 4 $ 14 $ 8 $ 43 Asset-backed: Residential mortgage-backed 1 — 1 1 Other asset-backed — — — 3 Total asset-backed 1 — 1 4 Total fixed maturity securities available-for-sale 5 14 9 47 Equity securities available-for-sale -- Common stock — 4 — 9 OTTI losses recognized in earnings $ 5 $ 18 $ 9 $ 56
Summary of fixed maturity and equity securities	The following tables present a summary of fixed maturity and equity securities. September 30, 2017 Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Unrealized OTTI Losses (Gains) (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 17,965 $ 1,645 $ 26 $ 19,584 $ — States, municipalities and political subdivisions 12,462 1,501 7 13,956 (14 ) Asset-backed: Residential mortgage-backed 4,906 127 28 5,005 (28 ) Commercial mortgage-backed 1,858 55 13 1,900 — Other asset-backed 1,047 18 4 1,061 — Total asset-backed 7,811 200 45 7,966 (28 ) U.S. Treasury and obligations of government-sponsored enterprises 115 3 3 115 — Foreign government 439 10 4 445 — Redeemable preferred stock 18 2 — 20 — Total fixed maturity securities available-for-sale 38,810 3,361 85 42,086 $ (42 ) Total fixed maturity securities trading 4 4 Equity securities available-for-sale: Common stock 16 7 1 22 Preferred stock 102 5 — 107 Total equity securities available-for-sale 118 12 1 129 Total $ 38,932 $ 3,373 $ 86 $ 42,219 December 31, 2016 Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Unrealized OTTI Losses (Gains) (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 17,711 $ 1,323 $ 76 $ 18,958 $ (1 ) States, municipalities and political subdivisions 12,060 1,213 33 13,240 (16 ) Asset-backed: Residential mortgage-backed 5,004 120 51 5,073 (28 ) Commercial mortgage-backed 2,016 48 24 2,040 — Other asset-backed 1,022 8 5 1,025 — Total asset-backed 8,042 176 80 8,138 (28 ) U.S. Treasury and obligations of government-sponsored enterprises 83 10 — 93 — Foreign government 435 13 3 445 — Redeemable preferred stock 18 1 — 19 — Total fixed maturity securities available-for-sale 38,349 2,736 192 40,893 $ (45 ) Total fixed maturity securities trading 12 12 Equity securities available-for-sale: Common stock 13 6 — 19 Preferred stock 93 2 4 91 Total equity securities available-for-sale 106 8 4 110 Total $ 38,467 $ 2,744 $ 196 $ 41,015
Securities in a gross unrealized loss position	The following tables present the estimated fair value and gross unrealized losses of fixed maturity and equity securities in a gross unrealized loss position by the length of time in which the securities have continuously been in that position. Less than 12 Months 12 Months or Longer Total September 30, 2017 Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 1,216 $ 21 $ 91 $ 5 $ 1,307 $ 26 States, municipalities and political subdivisions 583 6 56 1 639 7 Asset-backed: Residential mortgage-backed 1,522 25 106 3 1,628 28 Commercial mortgage-backed 378 6 138 7 516 13 Other asset-backed 129 4 10 — 139 4 Total asset-backed 2,029 35 254 10 2,283 45 U.S. Treasury and obligations of government-sponsored enterprises 67 3 6 — 73 3 Foreign government 191 4 5 — 196 4 Total fixed maturity securities available-for-sale 4,086 69 412 16 4,498 85 Equity securities available-for-sale: Common stock 2 1 — — 2 1 Preferred stock 16 — — — 16 — Total equity securities available-for-sale 18 1 — — 18 1 Total $ 4,104 $ 70 $ 412 $ 16 $ 4,516 $ 86 Less than 12 Months 12 Months or Longer Total December 31, 2016 Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses (In millions) Fixed maturity securities available-for-sale: Corporate and other bonds $ 2,615 $ 61 $ 254 $ 15 $ 2,869 $ 76 States, municipalities and political subdivisions 959 32 23 1 982 33 Asset-backed: Residential mortgage-backed 2,136 44 201 7 2,337 51 Commercial mortgage-backed 756 22 69 2 825 24 Other asset-backed 398 5 24 — 422 5 Total asset-backed 3,290 71 294 9 3,584 80 U.S. Treasury and obligations of government-sponsored enterprises 5 — — — 5 — Foreign government 108 3 — — 108 3 Total fixed maturity securities available-for-sale 6,977 167 571 25 7,548 192 Equity securities available-for-sale -- Preferred stock 12 — 13 4 25 4 Total $ 6,989 $ 167 $ 584 $ 29 $ 7,573 $ 196
Activity related to the pretax fixed maturity credit loss component reflected within retained earnings for securities still held for which a portion of an OTTI loss was recognized in OCI	The following table presents the activity related to the pretax credit loss component reflected in Retained earnings on fixed maturity securities still held as of September 30, 2017 and 2016 for which a portion of an OTTI loss was recognized in Other comprehensive income (loss). Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Beginning balance of credit losses on fixed maturity securities $ 30 $ 41 $ 36 $ 53 Reductions for securities sold during the period (2 ) (2 ) (8 ) (14 ) Reductions for securities the Company intends to sell or more likely than not will be required to sell — (1 ) — (1 ) Ending balance of credit losses on fixed maturity securities $ 28 $ 38 $ 28 $ 38
Contractual maturity	The following table presents available-for-sale fixed maturity securities by contractual maturity. September 30, 2017 December 31, 2016 (In millions) Cost or Amortized Cost Estimated Fair Value Cost or Amortized Cost Estimated Fair Value Due in one year or less $ 1,374 $ 1,404 $ 1,779 $ 1,828 Due after one year through five years 7,931 8,293 7,566 7,955 Due after five years through ten years 15,853 16,574 15,892 16,332 Due after ten years 13,652 15,815 13,112 14,778 Total $ 38,810 $ 42,086 $ 38,349 $ 40,893

