CNA Financial (CNA) 10-Q 31 Jul 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 27, 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	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		271,006,887

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues
Net earned premiums	$ 1,734	$ 1,730	$ 3,379	$ 3,429
Net investment income	475	502	1,020	937
Net realized investment gains (losses):
Other-than-temporary impairment losses	(2)	(15)	(4)	(38)
Other net realized investment gains	52	31	90	18
Net realized investment gains (losses) on fixed maturity securities	50	16	86	(20)
Other revenues	107	100	211	197
Total revenues	2,366	2,348	4,696	4,543
Claims, Benefits and Expenses
Insurance claims and policyholders’ benefits	1,280	1,339	2,573	2,747
Amortization of deferred acquisition costs	312	305	617	612
Other operating expenses	364	378	710	759
Interest	40	38	83	80
Total claims, benefits and expenses	1,996	2,060	3,983	4,198
Income before income tax	370	288	713	345
Income tax expense	(98)	(79)	(181)	(70)
Net income	$ 272	$ 209	$ 532	$ 275
Basic earnings per share (dollars per share)	$ 1.01	$ 0.77	$ 1.96	$ 1.02
Diluted earnings per share (dollars per share)	1	0.77	1.96	1.02
Dividends per share (dollars per share)	$ 0.25	$ 0.25	$ 2.50	$ 2.50
Weighted Average Outstanding Common Stock and Common Stock Equivalents
Basic (in shares)	271.1	270.5	271	270.4
Diluted (in shares)	271.9	270.9	271.9	270.9

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 272	$ 209	$ 532	$ 275
Other Comprehensive Income, Net of Tax
Net unrealized gains on investments with other-than-temporary impairments	0	(1)	(4)	4
Net unrealized gains on other investments	77	310	144	544
Net unrealized gains on investments	77	309	140	548
Foreign currency translation adjustment	42	(48)	53	(34)
Pension and postretirement benefits	5	5	12	11
Other comprehensive income, net of tax	124	266	205	525
Total comprehensive income	$ 396	$ 475	$ 737	$ 800

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Investments:
Fixed maturity securities at fair value (amortized cost of $38,668 and $38,361)	$ 41,749	$ 40,905
Equity securities at fair value (cost of $108 and $106)	118	110
Limited partnership investments	2,380	2,371
Other invested assets	42	36
Mortgage loans	646	591
Short term investments	1,333	1,407
Total investments	46,268	45,420
Cash	225	271
Reinsurance receivables (less allowance for uncollectible receivables of $38 and $37)	4,426	4,416
Insurance receivables (less allowance for uncollectible receivables of $46 and $46)	2,406	2,209
Accrued investment income	406	405
Deferred acquisition costs	647	600
Deferred income taxes	166	379
Property and equipment at cost (less accumulated depreciation of $263 and $254)	336	310
Goodwill	147	145
Other assets	1,178	1,078
Total assets	56,205	55,233
Insurance reserves:
Claim and claim adjustment expenses	22,179	22,343
Future policy benefits	10,824	10,326
Unearned premiums	4,107	3,762
Short term debt	150	0
Long term debt	2,561	2,710
Other liabilities (includes $28 and $50 due to Loews Corporation)	4,356	4,123
Total liabilities	44,177	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; 270,987,085 and 270,495,998 shares outstanding)	683	683
Additional paid-in capital	2,167	2,173
Retained earnings	9,211	9,359
Accumulated other comprehensive income (loss)	32	(173)
Treasury stock (2,053,158 and 2,544,245 shares), at cost	(65)	(73)
Total stockholders’ equity	12,028	11,969
Total liabilities and stockholders' equity	$ 56,205	$ 55,233

Condensed Consolidated Balance5

Condensed Consolidated Balance Sheets - (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Amortized cost	$ 38,668	$ 38,361
Cost	108	106
Allowance for uncollectible reinsurance	38	37
Allowance for uncollectible insurance receivables	46	46
Accumulated depreciation	263	254
Due to related parties	$ 28	$ 50
Common stock, par value (dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized (shares)	500,000,000	500,000,000
Common stock, shares issued (shares)	273,040,243	273,040,243
Common stock, shares outstanding (shares)	270,987,085	270,495,998
Treasury stock, share (shares)	2,053,158	2,544,245

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash Flows from Operating Activities
Net income	$ 532	$ 275
Adjustments to reconcile net income to net cash flows provided by operating activities:
Deferred income tax expense	122	63
Trading portfolio activity	(11)	(7)
Net realized investment (gains) losses	(86)	20
Equity method investees	42	230
Net amortization of investments	(21)	(10)
Depreciation and amortization	43	39
Changes in:
Receivables, net	(195)	(540)
Accrued investment income	1	4
Deferred acquisition costs	(41)	(25)
Insurance reserves	262	666
Other assets	(118)	(106)
Other liabilities	(45)	(27)
Other, net	30	31
Total adjustments	(17)	338
Net cash flows provided by operating activities	515	613
Dispositions:
Fixed maturity securities - sales	3,142	3,066
Fixed maturity securities - maturities, calls and redemptions	1,770	1,247
Equity securities	22	72
Limited partnerships	100	124
Mortgage loans	17	109
Purchases:
Fixed maturity securities	(4,840)	(4,874)
Equity securities	(8)	0
Limited partnerships	(47)	(206)
Mortgage loans	(72)	(41)
Change in other investments	(3)	11
Change in short term investments	81	281
Purchases of property and equipment	(68)	(65)
Disposals of property and equipment	0	107
Other, net	17	2
Net cash flows provided (used) by investing activities	111	(167)
Cash Flows from Financing Activities
Dividends paid to common stockholders	(676)	(677)
Proceeds from the issuance of debt	0	498
Repayment of debt	0	(358)
Other, net	(1)	(1)
Net cash flows used by financing activities	(677)	(538)
Effect of foreign exchange rate changes on cash	5	(6)
Net change in cash	(46)	(98)
Cash, beginning of year	271	387
Cash, end of period	$ 225	$ 289

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	AOCI Attributable to Parent	Treasury Stock
Balance, beginning of year at Dec. 31, 2015		$ 683	$ 2,153	$ 9,313	$ (315)	$ (78)
Stock-based compensation			2			5
Dividends paid to common stockholders				(677)
Net income	$ 275			275
Other comprehensive income	525				525
Balance, end of period at Jun. 30, 2016	11,886	683	2,155	8,911	210	(73)
Balance, beginning of year at Mar. 31, 2016					(56)
Net income	209
Other comprehensive income	266
Balance, end of period at Jun. 30, 2016	11,886	683	2,155	8,911	210	(73)
Balance, beginning of year at Dec. 31, 2016	11,969	683	2,173	9,359	(173)	(73)
Stock-based compensation			(6)			8
Dividends paid to common stockholders				(680)
Net income	532			532
Other comprehensive income	205				205
Balance, end of period at Jun. 30, 2017	12,028	683	2,167	9,211	32	(65)
Balance, beginning of year at Mar. 31, 2017					(92)
Net income	272
Other comprehensive income	124
Balance, end of period at Jun. 30, 2017	$ 12,028	$ 683	$ 2,167	$ 9,211	$ 32	$ (65)

General

General	6 Months Ended
	Jun. 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 90% of the outstanding common stock of CNAF as of June 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 June 30, 2017 and for the three and six months ended June 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 $0 million and $3 million to income tax expense for the three and six months ended June 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. As insurance contracts are out of scope, the Company anticipates the primary change will be to revenue recognition for certain of our warranty products and services. The Company has not made a decision on the method of adoption and is currently evaluating the effect the updated guidance will have on the Company’s financial statements, but we do not currently believe ASU 2014-09 will have a material effect on the Company's 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. 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	6 Months Ended
	Jun. 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 six months ended June 30, 2017 , approximately 847 thousand and 915 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 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 six months ended June 30, 2016 , approximately 409 thousand and 473 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 178 thousand and 180 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	6 Months Ended
	Jun. 30, 2017
Investments [Abstract]
Investments	Investments The significant components of Net investment income are presented in the following table. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Fixed maturity securities $ 457 $ 449 $ 912 $ 895 Equity securities 2 4 3 7 Limited partnership investments 16 46 106 32 Mortgage loans 8 13 15 22 Short term investments 3 1 6 4 Trading portfolio 4 4 6 6 Other — — 1 — Gross investment income 490 517 1,049 966 Investment expense (15 ) (15 ) (29 ) (29 ) Net investment income $ 475 $ 502 $ 1,020 $ 937 Net realized investment gains (losses) are presented in the following table. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Net realized investment gains (losses): Fixed maturity securities: Gross realized gains $ 56 $ 40 $ 105 $ 85 Gross realized losses (12 ) (24 ) (29 ) (86 ) Net realized investment gains (losses) on fixed maturity securities 44 16 76 (1 ) Equity securities: Gross realized gains 1 4 1 4 Gross realized losses (1 ) (1 ) (1 ) (6 ) Net realized investment gains (losses) on equity securities — 3 — (2 ) Derivatives (3 ) (6 ) (2 ) (13 ) Short term investments and other 9 3 12 (4 ) Net realized investment gains (losses) $ 50 $ 16 $ 86 $ (20 ) Net realized investment losses for the six months ended June 30, 2016 include $8 million 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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Fixed maturity securities available-for-sale: Corporate and other bonds $ 2 $ 13 $ 4 $ 29 Asset-backed: Residential mortgage-backed — 1 — 1 Other asset-backed — 1 — 3 Total asset-backed — 2 — 4 Total fixed maturity securities available-for-sale 2 15 4 33 Equity securities available-for-sale -- Common stock — — — 5 OTTI losses recognized in earnings $ 2 $ 15 $ 4 $ 38 The following tables present a summary of fixed maturity and equity securities. June 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 $ 17,823 $ 1,589 $ 29 $ 19,383 $ — States, municipalities and political subdivisions 12,461 1,380 15 13,826 (13 ) Asset-backed: Residential mortgage-backed 4,835 124 38 4,921 (27 ) Commercial mortgage-backed 1,907 59 14 1,952 — Other asset-backed 1,050 16 5 1,061 — Total asset-backed 7,792 199 57 7,934 (27 ) U.S. Treasury and obligations of government-sponsored enterprises 113 4 2 115 — Foreign government 438 12 1 449 — Redeemable preferred stock 18 1 — 19 — Total fixed maturity securities available-for-sale 38,645 3,185 104 41,726 $ (40 ) Total fixed maturity securities trading 23 23 Equity securities available-for-sale: Common stock 17 5 — 22 Preferred stock 91 6 1 96 Total equity securities available-for-sale 108 11 1 118 Total $ 38,776 $ 3,196 $ 105 $ 41,867 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 June 30, 2017 and December 31, 2016 , the net unrealized gains on investments included in AOCI were correspondingly reduced by Shadow Adjustments of $1,221 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 June 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 $ 1,314 $ 26 $ 52 $ 3 $ 1,366 $ 29 States, municipalities and political subdivisions 742 15 24 — 766 15 Asset-backed: Residential mortgage-backed 1,722 34 141 4 1,863 38 Commercial mortgage-backed 473 8 125 6 598 14 Other asset-backed 159 4 14 1 173 5 Total asset-backed 2,354 46 280 11 2,634 57 U.S. Treasury and obligations of government-sponsored enterprises 65 2 — — 65 2 Foreign government 109 1 — — 109 1 Total fixed maturity securities available-for-sale 4,584 90 356 14 4,940 104 Equity securities available-for-sale: Common stock 1 — — — 1 — Preferred stock 15 1 — — 15 1 Total equity securities available-for-sale 16 1 — — 16 1 Total $ 4,600 $ 91 $ 356 $ 14 $ 4,956 $ 105 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 June 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 June 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 June 30, 2017 and 2016 for which a portion of an OTTI loss was recognized in Other comprehensive income (loss). Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Beginning balance of credit losses on fixed maturity securities $ 32 $ 48 $ 36 $ 53 Reductions for securities sold during the period (2 ) (7 ) (6 ) (12 ) Ending balance of credit losses on fixed maturity securities $ 30 $ 41 $ 30 $ 41 Contractual Maturity The following table presents available-for-sale fixed maturity securities by contractual maturity. June 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 $ 1,590 $ 1,628 $ 1,779 $ 1,828 Due after one year through five years 7,732 8,098 7,566 7,955 Due after five years through ten years 15,754 16,404 15,892 16,332 Due after ten years 13,569 15,596 13,112 14,778 Total $ 38,645 $ 41,726 $ 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 $171 million and $174 million as of June 30, 2017 and December 31, 2016 and a fair value of $(1) million and $3 million as of June 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 June 30, 2017 , the Company had committed approximately $415 million to future capital calls from various third-party limited partnership investments in exchange for an ownership interest in the related partnerships. As of June 30, 2017 , the Company had mortgage loan commitments of $39 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 June 30, 2017 , the Company had commitments to purchase or fund additional amounts of $196 million and sell $165 million under the terms of such securities.

