Cincinnati Financial (CINF) 10-Q 26 Jul 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 20, 2018
Document Documentand Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	CINF
Entity Registrant Name	CINCINNATI FINANCIAL CORP
Entity Central Index Key	20,286
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		162,652,281

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Investments
Fixed maturities, at fair value (amortized cost: 2018—$10,552; 2017—$10,314)	$ 10,636	$ 10,699
Equity securities, at fair value (cost: 2018—$3,198; 2017—$3,094)	6,200	6,249
Other invested assets	108	103
Total investments	16,944	17,051
Cash and cash equivalents	521	657
Investment income receivable	130	134
Finance receivable	66	61
Premiums receivable	1,733	1,589
Reinsurance recoverable	420	432
Prepaid reinsurance premiums	39	42
Deferred policy acquisition costs	728	670
Land, building and equipment, net, for company use (accumulated depreciation: 2018—$264; 2017—$253)	188	185
Other assets	199	216
Separate accounts	792	806
Total assets	21,760	21,843
Insurance reserves
Loss and loss expense reserves	5,468	5,273
Life policy and investment contract reserves	2,760	2,729
Unearned premiums	2,578	2,404
Other liabilities	707	792
Deferred income tax	650	745
Note payable	61	24
Long-term debt and capital lease obligations	828	827
Separate accounts	792	806
Total liabilities	13,844	13,600
Commitments and contingent liabilities (Note 12)
Shareholders' Equity
Common stock, par value—$2 per share; (authorized: 2018 and 2017—500 million shares; issued: 2018 and 2017—198.3 million shares)	397	397
Paid-in capital	1,266	1,265
Retained earnings	7,696	5,180
Accumulated other comprehensive income	55	2,788
Treasury stock at cost (2018—35.7 million shares and 2017—34.4 million shares)	(1,498)	(1,387)
Total shareholders' equity	7,916	8,243
Total liabilities and shareholders' equity	$ 21,760	$ 21,843

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 10,552	$ 10,314
Available-for-sale Equity Securities, Amortized Cost Basis	3,198	3,094
Land, building and equipment, accumulated depreciation	$ 264	$ 253
Common stock, par value	$ 2	$ 2
Common stock, authorized	500	500
Common stock, issued	198.3	198.3
Common stock, outstanding	198.3	198.3
Treasury stock, shares	35.7	34.4

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues [Abstract]
Earned premiums	$ 1,294	$ 1,241	$ 2,554	$ 2,449
Investment income, net of expenses	154	151	304	300
Investment gains and losses, net	105	(11)	(86)	149
Fee revenues	4	4	8	9
Other revenues	1	1	2	2
Total revenues	1,558	1,386	2,782	2,909
Benefits and Expenses
Insurance losses and contract holders' benefits	883	854	1,737	1,707
Underwriting, acquisition and insurance expenses	395	387	798	764
Interest expense	13	13	26	26
Other operating expenses	3	4	7	8
Total benefits and expenses	1,294	1,258	2,568	2,505
Income Before Income Taxes	264	128	214	404
Provision (Benefit) for Income Taxes
Current	33	31	61	71
Deferred	14	(3)	(33)	32
Total provision for income taxes	47	28	28	103
Net Income	$ 217	$ 100	$ 186	$ 301
Per Common Share
Net income—basic	$ 1.33	$ 0.61	$ 1.13	$ 1.83
Net income—diluted	$ 1.32	$ 0.60	$ 1.12	$ 1.81

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Income	$ 217	$ 100	$ 186	$ 301
Change in unrealized gains on investments, net of tax (benefit) of ($18), $77, ($64) and $123, respectively	(62)	144	(237)	229
Amortization of pension actuarial loss and prior service cost, net of tax of $0, $0, $0 and $0, respectively	1	0	1	1
Change in life deferred acquisition costs, life policy reserves and other, net of tax of $1, $0, $2 and $1, respectively	1	1	6	2
Other comprehensive income (loss)	(60)	145	(230)	232
Comprehensive Income (Loss)	$ 157	$ 245	$ (44)	$ 533

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ (18)	$ 77	$ (64)	$ 123
Other Comprehensive Income Loss, Pension And Other Postretirement Benefit Plans, Net Actuarial Loss And Prior Service Cost Arising During Period, Tax	0	0	0	0
Other Comprehensive Income, Change in Life Deferred Acquisition Costs, Life Policy Reserves and Other, Tax	$ 1	$ 0	$ 2	$ 1

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common equities	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Beginning Balance (Previously Reported) at Dec. 31, 2016				$ 5,037	$ 1,693
Beginning Balance at Dec. 31, 2016		$ 397	$ 1,252	5,037	1,693	$ (1,319)
Share-based awards		0	(18)			19
Share-based compensation			14
Other			1			2
Net Income	$ 301			301
Dividends declared				(164)
Other comprehensive income (loss)	232				232
Shares acquired - share repurchase authorization						(70)
Shares acquired - share-based compensation plans						(4)
Ending Balance at Jun. 30, 2017	7,373	$ 397	1,249	5,174	1,925	(1,372)
Beginning Balance (in shares) at Dec. 31, 2016		164.4
Share-based awards (in shares)		0.6
Shares acquired - share repurchase authorization (in shares)		(1)
Shares acquired - share-based compensation plans (in shares)		(0.1)
Ending Balance (in shares) at Jun. 30, 2017		163.9
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax	0
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax					(2,503)
Beginning Balance (Previously Reported) at Dec. 31, 2017				5,180	2,788
Beginning Balance at Dec. 31, 2017	8,243	$ 397	1,265	7,683	285	(1,387)
Share-based awards		0	(17)			16
Share-based compensation			16
Other			2			1
Net Income	186			186
Dividends declared				(173)
Other comprehensive income (loss)	(230)				(230)
Shares acquired - share repurchase authorization						(125)
Shares acquired - share-based compensation plans						(3)
Ending Balance at Jun. 30, 2018	$ 7,916	$ 397	$ 1,266	7,696	55	$ (1,498)
Beginning Balance (in shares) at Dec. 31, 2017	198.3	163.9
Share-based awards (in shares)		0.5
Shares acquired - share repurchase authorization (in shares)		(1.8)
Shares acquired - share-based compensation plans (in shares)		0
Ending Balance (in shares) at Jun. 30, 2018	198.3	162.6
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax	$ 2,503			$ 2,503	$ (2,503)

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities
Net Income	$ 186	$ 301
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	32	27
Gain (Loss) on Sale of Investments	(90)	149
Share-based compensation	16	14
Interest credited to contract holders'	23	24
Deferred income tax expense	(33)	32
Changes in:
Investment income receivable	4	4
Premiums and reinsurance receivable	(129)	(91)
Deferred policy acquisition costs	(41)	(45)
Other assets	(14)	(37)
Loss and loss expense reserves	195	196
Life policy and investment contract reserves	47	50
Unearned premiums	174	154
Other liabilities	(85)	(82)
Current income tax receivable/payable	(1)	47
Net cash provided by operating activities	464	445
Cash Flows From Investing Activities
Sale of fixed maturities	5	12
Call or maturity of fixed maturities	674	540
Sale of equity securities	134	288
Purchase of fixed maturities	(905)	(802)
Purchase of equity securities	(149)	(352)
Investment in finance receivables	(16)	(14)
Collection of finance receivables	12	11
Investment in buildings and equipment	(9)	(9)
Change in other invested assets, net	(11)	(7)
Net cash used in investing activities	(265)	(333)
Cash Flows From Financing Activities
Payment of cash dividends to shareholders	(166)	(158)
Shares acquired - share repurchase authorization	(125)	(70)
Proceeds from (Repayments of) Notes Payable	37
Changes in note payable		(3)
Proceeds from stock options exercised	5	8
Contract holders' funds deposited	43	42
Contract holders' funds withdrawn	(88)	(83)
Other	(41)	(19)
Net cash used in financing activities	(335)	(283)
Net change in cash and cash equivalents	(136)	(171)
Cash and cash equivalents at beginning of year	657	777
Cash and cash equivalents at end of period	521	606
Supplemental Disclosures of Cash Flow Information:
Interest paid	26	26
Income taxes paid	60	23
Noncash Activities
Conversion of securities	3	5
Equipment acquired under capital lease obligations	8	6
Cashless exercise of stock options	3	4
Other assets and other liabilities	$ 28	$ 70