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2017
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. September 30, 2017 Total Assets/Liabilities at Fair Value (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate and other bonds $ — $ 19,469 $ 119 $ 19,588 States, municipalities and political subdivisions — 13,955 1 13,956 Asset-backed: Residential mortgage-backed — 4,829 176 5,005 Commercial mortgage-backed — 1,876 24 1,900 Other asset-backed — 915 146 1,061 Total asset-backed — 7,620 346 7,966 U.S. Treasury and obligations of government-sponsored enterprises 115 — — 115 Foreign government — 445 — 445 Redeemable preferred stock 20 — — 20 Total fixed maturity securities 135 41,489 466 42,090 Equity securities 110 — 19 129 Other invested assets — 5 — 5 Short term investments 479 876 — 1,355 Total assets $ 724 $ 42,370 $ 485 $ 43,579 Liabilities Other liabilities $ — $ 1 $ — $ 1 Total liabilities $ — $ 1 $ — $ 1 December 31, 2016 Total Assets/Liabilities at Fair Value (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate and other bonds $ — $ 18,840 $ 130 $ 18,970 States, municipalities and political subdivisions — 13,239 1 13,240 Asset-backed: Residential mortgage-backed — 4,944 129 5,073 Commercial mortgage-backed — 2,027 13 2,040 Other asset-backed — 968 57 1,025 Total asset-backed — 7,939 199 8,138 U.S. Treasury and obligations of government-sponsored enterprises 93 — — 93 Foreign government — 445 — 445 Redeemable preferred stock 19 — — 19 Total fixed maturity securities 112 40,463 330 40,905 Equity securities 91 — 19 110 Other invested assets — 5 — 5 Short term investments 475 853 — 1,328 Life settlement contracts, included in Other assets — — 58 58 Total assets $ 678 $ 41,321 $ 407 $ 42,406 Liabilities Other liabilities $ — $ (3 ) $ — $ (3 ) Total liabilities $ — $ (3 ) $ — $ (3 )
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) Balance as of July 1, 2017 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 100 $ 1 $ 1 $ 13 $ — $ (11 ) $ 15 $ — $ 119 $ — States, municipalities and political subdivisions 1 — — — — — — — 1 — Asset-backed: Residential mortgage-backed 123 1 1 — — (7 ) 58 — 176 — Commercial mortgage-backed 13 — (1 ) 12 — (2 ) 2 — 24 — Other asset-backed 82 (1 ) 1 27 — (4 ) 41 — 146 — Total asset-backed 218 — 1 39 — (13 ) 101 — 346 — Total fixed maturity securities 319 1 2 52 — (24 ) 116 — 466 — Equity securities 19 — — — — — — — 19 — Life settlement contracts 1 — — — (1 ) — — — — — Total $ 339 $ 1 $ 2 $ 52 $ (1 ) $ (24 ) $ 116 $ — $ 485 $ — Level 3 (In millions) Balance as of July 1, 2016 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 242 $ 1 $ 7 $ 16 $ — $ (5 ) $ — $ — $ 261 $ — States, municipalities and political subdivisions 2 — — — — (1 ) — — 1 — Asset-backed: Residential mortgage-backed 134 — (1 ) 5 — (1 ) — (58 ) 79 — Commercial mortgage-backed 11 — — 23 — (8 ) — (2 ) 24 — Other asset-backed 45 — — 34 — — — (36 ) 43 — Total asset-backed 190 — (1 ) 62 — (9 ) — (96 ) 146 — Total fixed maturity securities 434 1 6 78 — (15 ) — (96 ) 408 — Equity securities 19 (1 ) 1 — — — — — 19 (2 ) Life settlement contracts 67 — — — — — — — 67 — Total $ 520 $ — $ 7 $ 78 $ — $ (15 ) $ — $ (96 ) $ 494 $ (2 ) Level 3 (In millions) Balance as of January 1, 2017 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 130 $ 1 $ 2 $ 18 $ (1 ) $ (36 ) $ 15 $ (10 ) $ 119 $ — States, municipalities and political subdivisions 1 — — — — — — — — 1 — Asset-backed: Residential mortgage-backed 129 3 4 — — — (18 ) 58 — 176 — Commercial mortgage-backed 13 — (1 ) — 12 — (2 ) 2 — 24 — Other asset-backed 57 (2 ) 1 — 78 — (6 ) 93 (75 ) 146 — Total asset-backed 199 1 4 90 — (26 ) 153 (75 ) 346 — Total fixed maturity securities 330 2 6 108 (1 ) (62 ) 168 (85 ) 466 — Equity securities 19 — 2 — 1 (3 ) — — — 19 — Derivative financial instruments — 1 — — — (1 ) — — — — — Life settlement contracts 58 6 — — (59 ) (5 ) — — — — Total $ 407 $ 9 $ 8 $ 109 $ (64 ) $ (67 ) $ 168 $ (85 ) $ 485 $ — Level 3 (In millions) Balance as of January 1, 2016 Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)* Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss) Purchases Sales Settlements Transfers into Level 3 Transfers out of Level 3 Balance as of September 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of September 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 168 $ 1 $ 14 $ 163 $ (36 ) $ (15 ) $ — $ (34 ) $ 261 $ — States, municipalities and political subdivisions 2 — — — — (1 ) — — 1 — Asset-backed: Residential mortgage-backed 134 2 (2 ) 15 — (10 ) — (60 ) 79 — Commercial mortgage-backed 22 — — 32 — (17 ) 3 (16 ) 24 — Other asset-backed 53 — 2 69 (25 ) (1 ) 2 (57 ) 43 — Total asset-backed 209 2 — 116 (25 ) (28 ) 5 (133 ) 146 — Total fixed maturity securities 379 3 14 279 (61 ) (44 ) 5 (167 ) 408 — Equity securities 20 (1 ) — — — — — — 19 (2 ) Life settlement contracts 74 10 — — — (17 ) — — 67 2 Total $ 473 $ 12 $ 14 $ 279 $ (61 ) $ (61 ) $ 5 $ (167 ) $ 494 $ — *Net realized and unrealized gains and losses from Level 3 securities and derivatives are reported in Net income (loss) as follows: Major Category of Assets and Liabilities Condensed Consolidated Statements of Operations Line Items Fixed maturity securities available-for-sale (1) Net realized investment gains (losses) Fixed maturity securities trading Net investment income Equity securities (1) Net realized investment gains (losses) Other invested assets - Derivative financial instruments held in a trading portfolio Net investment income Other invested assets - Derivative financial instruments not held in a trading portfolio Net realized investment gains (losses) Life settlement contracts Other revenues Other liabilities - Derivative financial instruments Net realized investment gains (losses) (1) Unrealized gains and losses are reported within AOCI.
Qualitative information about assets and liabilities	*Net realized and unrealized gains and losses from Level 3 securities and derivatives are reported in Net income (loss) as follows: Major Category of Assets and Liabilities Condensed Consolidated Statements of Operations Line Items Fixed maturity securities available-for-sale (1) Net realized investment gains (losses) Fixed maturity securities trading Net investment income Equity securities (1) Net realized investment gains (losses) Other invested assets - Derivative financial instruments held in a trading portfolio Net investment income Other invested assets - Derivative financial instruments not held in a trading portfolio Net realized investment gains (losses) Life settlement contracts Other revenues Other liabilities - Derivative financial instruments Net realized investment gains (losses) (1) Unrealized gains and losses are reported within AOCI.
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 valuation of life settlement contracts was based on the terms of the sale of the contracts to a third party; therefore, the contracts are not included in the table below. September 30, 2017 Estimated Fair Value (In millions) Valuation Technique(s) Unobservable Input(s) Range (Weighted Average) Fixed maturity securities $ 139 Discounted cash flow Credit spread 1% - 12% (3%) December 31, 2016 Estimated Fair Value Valuation Technique(s) Unobservable Input(s) Range (Weighted Average) Fixed maturity securities $ 106 Discounted cash flow Credit spread 2% - 40% (4%)
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. September 30, 2017 Carrying Amount Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 722 $ — $ — $ 731 $ 731 Note receivable 45 — — — — 46 46 Liabilities Short term debt $ 150 $ — $ 152 $ — $ 152 Long term debt 2,707 — 2,916 — 2,916 December 31, 2016 Carrying Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 591 $ — $ — $ 594 $ 594 Liabilities Long term debt $ 2,710 $ — $ 2,952 $ — $ 2,952

Claim and Claim Adjustment Ex20

Claim and Claim Adjustment Expense Reserves (Tables)	9 Months Ended
	Sep. 30, 2017
Liability for Claims and Claims Adjustment Expense [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 Non-Core segment. For the nine months ended September 30 (In millions) 2017 2016 Reserves, beginning of year: Gross $ 22,343 $ 22,663 Ceded 4,094 4,087 Net reserves, beginning of year 18,249 18,576 Net incurred claim and claim adjustment expenses: Provision for insured events of current year 3,949 3,799 Decrease in provision for insured events of prior years (284 ) (332 ) Amortization of discount 138 134 Total net incurred (1) 3,803 3,601 Net payments attributable to: Current year events (560 ) (591 ) Prior year events (3,401 ) (3,209 ) Total net payments (3,961 ) (3,800 ) Foreign currency translation adjustment and other 110 39 Net reserves, end of period 18,201 18,416 Ceded reserves, end of period 4,008 4,256 Gross reserves, end of period $ 22,209 $ 22,672 (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, uncollectible reinsurance and loss deductible receivables, and benefit expenses related to future policy benefits, which are not reflected in the table above.
Net prior year development	The following tables and discussion present the net prior year development recorded for Specialty, Commercial, International and Corporate & Other Non-Core segments. Three months ended September 30, 2017 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (109 ) $ (7 ) $ 1 $ — $ (115 ) Pretax (favorable) unfavorable premium development (3 ) (11 ) (5 ) — (19 ) Total pretax (favorable) unfavorable net prior year development $ (112 ) $ (18 ) $ (4 ) $ — $ (134 ) Three months ended September 30, 2016 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (112 ) $ (5 ) $ (15 ) $ — $ (132 ) Pretax (favorable) unfavorable premium development — (3 ) (2 ) — (5 ) Total pretax (favorable) unfavorable net prior year development $ (112 ) $ (8 ) $ (17 ) $ — $ (137 ) Nine months ended September 30, 2017 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (163 ) $ (65 ) $ 1 $ — $ (227 ) Pretax (favorable) unfavorable premium development (13 ) 27 (16 ) — (2 ) Total pretax (favorable) unfavorable net prior year development $ (176 ) $ (38 ) $ (15 ) $ — $ (229 ) Nine months ended September 30, 2016 (In millions) Specialty Commercial International Corporate & Other Non-Core Total Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development $ (211 ) $ (37 ) $ (34 ) $ — $ (282 ) Pretax (favorable) unfavorable premium development (18 ) (7 ) (2 ) — (27 ) Total pretax (favorable) unfavorable net prior year development $ (229 ) $ (44 ) $ (36 ) $ — $ (309 )
Specialty
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year claim and allocated claim adjustment expense reserve development	The following table presents further detail of the net prior year claim and allocated claim adjustment expense reserve development (development) recorded for the Specialty segment. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ 1 $ 13 $ 5 $ (17 ) Other Professional Liability and Management Liability (27 ) (48 ) (96 ) (98 ) Surety (82 ) (63 ) (82 ) (63 ) Warranty (1 ) 2 5 7 Other — (16 ) 5 (40 ) Total pretax (favorable) unfavorable development $ (109 ) $ (112 ) $ (163 ) $ (211 )
Commercial
Liability for Claims and Claims Adjustment Expense [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. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Commercial Auto $ (14 ) $ (12 ) $ (40 ) $ (47 ) General Liability 7 14 6 (38 ) Workers' Compensation 7 (6 ) (39 ) 48 Property and Other (7 ) (1 ) 8 — Total pretax (favorable) unfavorable development $ (7 ) $ (5 ) $ (65 ) $ (37 )
International
Liability for Claims and Claims Adjustment Expense [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 International segment. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ 4 $ (2 ) $ (1 ) $ (3 ) Other Professional Liability (8 ) (1 ) 1 16 Liability 4 (2 ) (1 ) (21 ) Property & Marine (4 ) (9 ) (15 ) (16 ) Other 5 (1 ) 17 (10 ) Total pretax (favorable) unfavorable development $ 1 $ (15 ) $ 1 $ (34 )
CNAF Consolidated
Liability for Claims and Claims Adjustment Expense [Line Items]
Impact of loss portfolio transfer on the consolidated statement of operations	The following table presents the impact of the Loss Portfolio Transfer on the Condensed Consolidated Statements of Operations. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Net A&EP adverse development before consideration of LPT $ — $ — $ 60 $ 200 Retroactive reinsurance benefit recognized (17 ) (12 ) (60 ) (94 ) Pretax impact of A&EP reserve development and the LPT $ (17 ) $ (12 ) $ — $ 106