Fair Value

Fair Value	6 Months Ended
	Jun. 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. June 30, 2017 Total Assets/Liabilities at Fair Value (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate and other bonds $ — $ 19,306 $ 100 $ 19,406 States, municipalities and political subdivisions — 13,825 1 13,826 Asset-backed: Residential mortgage-backed — 4,798 123 4,921 Commercial mortgage-backed — 1,939 13 1,952 Other asset-backed — 979 82 1,061 Total asset-backed — 7,716 218 7,934 U.S. Treasury and obligations of government-sponsored enterprises 115 — — 115 Foreign government — 449 — 449 Redeemable preferred stock 19 — — 19 Total fixed maturity securities 134 41,296 319 41,749 Equity securities 99 — 19 118 Other invested assets — 5 — 5 Short term investments 260 981 — 1,241 Life settlement contracts, included in Other assets — — 1 1 Total assets $ 493 $ 42,282 $ 339 $ 43,114 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 April 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 June 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 121 $ — $ — $ — $ — $ (11 ) $ — $ (10 ) $ 100 $ — States, municipalities and political subdivisions 1 — — — — — — — 1 — Asset-backed: Residential mortgage-backed 126 1 1 — — (5 ) — — 123 — Commercial mortgage-backed 13 — — — — — — — 13 — Other asset-backed 117 — — 13 — (2 ) 24 (70 ) 82 — Total asset-backed 256 1 1 13 — (7 ) 24 (70 ) 218 — Total fixed maturity securities 378 1 1 13 — (18 ) 24 (80 ) 319 — Equity securities 19 — 1 — (1 ) — — — 19 — Life settlement contracts 46 — — — (45 ) — — — 1 — Total $ 443 $ 1 $ 2 $ 13 $ (46 ) $ (18 ) $ 24 $ (80 ) $ 339 $ — Level 3 (In millions) Balance as of April 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 June 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 193 $ 1 $ 3 $ 94 $ (20 ) $ (7 ) $ — $ (22 ) $ 242 $ — States, municipalities and political subdivisions 2 — — — — — — — 2 — Asset-backed: Residential mortgage-backed 128 1 (1 ) 10 — (4 ) — — 134 — Commercial mortgage-backed 27 — — — — (9 ) 3 (10 ) 11 — Other asset-backed 50 — 2 35 (25 ) (1 ) — (16 ) 45 — Total asset-backed 205 1 1 45 (25 ) (14 ) 3 (26 ) 190 — Total fixed maturity securities 400 2 4 139 (45 ) (21 ) 3 (48 ) 434 — Equity securities 19 — — — — — — — 19 — Life settlement contracts 72 6 — — — (11 ) — — 67 (3 ) Total $ 491 $ 8 $ 4 $ 139 $ (45 ) $ (32 ) $ 3 $ (48 ) $ 520 $ (3 ) 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 June 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 130 $ — $ 1 $ 5 $ (1 ) $ (25 ) $ — $ (10 ) $ 100 $ — States, municipalities and political subdivisions 1 — — — — — — — 1 — Asset-backed: Residential mortgage-backed 129 2 3 — — (11 ) — — 123 — Commercial mortgage-backed 13 — — — — — — — 13 — Other asset-backed 57 (1 ) — 51 — (2 ) 52 (75 ) 82 — Total asset-backed 199 1 3 51 — (13 ) 52 (75 ) 218 — Total fixed maturity securities 330 1 4 56 (1 ) (38 ) 52 (85 ) 319 — Equity securities 19 — 2 1 (3 ) — — — 19 — Derivative financial instruments — 1 — — (1 ) — — — — — Life settlement contracts 58 6 — — (58 ) (5 ) — — 1 — Total $ 407 $ 8 $ 6 $ 57 $ (63 ) $ (43 ) $ 52 $ (85 ) $ 339 $ — 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 June 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 168 $ — $ 7 $ 147 $ (36 ) $ (10 ) $ — $ (34 ) $ 242 $ — States, municipalities and political subdivisions 2 — — — — — — — 2 — Asset-backed: Residential mortgage-backed 134 2 (1 ) 10 — (9 ) — (2 ) 134 — Commercial mortgage-backed 22 — — 9 — (9 ) 3 (14 ) 11 — Other asset-backed 53 — 2 35 (25 ) (1 ) 2 (21 ) 45 — Total asset-backed 209 2 1 54 (25 ) (19 ) 5 (37 ) 190 — Total fixed maturity securities 379 2 8 201 (61 ) (29 ) 5 (71 ) 434 — Equity securities 20 — (1 ) — — — — — 19 — Life settlement contracts 74 10 — — — (17 ) — — 67 (3 ) Total $ 473 $ 12 $ 7 $ 201 $ (61 ) $ (46 ) $ 5 $ (71 ) $ 520 $ (3 ) *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 six months ended June 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 June 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 is recognized as the owner and beneficiary of each individual life settlement contract by the life insurance company that issued the policy. All but $1 million of the contracts have been released from escrow as of June 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 June 30, 2017 Condensed Consolidated Balance Sheet and interest income is accreted to the principal balance of the note receivable. The contracts remaining in escrow have not been derecognized, continue to be measured at the fair value per the PSA, and are expected to clear escrow in the third quarter of 2017. The fair value of the Company's investments in life settlement contracts were $1 million and $58 million as of June 30, 2017 and December 31, 2016 , and are included in Other assets on the Condensed Consolidated Balance Sheets. Despite the sale, the contracts have been 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. June 30, 2017 Estimated Fair Value (In millions) Valuation Technique(s) Unobservable Input(s) Range (Weighted Average) Fixed maturity securities $ 125 Discounted cash flow Credit spread 2% - 40% (4%) 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. June 30, 2017 Carrying Amount Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 646 $ — $ — $ 655 $ 655 Note receivable 45 — — 45 45 Liabilities Short term debt $ 150 $ — $ 154 $ — $ 154 Long term debt 2,561 — 2,819 — 2,819 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	6 Months Ended
	Jun. 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 $39 million and $73 million for the three and six months ended June 30, 2017 . Catastrophe losses in 2017 resulted primarily from U.S. weather-related events. The Company reported catastrophe losses, net of reinsurance, of $85 million and $121 million for the three and six months ended June 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 six months ended June 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 2,443 2,583 Decrease in provision for insured events of prior years (159 ) (198 ) Amortization of discount 93 93 Total net incurred (1) 2,377 2,478 Net payments attributable to: Current year events (266 ) (311 ) Prior year events (2,331 ) (2,185 ) Total net payments (2,597 ) (2,496 ) Foreign currency translation adjustment and other 70 46 Net reserves, end of period 18,099 18,604 Ceded reserves, end of period 4,080 4,371 Gross reserves, end of period $ 22,179 $ 22,975 (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 June 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 $ (23 ) $ (34 ) $ 2 $ — $ (55 ) Pretax (favorable) unfavorable premium development (5 ) 1 (4 ) — (8 ) Total pretax (favorable) unfavorable net prior year development $ (28 ) $ (33 ) $ (2 ) $ — $ (63 ) Three months ended June 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 $ (65 ) $ (18 ) $ (15 ) $ — $ (98 ) Pretax (favorable) unfavorable premium development (7 ) (2 ) 1 — (8 ) Total pretax (favorable) unfavorable net prior year development $ (72 ) $ (20 ) $ (14 ) $ — $ (106 ) Six months ended June 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 $ (54 ) $ (58 ) $ — $ — $ (112 ) Pretax (favorable) unfavorable premium development (10 ) 38 (11 ) — 17 Total pretax (favorable) unfavorable net prior year development $ (64 ) $ (20 ) $ (11 ) $ — $ (95 ) Six months ended June 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 $ (99 ) $ (32 ) $ (19 ) $ — $ (150 ) Pretax (favorable) unfavorable premium development (18 ) (4 ) — — (22 ) Total pretax (favorable) unfavorable net prior year development $ (117 ) $ (36 ) $ (19 ) $ — $ (172 ) 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 six months ended June 30, 2017 within 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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ 3 $ (23 ) $ 4 $ (30 ) Other Professional Liability and Management Liability (37 ) (41 ) (69 ) (50 ) Surety — — — — Warranty 6 3 6 5 Other 5 (4 ) 5 (24 ) Total pretax (favorable) unfavorable development $ (23 ) $ (65 ) $ (54 ) $ (99 ) Three Months 2017 Favorable development in other professional liability and management liability was primarily due to lower than expected claim frequency in accident years 2013 through 2015 and lower than expected severity in accident years 2014 through 2016 for professional liability. 2016 Favorable development in medical professional liability was due to lower than expected severity for individual healthcare professionals and allied facilities for accident years 2014 and prior. Favorable development in other professional liability and management liability was primarily related to lower than expected frequency of claims in accident years 2010 through 2015, mainly driven by professional services. This was partially offset by unfavorable development in accident year 2015 related to an increase in management liability frequency of larger claims. Six 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 2013 through 2015 for professional liability and lower than expected severity in accident years 2014 through 2016 for professional liability. 2016 Favorable development for medical professional liability was primarily due to lower than expected severity 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 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 lower than expected frequency of claims in accident years 2010 through 2015, mainly driven by professional services. Additional favorable development was related to favorable outcomes on larger claims in 2013 and prior in professional services. This was partially offset by unfavorable development in accident years 2014 and 2015 related to an increase in management liability frequency of larger claims. Favorable development for other coverages was due to better than expected claim frequency in property coverages provided to Specialty customers in accident year 2015. Commercial The following table presents further detail of the development recorded for the Commercial segment. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Commercial Auto $ — $ (20 ) $ (26 ) $ (35 ) General Liability (1 ) (37 ) (1 ) (52 ) Workers' Compensation (46 ) 50 (46 ) 54 Property and Other 13 (11 ) 15 1 Total pretax (favorable) unfavorable development $ (34 ) $ (18 ) $ (58 ) $ (32 ) Three Months 2017 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. 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. 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. Unfavorable development for workers’ compensation was due to a reduction in estimated recoveries on war hazard claims for Defense Base Act contractors, which was partially offset by favorable development related to lower than expected frequencies for our small and middle market businesses in accident years 2009 through 2014. Favorable development for property and other was primarily due to better than expected loss emergence in accident years 2013 through 2015. Six Months 2017 Favorable development for commercial auto was primarily due to lower than expected severity in accident years 2013 through 2015. 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. 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. 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. Unfavorable development for workers’ compensation was due to a reduction in estimated recoveries on war hazard claims for Defense Base Act contractors, which was partially offset by favorable development related to lower than expected frequencies for our small and middle market businesses in accident years 2009 through 2014. Unfavorable development for property and other was primarily due to higher than expected severity from a 2015 catastrophe event. Favorable development was primarily due to better than expected loss emergence in accident years 2013 through 2015. International The following table presents further detail of the development recorded for the International segment. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ (5 ) $ (1 ) $ (5 ) $ (1 ) Other Professional Liability 10 18 9 17 Liability (5 ) (19 ) (5 ) (19 ) Property & Marine (12 ) (3 ) (11 ) (7 ) Other 14 (10 ) 12 (9 ) Total pretax (favorable) unfavorable development $ 2 $ (15 ) $ — $ (19 ) Three Months 2017 Unfavorable development for other professional liability was primarily due to higher than expected severity in accident year 2015 arising from the management liability business. This was partially offset by favorable development in accident years 2014 and prior. 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. Favorable development for liability was primarily due to better than expected severity in accident years 2013 and prior. Favorable development for other coverages was primarily due to better than expected severity in auto liability in accident years 2011 through 2015. Six Months 2017 The drivers of development for the six month period were generally consistent with the three month summary above. 2016 Unfavorable development for other professional liability was primarily due to higher than expected large loss emergence in accident years 2011 through 2015. Favorable development for liability was primarily due to better than expected severity in accident years 2013 and prior. 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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Net A&EP adverse development before consideration of LPT $ — $ — $ 60 $ 200 Retroactive reinsurance benefit recognized (3 ) (9 ) (43 ) (82 ) Pretax impact of A&EP reserve development and the LPT $ (3 ) $ (9 ) $ 17 $ 118 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 six months ended June 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 June 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 $351 million and $334 million as of June 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 $2.8 billion as of June 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	6 Months Ended
	Jun. 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. This litigation is in its early stages, and as of yet no class has been certified. CCC and the other defendants are contesting the case. The parties are scheduled to attend a mediation in September 2017. Management believes the likelihood of loss is reasonably possible; however, given the status of the litigation, the novel issues raised by the allegations and the uncertainty as to how to assess potential damages, management is currently unable to predict the final outcome. The Plan trustees have provided notice to their fiduciary coverage insurance carriers. Based on management’s current assessment and 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 Condensed Consolidated Financial Statements; however, the timing of recognition of 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 is in the process of voluntarily issuing premium refunds related to affected policies. After the rating errors were identified written and earned premium have been reported net of any impact from the premium rate adjustments. Premium development recognized as a result of the rating errors was favorable of $1 million and adverse of $37 million for the three and six months ended June 30, 2017 , respectively. The estimated refund liability for the multi-peril product and workers' compensation policies as of June 30, 2017 was $96 million . The Company has reduced pretax operating income by $1 million and $6 million for the three and six months ended June 30, 2017 for interest due to policyholders on the aggregate refund amounts. The amount of the refund and corresponding liability will continue to increase until required changes to the automated rating processes are fully implemented. The required changes were implemented in the second quarter of 2017 for the multi-peril product and are expected to be implemented by the end of the third quarter of 2017 for workers' compensation policies. Any fines or penalties related to the foregoing are reasonably possible, but are not expected to be material to the Company's Condensed Consolidated Financial Statements. 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 Condensed Consolidated Financial Statements. Guarantees As of June 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 June 30, 2017 , the aggregate amount related to quantifiable guarantees was $434 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 June 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 June 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	6 Months Ended
	Jun. 30, 2017
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The components of net periodic cost (benefit) are presented in the following table. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pension cost (benefit) Interest cost on projected benefit obligation $ 26 $ 28 $ 52 $ 56 Expected return on plan assets (39 ) (40 ) (78 ) (80 ) Amortization of net actuarial loss 9 10 18 19 Settlement loss — — 2 — Net periodic pension cost (benefit) $ (4 ) $ (2 ) $ (6 ) $ (5 )