Accounting Policies

Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Accounting Policies	NOTE 1 — Accounting Policies The condensed consolidated financial statements include the accounts of Cincinnati Financial Corporation and its consolidated subsidiaries, each of which is wholly owned. These statements are presented in conformity with accounting principles generally accepted in the United States of America (GAAP). All intercompany balances and transactions have been eliminated in consolidation. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect amounts reported in the financial statements and accompanying notes. Our actual results could differ from those estimates. Certain financial information that is normally included in annual financial statements prepared in accordance with GAAP, but that is not required for interim reporting purposes, has been condensed or omitted. Our June 30, 2018 , condensed consolidated financial statements are unaudited. We believe that we have made all adjustments, consisting only of normal recurring accruals, that are necessary for fair presentation. These condensed consolidated financial statements should be read in conjunction with our consolidated financial statements included in our 2017 Annual Report on Form 10-K. The results of operations for interim periods do not necessarily indicate results to be expected for the full year. Adopted Accounting Updates ASU 2014-09 Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers . ASU 2014-09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Insurance contracts do not fall within the scope of this ASU. The effective date of ASU 2014-09 was for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU effective January 1, 2018, and it did not have a material impact on the company's consolidated financial position, cash flows or results of operations. ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 revised the accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. The effective date of ASU 2016-01 was for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU on January 1, 2018, and applied it prospectively without prior period amounts restated. As a result of the adoption, $2.503 billion of after-tax unrealized gains on equity securities was reclassified on January 1, 2018, from accumulated other comprehensive income to retained earnings. Results of operations were impacted as changes in fair value of equity securities are now reported in net income instead of reported in other comprehensive income. As a result of the adoption of this ASU, for the three and six months ended June 30, 2018, net investment gains of $105 million and net investment losses of $86 million in the condensed consolidated statements of income included an increase of $101 million and a decrease of $97 million from the fair value change of equity securities, respectively. ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . ASU 2016-15 addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The effective date of ASU 2016-15 is for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU effective January 1, 2018, and it did not have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Postretirement Benefit Costs . ASU 2017-07 provides guidance on how to present the components of net periodic benefit costs in the income statement for pension plans and other post-retirement benefit plans and allows only the service cost component of net benefit cost to be eligible for capitalization when applicable. The effective date of ASU 2017-07 is for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU effective January 1, 2018, and disclosed the line items used in the statements of income to present the service and non-service components of net periodic benefit costs in Note 11, Employee Retirement Benefits, to these consolidated financial statements. The adoption did not have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 clarifies when to account for a change to the terms or conditions of a share based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The effective date of ASU 2017-09 was for interim and annual reporting periods, beginning after December 15, 2017, and was applied prospectively. The company adopted this ASU effective January 1, 2018, and it did not have a material impact on our company's consolidated financial position, cash flows or results of operations. Pending Accounting Updates ASU 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The main provision of ASU 2016-02 requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous GAAP. The effective date of ASU 2016-02 is for interim and annual reporting periods beginning after December 15, 2018. The ASU has not yet been adopted; however, it is not expected to have a material impact on our company’s consolidated financial position, cash flows or results of operations. ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . ASU 2016-13 amends previous guidance on the impairment of financial instruments by adding an impairment model that allows an entity to recognize expected credit losses as an allowance rather than impairing as they are incurred. The new guidance is intended to reduce complexity of credit impairment models and result in a more timely recognition of expected credit losses. The effective date of ASU 2016-13 is for interim and annual reporting periods beginning after December 15, 2019. The ASU has not yet been adopted. Management is currently evaluating the impact on our company's consolidated financial position, cash flows or results of operations. ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. ASU 2017-08 amends guidance on the amortization period of premiums on certain purchased callable debt securities. The amendments shorten the amortization period of premiums on certain purchased callable debt securities to the earliest call date. The amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment to beginning retained earnings. The effective date of ASU 2017-08 is for interim and annual reporting periods beginning after December 15, 2018. The ASU has not yet been adopted; however, it is not expected to have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2018-07, Compensation - Stock Compensation (Topic 718) - Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . ASU 2018-07 expands the scope of Topic 718, Compensation - Stock Compensation, which currently only includes share-based payments issued to employees, to include share-based payments issued to nonemployees for the acquisition of goods and services. The effective date of ASU 2018-07 is for interim and annual reporting periods beginning after December 15, 2018. The ASU has not yet been adopted; however, it is not expected to have a material impact on our company's consolidated financial position, cash flows or results of operations.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Investments	Investments On January 1, 2018, we adopted ASU 2016-01, which resulted in changes in the fair value of equity securities still held, being reported in net income instead of being reported in other comprehensive income. See Note 1, Accounting Policies, for additional discussion. The following table provides cost or amortized cost, gross unrealized gains, gross unrealized losses and fair value for our fixed-maturity and equity securities: (Dollars in millions) Cost or amortized cost Gross unrealized Fair value At June 30, 2018 gains losses Fixed maturity securities: Corporate $ 5,625 $ 110 $ 57 $ 5,678 States, municipalities and political subdivisions 4,316 78 36 4,358 Commercial mortgage-backed 283 2 4 281 Government-sponsored enterprises 277 — 8 269 United States government 41 — 1 40 Foreign government 10 — — 10 Total $ 10,552 $ 190 $ 106 $ 10,636 At December 31, 2017 Fixed maturity securities: Corporate $ 5,420 $ 246 $ 13 $ 5,653 States, municipalities and political subdivisions 4,316 155 6 4,465 Commercial mortgage-backed 280 7 1 286 Government-sponsored enterprises 257 1 4 254 United States government 31 — — 31 Foreign government 10 — — 10 Subtotal 10,314 409 24 10,699 Equity securities: Common equities 2,918 3,135 14 6,039 Nonredeemable preferred equities 176 34 — 210 Subtotal 3,094 3,169 14 6,249 Total $ 13,408 $ 3,578 $ 38 $ 16,948 The net unrealized investment gains in our fixed-maturity portfolio at June 30, 2018 , are primarily the result of the continued low interest rate environment that increased the fair value of our fixed-maturity portfolio. Our commercial mortgage-backed securities had an average rating of Aa1/AA at June 30, 2018 , and December 31, 2017 . At June 30, 2018 , Apple Inc. (Nasdaq:AAPL) was our largest single equity holding with a fair value of $259 million , which was 4.3 percent of our publicly traded common equities portfolio and 1.5 percent of the total investment portfolio. The table below provides fair values and gross unrealized losses by investment category and by the duration of the securities’ continuous unrealized loss positions: (Dollars in millions) Less than 12 months 12 months or more Total At June 30, 2018 Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses Fixed maturity securities: Corporate $ 1,836 $ 39 $ 283 $ 18 $ 2,119 $ 57 States, municipalities and political subdivisions 1,070 22 262 14 1,332 36 Commercial mortgage-backed securities 113 2 35 2 148 4 Government-sponsored enterprises 110 2 158 6 268 8 Foreign government 10 — — — 10 — United States government 23 1 11 — 34 1 Total $ 3,162 $ 66 $ 749 $ 40 $ 3,911 $ 106 At December 31, 2017 Fixed maturity securities: Corporate $ 330 $ 4 $ 252 $ 9 $ 582 $ 13 States, municipalities and political subdivisions 88 1 264 5 352 6 Commercial mortgage-backed 33 — 36 1 69 1 Government-sponsored enterprises 96 1 124 3 220 4 Foreign government 10 — — — 10 — United States government 23 — 6 — 29 — Subtotal 580 6 682 18 1,262 24 