Benefit Plans (Tables)

Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Components of net periodic cost (benefit)	The components of net periodic cost (benefit) are presented in the following table. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Pension cost (benefit) Interest cost on projected benefit obligation $ 25 $ 29 $ 77 $ 85 Expected return on plan assets (38 ) (41 ) (116 ) (121 ) Amortization of net actuarial loss 9 9 27 28 Settlement loss 6 — 8 — Net periodic pension cost (benefit) $ 2 $ (3 ) $ (4 ) $ (8 )

Accumulated Other Comprehensi22

Accumulated Other Comprehensive Income (Loss) by Component (Tables)	9 Months Ended
	Sep. 30, 2017
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 OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of July 1, 2017 $ 26 $ 786 $ (635 ) $ (145 ) $ 32 Other comprehensive income (loss) before reclassifications 1 35 — 41 77 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $-, $(4), $5, $- and $1 — 12 (10 ) — 2 Other comprehensive income (loss) net of tax (expense) benefit of $-, $(16), $(5), $- and $(21) 1 23 10 41 75 Balance as of September 30, 2017 $ 27 $ 809 $ (625 ) $ (104 ) $ 107 (In millions) Net unrealized gains (losses) on investments with OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of July 1, 2016 $ 31 $ 934 $ (637 ) $ (118 ) $ 210 Other comprehensive income (loss) before reclassifications 7 69 — (24 ) 52 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(2), $(13), $3, $- and $(12) 4 27 (6 ) — 25 Other comprehensive income (loss) net of tax (expense) benefit of $(2), $(19), $(3), $- and $(24) 3 42 6 (24 ) 27 Balance as of September 30, 2016 $ 34 $ 976 $ (631 ) $ (142 ) $ 237 (In millions) Net unrealized gains (losses) on investments with OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2017 $ 30 $ 642 $ (647 ) $ (198 ) $ (173 ) Other comprehensive income (loss) before reclassifications — 228 — 94 322 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(1), $(28), $12, $- and $(17) 3 61 (22 ) — 42 Other comprehensive income (loss) net of tax (expense) benefit of $1, $(102), $(12), $- and $(113) (3 ) 167 22 94 280 Balance as of September 30, 2017 $ 27 $ 809 $ (625 ) $ (104 ) $ 107 (In millions) Net unrealized gains (losses) on investments with OTTI losses Net unrealized gains (losses) on other investments Pension and postretirement benefits Cumulative foreign currency translation adjustment Total Balance as of January 1, 2016 $ 27 $ 390 $ (648 ) $ (84 ) $ (315 ) Other comprehensive income (loss) before reclassifications 9 615 — (58 ) 566 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(1), $(12), $9, $- and $(4) 2 29 (17 ) — 14 Other comprehensive income (loss) net of tax (expense) benefit of $(4), $(292), $(9), $- and $(305) 7 586 17 (58 ) 552 Balance as of September 30, 2016 $ 34 $ 976 $ (631 ) $ (142 ) $ 237
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 Condensed Consolidated Statements of Operations Line Item Affected by Reclassifications Net unrealized gains (losses) on investments with OTTI losses Net realized investment gains (losses) Net unrealized gains (losses) on other investments Net realized investment gains (losses) Pension and postretirement benefits Other operating expenses