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss) by Component	6 Months Ended
	Jun. 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 April 1, 2017 $ 26 $ 709 $ (640 ) $ (187 ) $ (92 ) Other comprehensive income (loss) before reclassifications (1 ) 108 — 42 149 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $1, $(15), $3, $- and $(11) (1 ) 31 (5 ) — 25 Other comprehensive income (loss) net of tax (expense) benefit of $-, $(48), $(3), $- and $(51) — 77 5 42 124 Balance as of June 30, 2017 $ 26 $ 786 $ (635 ) $ (145 ) $ 32 (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 April 1, 2016 $ 32 $ 624 $ (642 ) $ (70 ) $ (56 ) Other comprehensive income (loss) before reclassifications (1 ) 323 — (48 ) 274 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $-, $(6), $3, $- and $(3) — 13 (5 ) — 8 Other comprehensive income (loss) net of tax (expense) benefit of $1, $(157), $(3), $- and $(159) (1 ) 310 5 (48 ) 266 Balance as of June 30, 2016 $ 31 $ 934 $ (637 ) $ (118 ) $ 210 (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 (1 ) 193 — 53 245 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(1), $(24), $7, $- and $(18) 3 49 (12 ) — 40 Other comprehensive income (loss) net of tax (expense) benefit of $1, $(86), $(7), $- and $(92) (4 ) 144 12 53 205 Balance as of June 30, 2017 $ 26 $ 786 $ (635 ) $ (145 ) $ 32 (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 2 546 — (34 ) 514 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $1, $1, $6, $- and $8 (2 ) 2 (11 ) — (11 ) Other comprehensive income (loss) net of tax (expense) benefit of $(2), $(273), $(6), $- and $(281) 4 544 11 (34 ) 525 Balance as of June 30, 2016 $ 31 $ 934 $ (637 ) $ (118 ) $ 210 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	6 Months Ended
	Jun. 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 June 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 689 $ 705 $ 206 $ 135 $ — $ (1 ) $ 1,734 Net investment income 120 143 13 195 4 — 475 Other revenues 98 9 (1 ) — 1 — 107 Total operating revenues 907 857 218 330 5 (1 ) 2,316 Claims, Benefits and Expenses Net incurred claims and benefits 398 422 129 328 (2 ) — 1,275 Policyholders’ dividends 1 4 — — — — 5 Amortization of deferred acquisition costs 149 118 45 — — — 312 Other insurance related expenses 72 128 31 32 (1 ) (1 ) 261 Other expenses 82 11 (1 ) 1 50 — 143 Total claims, benefits and expenses 702 683 204 361 47 (1 ) 1,996 Operating income (loss) before income tax 205 174 14 (31 ) (42 ) — 320 Income tax (expense) benefit on operating income (loss) (69 ) (59 ) (4 ) 36 15 — (81 ) Net operating income (loss) 136 115 10 5 (27 ) — 239 Net realized investment gains (losses) 14 19 7 7 3 — 50 Income tax (expense) benefit on net realized investment gains (losses) (5 ) (6 ) (1 ) (3 ) (2 ) — (17 ) Net realized investment gains (losses), after tax 9 13 6 4 1 — 33 Net income (loss) $ 145 $ 128 $ 16 $ 9 $ (26 ) $ — $ 272 Three months ended June 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 702 $ 696 $ 197 $ 136 $ — $ (1 ) $ 1,730 Net investment income 133 164 13 188 4 — 502 Other revenues 89 8 — 3 — — 100 Total operating revenues 924 868 210 327 4 (1 ) 2,332 Claims, Benefits and Expenses Net incurred claims and benefits 377 469 157 340 (8 ) — 1,335 Policyholders’ dividends 1 3 — — — — 4 Amortization of deferred acquisition costs 148 117 40 — — — 305 Other insurance related expenses 73 130 37 31 — (1 ) 270 Other expenses 79 11 7 2 47 — 146 Total claims, benefits and expenses 678 730 241 373 39 (1 ) 2,060 Operating income (loss) before income tax 246 138 (31 ) (46 ) (35 ) — 272 Income tax (expense) benefit on operating income (loss) (82 ) (46 ) 4 42 11 — (71 ) Net operating income (loss) 164 92 (27 ) (4 ) (24 ) — 201 Net realized investment gains (losses) 4 8 4 (2 ) 2 — 16 Income tax (expense) benefit on net realized investment gains (losses) (2 ) (3 ) (1 ) (3 ) 1 — (8 ) Net realized investment gains (losses), after tax 2 5 3 (5 ) 3 — 8 Net income (loss) $ 166 $ 97 $ (24 ) $ (9 ) $ (21 ) $ — $ 209 Six months ended June 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 1,353 $ 1,356 $ 403 $ 268 $ — $ (1 ) $ 3,379 Net investment income 273 321 25 392 9 — 1,020 Other revenues 192 18 (1 ) 1 1 — 211 Total operating revenues 1,818 1,695 427 661 10 (1 ) 4,610 Claims, Benefits and Expenses Net incurred claims and benefits 784 859 244 658 19 — 2,564 Policyholders’ dividends 2 7 — — — — 9 Amortization of deferred acquisition costs 292 234 91 — — — 617 Other insurance related expenses 141 254 58 64 (1 ) (1 ) 515 Other expenses 163 25 (7 ) 3 94 — 278 Total claims, benefits and expenses 1,382 1,379 386 725 112 (1 ) 3,983 Operating income (loss) before income tax 436 316 41 (64 ) (102 ) — 627 Income tax (expense) benefit on operating income (loss) (146 ) (107 ) (11 ) 73 38 — (153 ) Net operating income (loss) 290 209 30 9 (64 ) — 474 Net realized investment gains (losses) 21 30 13 17 5 — 86 Income tax (expense) benefit on net realized investment gains (losses) (8 ) (9 ) (2 ) (7 ) (2 ) — (28 ) Net realized investment gains (losses), after tax 13 21 11 10 3 — 58 Net income (loss) $ 303 $ 230 $ 41 $ 19 $ (61 ) $ — $ 532 June 30, 2017 (In millions) Reinsurance receivables $ 880 $ 591 $ 150 $ 461 $ 2,382 $ — $ 4,464 Insurance receivables 1,020 1,129 290 11 2 — 2,452 Deferred acquisition costs 318 234 95 — — — 647 Goodwill 117 — 30 — — — 147 Insurance reserves Claim and claim adjustment expenses 6,229 8,586 1,442 3,417 2,505 — 22,179 Unearned premiums 1,988 1,481 500 139 — (1 ) 4,107 Future policy benefits — — — 10,824 — — 10,824 Six months ended June 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 1,384 $ 1,384 $ 395 $ 267 $ — $ (1 ) $ 3,429 Net investment income 240 290 25 375 7 — 937 Other revenues 176 14 1 3 3 — 197 Total operating revenues 1,800 1,688 421 645 10 (1 ) 4,563 Claims, Benefits and Expenses Net incurred claims and benefits 767 911 278 663 120 — 2,739 Policyholders’ dividends 2 6 — — — — 8 Amortization of deferred acquisition costs 292 233 87 — — — 612 Other insurance related expenses 148 271 65 64 — (1 ) 547 Other expenses 154 16 16 5 101 — 292 Total claims, benefits and expenses 1,363 1,437 446 732 221 (1 ) 4,198 Operating income (loss) before income tax 437 251 (25 ) (87 ) (211 ) — 365 Income tax (expense) benefit on operating income (loss) (146 ) (85 ) 4 81 73 — (73 ) Net operating income (loss) 291 166 (21 ) (6 ) (138 ) — 292 Net realized investment gains (losses) (7 ) (10 ) 8 (5 ) (6 ) — (20 ) Income tax (expense) benefit on net realized investment gains (losses) 2 3 (2 ) (3 ) 3 — 3 Net realized investment gains (losses), after tax (5 ) (7 ) 6 (8 ) (3 ) — (17 ) Net income (loss) $ 286 $ 159 $ (15 ) $ (14 ) $ (141 ) $ — $ 275 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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Specialty Management & Professional Liability $ 646 $ 659 $ 1,307 $ 1,277 Surety 137 133 260 260 Warranty & Alternative Risks 138 136 272 256 Specialty revenues 921 928 1,839 1,793 Commercial Middle Market 462 434 920 835 Small Business 129 151 226 294 Other Commercial Insurance 285 291 579 549 Commercial revenues 876 876 1,725 1,678 International Canada 53 51 104 101 CNA Europe 79 81 152 159 Hardy 93 82 184 169 International revenues 225 214 440 429 Life & Group Non-Core revenues 337 325 678 640 Corporate & Other Non-Core revenues 8 6 15 4 Eliminations (1 ) (1 ) (1 ) (1 ) Total revenues $ 2,366 $ 2,348 $ 4,696 $ 4,543