Equity securities: Common equities 229 14 — — 229 14 Subtotal 229 14 — — 229 14 Total $ 809 $ 20 $ 682 $ 18 $ 1,491 $ 38 Contractual maturity dates for fixed-maturity investments were: (Dollars in millions) Amortized cost Fair value % of fair value At June 30, 2018 Maturity dates: Due in one year or less $ 720 $ 733 6.9 % Due after one year through five years 2,745 2,781 26.1 Due after five years through ten years 3,630 3,641 34.3 Due after ten years 3,457 3,481 32.7 Total $ 10,552 $ 10,636 100.0 % Actual maturities may differ from contractual maturities when there is a right to call or prepay obligations with or without call or prepayment penalties. The following table provides investment income and investment gains and losses, net: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Investment income: Interest $ 112 $ 111 $ 222 $ 222 Dividends 44 42 86 81 Other 1 1 2 2 Total 157 154 310 305 Less investment expenses 3 3 6 5 Total $ 154 $ 151 $ 304 $ 300 Investment gains and losses, net: Equity securities: Investment gains and losses on securities sold, net $ 4 $ — $ 7 $ — Unrealized gains and losses on securities still held, net 101 — (97 ) — Gross realized gains — 6 — 159 Gross realized losses — (10 ) — (14 ) Other-than-temporary impairments — (3 ) — (3 ) Subtotal 105 (7 ) (90 ) 142 Fixed maturities: Gross realized gains 3 3 7 13 Gross realized losses (1 ) — (1 ) — Other-than-temporary impairments — (6 ) — (6 ) Subtotal 2 (3 ) 6 7 Other (2 ) (1 ) (2 ) — Total $ 105 $ (11 ) $ (86 ) $ 149 During the three and six months ended June 30, 2018 , there were no fixed-maturity securities other-than-temporarily impaired. During the three and six months ended June 30, 2017 , there were five equity securities and one fixed-maturity security other-than-temporarily impaired. There were no credit losses on fixed-maturity securities for which a portion of other-than-temporary impairment (OTTI) has been recognized in other comprehensive income for the three and six months ended June 30, 2018 and 2017 . At June 30, 2018 , 263 fixed-maturity securities with a total unrealized loss of $40 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity security had a fair value below 70 percent of amortized cost. At December 31, 2017 , 249 fixed-maturity securities with a total unrealized loss of $18 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity securities had fair values below 70 percent of amortized cost. There were no equity securities in an unrealized loss position for 12 months or more as of December 31, 2017 .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements In accordance with accounting guidance for fair value measurements and disclosures, we categorized our financial instruments, based on the priority of the observable and market-based data for the valuation technique used, into a three-level fair value hierarchy. The fair value hierarchy gives the highest priority to quoted prices with readily available independent data in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable market inputs (Level 3). When various inputs for measurement fall within different levels of the fair value hierarchy, the lowest observable input that has a significant impact on fair value measurement is used. Our valuation techniques have not changed from those used at December 31, 2017 , and ultimately management determines fair value. See our 2017 Annual Report on Form 10-K, Item 8, Note 3, Fair Value Measurements, Page 132, for information on characteristics and valuation techniques used in determining fair value. Fair Value Disclosures for Assets The following tables illustrate the fair value hierarchy for those assets measured at fair value on a recurring basis at June 30, 2018 , and December 31, 2017 . We do not have any liabilities carried at fair value. There were no transfers between Level 1 and Level 2. (Dollars in millions) Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Total At June 30, 2018 Fixed maturities, available for sale: Corporate $ — $ 5,677 $ 1 $ 5,678 States, municipalities and political subdivisions — 4,354 4 4,358 Commercial mortgage-backed — 281 — 281 Government-sponsored enterprises — 269 — 269 United States government 40 — — 40 Foreign government — 10 — 10 Subtotal 40 10,591 5 10,636 Common equities 6,008 — — 6,008 Nonredeemable preferred equities — 192 — 192 Separate accounts taxable fixed maturities — 781 — 781 Top Hat savings plan mutual funds and common 33 — — 33 Total $ 6,081 $ 11,564 $ 5 $ 17,650 At December 31, 2017 Fixed maturities, available for sale: Corporate $ — $ 5,652 $ 1 $ 5,653 States, municipalities and political subdivisions — 4,460 5 4,465 Commercial mortgage-backed — 286 — 286 Government-sponsored enterprises — 254 — 254 United States government 31 — — 31 Foreign government — 10 — 10 Subtotal 31 10,662 6 10,699 Common equities, available for sale 6,039 — — 6,039 Nonredeemable preferred equities, available for sale — 210 — 210 Separate accounts taxable fixed maturities — 795 — 795 Top Hat savings plan mutual funds and common equity (included in Other assets) 31 — — 31 Total $ 6,101 $ 11,667 $ 6 $ 17,774 Each financial instrument that was deemed to have significant unobservable inputs when determining valuation is identified in the following tables by security type with a summary of changes in fair value as of June 30, 2018 . Total Level 3 assets continue to be less than 1 percent of financial assets measured at fair value in the condensed consolidated balance sheets. Assets presented in the table below were valued based primarily on broker/dealer quotes for which there is a lack of transparency as to inputs used to develop the valuations. Transfers out of Level 3 included situations where a broker quote was used without observable inputs or data that could be corroborated by our pricing vendors in the prior period and significant other observable inputs were identified in the current period. The quantitative detail of these unobservable inputs is neither provided nor reasonably available to us. The following table provides the change in Level 3 assets for the three months ended June 30 : (Dollars in millions) Asset fair value measurements using significant unobservable inputs Corporate States, Total Beginning balance, April 1, 2018 $ 1 $ 4 $ 5 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — — — Purchases — — — Sales — — — Transfers into Level 3 — — — Transfers out of Level 3 — — — Ending balance, June 30, 2018 $ 1 $ 4 $ 5 Beginning balance, April 1, 2017 $ 1 $ — $ 1 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — — — Purchases — — — Sales — — — Transfers into Level 3 — 5 5 Transfers out of Level 3 — — — Ending balance, June 30, 2017 $ 1 $ 5 $ 6 The following table provides the change in Level 3 assets for the six months ended June 30 : (Dollars in millions) Asset fair value measurements using significant unobservable inputs Corporate fixed maturities States, Total Beginning balance, January 1, 2018 $ 1 $ 5 $ 6 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — (1 ) (1 ) Purchases — — — Sales — — — Transfers into Level 3 — — — Transfers out of Level 3 — — — Ending balance, June 30, 2018 $ 1 $ 4 $ 5 Beginning balance, January 1, 2017 $ 78 $ — $ 78 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — — — Purchases — 5 5 Sales — — — Transfers into Level 3 — — — Transfers out of Level 3 (77 ) — (77 ) Ending balance, June 30, 2017 $ 1 $ 5 $ 6 With the exception of the above tables, additional disclosures for the Level 3 category are not material and therefore not provided. Fair Value Disclosures for Assets and Liabilities Not Carried at Fair Value The disclosures below are presented to provide information about the effects of current market conditions on financial instruments that are not reported at fair value in our condensed consolidated financial statements. This table summarizes the book value and principal amounts of our long-term debt: (Dollars in millions) Book value Principal amount Interest rate Year of issue June 30, December 31, June 30, December 31, 2018 2017 2018 2017 6.900 % 1998 Senior debentures, due 2028 $ 26 $ 26 $ 28 $ 28 6.920 % 2005 Senior debentures, due 2028 391 391 391 391 6.125 % 2004 Senior notes, due 2034 370 370 374 374 Total $ 787 $ 787 $ 793 $ 793 The following table shows fair values of our note payable and long-term debt: (Dollars in millions) Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Total At June 30, 2018 Note payable $ — $ 61 $ — $ 61 6.900% senior debentures, due 2028 — 32 — 32 6.920% senior debentures, due 2028 — 478 — 478 6.125% senior notes, due 2034 — 448 — 448 Total $ — $ 1,019 $ — $ 1,019 At December 31, 2017 Note payable $ — $ 24 $ — $ 24 6.900% senior debentures, due 2028 — 34 — 34 6.920% senior debentures, due 2028 — 505 — 505 6.125% senior notes, due 2034 — 477 — 477 Total $ — $ 1,040 $ — $ 1,040 The following table shows the fair value of our life policy loans included in other invested assets and the fair values of our deferred annuities and structured settlements included in life policy and investment contract reserves: (Dollars in millions) Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Total At June 30, 2018 Life policy loans $ — $ — $ 40 $ 40 Deferred annuities — — 769 769 Structured settlements — 192 — 192 Total $ — $ 192 $ 769 $ 961 At December 31, 2017 Life policy loans $ — $ — $ 41 $ 41 Deferred annuities — — 834 834 Structured settlements — 210 — 210 Total $ — $ 210 $ 834 $ 1,044 Outstanding principal and interest for these life policy loans totaled $32 million and $31 million at June 30, 2018 , and December 31, 2017 , respectively. Recorded reserves for the deferred annuities were $813 million and $835 million at June 30, 2018 , and December 31, 2017 , respectively. Recorded reserves for the structured settlements were $159 million and $161 million at June 30, 2018 , and December 31, 2017 , respectively.