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 703 $ 741 $ 226 $ 136 $ — $ — $ 1,806 Net investment income 134 161 13 195 6 — 509 Other revenues 99 7 1 — — — 107 Total operating revenues 936 909 240 331 6 — 2,422 Claims, Benefits and Expenses Net incurred claims and benefits 357 611 200 322 (15 ) — 1,475 Policyholders’ dividends 1 4 — — — — 5 Amortization of deferred acquisition costs 153 120 36 — — — 309 Other insurance related expenses 68 133 48 32 — — 281 Other expenses 85 6 (4 ) 2 52 — 141 Total claims, benefits and expenses 664 874 280 356 37 — 2,211 Operating income (loss) before income tax 272 35 (40 ) (25 ) (31 ) — 211 Income tax (expense) benefit on operating income (loss) (92 ) (10 ) 2 35 13 — (52 ) Net operating income (loss) 180 25 (38 ) 10 (18 ) — 159 Net realized investment gains (losses) 4 6 4 3 (41 ) — (24 ) Income tax (expense) benefit on net realized investment gains (losses) (1 ) (3 ) (1 ) (1 ) 15 — 9 Net realized investment gains (losses), after tax 3 3 3 2 (26 ) — (15 ) Net income (loss) $ 183 $ 28 $ (35 ) $ 12 $ (44 ) $ — $ 144 Three months ended September 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 704 $ 719 $ 210 $ 134 $ — $ — $ 1,767 Net investment income 140 175 13 192 4 — 524 Other revenues 93 7 — (4 ) — — 96 Total operating revenues 937 901 223 322 4 — 2,387 Claims, Benefits and Expenses Net incurred claims and benefits 330 446 117 313 (11 ) — 1,195 Policyholders’ dividends 4 3 — — — — 7 Amortization of deferred acquisition costs 151 118 45 — — — 314 Other insurance related expenses 77 151 33 37 (3 ) — 295 Other expenses 78 9 1 2 57 — 147 Total claims, benefits and expenses 640 727 196 352 43 — 1,958 Operating income (loss) before income tax 297 174 27 (30 ) (39 ) — 429 Income tax (expense) benefit on operating income (loss) (102 ) (60 ) (7 ) 36 15 — (118 ) Net operating income (loss) 195 114 20 6 (24 ) — 311 Net realized investment gains (losses) 9 12 6 17 2 — 46 Income tax (expense) benefit on net realized investment gains (losses) (3 ) (3 ) (1 ) (6 ) (1 ) — (14 ) Net realized investment gains (losses), after tax 6 9 5 11 1 — 32 Net income (loss) $ 201 $ 123 $ 25 $ 17 $ (23 ) $ — $ 343 Nine months ended September 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 2,056 $ 2,097 $ 629 $ 404 $ — $ (1 ) $ 5,185 Net investment income 407 482 38 587 15 — 1,529 Other revenues 291 25 — 1 1 — 318 Total operating revenues 2,754 2,604 667 992 16 (1 ) 7,032 Claims, Benefits and Expenses Net incurred claims and benefits 1,141 1,470 444 980 4 — 4,039 Policyholders’ dividends 3 11 — — — — 14 Amortization of deferred acquisition costs 445 354 127 — — — 926 Other insurance related expenses 209 387 106 96 (1 ) (1 ) 796 Other expenses 248 31 (11 ) 5 146 — 419 Total claims, benefits and expenses 2,046 2,253 666 1,081 149 (1 ) 6,194 Operating income (loss) before income tax 708 351 1 (89 ) (133 ) — 838 Income tax (expense) benefit on operating income (loss) (238 ) (117 ) (9 ) 108 51 — (205 ) Net operating income (loss) 470 234 (8 ) 19 (82 ) — 633 Net realized investment gains (losses) 25 36 17 20 (36 ) — 62 Income tax (expense) benefit on net realized investment gains (losses) (9 ) (12 ) (3 ) (8 ) 13 — (19 ) Net realized investment gains (losses), after tax 16 24 14 12 (23 ) — 43 Net income (loss) $ 486 $ 258 $ 6 $ 31 $ (105 ) $ — $ 676 September 30, 2017 (In millions) Reinsurance receivables $ 819 $ 590 $ 227 $ 453 $ 2,280 $ — $ 4,369 Insurance receivables 984 1,087 256 11 2 — 2,340 Deferred acquisition costs 318 230 95 — — — 643 Goodwill 117 — 30 — — — 147 Insurance reserves Claim and claim adjustment expenses 6,063 8,630 1,640 3,468 2,408 — 22,209 Unearned premiums 2,010 1,426 490 134 — — 4,060 Future policy benefits — — — 11,040 — — 11,040 Nine months ended September 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 2,088 $ 2,103 $ 605 $ 401 $ — $ (1 ) $ 5,196 Net investment income 380 465 38 567 11 — 1,461 Other revenues 269 21 1 (1 ) 3 — 293 Total operating revenues 2,737 2,589 644 967 14 (1 ) 6,950 Claims, Benefits and Expenses Net incurred claims and benefits 1,097 1,357 395 976 109 — 3,934 Policyholders’ dividends 6 9 — — — — 15 Amortization of deferred acquisition costs 443 351 132 — — — 926 Other insurance related expenses 225 422 98 101 (3 ) (1 ) 842 Other expenses 232 25 17 7 158 — 439 Total claims, benefits and expenses 2,003 2,164 642 1,084 264 (1 ) 6,156 Operating income (loss) before income tax 734 425 2 (117 ) (250 ) — 794 Income tax (expense) benefit on operating income (loss) (248 ) (145 ) (3 ) 117 88 — (191 ) Net operating income (loss) 486 280 (1 ) — (162 ) — 603 Net realized investment gains (losses) 2 2 14 12 (4 ) — 26 Income tax (expense) benefit on net realized investment gains (losses) (1 ) — (3 ) (9 ) 2 — (11 ) Net realized investment gains (losses), after tax 1 2 11 3 (2 ) — 15 Net income (loss) $ 487 $ 282 $ 10 $ 3 $ (164 ) $ — $ 618 December 31, 2016 (In millions) Reinsurance receivables $ 760 $ 621 $ 131 $ 462 $ 2,479 $ — $ 4,453 Insurance receivables 982 1,021 233 17 2 — 2,255 Deferred acquisition costs 310 214 76 — — — 600 Goodwill 117 — 28 — — — 145 Insurance reserves Claim and claim adjustment expenses 6,149 8,894 1,328 3,358 2,614 — 22,343 Unearned premiums 1,911 1,323 396 132 — — 3,762 Future policy benefits — — — 10,326 — — 10,326
Revenues by line of business	The following table presents revenue by line of business for each reportable segment. Revenues are comprised of operating revenues and net realized investment gains and losses. Periods ended September 30 Three Months Nine Months (In millions) 2017 2016 2017 2016 Specialty Management & Professional Liability $ 656 $ 677 $ 1,963 $ 1,954 Surety 144 139 404 399 Warranty & Alternative Risks 140 130 412 386 Specialty revenues 940 946 2,779 2,739 Commercial Middle Market 501 463 1,421 1,298 Small Business 131 154 357 448 Other Commercial Insurance 283 296 862 845 Commercial revenues 915 913 2,640 2,591 International Canada 60 51 164 152 CNA Europe 87 82 239 241 Hardy 97 96 281 265 International revenues 244 229 684 658 Life & Group Non-Core revenues 334 339 1,012 979 Corporate & Other Non-Core revenues (35 ) 6 (20 ) 10 Eliminations — — (1 ) (1 ) Total revenues $ 2,398 $ 2,433 $ 7,094 $ 6,976

General - Narrative (Details)

General - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)
Noncontrolling Interest [Line Items]
Employee service share-based compensation, tax benefit realized from exercise of stock options	$ 2	$ 5
CNAF Consolidated | Loews
Noncontrolling Interest [Line Items]
Ownership percentage of outstanding common stock of CNAF	89.00%	89.00%

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Incremental common shares attributable to dilutive effect of share-based payment arrangements	907	707	916	549
Antidilutive securities excluded from computation of earnings per share, amount (approximately)	1	175	4	178

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Investments [Abstract]
Net realized investment gains (losses)	$ 42	$ 42	$ 8
Redemption senior notes		350	$ 350
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments	1,321	1,321		$ 1,014
Embedded derivative notional value	170	170		174
Embedded derivative fair value	(1)	(1)		$ 3
Future capital call commitments for limited partnership investments	405	405
Mortgage loan commitments	68	68
Commitments to purchase or fund privately placed debt securities	205	205
Commitments to sell various privately placed debt securities	$ 185	$ 185

Investments - Net investment in

Investments - Net investment income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Investment Income [Line Items]
Gross investment income	$ 524	$ 538	$ 1,573	$ 1,504
Investment expense	(15)	(14)	(44)	(43)
Net investment income	509	524	1,529	1,461
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	455	457	1,367	1,352
Equity securities
Net Investment Income [Line Items]
Gross investment income	1	1	4	8
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	51	65	157	97
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	9	8	24	30
Short term investments
Net Investment Income [Line Items]
Gross investment income	4	2	10	6
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	3	1	9	7
Other
Net Investment Income [Line Items]
Gross investment income	$ 1	$ 4	$ 2	$ 4

Investments - Net realized inve

Investments - Net realized investment gains (losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Net realized investment (losses) gains	$ (24)	$ 46	$ 62	$ 26
Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	34	67	139	152
Gross realized losses	(18)	(20)	(47)	(106)
Net realized investment (losses) gains	16	47	92	46
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	0	1	1	5
Gross realized losses	0	(4)	(1)	(10)
Net realized investment (losses) gains	0	(3)	0	(5)
Derivatives
Schedule of Available-for-sale Securities [Line Items]
Net realized investment (losses) gains	(1)	1	(3)	(12)
Short term investments and other
Schedule of Available-for-sale Securities [Line Items]
Net realized investment (losses) gains	$ (39)	$ 1	$ (27)	$ (3)

Investments - Components of oth

Investments - Components of other-than-temporary impairment losses recognized in earnings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	$ 5	$ 18	$ 9	$ 56
Corporate and other bonds
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	4	14	8	43
Residential mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	1	0	1	1
Other asset-backed
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	0	0	0	3
Total asset-backed
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	1	0	1	4
Total fixed maturity securities available-for-sale
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	5	14	9	47
Equity securities available-for-sale -- Common stock
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	$ 0	$ 4	$ 0	$ 9