General (Policies)

General (Policies)	6 Months Ended
	Jun. 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 $0 million and $3 million to income tax expense for the three and six months ended June 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. As insurance contracts are out of scope, the Company anticipates the primary change will be to revenue recognition for certain of our warranty products and services. The Company has not made a decision on the method of adoption and is currently evaluating the effect the updated guidance will have on the Company’s financial statements, but we do not currently believe ASU 2014-09 will have a material effect on the Company's 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. 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)	6 Months Ended
	Jun. 30, 2017
Investments [Abstract]
Net investment income	The significant components of Net investment income are presented in the following table. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Fixed maturity securities $ 457 $ 449 $ 912 $ 895 Equity securities 2 4 3 7 Limited partnership investments 16 46 106 32 Mortgage loans 8 13 15 22 Short term investments 3 1 6 4 Trading portfolio 4 4 6 6 Other — — 1 — Gross investment income 490 517 1,049 966 Investment expense (15 ) (15 ) (29 ) (29 ) Net investment income $ 475 $ 502 $ 1,020 $ 937
Net realized investment gains (losses)	Net realized investment gains (losses) are presented in the following table. Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Net realized investment gains (losses): Fixed maturity securities: Gross realized gains $ 56 $ 40 $ 105 $ 85 Gross realized losses (12 ) (24 ) (29 ) (86 ) Net realized investment gains (losses) on fixed maturity securities 44 16 76 (1 ) Equity securities: Gross realized gains 1 4 1 4 Gross realized losses (1 ) (1 ) (1 ) (6 ) Net realized investment gains (losses) on equity securities — 3 — (2 ) Derivatives (3 ) (6 ) (2 ) (13 ) Short term investments and other 9 3 12 (4 ) Net realized investment gains (losses) $ 50 $ 16 $ 86 $ (20 )
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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Fixed maturity securities available-for-sale: Corporate and other bonds $ 2 $ 13 $ 4 $ 29 Asset-backed: Residential mortgage-backed — 1 — 1 Other asset-backed — 1 — 3 Total asset-backed — 2 — 4 Total fixed maturity securities available-for-sale 2 15 4 33 Equity securities available-for-sale -- Common stock — — — 5 OTTI losses recognized in earnings $ 2 $ 15 $ 4 $ 38
Summary of fixed maturity and equity securities	The following tables present a summary of fixed maturity and equity securities. June 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 $ 17,823 $ 1,589 $ 29 $ 19,383 $ — States, municipalities and political subdivisions 12,461 1,380 15 13,826 (13 ) Asset-backed: Residential mortgage-backed 4,835 124 38 4,921 (27 ) Commercial mortgage-backed 1,907 59 14 1,952 — Other asset-backed 1,050 16 5 1,061 — Total asset-backed 7,792 199 57 7,934 (27 ) U.S. Treasury and obligations of government-sponsored enterprises 113 4 2 115 — Foreign government 438 12 1 449 — Redeemable preferred stock 18 1 — 19 — Total fixed maturity securities available-for-sale 38,645 3,185 104 41,726 $ (40 ) Total fixed maturity securities trading 23 23 Equity securities available-for-sale: Common stock 17 5 — 22 Preferred stock 91 6 1 96 Total equity securities available-for-sale 108 11 1 118 Total $ 38,776 $ 3,196 $ 105 $ 41,867 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 June 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 $ 1,314 $ 26 $ 52 $ 3 $ 1,366 $ 29 States, municipalities and political subdivisions 742 15 24 — 766 15 Asset-backed: Residential mortgage-backed 1,722 34 141 4 1,863 38 Commercial mortgage-backed 473 8 125 6 598 14 Other asset-backed 159 4 14 1 173 5 Total asset-backed 2,354 46 280 11 2,634 57 U.S. Treasury and obligations of government-sponsored enterprises 65 2 — — 65 2 Foreign government 109 1 — — 109 1 Total fixed maturity securities available-for-sale 4,584 90 356 14 4,940 104 Equity securities available-for-sale: Common stock 1 — — — 1 — Preferred stock 15 1 — — 15 1 Total equity securities available-for-sale 16 1 — — 16 1 Total $ 4,600 $ 91 $ 356 $ 14 $ 4,956 $ 105 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 June 30, 2017 and 2016 for which a portion of an OTTI loss was recognized in Other comprehensive income (loss). Periods ended June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Beginning balance of credit losses on fixed maturity securities $ 32 $ 48 $ 36 $ 53 Reductions for securities sold during the period (2 ) (7 ) (6 ) (12 ) Ending balance of credit losses on fixed maturity securities $ 30 $ 41 $ 30 $ 41
Contractual maturity	The following table presents available-for-sale fixed maturity securities by contractual maturity. June 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 $ 1,590 $ 1,628 $ 1,779 $ 1,828 Due after one year through five years 7,732 8,098 7,566 7,955 Due after five years through ten years 15,754 16,404 15,892 16,332 Due after ten years 13,569 15,596 13,112 14,778 Total $ 38,645 $ 41,726 $ 38,349 $ 40,893