Property Casualty Loss and Loss

Property Casualty Loss and Loss Expenses	6 Months Ended
	Jun. 30, 2018
Premiums Written, Net [Abstract]
Property Casualty Loss And Loss Expenses	Property Casualty Loss and Loss Expenses This table summarizes activity for our consolidated property casualty loss and loss expense reserves: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Gross loss and loss expense reserves, beginning of period $ 5,293 $ 5,128 $ 5,219 $ 5,035 Less reinsurance recoverable 184 297 187 298 Net loss and loss expense reserves, beginning of period 5,109 4,831 5,032 4,737 Net incurred loss and loss expenses related to: Current accident year 852 832 1,691 1,658 Prior accident years (31 ) (38 ) (79 ) (76 ) Total incurred 821 794 1,612 1,582 Net paid loss and loss expenses related to: Current accident year 341 373 536 558 Prior accident years 354 322 873 831 Total paid 695 695 1,409 1,389 Net loss and loss expense reserves, end of period 5,235 4,930 5,235 4,930 Plus reinsurance recoverable 188 283 188 283 Gross loss and loss expense reserves, end of period $ 5,423 $ 5,213 $ 5,423 $ 5,213 We use actuarial methods, models and judgment to estimate, as of a financial statement date, the property casualty loss and loss expense reserves required to pay for and settle all outstanding insured claims, including incurred but not reported (IBNR) claims, as of that date. The actuarial estimate is subject to review and adjustment by an inter-departmental committee that includes actuarial, claims, underwriting, loss prevention and accounting management. This committee is familiar with relevant company and industry business, claims and underwriting trends, as well as general economic and legal trends that could affect future loss and loss expense payments. The amount we will actually have to pay for claims can be highly uncertain. This uncertainty, together with the size of our reserves, makes the loss and loss expense reserves our most significant estimate. The reserve for loss and loss expenses in the condensed consolidated balance sheets also included $45 million at June 30, 2018 , and $68 million at June 30, 2017 , for certain life and health loss and loss expense reserves. For the three months ended June 30, 2018 , we experienced $31 million of favorable development on prior accident years, including $42 million of favorable development in commercial lines, $17 million of unfavorable development in personal lines, $4 million of favorable development in excess and surplus lines and $2 million of favorable development in our reinsurance assumed operations. Within commercial lines, we recognized favorable reserve development of $18 million for the workers' compensation line, $14 million for the commercial casualty line, $7 million for the commercial property line and $8 million for the other commercial lines due to reduced uncertainty of prior accident year loss and loss adjustment expense for these lines. This was partially offset by unfavorable reserve development of $5 million for the commercial auto line. Within personal lines, we recognized unfavorable reserve development of $14 million for the homeowner line of business due primarily to higher-than-anticipated loss emergence on known claims. For the six months ended June 30, 2018 , we experienced $79 million of favorable development on prior accident years, including $77 million of favorable development in commercial lines, $16 million of unfavorable development in personal lines, $14 million of favorable development in excess and surplus lines and $4 million of favorable development in our reinsurance assumed operations. This included $7 million from favorable development of catastrophe losses. Within commercial lines, we recognized favorable reserve development of $31 million for the workers' compensation line, $28 million for the commercial property line, $10 million for the commercial casualty line and $12 million for the other commercial lines due to reduced uncertainty of prior accident year loss and loss adjustment expense for these lines. This was partially offset by unfavorable reserve development of $4 million for the commercial auto line. Within personal lines, we recognized unfavorable reserve development of $17 million for the homeowner line of business due primarily to higher-than-anticipated loss emergence on known claims. For the three months ended June 30, 2017, we experienced $38 million of favorable development on prior accident years, including $26 million of favorable development in commercial lines, $3 million of favorable development in personal lines and $9 million of favorable development in excess and surplus lines. This included $3 million from favorable development of catastrophe losses. Within commercial lines, we recognized favorable reserve development of $12 million for the workers' compensation line, $7 million for the commercial casualty line, $5 million for the commercial property line and $11 million for the other commercial lines due to reduced uncertainty of prior accident year loss and loss adjustment expense for these lines. This was partially offset by unfavorable reserve development of $9 million for the commercial auto line. For the six months ended June 30, 2017 , we experienced $76 million of favorable development on prior accident years, including $37 million of favorable development in commercial lines, $13 million of favorable development in personal lines, $22 million of favorable development in excess and surplus lines and $4 million of favorable development in our reinsurance assumed operations. This included $14 million from favorable development of catastrophe losses. Within commercial lines, we recognized favorable reserve development of $31 million for the workers' compensation line, $15 million for the commercial property line and $19 million for the other commercial lines due to reduced uncertainty of prior accident year loss and loss adjustment expenses for these lines. This was partially offset by unfavorable reserve development of $20 million for the commercial auto line and $8 million for the commercial casualty line. Commercial auto developed unfavorably due to higher loss cost effects in recent accident years, resulting in an increase of our reserve estimate for claims that have not yet been settled. The unfavorable reserve development for commercial casualty reflected higher than usual large loss activity.