Investments - Summary of fixed

Investments - Summary of fixed maturity and equity securities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	$ 38,932	$ 38,467
Gross Unrealized Gains	3,373	2,744
Gross Unrealized Losses	86	196
Estimated Fair Value	42,219	41,015
Corporate and other bonds
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	17,965	17,711
Gross Unrealized Gains	1,645	1,323
Gross Unrealized Losses	26	76
Estimated Fair Value	19,584	18,958
Unrealized OTTI Losses (Gains)	0	(1)
States, municipalities and political subdivisions
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	12,462	12,060
Gross Unrealized Gains	1,501	1,213
Gross Unrealized Losses	7	33
Estimated Fair Value	13,956	13,240
Unrealized OTTI Losses (Gains)	(14)	(16)
Residential mortgage-backed
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	4,906	5,004
Gross Unrealized Gains	127	120
Gross Unrealized Losses	28	51
Estimated Fair Value	5,005	5,073
Unrealized OTTI Losses (Gains)	(28)	(28)
Commercial mortgage-backed
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	1,858	2,016
Gross Unrealized Gains	55	48
Gross Unrealized Losses	13	24
Estimated Fair Value	1,900	2,040
Unrealized OTTI Losses (Gains)	0	0
Other asset-backed
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	1,047	1,022
Gross Unrealized Gains	18	8
Gross Unrealized Losses	4	5
Estimated Fair Value	1,061	1,025
Unrealized OTTI Losses (Gains)	0	0
Total asset-backed
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	7,811	8,042
Gross Unrealized Gains	200	176
Gross Unrealized Losses	45	80
Estimated Fair Value	7,966	8,138
Unrealized OTTI Losses (Gains)	(28)	(28)
U.S. Treasury and obligations of government-sponsored enterprises
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	115	83
Gross Unrealized Gains	3	10
Gross Unrealized Losses	3	0
Estimated Fair Value	115	93
Unrealized OTTI Losses (Gains)	0	0
Foreign government
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	439	435
Gross Unrealized Gains	10	13
Gross Unrealized Losses	4	3
Estimated Fair Value	445	445
Unrealized OTTI Losses (Gains)	0	0
Redeemable preferred stock
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	18	18
Gross Unrealized Gains	2	1
Gross Unrealized Losses	0	0
Estimated Fair Value	20	19
Unrealized OTTI Losses (Gains)	0	0
Total fixed maturity securities available-for-sale
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	38,810	38,349
Gross Unrealized Gains	3,361	2,736
Gross Unrealized Losses	85	192
Estimated Fair Value	42,086	40,893
Unrealized OTTI Losses (Gains)	(42)	(45)
Total fixed maturity securities trading
Schedule of Available-for-Sale and Trading Securities [Line Items]
Total fixed maturity securities trading, cost	4	12
Total fixed maturity securities trading, fair value	4	12
Equity securities available-for-sale -- Common stock
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	16	13
Gross Unrealized Gains	7	6
Gross Unrealized Losses	1	0
Estimated Fair Value	22	19
Preferred stock
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	102	93
Gross Unrealized Gains	5	2
Gross Unrealized Losses	0	4
Estimated Fair Value	107	91
Equity securities
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	118	106
Gross Unrealized Gains	12	8
Gross Unrealized Losses	1	4
Estimated Fair Value	$ 129	$ 110

Investments - Securities in a g

Investments - Securities in a gross unrealized loss position (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	$ 4,104	$ 6,989
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	70	167
Estimated fair value, 12 months or longer	412	584
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	16	29
Estimated fair value, total	4,516	7,573
Available-for-sale securities, continuous unrealized loss position, accumulated loss	86	196
Corporate and other bonds
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	1,216	2,615
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	21	61
Estimated fair value, 12 months or longer	91	254
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	5	15
Estimated fair value, total	1,307	2,869
Available-for-sale securities, continuous unrealized loss position, accumulated loss	26	76
States, municipalities and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	583	959
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	6	32
Estimated fair value, 12 months or longer	56	23
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	1	1
Estimated fair value, total	639	982
Available-for-sale securities, continuous unrealized loss position, accumulated loss	7	33
Residential mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	1,522	2,136
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	25	44
Estimated fair value, 12 months or longer	106	201
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	3	7
Estimated fair value, total	1,628	2,337
Available-for-sale securities, continuous unrealized loss position, accumulated loss	28	51
Commercial mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	378	756
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	6	22
Estimated fair value, 12 months or longer	138	69
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	7	2
Estimated fair value, total	516	825
Available-for-sale securities, continuous unrealized loss position, accumulated loss	13	24
Other asset-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	129	398
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	4	5
Estimated fair value, 12 months or longer	10	24
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Estimated fair value, total	139	422
Available-for-sale securities, continuous unrealized loss position, accumulated loss	4	5
Total asset-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	2,029	3,290
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	35	71
Estimated fair value, 12 months or longer	254	294
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	10	9
Estimated fair value, total	2,283	3,584
Available-for-sale securities, continuous unrealized loss position, accumulated loss	45	80
U.S. Treasury and obligations of government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	67	5
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	3	0
Estimated fair value, 12 months or longer	6	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Estimated fair value, total	73	5
Available-for-sale securities, continuous unrealized loss position, accumulated loss	3	0
Foreign government
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	191	108
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	4	3
Estimated fair value, 12 months or longer	5	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Estimated fair value, total	196	108
Available-for-sale securities, continuous unrealized loss position, accumulated loss	4	3
Total fixed maturity securities available-for-sale
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	4,086	6,977
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	69	167
Estimated fair value, 12 months or longer	412	571
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	16	25
Estimated fair value, total	4,498	7,548
Available-for-sale securities, continuous unrealized loss position, accumulated loss	85	192
Equity securities available-for-sale -- Common stock
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	2
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	1
Estimated fair value, 12 months or longer	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0
Estimated fair value, total	2
Available-for-sale securities, continuous unrealized loss position, accumulated loss	1
Equity securities available-for-sale -- Preferred stock
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	16	12
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	0	0
Estimated fair value, 12 months or longer	0	13
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	4
Estimated fair value, total	16	25
Available-for-sale securities, continuous unrealized loss position, accumulated loss	0	$ 4
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	18
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	1
Estimated fair value, 12 months or longer	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0
Estimated fair value, total	18
Available-for-sale securities, continuous unrealized loss position, accumulated loss	$ 1

Investments - Activity related

Investments - Activity related to the pretax fixed maturity credit loss component reflected within retained earnings for securities still held for which a portion of an OTTI loss was recognized in OCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance of credit losses on fixed maturity securities	$ 30	$ 41	$ 36	$ 53
Reductions for securities sold during the period	(2)	(2)	(8)	(14)
Reductions for securities the Company intends to sell or more likely than not will be required to sell	0	(1)	0	(1)
Ending balance of credit losses on fixed maturity securities	$ 28	$ 38	$ 28	$ 38

Investments - Contractual matur

Investments - Contractual maturity (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Due in one year or less, cost or amortized cost	$ 1,374	$ 1,779
Due after one year through five years, cost or amortized cost	7,931	7,566
Due after five years through ten years, cost or amortized cost	15,853	15,892
Due after ten years, cost or amortized cost	13,652	13,112
Total Amortized Cost Basis	38,810	38,349
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]
Due in one year or less, estimated fair value	1,404	1,828
Due after one year through five years, estimated fair value	8,293	7,955
Due after five years through ten years, estimated fair value	16,574	16,332
Due after ten years, estimated fair value	15,815	14,778
Total Estimated Fair Value	$ 42,086	$ 40,893

Fair Value - Narrative (Details

Fair Value - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair value, assets, level 2 to level 1, transfers	$ 0	$ 0	$ 0	$ 0
Fair value, assets, level 1 to level 2, transfers	0	$ 0	0	$ 0
Other invested assets overseas deposit	37,000,000		$ 37,000,000		$ 31,000,000
Life settlement contracts, receivable, payment period			3 years
Life settlement contracts, fair value	$ 0		$ 0		$ 58,000,000

Fair Value - Assets and liabili

Fair Value - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 43,579	$ 42,406
Liabilities	1	(3)
Corporate and other bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19,588	18,970
States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	13,956	13,240
Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	5,005	5,073
Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,900	2,040
Other asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,061	1,025
Total asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	7,966	8,138
U.S. Treasury and obligations of government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	115	93
Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	445	445
Redeemable preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	20	19
Fixed maturity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	42,090	40,905
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	129	110
Other invested assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	5	5
Short term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,355	1,328
Life settlement contracts, included in Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		58
Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	1	(3)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	724	678
Liabilities	0	0
Level 1 | Corporate and other bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Other asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Total asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | U.S. Treasury and obligations of government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	115	93
Level 1 | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Redeemable preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	20	19
Level 1 | Fixed maturity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	135	112
Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	110	91
Level 1 | Other invested assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Short term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	479	475
Level 1 | Life settlement contracts, included in Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0
Level 1 | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	42,370	41,321
Liabilities	1	(3)
Level 2 | Corporate and other bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19,469	18,840
Level 2 | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	13,955	13,239
Level 2 | Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	4,829	4,944
Level 2 | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,876	2,027
Level 2 | Other asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	915	968
Level 2 | Total asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	7,620	7,939
Level 2 | U.S. Treasury and obligations of government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	445	445
Level 2 | Redeemable preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Fixed maturity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	41,489	40,463
Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Other invested assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	5	5
Level 2 | Short term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	876	853
Level 2 | Life settlement contracts, included in Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0
Level 2 | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	1	(3)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	485	407
Liabilities	0	0
Level 3 | Corporate and other bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	119	130
Level 3 | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1	1
Level 3 | Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	176	129
Level 3 | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	24	13
Level 3 | Other asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	146	57
Level 3 | Total asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	346	199
Level 3 | U.S. Treasury and obligations of government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Redeemable preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Fixed maturity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	466	330
Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19	19
Level 3 | Other invested assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Short term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Life settlement contracts, included in Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		58
Level 3 | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 0	$ 0