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 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. June 30, 2017 Total Assets/Liabilities at Fair Value (In millions) Level 1 Level 2 Level 3 Assets Fixed maturity securities: Corporate and other bonds $ — $ 19,306 $ 100 $ 19,406 States, municipalities and political subdivisions — 13,825 1 13,826 Asset-backed: Residential mortgage-backed — 4,798 123 4,921 Commercial mortgage-backed — 1,939 13 1,952 Other asset-backed — 979 82 1,061 Total asset-backed — 7,716 218 7,934 U.S. Treasury and obligations of government-sponsored enterprises 115 — — 115 Foreign government — 449 — 449 Redeemable preferred stock 19 — — 19 Total fixed maturity securities 134 41,296 319 41,749 Equity securities 99 — 19 118 Other invested assets — 5 — 5 Short term investments 260 981 — 1,241 Life settlement contracts, included in Other assets — — 1 1 Total assets $ 493 $ 42,282 $ 339 $ 43,114 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 April 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 June 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 121 $ — $ — $ — $ — $ (11 ) $ — $ (10 ) $ 100 $ — States, municipalities and political subdivisions 1 — — — — — — — 1 — Asset-backed: Residential mortgage-backed 126 1 1 — — (5 ) — — 123 — Commercial mortgage-backed 13 — — — — — — — 13 — Other asset-backed 117 — — 13 — (2 ) 24 (70 ) 82 — Total asset-backed 256 1 1 13 — (7 ) 24 (70 ) 218 — Total fixed maturity securities 378 1 1 13 — (18 ) 24 (80 ) 319 — Equity securities 19 — 1 — (1 ) — — — 19 — Life settlement contracts 46 — — — (45 ) — — — 1 — Total $ 443 $ 1 $ 2 $ 13 $ (46 ) $ (18 ) $ 24 $ (80 ) $ 339 $ — Level 3 (In millions) Balance as of April 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 June 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 193 $ 1 $ 3 $ 94 $ (20 ) $ (7 ) $ — $ (22 ) $ 242 $ — States, municipalities and political subdivisions 2 — — — — — — — 2 — Asset-backed: Residential mortgage-backed 128 1 (1 ) 10 — (4 ) — — 134 — Commercial mortgage-backed 27 — — — — (9 ) 3 (10 ) 11 — Other asset-backed 50 — 2 35 (25 ) (1 ) — (16 ) 45 — Total asset-backed 205 1 1 45 (25 ) (14 ) 3 (26 ) 190 — Total fixed maturity securities 400 2 4 139 (45 ) (21 ) 3 (48 ) 434 — Equity securities 19 — — — — — — — 19 — Life settlement contracts 72 6 — — — (11 ) — — 67 (3 ) Total $ 491 $ 8 $ 4 $ 139 $ (45 ) $ (32 ) $ 3 $ (48 ) $ 520 $ (3 ) 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 June 30, 2017 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2017 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 130 $ — $ 1 $ 5 $ (1 ) $ (25 ) $ — $ (10 ) $ 100 $ — States, municipalities and political subdivisions 1 — — — — — — — 1 — Asset-backed: Residential mortgage-backed 129 2 3 — — (11 ) — — 123 — Commercial mortgage-backed 13 — — — — — — — 13 — Other asset-backed 57 (1 ) — 51 — (2 ) 52 (75 ) 82 — Total asset-backed 199 1 3 51 — (13 ) 52 (75 ) 218 — Total fixed maturity securities 330 1 4 56 (1 ) (38 ) 52 (85 ) 319 — Equity securities 19 — 2 1 (3 ) — — — 19 — Derivative financial instruments — 1 — — (1 ) — — — — — Life settlement contracts 58 6 — — (58 ) (5 ) — — 1 — Total $ 407 $ 8 $ 6 $ 57 $ (63 ) $ (43 ) $ 52 $ (85 ) $ 339 $ — 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 June 30, 2016 Unrealized gains (losses) on Level 3 assets and liabilities held as of June 30, 2016 recognized in Net income (loss)* Fixed maturity securities: Corporate and other bonds $ 168 $ — $ 7 $ 147 $ (36 ) $ (10 ) $ — $ (34 ) $ 242 $ — States, municipalities and political subdivisions 2 — — — — — — — 2 — Asset-backed: Residential mortgage-backed 134 2 (1 ) 10 — (9 ) — (2 ) 134 — Commercial mortgage-backed 22 — — 9 — (9 ) 3 (14 ) 11 — Other asset-backed 53 — 2 35 (25 ) (1 ) 2 (21 ) 45 — Total asset-backed 209 2 1 54 (25 ) (19 ) 5 (37 ) 190 — Total fixed maturity securities 379 2 8 201 (61 ) (29 ) 5 (71 ) 434 — Equity securities 20 — (1 ) — — — — — 19 — Life settlement contracts 74 10 — — — (17 ) — — 67 (3 ) Total $ 473 $ 12 $ 7 $ 201 $ (61 ) $ (46 ) $ 5 $ (71 ) $ 520 $ (3 ) *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. June 30, 2017 Estimated Fair Value (In millions) Valuation Technique(s) Unobservable Input(s) Range (Weighted Average) Fixed maturity securities $ 125 Discounted cash flow Credit spread 2% - 40% (4%) 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. June 30, 2017 Carrying Amount Estimated Fair Value (In millions) Level 1 Level 2 Level 3 Total Assets Mortgage loans $ 646 $ — $ — $ 655 $ 655 Note receivable 45 — — 45 45 Liabilities Short term debt $ 150 $ — $ 154 $ — $ 154 Long term debt 2,561 — 2,819 — 2,819 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)	6 Months Ended
	Jun. 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 six months ended June 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 2,443 2,583 Decrease in provision for insured events of prior years (159 ) (198 ) Amortization of discount 93 93 Total net incurred (1) 2,377 2,478 Net payments attributable to: Current year events (266 ) (311 ) Prior year events (2,331 ) (2,185 ) Total net payments (2,597 ) (2,496 ) Foreign currency translation adjustment and other 70 46 Net reserves, end of period 18,099 18,604 Ceded reserves, end of period 4,080 4,371 Gross reserves, end of period $ 22,179 $ 22,975 (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 June 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 $ (23 ) $ (34 ) $ 2 $ — $ (55 ) Pretax (favorable) unfavorable premium development (5 ) 1 (4 ) — (8 ) Total pretax (favorable) unfavorable net prior year development $ (28 ) $ (33 ) $ (2 ) $ — $ (63 ) Three months ended June 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 $ (65 ) $ (18 ) $ (15 ) $ — $ (98 ) Pretax (favorable) unfavorable premium development (7 ) (2 ) 1 — (8 ) Total pretax (favorable) unfavorable net prior year development $ (72 ) $ (20 ) $ (14 ) $ — $ (106 ) Six months ended June 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 $ (54 ) $ (58 ) $ — $ — $ (112 ) Pretax (favorable) unfavorable premium development (10 ) 38 (11 ) — 17 Total pretax (favorable) unfavorable net prior year development $ (64 ) $ (20 ) $ (11 ) $ — $ (95 ) Six months ended June 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 $ (99 ) $ (32 ) $ (19 ) $ — $ (150 ) Pretax (favorable) unfavorable premium development (18 ) (4 ) — — (22 ) Total pretax (favorable) unfavorable net prior year development $ (117 ) $ (36 ) $ (19 ) $ — $ (172 )
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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ 3 $ (23 ) $ 4 $ (30 ) Other Professional Liability and Management Liability (37 ) (41 ) (69 ) (50 ) Surety — — — — Warranty 6 3 6 5 Other 5 (4 ) 5 (24 ) Total pretax (favorable) unfavorable development $ (23 ) $ (65 ) $ (54 ) $ (99 )
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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Commercial Auto $ — $ (20 ) $ (26 ) $ (35 ) General Liability (1 ) (37 ) (1 ) (52 ) Workers' Compensation (46 ) 50 (46 ) 54 Property and Other 13 (11 ) 15 1 Total pretax (favorable) unfavorable development $ (34 ) $ (18 ) $ (58 ) $ (32 )
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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pretax (favorable) unfavorable development: Medical Professional Liability $ (5 ) $ (1 ) $ (5 ) $ (1 ) Other Professional Liability 10 18 9 17 Liability (5 ) (19 ) (5 ) (19 ) Property & Marine (12 ) (3 ) (11 ) (7 ) Other 14 (10 ) 12 (9 ) Total pretax (favorable) unfavorable development $ 2 $ (15 ) $ — $ (19 )
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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Net A&EP adverse development before consideration of LPT $ — $ — $ 60 $ 200 Retroactive reinsurance benefit recognized (3 ) (9 ) (43 ) (82 ) Pretax impact of A&EP reserve development and the LPT $ (3 ) $ (9 ) $ 17 $ 118

Benefit Plans (Tables)

Benefit Plans (Tables)	6 Months Ended
	Jun. 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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Pension cost (benefit) Interest cost on projected benefit obligation $ 26 $ 28 $ 52 $ 56 Expected return on plan assets (39 ) (40 ) (78 ) (80 ) Amortization of net actuarial loss 9 10 18 19 Settlement loss — — 2 — Net periodic pension cost (benefit) $ (4 ) $ (2 ) $ (6 ) $ (5 )

Accumulated Other Comprehensi22

Accumulated Other Comprehensive Income (Loss) by Component (Tables)	6 Months Ended
	Jun. 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 April 1, 2017 $ 26 $ 709 $ (640 ) $ (187 ) $ (92 ) Other comprehensive income (loss) before reclassifications (1 ) 108 — 42 149 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $1, $(15), $3, $- and $(11) (1 ) 31 (5 ) — 25 Other comprehensive income (loss) net of tax (expense) benefit of $-, $(48), $(3), $- and $(51) — 77 5 42 124 Balance as of June 30, 2017 $ 26 $ 786 $ (635 ) $ (145 ) $ 32 (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 April 1, 2016 $ 32 $ 624 $ (642 ) $ (70 ) $ (56 ) Other comprehensive income (loss) before reclassifications (1 ) 323 — (48 ) 274 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $-, $(6), $3, $- and $(3) — 13 (5 ) — 8 Other comprehensive income (loss) net of tax (expense) benefit of $1, $(157), $(3), $- and $(159) (1 ) 310 5 (48 ) 266 Balance as of June 30, 2016 $ 31 $ 934 $ (637 ) $ (118 ) $ 210 (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 (1 ) 193 — 53 245 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $(1), $(24), $7, $- and $(18) 3 49 (12 ) — 40 Other comprehensive income (loss) net of tax (expense) benefit of $1, $(86), $(7), $- and $(92) (4 ) 144 12 53 205 Balance as of June 30, 2017 $ 26 $ 786 $ (635 ) $ (145 ) $ 32 (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 2 546 — (34 ) 514 Amounts reclassified from accumulated other comprehensive income (loss) net of tax (expense) benefit of $1, $1, $6, $- and $8 (2 ) 2 (11 ) — (11 ) Other comprehensive income (loss) net of tax (expense) benefit of $(2), $(273), $(6), $- and $(281) 4 544 11 (34 ) 525 Balance as of June 30, 2016 $ 31 $ 934 $ (637 ) $ (118 ) $ 210
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)	6 Months Ended
	Jun. 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 June 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 689 $ 705 $ 206 $ 135 $ — $ (1 ) $ 1,734 Net investment income 120 143 13 195 4 — 475 Other revenues 98 9 (1 ) — 1 — 107 Total operating revenues 907 857 218 330 5 (1 ) 2,316 Claims, Benefits and Expenses Net incurred claims and benefits 398 422 129 328 (2 ) — 1,275 Policyholders’ dividends 1 4 — — — — 5 Amortization of deferred acquisition costs 149 118 45 — — — 312 Other insurance related expenses 72 128 31 32 (1 ) (1 ) 261 Other expenses 82 11 (1 ) 1 50 — 143 Total claims, benefits and expenses 702 683 204 361 47 (1 ) 1,996 Operating income (loss) before income tax 205 174 14 (31 ) (42 ) — 320 Income tax (expense) benefit on operating income (loss) (69 ) (59 ) (4 ) 36 15 — (81 ) Net operating income (loss) 136 115 10 5 (27 ) — 239 Net realized investment gains (losses) 14 19 7 7 3 — 50 Income tax (expense) benefit on net realized investment gains (losses) (5 ) (6 ) (1 ) (3 ) (2 ) — (17 ) Net realized investment gains (losses), after tax 9 13 6 4 1 — 33 Net income (loss) $ 145 $ 128 $ 16 $ 9 $ (26 ) $ — $ 272 Three months ended June 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 702 $ 696 $ 197 $ 136 $ — $ (1 ) $ 1,730 Net investment income 133 164 13 188 4 — 502 Other revenues 89 8 — 3 — — 100 Total operating revenues 924 868 210 327 4 (1 ) 2,332 Claims, Benefits and Expenses Net incurred claims and benefits 377 469 157 340 (8 ) — 1,335 Policyholders’ dividends 1 3 — — — — 4 Amortization of deferred acquisition costs 148 117 40 — — — 305 Other insurance related expenses 73 130 37 31 — (1 ) 270 Other expenses 79 11 7 2 47 — 146 Total claims, benefits and expenses 678 730 241 373 39 (1 ) 2,060 Operating income (loss) before income tax 246 138 (31 ) (46 ) (35 ) — 272 Income tax (expense) benefit on operating income (loss) (82 ) (46 ) 4 42 11 — (71 ) Net operating income (loss) 164 92 (27 ) (4 ) (24 ) — 201 Net realized investment gains (losses) 4 8 4 (2 ) 2 — 16 Income tax (expense) benefit on net realized investment gains (losses) (2 ) (3 ) (1 ) (3 ) 1 — (8 ) Net realized investment gains (losses), after tax 2 5 3 (5 ) 3 — 8 Net income (loss) $ 166 $ 97 $ (24 ) $ (9 ) $ (21 ) $ — $ 209 Six months ended June 30, 2017 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 1,353 $ 1,356 $ 403 $ 268 $ — $ (1 ) $ 3,379 Net investment income 273 321 25 392 9 — 1,020 Other revenues 192 18 (1 ) 1 1 — 211 Total operating revenues 1,818 1,695 427 661 10 (1 ) 4,610 Claims, Benefits and Expenses Net incurred claims and benefits 784 859 244 658 19 — 2,564 Policyholders’ dividends 2 7 — — — — 9 Amortization of deferred acquisition costs 292 234 91 — — — 617 Other insurance related expenses 141 254 58 64 (1 ) (1 ) 515 Other expenses 163 25 (7 ) 3 94 — 278 Total claims, benefits and expenses 1,382 1,379 386 725 112 (1 ) 3,983 Operating income (loss) before income tax 436 316 41 (64 ) (102 ) — 627 Income tax (expense) benefit on operating income (loss) (146 ) (107 ) (11 ) 73 38 — (153 ) Net operating income (loss) 290 209 30 9 (64 ) — 474 Net realized investment gains (losses) 21 30 13 17 5 — 86 Income tax (expense) benefit on net realized investment gains (losses) (8 ) (9 ) (2 ) (7 ) (2 ) — (28 ) Net realized investment gains (losses), after tax 13 21 11 10 3 — 58 Net income (loss) $ 303 $ 230 $ 41 $ 19 $ (61 ) $ — $ 532 June 30, 2017 (In millions) Reinsurance receivables $ 880 $ 591 $ 150 $ 461 $ 2,382 $ — $ 4,464 Insurance receivables 1,020 1,129 290 11 2 — 2,452 Deferred acquisition costs 318 234 95 — — — 647 Goodwill 117 — 30 — — — 147 Insurance reserves Claim and claim adjustment expenses 6,229 8,586 1,442 3,417 2,505 — 22,179 Unearned premiums 1,988 1,481 500 139 — (1 ) 4,107 Future policy benefits — — — 10,824 — — 10,824 Six months ended June 30, 2016 Specialty Commercial International Life & Group Non-Core Corporate & Other Non-Core (In millions) Eliminations Total Operating revenues Net earned premiums $ 1,384 $ 1,384 $ 395 $ 267 $ — $ (1 ) $ 3,429 Net investment income 240 290 25 375 7 — 937 Other revenues 176 14 1 3 3 — 197 Total operating revenues 1,800 1,688 421 645 10 (1 ) 4,563 Claims, Benefits and Expenses Net incurred claims and benefits 767 911 278 663 120 — 2,739 Policyholders’ dividends 2 6 — — — — 8 Amortization of deferred acquisition costs 292 233 87 — — — 612 Other insurance related expenses 148 271 65 64 — (1 ) 547 Other expenses 154 16 16 5 101 — 292 Total claims, benefits and expenses 1,363 1,437 446 732 221 (1 ) 4,198 Operating income (loss) before income tax 437 251 (25 ) (87 ) (211 ) — 365 Income tax (expense) benefit on operating income (loss) (146 ) (85 ) 4 81 73 — (73 ) Net operating income (loss) 291 166 (21 ) (6 ) (138 ) — 292 Net realized investment gains (losses) (7 ) (10 ) 8 (5 ) (6 ) — (20 ) Income tax (expense) benefit on net realized investment gains (losses) 2 3 (2 ) (3 ) 3 — 3 Net realized investment gains (losses), after tax (5 ) (7 ) 6 (8 ) (3 ) — (17 ) Net income (loss) $ 286 $ 159 $ (15 ) $ (14 ) $ (141 ) $ — $ 275 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 June 30 Three Months Six Months (In millions) 2017 2016 2017 2016 Specialty Management & Professional Liability $ 646 $ 659 $ 1,307 $ 1,277 Surety 137 133 260 260 Warranty & Alternative Risks 138 136 272 256 Specialty revenues 921 928 1,839 1,793 Commercial Middle Market 462 434 920 835 Small Business 129 151 226 294 Other Commercial Insurance 285 291 579 549 Commercial revenues 876 876 1,725 1,678 International Canada 53 51 104 101 CNA Europe 79 81 152 159 Hardy 93 82 184 169 International revenues 225 214 440 429 Life & Group Non-Core revenues 337 325 678 640 Corporate & Other Non-Core revenues 8 6 15 4 Eliminations (1 ) (1 ) (1 ) (1 ) Total revenues $ 2,366 $ 2,348 $ 4,696 $ 4,543