Life Policy and Investment Cont

Life Policy and Investment Contract Reserves	6 Months Ended
	Jun. 30, 2018
Liability for Future Policy Benefits [Abstract]
Life Policy And Investment Contract Reserves	Life Policy and Investment Contract Reserves We establish the reserves for traditional life insurance policies based on expected expenses, mortality, morbidity, withdrawal rates, timing of claim presentation and investment yields, including a provision for uncertainty. Once these assumptions are established, they generally are maintained throughout the lives of the contracts. We use both our own experience and industry experience, adjusted for historical trends, in arriving at our assumptions for expected mortality, morbidity and withdrawal rates as well as for expected expenses. We base our assumptions for expected investment income on our own experience adjusted for current economic conditions. We establish reserves for the company’s deferred annuity, universal life and structured settlement policies equal to the cumulative account balances, which include premium deposits plus credited interest less charges and withdrawals. Some of our universal life policies contain no-lapse guarantee provisions. For these policies, we establish a reserve in addition to the account balance, based on expected no-lapse guarantee benefits and expected policy assessments. This table summarizes our life policy and investment contract reserves: (Dollars in millions) June 30, December 31, 2017 Life policy reserves: Ordinary/traditional life $ 1,118 $ 1,080 Other 48 47 Subtotal 1,166 1,127 Investment contract reserves: Deferred annuities 813 835 Universal life 616 601 Structured settlements 159 160 Other 6 6 Subtotal 1,594 1,602 Total life policy and investment contract reserves $ 2,760 $ 2,729

Deferred Acquisition Costs

Deferred Acquisition Costs	6 Months Ended
	Jun. 30, 2018
Deferred Costs [Abstract]
Deferred Acquisition Costs	Deferred Policy Acquisition Costs Expenses directly related to successfully acquired insurance policies – primarily commissions, premium taxes and underwriting costs – are deferred and amortized over the terms of the policies. We update our acquisition cost assumptions periodically to reflect actual experience, and we evaluate the costs for recoverability. The table below shows the deferred policy acquisition costs and asset reconciliation. (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Property casualty: Deferred policy acquisition costs asset, beginning of period $ 446 $ 428 $ 438 $ 408 Capitalized deferred policy acquisition costs 251 237 483 463 Amortized deferred policy acquisition costs (225 ) (217 ) (449 ) (423 ) Deferred policy acquisition costs asset, end of period $ 472 $ 448 $ 472 $ 448 Life: Deferred policy acquisition costs asset, beginning of period $ 245 $ 232 $ 232 $ 229 Capitalized deferred policy acquisition costs 15 12 28 25 Amortized deferred policy acquisition costs (11 ) (12 ) (21 ) (20 ) Amortized shadow deferred policy acquisition costs 7 (2 ) 17 (4 ) Deferred policy acquisition costs asset, end of period $ 256 $ 230 $ 256 $ 230 Consolidated: Deferred policy acquisition costs asset, beginning of period $ 691 $ 660 $ 670 $ 637 Capitalized deferred policy acquisition costs 266 249 511 488 Amortized deferred policy acquisition costs (236 ) (229 ) (470 ) (443 ) Amortized shadow deferred policy acquisition costs 7 (2 ) 17 (4 ) Deferred policy acquisition costs asset, end of period $ 728 $ 678 $ 728 $ 678 No premium deficiencies were recorded in the condensed consolidated statements of income, as the sum of the anticipated loss and loss expenses, policyholder dividends and unamortized deferred acquisition expenses did not exceed the related unearned premiums and anticipated investment income.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2018
Accumulated Other Comprehensive Income [Abstract]
Comprehensive Income (Loss) Note	Accumulated Other Comprehensive Income Accumulated other comprehensive income (AOCI) includes changes in unrealized gains and losses on investments, changes in pension obligations and changes in life deferred acquisition costs, life policy reserves and other as follows: (Dollars in millions) Three months ended June 30, 2018 2017 Before tax Income tax Net Before tax Income tax Net Investments: AOCI, beginning of period $ 164 $ 35 $ 129 $ 2,756 $ 954 $ 1,802 OCI before investment gains and losses, net, recognized in net income (78 ) (18 ) (60 ) 211 74 137 Investment gains and losses, net, recognized in net income (2 ) — (2 ) 10 3 7 OCI (80 ) (18 ) (62 ) 221 77 144 AOCI, end of period $ 84 $ 17 $ 67 $ 2,977 $ 1,031 $ 1,946 Pension obligations: AOCI, beginning of period $ (12 ) $ (1 ) $ (11 ) $ (25 ) $ (8 ) $ (17 ) OCI excluding amortization recognized in net income — — — — — — Amortization recognized in net income 1 — 1 — — — OCI 1 — 1 — — — AOCI, end of period $ (11 ) $ (1 ) $ (10 ) $ (25 ) $ (8 ) $ (17 ) Life deferred acquisition costs, life policy reserves and other: AOCI, beginning of period $ (4 ) $ (1 ) $ (3 ) $ (7 ) $ (2 ) $ (5 ) OCI before investment gains and losses, net, recognized in net income — — — — (1 ) 1 Investment gains and losses, net, recognized in net income 2 1 1 1 1 — OCI 2 1 1 1 — 1 AOCI, end of period $ (2 ) $ — $ (2 ) $ (6 ) $ (2 ) $ (4 ) Summary of AOCI: AOCI, beginning of period $ 148 $ 33 $ 115 $ 2,724 $ 944 $ 1,780 Investments OCI (80 ) (18 ) (62 ) 221 77 144 Pension obligations OCI 1 — 1 — — — Life deferred acquisition costs, life policy reserves and other OCI 2 1 1 1 — 1 Total OCI (77 ) (17 ) (60 ) 222 77 145 AOCI, end of period $ 71 $ 16 $ 55 $ 2,946 $ 1,021 $ 1,925 (Dollars in millions) Six months ended June 30, 2018 2017 Before tax Income tax Net Before tax Income tax Net Investments: AOCI, beginning of period $ 3,540 $ 733 $ 2,807 $ 2,625 $ 908 $ 1,717 Cumulative effect of change in accounting for equity securities as of January 1, 2018 (3,155 ) (652 ) (2,503 ) — — — Adjusted AOCI, beginning of period 385 81 304 2,625 908 1,717 OCI before investment gains and losses, net, recognized in net income (295 ) (63 ) (232 ) 501 176 325 Investment gains and losses, net, recognized in net income (6 ) (1 ) (5 ) (149 ) (53 ) (96 ) OCI (301 ) (64 ) (237 ) 352 123 229 AOCI, end of period $ 84 $ 17 $ 67 $ 2,977 $ 1,031 $ 1,946 Pension obligations: AOCI, beginning of period $ (12 ) $ (1 ) $ (11 ) $ (26 ) $ (8 ) $ (18 ) OCI excluding amortization recognized in net income — — — — — — Amortization recognized in net income 1 — 1 1 — 1 OCI 1 — 1 1 — 1 AOCI, end of period $ (11 ) $ (1 ) $ (10 ) $ (25 ) $ (8 ) $ (17 ) Life deferred acquisition costs, life policy reserves and other: AOCI, beginning of period $ (10 ) $ (2 ) $ (8 ) $ (9 ) $ (3 ) $ (6 ) OCI before investment gains and losses, net, recognized in net income 6 1 5 3 1 2 Investment gains and losses, net, recognized in net income 2 1 1 — — — OCI 8 2 6 3 1 2 AOCI, end of period $ (2 ) $ — $ (2 ) $ (6 ) $ (2 ) $ (4 ) Summary of AOCI: AOCI, beginning of period $ 3,518 $ 730 $ 2,788 $ 2,590 $ 897 $ 1,693 Cumulative effect of change in accounting for equity securities as of January 1, 2018 (3,155 ) (652 ) (2,503 ) — — — Adjusted AOCI, beginning of period 363 78 285 2,590 897 1,693 Investments OCI (301 ) (64 ) (237 ) 352 123 229 Pension obligations OCI 1 — 1 1 — 1 Life deferred acquisition costs, life policy reserves and other OCI 8 2 6 3 1 2 Total OCI (292 ) (62 ) (230 ) 356 124 232 AOCI, end of period $ 71 $ 16 $ 55 $ 2,946 $ 1,021 $ 1,925 Investment gains and losses, net and life deferred acquisition costs, life policy reserves and other investment gains and losses, net, are recorded in the investment gains and losses, net, line item in the condensed consolidated statements of income. Amortization on pension obligations is recorded in the insurance losses and contract holders' benefits and underwriting, acquisition and insurance expenses in the condensed consolidated statements of income.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2018
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance Primary components of our property casualty reinsurance assumed operations include involuntary and voluntary assumed risks as well as contracts from our reinsurance assumed operations, known as Cincinnati Re. Primary components of our ceded reinsurance include a property per risk treaty, property excess treaty, casualty per occurrence treaty, casualty excess treaty, property catastrophe treaty and catastrophe bonds and retrocessions on our reinsurance assumed operations. Management's decisions about the appropriate level of risk retention are affected by various factors, including changes in our underwriting practices, capacity to retain risks and reinsurance market conditions. The table below summarizes our consolidated property casualty insurance net written premiums, earned premiums and incurred loss and loss expenses: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Direct written premiums $ 1,336 $ 1,265 $ 2,583 $ 2,491 Assumed written premiums 52 42 101 75 Ceded written premiums (39 ) (36 ) (77 ) (64 ) Net written premiums $ 1,349 $ 1,271 $ 2,607 $ 2,502 Direct earned premiums $ 1,235 $ 1,189 $ 2,442 $ 2,352 Assumed earned premiums 36 33 69 60 Ceded earned premiums (41 ) (41 ) (81 ) (80 ) Earned premiums $ 1,230 $ 1,181 $ 2,430 $ 2,332 Direct incurred loss and loss expenses $ 821 $ 770 $ 1,602 $ 1,558 Assumed incurred loss and loss expenses 13 20 29 35 Ceded incurred loss and loss expenses (13 ) 4 (19 ) (11 ) Incurred loss and loss expenses $ 821 $ 794 $ 1,612 $ 1,582 Our life insurance company purchases reinsurance for protection of a portion of the risks that are written. Primary components of our life reinsurance program include individual mortality coverage, aggregate catastrophe and accidental death coverage in excess of certain deductibles. The table below summarizes our consolidated life insurance earned premiums and contract holders' benefits incurred: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Direct earned premiums $ 81 $ 77 $ 158 $ 151 Ceded earned premiums (17 ) (17 ) (34 ) (34 ) Earned premiums $ 64 $ 60 $ 124 $ 117 Direct contract holders' benefits incurred 70 87 146 163 Ceded contract holders' benefits incurred (8 ) (27 ) (21 ) (38 ) Contract holders' benefits incurred $ 62 $ 60 $ 125 $ 125 The ceded benefits incurred can vary depending on the type of life insurance policy held and the year the policy was issued.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes As of June 30, 2018 , and December 31, 2017 , we had no liability for unrecognized tax benefits. The differences between the 21 percent and 35 percent statutory federal income tax rates and our effective income tax rate were as follows: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Tax at statutory rate: $ 56 21.0 % $ 44 35.0 % $ 45 21.0 % $ 141 35.0 % Increase (decrease) resulting from: Tax-exempt income from municipal bonds (5 ) (1.9 ) (9 ) (7.0 ) (10 ) (4.7 ) (18 ) (4.5 ) Dividend received exclusion (5 ) (1.5 ) (9 ) (7.0 ) (8 ) (3.7 ) (17 ) (4.2 ) Other 1 0.2 2 0.9 1 0.5 (3 ) (0.8 ) Provision for income taxes $ 47 17.8 % $ 28 21.9 % $ 28 13.1 % $ 103 25.5 % The provision for federal income taxes is based upon filing a consolidated income tax return for the company and its subsidiaries. See our 2017 Annual Report on Form 10-K, Item 8, Note 11, Income Taxes, Page 153, which discusses enactment of the Tax Cuts and Jobs Act (the “Tax Act”) on December 22, 2017, and its impact on our financial results for that period. Interpretive guidance of the Tax Act will be received throughout 2018, and we expect to update our estimates and our disclosure on a quarterly basis as interpretative guidance is received within each quarter that it is received. During the period ended June 30, 2018, the U.S. Treasury Department and the Internal Revenue Service have not issued further clarification or guidance for the items for which our accounting for the Tax Act is incomplete. We expect to complete determination of the effects of the Tax Act on our deferred tax assets and liabilities as part of the annual income tax return filing process. As of June 30, 2018 , we had no operating or capital loss carryforwards.