Fair Value - Reconciliation for

Fair Value - Reconciliation for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	$ 339	$ 520	$ 407	$ 473
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	0	9	12
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	2	7	8	14
Purchases	52	78	109	279
Sales	(1)	0	(64)	(61)
Settlements	(24)	(15)	(67)	(61)
Transfers into Level 3	116	0	168	5
Transfers out of Level 3	0	(96)	(85)	(167)
Balance, end of year	485	494	485	494
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	(2)	0	0
Corporate and other bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	100	242	130	168
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1	1	1
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	7	2	14
Purchases	13	16	18	163
Sales	0	0	(1)	(36)
Settlements	(11)	(5)	(36)	(15)
Transfers into Level 3	15	0	15	0
Transfers out of Level 3	0	0	(10)	(34)
Balance, end of year	119	261	119	261
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
States, municipalities and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	1	2	1	2
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	0	0
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	(1)	0	(1)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of year	1	1	1	1
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
Residential mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	123	134	129	134
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	0	3	2
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	(1)	4	(2)
Purchases	0	5	0	15
Sales	0	0	0	0
Settlements	(7)	(1)	(18)	(10)
Transfers into Level 3	58	0	58	0
Transfers out of Level 3	0	(58)	0	(60)
Balance, end of year	176	79	176	79
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
Commercial mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	13	11	13	22
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	0	0
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	(1)	0	(1)	0
Purchases	12	23	12	32
Sales	0	0	0	0
Settlements	(2)	(8)	(2)	(17)
Transfers into Level 3	2	0	2	3
Transfers out of Level 3	0	(2)	0	(16)
Balance, end of year	24	24	24	24
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
Other asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	82	45	57	53
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(1)	0	(2)	0
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	0	1	2
Purchases	27	34	78	69
Sales	0	0	0	(25)
Settlements	(4)	0	(6)	(1)
Transfers into Level 3	41	0	93	2
Transfers out of Level 3	0	(36)	(75)	(57)
Balance, end of year	146	43	146	43
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
Total asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	218	190	199	209
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	1	2
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	(1)	4	0
Purchases	39	62	90	116
Sales	0	0	0	(25)
Settlements	(13)	(9)	(26)	(28)
Transfers into Level 3	101	0	153	5
Transfers out of Level 3	0	(96)	(75)	(133)
Balance, end of year	346	146	346	146
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
Total fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	319	434	330	379
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1	2	3
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	2	6	6	14
Purchases	52	78	108	279
Sales	0	0	(1)	(61)
Settlements	(24)	(15)	(62)	(44)
Transfers into Level 3	116	0	168	5
Transfers out of Level 3	0	(96)	(85)	(167)
Balance, end of year	466	408	466	408
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	0	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	19	19	19	20
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	(1)	0	(1)
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	0	1	2	0
Purchases	0	0	1	0
Sales	0	0	(3)	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of year	19	19	19	19
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	(2)	0	(2)
Derivative financial instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year			0
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)			1
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)			0
Purchases			0
Sales			(1)
Settlements			0
Transfers into Level 3			0
Transfers out of Level 3			0
Balance, end of year	0		0
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance			0
Life settlement contracts, included in Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	1	67	58	74
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	6	10
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Sales	(1)	0	(59)	0
Settlements	0	0	(5)	(17)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of year	0	67	0	67
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	$ 0	$ 0	$ 0	$ 2

Fair Value - Quantitative infor

Fair Value - Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets (Details) - Fixed maturity securities - Income Approach Valuation Technique - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated Fair Value (In millions)	$ 139	$ 106
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread	1.00%	2.00%
Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread	12.00%	40.00%
Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread	3.00%	4.00%

Fair Value - Carrying amount an

Fair Value - Carrying amount and estimated fair value of financial instrument assets and liabilities which are not measured at fair value (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Assets
Mortgage loans	$ 722,000,000	$ 591,000,000
Liabilities
Short term debt	150,000,000	0
Long term debt	2,707,000,000	2,710,000,000
Carrying Amount
Assets
Mortgage loans	722,000,000	591,000,000
Note receivable	45,000,000
Liabilities
Short term debt	150,000,000
Long term debt	2,707,000,000	2,710,000,000
Estimated Fair Value
Assets
Mortgage loans	731,000,000	594,000,000
Note receivable	46,000,000
Liabilities
Short term debt	152,000,000
Long term debt	2,916,000,000	2,952,000,000
Level 1 | Estimated Fair Value
Assets
Mortgage loans	0	0
Note receivable	0
Liabilities
Short term debt	0
Long term debt	0	0
Level 2 | Estimated Fair Value
Assets
Mortgage loans	0	0
Note receivable	0
Liabilities
Short term debt	152,000,000
Long term debt	2,916,000,000	2,952,000,000
Level 3 | Estimated Fair Value
Assets
Mortgage loans	731,000,000	594,000,000
Note receivable	46,000,000
Liabilities
Short term debt	0
Long term debt	$ 0	$ 0

Claim and Claim Adjustment Ex39

Claim and Claim Adjustment Expense Reserves - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2010
Liability for Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses net of reinsurance	$ 269,000,000	$ 16,000,000	$ 342,000,000	$ 137,000,000
Reinsurance reinstatement premium	6,000,000		6,000,000
Loss Portfolio Transfer
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
Net A&EP adverse development before consideration of LPT	0	$ 0	60,000,000	$ 200,000,000
Cumulative amounts ceded under AEP Loss Portfolio Transfer	2,900,000,000		2,900,000,000		$ 2,800,000,000
Deferred reinsurance benefit yet to be recognized	334,000,000		334,000,000		334,000,000
Fair value of collateral trust account established by NICO under A&EP Loss Portfolio Transfer	2,900,000,000		2,900,000,000		$ 2,800,000,000
Hurricane Harvey
Liability for Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses	149,000,000		149,000,000
Hurricane Irma
Liability for Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses	95,000,000		95,000,000
Hurricane Maria
Liability for Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses	$ 20,000,000		$ 20,000,000

Claim and Claim Adjustment Ex40

Claim and Claim Adjustment Expense Reserves - Reconciliation of claim and claim adjustment expense reserves (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross, beginning of year	$ 22,343	$ 22,663
Ceded, beginning of year	4,094	4,087
Net reserves, beginning of year	18,249	18,576
Net incurred claim and claim adjustment expenses:
Provision for insured events of current year	3,949	3,799
Decrease in provision for insured events of prior years	(284)	(332)
Amortization of discount	138	134
Total net incurred	3,803	3,601
Net payments attributable to:
Current year events	(560)	(591)
Prior year events	(3,401)	(3,209)
Total net payments	(3,961)	(3,800)
Foreign currency translation adjustment and other	110	39
Net reserves, end of period	18,201	18,416
Ceded reserves, end of year	4,008	4,256
Gross reserves, end of year	$ 22,209	$ 22,672

Claim and Claim Adjustment Ex41

Claim and Claim Adjustment Expense Reserves - Net prior year development (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (115)	$ (132)	$ (227)	$ (282)
Pretax (favorable) unfavorable premium development	(19)	(5)	(2)	(27)
Total pretax (favorable) unfavorable net prior year development	(134)	(137)	(229)	(309)
Specialty
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	(109)	(112)	(163)	(211)
Pretax (favorable) unfavorable premium development	(3)	0	(13)	(18)
Total pretax (favorable) unfavorable net prior year development	(112)	(112)	(176)	(229)
Commercial
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	(7)	(5)	(65)	(37)
Pretax (favorable) unfavorable premium development	(11)	(3)	27	(7)
Total pretax (favorable) unfavorable net prior year development	(18)	(8)	(38)	(44)
International
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	1	(15)	1	(34)
Pretax (favorable) unfavorable premium development	(5)	(2)	(16)	(2)
Total pretax (favorable) unfavorable net prior year development	(4)	(17)	(15)	(36)
Corporate & Other Non-Core
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	0	0	0	0
Pretax (favorable) unfavorable premium development	0	0	0	0
Total pretax (favorable) unfavorable net prior year development	$ 0	$ 0	$ 0	$ 0