General - Narrative (Details)

General - Narrative (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2017USD ($)
Noncontrolling Interest [Line Items]
Employee service share-based compensation, tax benefit realized from exercise of stock options	$ 0	$ 3
CNAF Consolidated | Loews
Noncontrolling Interest [Line Items]
Ownership percentage of outstanding common stock of CNAF	90.00%	90.00%

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Incremental common shares attributable to dilutive effect of share-based payment arrangements	847	409	915	473
Antidilutive securities excluded from computation of earnings per share, amount (less than)	1	178	1	180

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Investments [Abstract]
Net realized investment losses	$ 8
Redemption senior notes	$ 350
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments		$ 1,221	$ 1,014
Embedded derivative notional value		171	174
Embedded Derivative, Fair Value of Embedded Derivative Liability		(1)	$ 3
Future capital call commitments for limited partnership investments		415
Mortgage loan commitments		39
Commitments to purchase or fund privately placed debt securities		196
Commitments to sell various privately placed debt securities		$ 165

Investments - Net investment in

Investments - Net investment income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Investment Income [Line Items]
Gross investment income	$ 490	$ 517	$ 1,049	$ 966
Investment expense	(15)	(15)	(29)	(29)
Net investment income	475	502	1,020	937
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	457	449	912	895
Equity securities
Net Investment Income [Line Items]
Gross investment income	2	4	3	7
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	16	46	106	32
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	8	13	15	22
Short term investments
Net Investment Income [Line Items]
Gross investment income	3	1	6	4
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	4	4	6	6
Other
Net Investment Income [Line Items]
Gross investment income	$ 0	$ 0	$ 1	$ 0

Investments - Net realized inve

Investments - Net realized investment gains (losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Net realized investment gains (losses) on fixed maturity securities	$ 50	$ 16	$ 86	$ (20)
Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	56	40	105	85
Gross realized losses	(12)	(24)	(29)	(86)
Net realized investment gains (losses) on fixed maturity securities	44	16	76	(1)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	1	4	1	4
Gross realized losses	(1)	(1)	(1)	(6)
Net realized investment gains (losses) on fixed maturity securities	0	3	0	(2)
Derivatives
Schedule of Available-for-sale Securities [Line Items]
Net realized investment gains (losses) on fixed maturity securities	(3)	(6)	(2)	(13)
Short term investments and other
Schedule of Available-for-sale Securities [Line Items]
Net realized investment gains (losses) on fixed maturity securities	$ 9	$ 3	$ 12	$ (4)

Investments - Components of oth

Investments - Components of other-than-temporary impairment losses recognized in earnings (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	$ 2	$ 15	$ 4	$ 38
Corporate and other bonds
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	2	13	4	29
Residential mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	0	1	0	1
Other asset-backed
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	0	1	0	3
Total asset-backed
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	0	2	0	4
Total fixed maturity securities available-for-sale
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	2	15	4	33
Equity securities available-for-sale -- Common stock
Schedule of Available-for-sale Securities [Line Items]
OTTI losses recognized in earnings	$ 0	$ 0	$ 0	$ 5

Investments - Summary of fixed

Investments - Summary of fixed maturity and equity securities (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	$ 38,776	$ 38,467
Gross Unrealized Gains	3,196	2,744
Gross Unrealized Losses	105	196
Estimated Fair Value	41,867	41,015
Corporate and other bonds
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	17,823	17,711
Gross Unrealized Gains	1,589	1,323
Gross Unrealized Losses	29	76
Estimated Fair Value	19,383	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	12,461	12,060
Gross Unrealized Gains	1,380	1,213
Gross Unrealized Losses	15	33
Estimated Fair Value	13,826	13,240
Unrealized OTTI Losses (Gains)	(13)	(16)
Residential mortgage-backed
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	4,835	5,004
Gross Unrealized Gains	124	120
Gross Unrealized Losses	38	51
Estimated Fair Value	4,921	5,073
Unrealized OTTI Losses (Gains)	(27)	(28)
Commercial mortgage-backed
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	1,907	2,016
Gross Unrealized Gains	59	48
Gross Unrealized Losses	14	24
Estimated Fair Value	1,952	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	1,050	1,022
Gross Unrealized Gains	16	8
Gross Unrealized Losses	5	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	7,792	8,042
Gross Unrealized Gains	199	176
Gross Unrealized Losses	57	80
Estimated Fair Value	7,934	8,138
Unrealized OTTI Losses (Gains)	(27)	(28)
U.S. Treasury and obligations of government-sponsored enterprises
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	113	83
Gross Unrealized Gains	4	10
Gross Unrealized Losses	2	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	438	435
Gross Unrealized Gains	12	13
Gross Unrealized Losses	1	3
Estimated Fair Value	449	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	1	1
Gross Unrealized Losses	0	0
Estimated Fair Value	19	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	38,645	38,349
Gross Unrealized Gains	3,185	2,736
Gross Unrealized Losses	104	192
Estimated Fair Value	41,726	40,893
Unrealized OTTI Losses (Gains)	(40)	(45)
Total fixed maturity securities trading
Schedule of Available-for-Sale and Trading Securities [Line Items]
Total fixed maturity securities trading, cost	23	12
Total fixed maturity securities trading, fair value	23	12
Equity securities available-for-sale -- Common stock
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	17	13
Gross Unrealized Gains	5	6
Gross Unrealized Losses	0	0
Estimated Fair Value	22	19
Preferred stock
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	91	93
Gross Unrealized Gains	6	2
Gross Unrealized Losses	1	4
Estimated Fair Value	96	91
Equity securities
Schedule of Available-for-Sale and Trading Securities [Line Items]
Cost or Amortized Cost	108	106
Gross Unrealized Gains	11	8
Gross Unrealized Losses	1	4
Estimated Fair Value	$ 118	$ 110

Investments - Securities in a g

Investments - Securities in a gross unrealized loss position (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	$ 4,600	$ 6,989
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	91	167
Estimated fair value, 12 months or longer	356	584
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	14	29
Estimated fair value, total	4,956	7,573
Available-for-sale securities, continuous unrealized loss position, accumulated loss	105	196
Corporate and other bonds
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	1,314	2,615
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	26	61
Estimated fair value, 12 months or longer	52	254
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	3	15
Estimated fair value, total	1,366	2,869
Available-for-sale securities, continuous unrealized loss position, accumulated loss	29	76
States, municipalities and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	742	959
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	15	32
Estimated fair value, 12 months or longer	24	23
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	1
Estimated fair value, total	766	982
Available-for-sale securities, continuous unrealized loss position, accumulated loss	15	33
Residential mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	1,722	2,136
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	34	44
Estimated fair value, 12 months or longer	141	201
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	4	7
Estimated fair value, total	1,863	2,337
Available-for-sale securities, continuous unrealized loss position, accumulated loss	38	51
Commercial mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	473	756
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	8	22
Estimated fair value, 12 months or longer	125	69
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	6	2
Estimated fair value, total	598	825
Available-for-sale securities, continuous unrealized loss position, accumulated loss	14	24
Other asset-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	159	398
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	4	5
Estimated fair value, 12 months or longer	14	24
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	1	0
Estimated fair value, total	173	422
Available-for-sale securities, continuous unrealized loss position, accumulated loss	5	5
Total asset-backed
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	2,354	3,290
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	46	71
Estimated fair value, 12 months or longer	280	294
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	11	9
Estimated fair value, total	2,634	3,584
Available-for-sale securities, continuous unrealized loss position, accumulated loss	57	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	65	5
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	2	0
Estimated fair value, 12 months or longer	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Estimated fair value, total	65	5
Available-for-sale securities, continuous unrealized loss position, accumulated loss	2	0
Foreign government
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	109	108
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	1	3
Estimated fair value, 12 months or longer	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Estimated fair value, total	109	108
Available-for-sale securities, continuous unrealized loss position, accumulated loss	1	3
Total fixed maturity securities available-for-sale
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	4,584	6,977
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	90	167
Estimated fair value, 12 months or longer	356	571
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	14	25
Estimated fair value, total	4,940	7,548
Available-for-sale securities, continuous unrealized loss position, accumulated loss	104	192
Equity securities available-for-sale -- Common stock
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	1
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	0
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	1
Available-for-sale securities, continuous unrealized loss position, accumulated loss	0
Equity securities available-for-sale -- Preferred stock
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	15	12
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	1	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	15	25
Available-for-sale securities, continuous unrealized loss position, accumulated loss	1	$ 4
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Estimated fair value, less than 12 months	16
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	16
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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance of credit losses on fixed maturity securities	$ 32	$ 48	$ 36	$ 53
Reductions for securities sold during the period	(2)	(7)	(6)	(12)
Ending balance of credit losses on fixed maturity securities	$ 30	$ 41	$ 30	$ 41