Net Income Per Common Share

Net Income Per Common Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income Per Common Share	Basic earnings per share are computed based on the weighted average number of common shares outstanding. Diluted earnings per share are computed based on the weighted average number of common and dilutive potential common shares outstanding using the treasury stock method. The table shows calculations for basic and diluted earnings per share: (In millions, except per share data) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Numerator: Net income—basic and diluted $ 217 $ 100 $ 186 $ 301 Denominator: Basic weighted-average common shares outstanding 163.2 164.3 163.6 164.4 Effect of share-based awards: Stock options 0.8 1.0 0.9 1.1 Nonvested shares 0.5 0.7 0.5 0.7 Diluted weighted-average shares 164.5 166.0 165.0 166.2 Earnings per share: Basic $ 1.33 $ 0.61 $ 1.13 $ 1.83 Diluted $ 1.32 $ 0.60 $ 1.12 $ 1.81 Number of anti-dilutive share-based awards 1.3 0.6 1.3 0.7 The sources of dilution of our common shares are certain equity-based awards. See our 2017 Annual Report on Form 10-K, Item 8, Note 17, Share-Based Associate Compensation Plans, Page 161, for information about share-based awards. The above table shows the number of anti-dilutive share-based awards for the three and six months ended June 30, 2018 and 2017 . These share-based awards were not included in the computation of net income per common share (diluted) because their exercise would have anti-dilutive effects.