Claim and Claim Adjustment Ex42

Claim and Claim Adjustment Expense Reserves - Net prior year claim and allocated claim adjustment expense reserve development for Specialty segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (115)	$ (132)	$ (227)	$ (282)
Specialty
Liability for Claims and Claims Adjustment Expense [Line Items]
Medical Professional Liability	1	13	5	(17)
Other Professional Liability and Management Liability	(27)	(48)	(96)	(98)
Surety	(82)	(63)	(82)	(63)
Warranty	(1)	2	5	7
Other	0	(16)	5	(40)
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (109)	$ (112)	$ (163)	$ (211)

Claim and Claim Adjustment Ex43

Claim and Claim Adjustment Expense Reserves - Net prior year claim and allocated claim adjustment expense reserve development for Commercial segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (115)	$ (132)	$ (227)	$ (282)
Commercial
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial Auto	(14)	(12)	(40)	(47)
General Liability	7	14	6	(38)
Workers' Compensation	7	(6)	(39)	48
Property and Other	(7)	(1)	8	0
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (7)	$ (5)	$ (65)	$ (37)

Claim and Claim Adjustment Ex44

Claim and Claim Adjustment Expense Reserves - Net prior year claim and allocated claim adjustment expense reserve development for International segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (115)	$ (132)	$ (227)	$ (282)
International
Liability for Claims and Claims Adjustment Expense [Line Items]
Medical Professional Liability	4	(2)	(1)	(3)
Other Professional Liability	(8)	(1)	1	16
Liability	4	(2)	(1)	(21)
Property & Marine	(4)	(9)	(15)	(16)
Other	5	(1)	17	(10)
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ 1	$ (15)	$ 1	$ (34)

Claim and Claim Adjustment Ex45

Claim and Claim Adjustment Expense Reserves - Impact of Loss Portfolio Transfer on the Consolidated Statement of Operations (Details) - Loss Portfolio Transfer - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Net A&EP adverse development before consideration of LPT	$ 0	$ 0	$ 60	$ 200
Retroactive reinsurance benefit recognized	(17)	(12)	(60)	(94)
Pretax impact of A&EP reserve development and the LPT	$ (17)	$ (12)	$ 0	$ 106

Legal Proceedings and Guarant46

Legal Proceedings and Guarantees - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Favorable premium development due to the small business premium rate adjustment contingency recognized	$ 0
Adverse premium development recognized as result of rating errors		$ 37,000,000
Reduction to pretax operating income	1,000,000	7,000,000
Guarantee Obligations
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	1,800,000,000	1,800,000,000
Indemnification Agreement
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	254,000,000	254,000,000
Guarantee agreement
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	375,000,000	375,000,000
Guarantee and Indemnification
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, current carrying value	5,000,000	5,000,000	$ 5,000,000
Multi-Peril Package Product | Insurance Premium Rate Adjustment
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Loss contingency accrual	$ 61,000,000	$ 61,000,000

Benefit Plans - Components of n

Benefit Plans - Components of net periodic cost (benefit) (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 25	$ 29	$ 77	$ 85
Expected return on plan assets	(38)	(41)	(116)	(121)
Amortization of net actuarial loss	9	9	27	28
Settlement loss	6	0	8	0
Net periodic pension cost (benefit)	2	$ (3)	(4)	$ (8)
Company contributions, pension plans			26
Company contributions, remainder of fiscal year	$ 2		$ 2

Accumulated Other Comprehensi48

Accumulated Other Comprehensive Income (Loss) by Component - Changes in accumulated other comprehensive income (loss) by component (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year			$ 11,969
Other comprehensive income (loss) before reclassifications	$ 77	$ 52	322	$ 566
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	2	25	42	14
Other comprehensive income (loss) after tax (expense) benefit	75	27	280	552
Balance, end of period	12,169	12,195	12,169	12,195
Reclassification from AOCI, current period, tax	1	(12)	(17)	(4)
Tax (expense) benefit on other comprehensive income (loss)	(21)	(24)	(113)	(305)
Net unrealized gains (losses) on investments with OTTI losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	26	31	30	27
Other comprehensive income (loss) before reclassifications	1	7	0	9
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	0	4	3	2
Other comprehensive income (loss) after tax (expense) benefit	1	3	(3)	7
Balance, end of period	27	34	27	34
Reclassification from AOCI, current period, tax	0	(2)	(1)	(1)
Tax (expense) benefit on other comprehensive income (loss)	0	(2)	1	(4)
Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	786	934	642	390
Other comprehensive income (loss) before reclassifications	35	69	228	615
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	12	27	61	29
Other comprehensive income (loss) after tax (expense) benefit	23	42	167	586
Balance, end of period	809	976	809	976
Reclassification from AOCI, current period, tax	(4)	(13)	(28)	(12)
Tax (expense) benefit on other comprehensive income (loss)	(16)	(19)	(102)	(292)
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	(635)	(637)	(647)	(648)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	(10)	(6)	(22)	(17)
Other comprehensive income (loss) after tax (expense) benefit	10	6	22	17
Balance, end of period	(625)	(631)	(625)	(631)
Reclassification from AOCI, current period, tax	5	3	12	9
Tax (expense) benefit on other comprehensive income (loss)	(5)	(3)	(12)	(9)
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	(145)	(118)	(198)	(84)
Other comprehensive income (loss) before reclassifications	41	(24)	94	(58)
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	0	0	0	0
Other comprehensive income (loss) after tax (expense) benefit	41	(24)	94	(58)
Balance, end of period	(104)	(142)	(104)	(142)
Reclassification from AOCI, current period, tax	0	0	0	0
Tax (expense) benefit on other comprehensive income (loss)	0	0	0	0
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	32	210	(173)	(315)
Balance, end of period	$ 107	$ 237	$ 107	$ 237

Business Segments - Narrative (

Business Segments - Narrative (Details)	9 Months Ended
	Sep. 30, 2017segments
Core Segments - Specialty, Commercial and International
Segment Reporting Information [Line Items]
Number of operating segments	3
Non-Core Segments - Life & Group Non-Core and Corporate and Other Non-Core
Segment Reporting Information [Line Items]
Number of operating segments	2