Investments - Contractual matur

Investments - Contractual maturity (Details) - USD ($) $ in Millions	Jun. 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	$ 1,590	$ 1,779
Due after one year through five years, cost or amortized cost	7,732	7,566
Due after five years through ten years, cost or amortized cost	15,754	15,892
Due after ten years, cost or amortized cost	13,569	13,112
Total Amortized Cost Basis	38,645	38,349
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]
Due in one year or less, estimated fair value	1,628	1,828
Due after one year through five years, estimated fair value	8,098	7,955
Due after five years through ten years, estimated fair value	16,404	16,332
Due after ten years, estimated fair value	15,596	14,778
Total Estimated Fair Value	$ 41,726	$ 40,893

Fair Value - Narrative (Details

Fair Value - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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, escrow amount	1,000,000		$ 1,000,000
Life settlement contracts, receivable, payment period			3 years
Life settlement contracts, fair value	$ 1,000,000		$ 1,000,000		$ 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	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 43,114	$ 42,406
Liabilities	1	(3)
Corporate and other bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19,406	18,970
States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	13,826	13,240
Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	4,921	5,073
Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,952	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	7,934	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	449	445
Redeemable preferred stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19	19
Fixed maturity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	41,749	40,905
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	118	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	1,241	1,328
Life settlement contracts, included in Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1	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	493	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	19	19
Level 1 | Fixed maturity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	134	112
Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	99	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	260	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	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	42,282	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	19,306	18,840
Level 2 | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	13,825	13,239
Level 2 | Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	4,798	4,944
Level 2 | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,939	2,027
Level 2 | Other asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	979	968
Level 2 | Total asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	7,716	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	449	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	41,296	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	981	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	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	339	407
Liabilities	0	0
Level 3 | Corporate and other bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	100	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	123	129
Level 3 | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	13	13
Level 3 | Other asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	82	57
Level 3 | Total asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	218	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	319	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	1	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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	$ 443	$ 491	$ 407	$ 473
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	8	8	12
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	2	4	6	7
Purchases	13	139	57	201
Sales	(46)	(45)	(63)	(61)
Settlements	(18)	(32)	(43)	(46)
Transfers into Level 3	24	3	52	5
Transfers out of Level 3	(80)	(48)	(85)	(71)
Balance, end of year	339	520	339	520
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	0	(3)	0	(3)
Corporate and other bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	121	193	130	168
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	1	0	0
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	0	3	1	7
Purchases	0	94	5	147
Sales	0	(20)	(1)	(36)
Settlements	(11)	(7)	(25)	(10)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(10)	(22)	(10)	(34)
Balance, end of year	100	242	100	242
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	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of year	1	2	1	2
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	126	128	129	134
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1	2	2
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	(1)	3	(1)
Purchases	0	10	0	10
Sales	0	0	0	0
Settlements	(5)	(4)	(11)	(9)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	(2)
Balance, end of year	123	134	123	134
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	27	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)	0	0	0	0
Purchases	0	0	0	9
Sales	0	0	0	0
Settlements	0	(9)	0	(9)
Transfers into Level 3	0	3	0	3
Transfers out of Level 3	0	(10)	0	(14)
Balance, end of year	13	11	13	11
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	117	50	57	53
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	(1)	0
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	0	2	0	2
Purchases	13	35	51	35
Sales	0	(25)	0	(25)
Settlements	(2)	(1)	(2)	(1)
Transfers into Level 3	24	0	52	2
Transfers out of Level 3	(70)	(16)	(75)	(21)
Balance, end of year	82	45	82	45
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	256	205	199	209
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1	1	2
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	1	3	1
Purchases	13	45	51	54
Sales	0	(25)	0	(25)
Settlements	(7)	(14)	(13)	(19)
Transfers into Level 3	24	3	52	5
Transfers out of Level 3	(70)	(26)	(75)	(37)
Balance, end of year	218	190	218	190
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	378	400	330	379
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	2	1	2
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	4	4	8
Purchases	13	139	56	201
Sales	0	(45)	(1)	(61)
Settlements	(18)	(21)	(38)	(29)
Transfers into Level 3	24	3	52	5
Transfers out of Level 3	(80)	(48)	(85)	(71)
Balance, end of year	319	434	319	434
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	0	0	0
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	1	0	2	(1)
Purchases	0	0	1	0
Sales	(1)	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	0	0	0
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	46	72	58	74
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	6	6	10
Net change in unrealized appreciation (depreciation) included in Other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Sales	(45)	0	(58)	0
Settlements	0	(11)	(5)	(17)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of year	1	67	1	67
Unrealized gains (losses) on Level 3 assets and liabilities, ending balance	$ 0	$ (3)	$ 0	$ (3)

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	Jun. 30, 2017	Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated Fair Value (In millions)	$ 125	$ 106
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread	2.00%	2.00%
Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread	40.00%	40.00%
Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spread	4.00%	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 ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Assets
Mortgage loans	$ 646	$ 591
Liabilities
Short term debt	150	0
Long term debt	2,561	2,710
Carrying Amount
Assets
Mortgage loans	646	591
Note receivable	45
Liabilities
Short term debt	150
Long term debt	2,561	2,710
Estimated Fair Value
Assets
Mortgage loans	655	594
Note receivable	45
Liabilities
Short term debt	154
Long term debt	2,819	2,952
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	154
Long term debt	2,819	2,952
Level 3 | Estimated Fair Value
Assets
Mortgage loans	655	594
Note receivable	45
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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2010
Liability for Claims and Claims Adjustment Expense [Line Items]
Catastrophe losses net of reinsurance	$ 39,000,000	$ 85,000,000	$ 73,000,000	$ 121,000,000
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	351,000,000		351,000,000		334,000,000
Fair value of collateral trust account established by NICO under A&EP Loss Portfolio Transfer	$ 2,800,000,000		$ 2,800,000,000		$ 2,800,000,000

Claim and Claim Adjustment Ex40

Claim and Claim Adjustment Expense Reserves - Reconciliation of claim and claim adjustment expense reserves (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 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	2,443	2,583
Decrease in provision for insured events of prior years	(159)	(198)
Amortization of discount	93	93
Total net incurred	2,377	2,478
Net payments attributable to:
Current year events	(266)	(311)
Prior year events	(2,331)	(2,185)
Total net payments	(2,597)	(2,496)
Foreign currency translation adjustment and other	70	46
Net reserves, end of period	18,099	18,604
Ceded reserves, end of year	4,080	4,371
Gross reserves, end of year	$ 22,179	$ 22,975

Claim and Claim Adjustment Ex41

Claim and Claim Adjustment Expense Reserves - Net prior year development (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (55)	$ (98)	$ (112)	$ (150)
Pretax (favorable) unfavorable premium development	(8)	(8)	17	(22)
Total pretax (favorable) unfavorable net prior year development	(63)	(106)	(95)	(172)
Specialty
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	(23)	(65)	(54)	(99)
Pretax (favorable) unfavorable premium development	(5)	(7)	(10)	(18)
Total pretax (favorable) unfavorable net prior year development	(28)	(72)	(64)	(117)
Commercial
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	(34)	(18)	(58)	(32)
Pretax (favorable) unfavorable premium development	1	(2)	38	(4)
Total pretax (favorable) unfavorable net prior year development	(33)	(20)	(20)	(36)
International
Segment Reporting Information [Line Items]
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	2	(15)	0	(19)
Pretax (favorable) unfavorable premium development	(4)	1	(11)	0
Total pretax (favorable) unfavorable net prior year development	(2)	(14)	(11)	(19)
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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ (55)	$ (98)	$ (112)	$ (150)
Specialty
Liability for Claims and Claims Adjustment Expense [Line Items]
Medical Professional Liability	3	(23)	4	(30)
Other Professional Liability and Management Liability	(37)	(41)	(69)	(50)
Surety	0	0	0	0
Warranty	6	3	6	5
Other	5	(4)	5	(24)
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (23)	$ (65)	$ (54)	$ (99)

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ (55)	$ (98)	$ (112)	$ (150)
Commercial
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial Auto	0	(20)	(26)	(35)
General Liability	(1)	(37)	(1)	(52)
Workers' Compensation	(46)	50	(46)	54
Property and Other	13	(11)	15	1
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ (34)	$ (18)	$ (58)	$ (32)

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ (55)	$ (98)	$ (112)	$ (150)
International
Liability for Claims and Claims Adjustment Expense [Line Items]
Medical Professional Liability	(5)	(1)	(5)	(1)
Other Professional Liability	10	18	9	17
Liability	(5)	(19)	(5)	(19)
Property & Marine	(12)	(3)	(11)	(7)
Other	14	(10)	12	(9)
Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development	$ 2	$ (15)	$ 0	$ (19)

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	(3)	(9)	(43)	(82)
Pretax impact of A&EP reserve development and the LPT	$ (3)	$ (9)	$ 17	$ 118

Legal Proceedings and Guarant46

Legal Proceedings and Guarantees - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Adverse premium development recognized as result of rating errors	$ 1	$ 37
Guarantee Obligations
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	1,800	1,800
Indemnification Agreement
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	254	254
Guarantee agreement
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	434	434
Guarantee and Indemnification
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Guarantor obligations, current carrying value	5	5	$ 5
Insurance Premium Rate Adjustment
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Interest due to policyholders	1	6
Multi-Peril Package Product | Insurance Premium Rate Adjustment
Legal Proceedings, Commitments and Contingencies, and Guarantees [Line Items]
Loss contingency accrual	$ 96	$ 96

Benefit Plans - Components of n

Benefit Plans - Components of net periodic cost (benefit) (Details) - Pension Plans, Defined Benefit - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 26	$ 28	$ 52	$ 56
Expected return on plan assets	(39)	(40)	(78)	(80)
Amortization of net actuarial loss	9	10	18	19
Settlement loss	0	0	2	0
Net periodic pension cost (benefit)	$ (4)	$ (2)	$ (6)	$ (5)