Employee Retirement Benefits

Employee Retirement Benefits	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Employee Retirement Benefits	Employee Retirement Benefits The following summarizes the components of net periodic benefit cost for our qualified and supplemental pension plans: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Service cost $ 2 $ 2 $ 5 $ 5 Non-service costs (benefit): Interest cost 3 4 6 7 Expected return on plan assets (6 ) (5 ) (11 ) (10 ) Amortization of actuarial loss and prior service cost 1 — 1 1 Total non-service benefit (2 ) (1 ) (4 ) (2 ) Net periodic benefit cost $ — $ 1 $ 1 $ 3 See our 2017 Annual Report on Form 10-K, Item 8, Note 13, Employee Retirement Benefits, Page 156, for information on our retirement benefits. Service costs and non-service costs (benefit) are allocated in the same proportion primarily to the underwriting, acquisition and insurance expenses line item with the remainder allocated to the insurance losses and contract holders' benefits line item on the condensed consolidated statements of income for both 2018 and 2017. We made matching contributions totaling $4 million and $3 million to our 401(k) and Top Hat savings plans during the second quarter of 2018 and 2017 and contributions of $10 million and $9 million for the first half of 2018 and 2017, respectively. We contributed $5 million to our qualified pension plan during the first six months of 2018.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingent Liabilities	Commitments and Contingent Liabilities In the ordinary course of conducting business, the company and its subsidiaries are named as defendants in various legal proceedings. Most of these proceedings are claims litigation involving the company's insurance subsidiaries in which the company is either defending or providing indemnity for third-party claims brought against insureds or litigating first-party coverage claims. The company accounts for such activity through the establishment of unpaid loss and loss expense reserves. We believe that the ultimate liability, if any, with respect to such ordinary-course claims litigation, after consideration of provisions made for potential losses and costs of defense, is immaterial to our consolidated financial condition, results of operations and cash flows. The company and its subsidiaries also are occasionally involved in other legal and regulatory proceedings, some of which assert claims for substantial amounts. These actions include, among others, putative class actions seeking certification of a state or national class. Such proceedings have alleged, for example, breach of an alleged duty to search national databases to ascertain unreported deaths of insureds under life insurance policies. The company's insurance subsidiaries also are occasionally parties to individual actions in which extra-contractual damages, punitive damages or penalties are sought, such as claims alleging bad faith handling of insurance claims or writing unauthorized coverage or claims alleging discrimination by former or current associates. On a quarterly basis, we review these outstanding matters. Under current accounting guidance, we establish accruals when it is probable that a loss has been incurred and we can reasonably estimate its potential exposure. The company accounts for such probable and estimable losses, if any, through the establishment of legal expense reserves. Based on our quarterly review, we believe that our accruals for probable and estimable losses are reasonable and that the amounts accrued do not have a material effect on our consolidated financial condition or results of operations. However, if any one or more of these matters results in a judgment against us or settlement for an amount that is significantly greater than the amount accrued, the resulting liability could have a material effect on the company's consolidated results of operations or cash flows. Based on our most recent review, our estimate for any other matters for which the risk of loss is not probable, but more than remote, is immaterial.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information We operate primarily in two industries, property casualty insurance and life insurance. Our chief operating decision maker regularly reviews our reporting segments to make decisions about allocating resources and assessing performance. Our reporting segments are: • Commercial lines insurance • Personal lines insurance • Excess and surplus lines insurance • Life insurance • Investments We report as Other the noninvestment operations of the parent company and its noninsurer subsidiary, CFC Investment Company and Cincinnati Re, our reinsurance assumed operations. See our 2017 Annual Report on Form 10-K, Item 8, Note 18, Segment Information, Page 164, for a description of revenue, income or loss before income taxes and identifiable assets for each of the five segments. Segment information is summarized in the following table: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Revenues: Commercial lines insurance Commercial casualty $ 272 $ 271 $ 537 $ 536 Commercial property 231 226 459 449 Commercial auto 166 158 327 313 Workers' compensation 85 86 165 170 Other commercial 58 55 114 109 Commercial lines insurance premiums 812 796 1,602 1,577 Fee revenues — 1 2 2 Total commercial lines insurance 812 797 1,604 1,579 Personal lines insurance Personal auto 153 144 304 285 Homeowner 139 128 275 253 Other personal 39 35 77 69 Personal lines insurance premiums 331 307 656 607 Fee revenues 2 1 3 3 Total personal lines insurance 333 308 659 610 Excess and surplus lines insurance 57 52 113 100 Fee revenues 1 1 1 1 Total excess and surplus lines insurance 58 53 114 101 Life insurance premiums 64 60 124 117 Fee revenues 1 1 2 3 Total life insurance 65 61 126 120 Investments Investment income, net of expenses 154 151 304 300 Investment gains and losses, net 105 (11 ) (86 ) 149 Total investment revenue 259 140 218 449 Other Cincinnati Re insurance premiums 30 26 59 48 Other 1 1 2 2 Total other revenues 31 27 61 50 Total revenues $ 1,558 $ 1,386 $ 2,782 $ 2,909 Income (loss) before income taxes: Insurance underwriting results Commercial lines insurance $ 47 $ 24 $ 62 $ 22 Personal lines insurance (32 ) (24 ) (41 ) (39 ) Excess and surplus lines insurance 13 19 31 37 Life insurance 8 4 10 4 Investments 235 117 170 403 Other (7 ) (12 ) (18 ) (23 ) $ 264 $ 128 $ 214 $ 404 Identifiable assets: June 30, December 31, 2017 Property casualty insurance $ 3,011 $ 2,863 Life insurance 1,406 1,409 Investments 16,972 17,112 Other 371 459 Total $ 21,760 $ 21,843

Accounting Policies Pending Acc

Accounting Policies Pending Accounting Updates (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Adopted Accounting Updates and Pending Accounting Updates	Adopted Accounting Updates ASU 2014-09 Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers . ASU 2014-09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Insurance contracts do not fall within the scope of this ASU. The effective date of ASU 2014-09 was for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU effective January 1, 2018, and it did not have a material impact on the company's consolidated financial position, cash flows or results of operations. ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10) - Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 revised the accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. The effective date of ASU 2016-01 was for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU on January 1, 2018, and applied it prospectively without prior period amounts restated. As a result of the adoption, $2.503 billion of after-tax unrealized gains on equity securities was reclassified on January 1, 2018, from accumulated other comprehensive income to retained earnings. Results of operations were impacted as changes in fair value of equity securities are now reported in net income instead of reported in other comprehensive income. As a result of the adoption of this ASU, for the three and six months ended June 30, 2018, net investment gains of $105 million and net investment losses of $86 million in the condensed consolidated statements of income included an increase of $101 million and a decrease of $97 million from the fair value change of equity securities, respectively. ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . ASU 2016-15 addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The effective date of ASU 2016-15 is for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU effective January 1, 2018, and it did not have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Postretirement Benefit Costs . ASU 2017-07 provides guidance on how to present the components of net periodic benefit costs in the income statement for pension plans and other post-retirement benefit plans and allows only the service cost component of net benefit cost to be eligible for capitalization when applicable. The effective date of ASU 2017-07 is for interim and annual reporting periods beginning after December 15, 2017. The company adopted this ASU effective January 1, 2018, and disclosed the line items used in the statements of income to present the service and non-service components of net periodic benefit costs in Note 11, Employee Retirement Benefits, to these consolidated financial statements. The adoption did not have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 clarifies when to account for a change to the terms or conditions of a share based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The effective date of ASU 2017-09 was for interim and annual reporting periods, beginning after December 15, 2017, and was applied prospectively. The company adopted this ASU effective January 1, 2018, and it did not have a material impact on our company's consolidated financial position, cash flows or results of operations. Pending Accounting Updates ASU 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The main provision of ASU 2016-02 requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous GAAP. The effective date of ASU 2016-02 is for interim and annual reporting periods beginning after December 15, 2018. The ASU has not yet been adopted; however, it is not expected to have a material impact on our company’s consolidated financial position, cash flows or results of operations. ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . ASU 2016-13 amends previous guidance on the impairment of financial instruments by adding an impairment model that allows an entity to recognize expected credit losses as an allowance rather than impairing as they are incurred. The new guidance is intended to reduce complexity of credit impairment models and result in a more timely recognition of expected credit losses. The effective date of ASU 2016-13 is for interim and annual reporting periods beginning after December 15, 2019. The ASU has not yet been adopted. Management is currently evaluating the impact on our company's consolidated financial position, cash flows or results of operations. ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. ASU 2017-08 amends guidance on the amortization period of premiums on certain purchased callable debt securities. The amendments shorten the amortization period of premiums on certain purchased callable debt securities to the earliest call date. The amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment to beginning retained earnings. The effective date of ASU 2017-08 is for interim and annual reporting periods beginning after December 15, 2018. The ASU has not yet been adopted; however, it is not expected to have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2018-07, Compensation - Stock Compensation (Topic 718) - Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . ASU 2018-07 expands the scope of Topic 718, Compensation - Stock Compensation, which currently only includes share-based payments issued to employees, to include share-based payments issued to nonemployees for the acquisition of goods and services. The effective date of ASU 2018-07 is for interim and annual reporting periods beginning after December 15, 2018. The ASU has not yet been adopted; however, it is not expected to have a material impact on our company's consolidated financial position, cash flows or results of operations.