Business Segments - Income Stat

Business Segments - Income Statement Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating revenues
Net earned premiums	$ 1,806	$ 1,767	$ 5,185	$ 5,196
Net investment income	509	524	1,529	1,461
Other revenues	107	96	318	293
Total operating revenues	2,422	2,387	7,032	6,950
Claims, Benefits and Expenses
Net incurred claims and benefits	1,475	1,195	4,039	3,934
Policyholders’ dividends	5	7	14	15
Amortization of deferred acquisition costs	309	314	926	926
Other insurance related expenses	281	295	796	842
Other expenses	141	147	419	439
Total claims, benefits and expenses	2,211	1,958	6,194	6,156
Operating income (loss) before income tax	211	429	838	794
Income tax (expense) benefit on operating income (loss)	(52)	(118)	(205)	(191)
Net operating income (loss)	159	311	633	603
Net realized investment gains (losses)	(24)	46	62	26
Income tax (expense) benefit on net realized investment gains (losses)	9	(14)	(19)	(11)
Net realized investment gains (losses), after tax	(15)	32	43	15
Net income (loss)	144	343	676	618
Operating Segments | Specialty
Operating revenues
Net earned premiums	703	704	2,056	2,088
Net investment income	134	140	407	380
Other revenues	99	93	291	269
Total operating revenues	936	937	2,754	2,737
Claims, Benefits and Expenses
Net incurred claims and benefits	357	330	1,141	1,097
Policyholders’ dividends	1	4	3	6
Amortization of deferred acquisition costs	153	151	445	443
Other insurance related expenses	68	77	209	225
Other expenses	85	78	248	232
Total claims, benefits and expenses	664	640	2,046	2,003
Operating income (loss) before income tax	272	297	708	734
Income tax (expense) benefit on operating income (loss)	(92)	(102)	(238)	(248)
Net operating income (loss)	180	195	470	486
Net realized investment gains (losses)	4	9	25	2
Income tax (expense) benefit on net realized investment gains (losses)	(1)	(3)	(9)	(1)
Net realized investment gains (losses), after tax	3	6	16	1
Net income (loss)	183	201	486	487
Operating Segments | Commercial
Operating revenues
Net earned premiums	741	719	2,097	2,103
Net investment income	161	175	482	465
Other revenues	7	7	25	21
Total operating revenues	909	901	2,604	2,589
Claims, Benefits and Expenses
Net incurred claims and benefits	611	446	1,470	1,357
Policyholders’ dividends	4	3	11	9
Amortization of deferred acquisition costs	120	118	354	351
Other insurance related expenses	133	151	387	422
Other expenses	6	9	31	25
Total claims, benefits and expenses	874	727	2,253	2,164
Operating income (loss) before income tax	35	174	351	425
Income tax (expense) benefit on operating income (loss)	(10)	(60)	(117)	(145)
Net operating income (loss)	25	114	234	280
Net realized investment gains (losses)	6	12	36	2
Income tax (expense) benefit on net realized investment gains (losses)	(3)	(3)	(12)	0
Net realized investment gains (losses), after tax	3	9	24	2
Net income (loss)	28	123	258	282
Operating Segments | International
Operating revenues
Net earned premiums	226	210	629	605
Net investment income	13	13	38	38
Other revenues	1	0	0	1
Total operating revenues	240	223	667	644
Claims, Benefits and Expenses
Net incurred claims and benefits	200	117	444	395
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	36	45	127	132
Other insurance related expenses	48	33	106	98
Other expenses	(4)	1	(11)	17
Total claims, benefits and expenses	280	196	666	642
Operating income (loss) before income tax	(40)	27	1	2
Income tax (expense) benefit on operating income (loss)	2	(7)	(9)	(3)
Net operating income (loss)	(38)	20	(8)	(1)
Net realized investment gains (losses)	4	6	17	14
Income tax (expense) benefit on net realized investment gains (losses)	(1)	(1)	(3)	(3)
Net realized investment gains (losses), after tax	3	5	14	11
Net income (loss)	(35)	25	6	10
Operating Segments | Life & Group Non-Core
Operating revenues
Net earned premiums	136	134	404	401
Net investment income	195	192	587	567
Other revenues	0	(4)	1	(1)
Total operating revenues	331	322	992	967
Claims, Benefits and Expenses
Net incurred claims and benefits	322	313	980	976
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	32	37	96	101
Other expenses	2	2	5	7
Total claims, benefits and expenses	356	352	1,081	1,084
Operating income (loss) before income tax	(25)	(30)	(89)	(117)
Income tax (expense) benefit on operating income (loss)	35	36	108	117
Net operating income (loss)	10	6	19	0
Net realized investment gains (losses)	3	17	20	12
Income tax (expense) benefit on net realized investment gains (losses)	(1)	(6)	(8)	(9)
Net realized investment gains (losses), after tax	2	11	12	3
Net income (loss)	12	17	31	3
Operating Segments | Corporate & Other Non-Core
Operating revenues
Net earned premiums	0	0	0	0
Net investment income	6	4	15	11
Other revenues	0	0	1	3
Total operating revenues	6	4	16	14
Claims, Benefits and Expenses
Net incurred claims and benefits	(15)	(11)	4	109
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	0	(3)	(1)	(3)
Other expenses	52	57	146	158
Total claims, benefits and expenses	37	43	149	264
Operating income (loss) before income tax	(31)	(39)	(133)	(250)
Income tax (expense) benefit on operating income (loss)	13	15	51	88
Net operating income (loss)	(18)	(24)	(82)	(162)
Net realized investment gains (losses)	(41)	2	(36)	(4)
Income tax (expense) benefit on net realized investment gains (losses)	15	(1)	13	2
Net realized investment gains (losses), after tax	(26)	1	(23)	(2)
Net income (loss)	(44)	(23)	(105)	(164)
Eliminations
Operating revenues
Net earned premiums	0	0	(1)	(1)
Net investment income	0	0	0	0
Other revenues	0	0	0	0
Total operating revenues	0	0	(1)	(1)
Claims, Benefits and Expenses
Net incurred claims and benefits	0	0	0	0
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	0	0	(1)	(1)
Other expenses	0	0	0	0
Total claims, benefits and expenses	0	0	(1)	(1)
Operating income (loss) before income tax	0	0	0	0
Income tax (expense) benefit on operating income (loss)	0	0	0	0
Net operating income (loss)	0	0	0	0
Net realized investment gains (losses)	0	0	0	0
Income tax (expense) benefit on net realized investment gains (losses)	0	0	0	0
Net realized investment gains (losses), after tax	0	0	0	0
Net income (loss)	$ 0	$ 0	$ 0	$ 0

Business Segments - Balance She

Business Segments - Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Reinsurance receivables	$ 4,369	$ 4,453
Insurance receivables	2,340	2,255
Deferred acquisition costs	643	600
Goodwill	147	145
Insurance reserves
Claim and claim adjustment expenses	22,209	22,343
Unearned premiums	4,060	3,762
Future policy benefits	11,040	10,326
Operating Segments | Specialty
Segment Reporting Information [Line Items]
Reinsurance receivables	819	760
Insurance receivables	984	982
Deferred acquisition costs	318	310
Goodwill	117	117
Insurance reserves
Claim and claim adjustment expenses	6,063	6,149
Unearned premiums	2,010	1,911
Future policy benefits	0	0
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Reinsurance receivables	590	621
Insurance receivables	1,087	1,021
Deferred acquisition costs	230	214
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	8,630	8,894
Unearned premiums	1,426	1,323
Future policy benefits	0	0
Operating Segments | International
Segment Reporting Information [Line Items]
Reinsurance receivables	227	131
Insurance receivables	256	233
Deferred acquisition costs	95	76
Goodwill	30	28
Insurance reserves
Claim and claim adjustment expenses	1,640	1,328
Unearned premiums	490	396
Future policy benefits	0	0
Operating Segments | Life & Group Non-Core
Segment Reporting Information [Line Items]
Reinsurance receivables	453	462
Insurance receivables	11	17
Deferred acquisition costs	0	0
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	3,468	3,358
Unearned premiums	134	132
Future policy benefits	11,040	10,326
Operating Segments | Corporate & Other Non-Core
Segment Reporting Information [Line Items]
Reinsurance receivables	2,280	2,479
Insurance receivables	2	2
Deferred acquisition costs	0	0
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	2,408	2,614
Unearned premiums	0	0
Future policy benefits	0	0
Eliminations
Segment Reporting Information [Line Items]
Reinsurance receivables	0	0
Insurance receivables	0	0
Deferred acquisition costs	0	0
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	0	0
Unearned premiums	0	0
Future policy benefits	$ 0	$ 0

Business Segments - Revenues by

Business Segments - Revenues by Line of Business (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 2,398	$ 2,433	$ 7,094	$ 6,976
Operating Segments | Specialty
Segment Reporting Information [Line Items]
Revenues	940	946	2,779	2,739
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Revenues	915	913	2,640	2,591
Operating Segments | International
Segment Reporting Information [Line Items]
Revenues	244	229	684	658
Operating Segments | Life & Group Non-Core
Segment Reporting Information [Line Items]
Revenues	334	339	1,012	979
Operating Segments | Corporate & Other Non-Core
Segment Reporting Information [Line Items]
Revenues	(35)	6	(20)	10
Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	(1)	(1)
Management & Professional Liability | Operating Segments
Segment Reporting Information [Line Items]
Revenues	656	677	1,963	1,954
Surety | Operating Segments
Segment Reporting Information [Line Items]
Revenues	144	139	404	399
Warranty & Alternative Risks | Operating Segments
Segment Reporting Information [Line Items]
Revenues	140	130	412	386
Middle Market | Operating Segments
Segment Reporting Information [Line Items]
Revenues	501	463	1,421	1,298
Small Business | Operating Segments
Segment Reporting Information [Line Items]
Revenues	131	154	357	448
Other Commercial Insurance | Operating Segments
Segment Reporting Information [Line Items]
Revenues	283	296	862	845
Canada | Operating Segments
Segment Reporting Information [Line Items]
Revenues	60	51	164	152
CNA Europe | Operating Segments
Segment Reporting Information [Line Items]
Revenues	87	82	239	241
Hardy | Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 97	$ 96	$ 281	$ 265