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year			$ 11,969
Other comprehensive income (loss) before reclassifications	$ 149	$ 274	245	$ 514
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	25	8	40	(11)
Other comprehensive income (loss) after tax (expense) benefit	124	266	205	525
Balance, end of period	12,028	11,886	12,028	11,886
Reclassification from AOCI, current period, tax	(11)	(3)	(18)	8
Tax (expense) benefit on other comprehensive income (loss)	(51)	(159)	(92)	(281)
Net unrealized gains (losses) on investments with OTTI losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	26	32	30	27
Other comprehensive income (loss) before reclassifications	(1)	(1)	(1)	2
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	(1)	0	3	(2)
Other comprehensive income (loss) after tax (expense) benefit	0	(1)	(4)	4
Balance, end of period	26	31	26	31
Reclassification from AOCI, current period, tax	1	0	(1)	1
Tax (expense) benefit on other comprehensive income (loss)	0	1	1	(2)
Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	709	624	642	390
Other comprehensive income (loss) before reclassifications	108	323	193	546
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	31	13	49	2
Other comprehensive income (loss) after tax (expense) benefit	77	310	144	544
Balance, end of period	786	934	786	934
Reclassification from AOCI, current period, tax	(15)	(6)	(24)	1
Tax (expense) benefit on other comprehensive income (loss)	(48)	(157)	(86)	(273)
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	(640)	(642)	(647)	(648)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	(5)	(5)	(12)	(11)
Other comprehensive income (loss) after tax (expense) benefit	5	5	12	11
Balance, end of period	(635)	(637)	(635)	(637)
Reclassification from AOCI, current period, tax	3	3	7	6
Tax (expense) benefit on other comprehensive income (loss)	(3)	(3)	(7)	(6)
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year	(187)	(70)	(198)	(84)
Other comprehensive income (loss) before reclassifications	42	(48)	53	(34)
Amounts reclassified from accumulated other comprehensive income (loss) after tax (expense) benefit	0	0	0	0
Other comprehensive income (loss) after tax (expense) benefit	42	(48)	53	(34)
Balance, end of period	(145)	(118)	(145)	(118)
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	(92)	(56)	(173)	(315)
Balance, end of period	$ 32	$ 210	$ 32	$ 210

Business Segments - Narrative (

Business Segments - Narrative (Details)	6 Months Ended
	Jun. 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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating revenues
Net earned premiums	$ 1,734	$ 1,730	$ 3,379	$ 3,429
Net investment income	475	502	1,020	937
Other revenues	107	100	211	197
Total operating revenues	2,316	2,332	4,610	4,563
Claims, Benefits and Expenses
Net incurred claims and benefits	1,275	1,335	2,564	2,739
Policyholders’ dividends	5	4	9	8
Amortization of deferred acquisition costs	312	305	617	612
Other insurance related expenses	261	270	515	547
Other expenses	143	146	278	292
Total claims, benefits and expenses	1,996	2,060	3,983	4,198
Operating income (loss) before income tax	320	272	627	365
Income tax (expense) benefit on operating income (loss)	(81)	(71)	(153)	(73)
Net operating income (loss)	239	201	474	292
Net realized investment gains (losses)	50	16	86	(20)
Income tax (expense) benefit on net realized investment gains (losses)	(17)	(8)	(28)	3
Net realized investment gains (losses), after tax	33	8	58	(17)
Net income (loss)	272	209	532	275
Operating Segments | Specialty
Operating revenues
Net earned premiums	689	702	1,353	1,384
Net investment income	120	133	273	240
Other revenues	98	89	192	176
Total operating revenues	907	924	1,818	1,800
Claims, Benefits and Expenses
Net incurred claims and benefits	398	377	784	767
Policyholders’ dividends	1	1	2	2
Amortization of deferred acquisition costs	149	148	292	292
Other insurance related expenses	72	73	141	148
Other expenses	82	79	163	154
Total claims, benefits and expenses	702	678	1,382	1,363
Operating income (loss) before income tax	205	246	436	437
Income tax (expense) benefit on operating income (loss)	(69)	(82)	(146)	(146)
Net operating income (loss)	136	164	290	291
Net realized investment gains (losses)	14	4	21	(7)
Income tax (expense) benefit on net realized investment gains (losses)	(5)	(2)	(8)	2
Net realized investment gains (losses), after tax	9	2	13	(5)
Net income (loss)	145	166	303	286
Operating Segments | Commercial
Operating revenues
Net earned premiums	705	696	1,356	1,384
Net investment income	143	164	321	290
Other revenues	9	8	18	14
Total operating revenues	857	868	1,695	1,688
Claims, Benefits and Expenses
Net incurred claims and benefits	422	469	859	911
Policyholders’ dividends	4	3	7	6
Amortization of deferred acquisition costs	118	117	234	233
Other insurance related expenses	128	130	254	271
Other expenses	11	11	25	16
Total claims, benefits and expenses	683	730	1,379	1,437
Operating income (loss) before income tax	174	138	316	251
Income tax (expense) benefit on operating income (loss)	(59)	(46)	(107)	(85)
Net operating income (loss)	115	92	209	166
Net realized investment gains (losses)	19	8	30	(10)
Income tax (expense) benefit on net realized investment gains (losses)	(6)	(3)	(9)	3
Net realized investment gains (losses), after tax	13	5	21	(7)
Net income (loss)	128	97	230	159
Operating Segments | International
Operating revenues
Net earned premiums	206	197	403	395
Net investment income	13	13	25	25
Other revenues	(1)	0	(1)	1
Total operating revenues	218	210	427	421
Claims, Benefits and Expenses
Net incurred claims and benefits	129	157	244	278
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	45	40	91	87
Other insurance related expenses	31	37	58	65
Other expenses	(1)	7	(7)	16
Total claims, benefits and expenses	204	241	386	446
Operating income (loss) before income tax	14	(31)	41	(25)
Income tax (expense) benefit on operating income (loss)	(4)	4	(11)	4
Net operating income (loss)	10	(27)	30	(21)
Net realized investment gains (losses)	7	4	13	8
Income tax (expense) benefit on net realized investment gains (losses)	(1)	(1)	(2)	(2)
Net realized investment gains (losses), after tax	6	3	11	6
Net income (loss)	16	(24)	41	(15)
Operating Segments | Life & Group Non-Core
Operating revenues
Net earned premiums	135	136	268	267
Net investment income	195	188	392	375
Other revenues	0	3	1	3
Total operating revenues	330	327	661	645
Claims, Benefits and Expenses
Net incurred claims and benefits	328	340	658	663
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	32	31	64	64
Other expenses	1	2	3	5
Total claims, benefits and expenses	361	373	725	732
Operating income (loss) before income tax	(31)	(46)	(64)	(87)
Income tax (expense) benefit on operating income (loss)	36	42	73	81
Net operating income (loss)	5	(4)	9	(6)
Net realized investment gains (losses)	7	(2)	17	(5)
Income tax (expense) benefit on net realized investment gains (losses)	(3)	(3)	(7)	(3)
Net realized investment gains (losses), after tax	4	(5)	10	(8)
Net income (loss)	9	(9)	19	(14)
Operating Segments | Corporate & Other Non-Core
Operating revenues
Net earned premiums	0	0	0	0
Net investment income	4	4	9	7
Other revenues	1	0	1	3
Total operating revenues	5	4	10	10
Claims, Benefits and Expenses
Net incurred claims and benefits	(2)	(8)	19	120
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	(1)	0	(1)	0
Other expenses	50	47	94	101
Total claims, benefits and expenses	47	39	112	221
Operating income (loss) before income tax	(42)	(35)	(102)	(211)
Income tax (expense) benefit on operating income (loss)	15	11	38	73
Net operating income (loss)	(27)	(24)	(64)	(138)
Net realized investment gains (losses)	3	2	5	(6)
Income tax (expense) benefit on net realized investment gains (losses)	(2)	1	(2)	3
Net realized investment gains (losses), after tax	1	3	3	(3)
Net income (loss)	(26)	(21)	(61)	(141)
Intersegment Eliminations
Operating revenues
Net earned premiums	(1)	(1)	(1)	(1)
Net investment income	0	0	0	0
Other revenues	0	0	0	0
Total operating revenues	(1)	(1)	(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	(1)	(1)	(1)	(1)
Other expenses	0	0	0	0
Total claims, benefits and expenses	(1)	(1)	(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	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Reinsurance receivables	$ 4,464	$ 4,453
Insurance receivables	2,452	2,255
Deferred acquisition costs	647	600
Goodwill	147	145
Insurance reserves
Claim and claim adjustment expenses	22,179	22,343
Unearned premiums	4,107	3,762
Future policy benefits	10,824	10,326
Operating Segments | Specialty
Segment Reporting Information [Line Items]
Reinsurance receivables	880	760
Insurance receivables	1,020	982
Deferred acquisition costs	318	310
Goodwill	117	117
Insurance reserves
Claim and claim adjustment expenses	6,229	6,149
Unearned premiums	1,988	1,911
Future policy benefits	0	0
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Reinsurance receivables	591	621
Insurance receivables	1,129	1,021
Deferred acquisition costs	234	214
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	8,586	8,894
Unearned premiums	1,481	1,323
Future policy benefits	0	0
Operating Segments | International
Segment Reporting Information [Line Items]
Reinsurance receivables	150	131
Insurance receivables	290	233
Deferred acquisition costs	95	76
Goodwill	30	28
Insurance reserves
Claim and claim adjustment expenses	1,442	1,328
Unearned premiums	500	396
Future policy benefits	0	0
Operating Segments | Life & Group Non-Core
Segment Reporting Information [Line Items]
Reinsurance receivables	461	462
Insurance receivables	11	17
Deferred acquisition costs	0	0
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	3,417	3,358
Unearned premiums	139	132
Future policy benefits	10,824	10,326
Operating Segments | Corporate & Other Non-Core
Segment Reporting Information [Line Items]
Reinsurance receivables	2,382	2,479
Insurance receivables	2	2
Deferred acquisition costs	0	0
Goodwill	0	0
Insurance reserves
Claim and claim adjustment expenses	2,505	2,614
Unearned premiums	0	0
Future policy benefits	0	0
Intersegment 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	(1)	0
Future policy benefits	$ 0	$ 0

Business Segments - Revenues by

Business Segments - Revenues by Line of Business (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 2,366	$ 2,348	$ 4,696	$ 4,543
Operating Segments | Specialty
Segment Reporting Information [Line Items]
Revenues	921	928	1,839	1,793
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Revenues	876	876	1,725	1,678
Operating Segments | International
Segment Reporting Information [Line Items]
Revenues	225	214	440	429
Operating Segments | Life & Group Non-Core
Segment Reporting Information [Line Items]
Revenues	337	325	678	640
Operating Segments | Corporate & Other Non-Core
Segment Reporting Information [Line Items]
Revenues	8	6	15	4
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(1)	(1)	(1)	(1)
Specialty | Operating Segments
Segment Reporting Information [Line Items]
Revenues	646	659	1,307	1,277
Surety | Operating Segments
Segment Reporting Information [Line Items]
Revenues	137	133	260	260
Warranty & Alternative Risks | Operating Segments
Segment Reporting Information [Line Items]
Revenues	138	136	272	256
Middle Market | Operating Segments
Segment Reporting Information [Line Items]
Revenues	462	434	920	835
Small Business | Operating Segments
Segment Reporting Information [Line Items]
Revenues	129	151	226	294
Other Commercial Insurance | Operating Segments
Segment Reporting Information [Line Items]
Revenues	285	291	579	549
Canada | Operating Segments
Segment Reporting Information [Line Items]
Revenues	53	51	104	101
CNA Europe | Operating Segments
Segment Reporting Information [Line Items]
Revenues	79	81	152	159
Hardy | Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 93	$ 82	$ 184	$ 169