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Analysis Of Cost Or Amortized Cost, Gross Unrealized Gains And Losses And Fair Value for Investments	The following table provides cost or amortized cost, gross unrealized gains, gross unrealized losses and fair value for our fixed-maturity and equity securities: (Dollars in millions) Cost or amortized cost Gross unrealized Fair value At June 30, 2018 gains losses Fixed maturity securities: Corporate $ 5,625 $ 110 $ 57 $ 5,678 States, municipalities and political subdivisions 4,316 78 36 4,358 Commercial mortgage-backed 283 2 4 281 Government-sponsored enterprises 277 — 8 269 United States government 41 — 1 40 Foreign government 10 — — 10 Total $ 10,552 $ 190 $ 106 $ 10,636 At December 31, 2017 Fixed maturity securities: Corporate $ 5,420 $ 246 $ 13 $ 5,653 States, municipalities and political subdivisions 4,316 155 6 4,465 Commercial mortgage-backed 280 7 1 286 Government-sponsored enterprises 257 1 4 254 United States government 31 — — 31 Foreign government 10 — — 10 Subtotal 10,314 409 24 10,699 Equity securities: Common equities 2,918 3,135 14 6,039 Nonredeemable preferred equities 176 34 — 210 Subtotal 3,094 3,169 14 6,249 Total $ 13,408 $ 3,578 $ 38 $ 16,948
Fair Values And Unrealized Losses by Investment Category And By The Duration Of The Securities' Continuous Unrealized Loss Position	The table below provides fair values and gross unrealized losses by investment category and by the duration of the securities’ continuous unrealized loss positions: (Dollars in millions) Less than 12 months 12 months or more Total At June 30, 2018 Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses Fixed maturity securities: Corporate $ 1,836 $ 39 $ 283 $ 18 $ 2,119 $ 57 States, municipalities and political subdivisions 1,070 22 262 14 1,332 36 Commercial mortgage-backed securities 113 2 35 2 148 4 Government-sponsored enterprises 110 2 158 6 268 8 Foreign government 10 — — — 10 — United States government 23 1 11 — 34 1 Total $ 3,162 $ 66 $ 749 $ 40 $ 3,911 $ 106 At December 31, 2017 Fixed maturity securities: Corporate $ 330 $ 4 $ 252 $ 9 $ 582 $ 13 States, municipalities and political subdivisions 88 1 264 5 352 6 Commercial mortgage-backed 33 — 36 1 69 1 Government-sponsored enterprises 96 1 124 3 220 4 Foreign government 10 — — — 10 — United States government 23 — 6 — 29 — Subtotal 580 6 682 18 1,262 24 Equity securities: Common equities 229 14 — — 229 14 Subtotal 229 14 — — 229 14 Total $ 809 $ 20 $ 682 $ 18 $ 1,491 $ 38
Investments Classified by Contractual Maturity Date [Table Text Block]	Contractual maturity dates for fixed-maturity investments were: (Dollars in millions) Amortized cost Fair value % of fair value At June 30, 2018 Maturity dates: Due in one year or less $ 720 $ 733 6.9 % Due after one year through five years 2,745 2,781 26.1 Due after five years through ten years 3,630 3,641 34.3 Due after ten years 3,457 3,481 32.7 Total $ 10,552 $ 10,636 100.0 %
Investment Income, Realized Investment Gains And Losses And Change In Unrealized Investment Gains And Losses	The following table provides investment income and investment gains and losses, net: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Investment income: Interest $ 112 $ 111 $ 222 $ 222 Dividends 44 42 86 81 Other 1 1 2 2 Total 157 154 310 305 Less investment expenses 3 3 6 5 Total $ 154 $ 151 $ 304 $ 300 Investment gains and losses, net: Equity securities: Investment gains and losses on securities sold, net $ 4 $ — $ 7 $ — Unrealized gains and losses on securities still held, net 101 — (97 ) — Gross realized gains — 6 — 159 Gross realized losses — (10 ) — (14 ) Other-than-temporary impairments — (3 ) — (3 ) Subtotal 105 (7 ) (90 ) 142 Fixed maturities: Gross realized gains 3 3 7 13 Gross realized losses (1 ) — (1 ) — Other-than-temporary impairments — (6 ) — (6 ) Subtotal 2 (3 ) 6 7 Other (2 ) (1 ) (2 ) — Total $ 105 $ (11 ) $ (86 ) $ 149

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Hierarchy for Assets Measured at Fair Value on a Recurring Basis	The following tables illustrate the fair value hierarchy for those assets measured at fair value on a recurring basis at June 30, 2018 , and December 31, 2017 . We do not have any liabilities carried at fair value. There were no transfers between Level 1 and Level 2. (Dollars in millions) Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Total At June 30, 2018 Fixed maturities, available for sale: Corporate $ — $ 5,677 $ 1 $ 5,678 States, municipalities and political subdivisions — 4,354 4 4,358 Commercial mortgage-backed — 281 — 281 Government-sponsored enterprises — 269 — 269 United States government 40 — — 40 Foreign government — 10 — 10 Subtotal 40 10,591 5 10,636 Common equities 6,008 — — 6,008 Nonredeemable preferred equities — 192 — 192 Separate accounts taxable fixed maturities — 781 — 781 Top Hat savings plan mutual funds and common 33 — — 33 Total $ 6,081 $ 11,564 $ 5 $ 17,650 At December 31, 2017 Fixed maturities, available for sale: Corporate $ — $ 5,652 $ 1 $ 5,653 States, municipalities and political subdivisions — 4,460 5 4,465 Commercial mortgage-backed — 286 — 286 Government-sponsored enterprises — 254 — 254 United States government 31 — — 31 Foreign government — 10 — 10 Subtotal 31 10,662 6 10,699 Common equities, available for sale 6,039 — — 6,039 Nonredeemable preferred equities, available for sale — 210 — 210 Separate accounts taxable fixed maturities — 795 — 795 Top Hat savings plan mutual funds and common equity (included in Other assets) 31 — — 31 Total $ 6,101 $ 11,667 $ 6 $ 17,774
Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)	(Dollars in millions) Asset fair value measurements using significant unobservable inputs Corporate States, Total Beginning balance, April 1, 2018 $ 1 $ 4 $ 5 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — — — Purchases — — — Sales — — — Transfers into Level 3 — — — Transfers out of Level 3 — — — Ending balance, June 30, 2018 $ 1 $ 4 $ 5 Beginning balance, April 1, 2017 $ 1 $ — $ 1 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — — — Purchases — — — Sales — — — Transfers into Level 3 — 5 5 Transfers out of Level 3 — — — Ending balance, June 30, 2017 $ 1 $ 5 $ 6 The following table provides the change in Level 3 assets for the six months ended June 30 : (Dollars in millions) Asset fair value measurements using significant unobservable inputs Corporate fixed maturities States, Total Beginning balance, January 1, 2018 $ 1 $ 5 $ 6 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — (1 ) (1 ) Purchases — — — Sales — — — Transfers into Level 3 — — — Transfers out of Level 3 — — — Ending balance, June 30, 2018 $ 1 $ 4 $ 5 Beginning balance, January 1, 2017 $ 78 $ — $ 78 Total gains or losses (realized/unrealized): Included in net income — — — Included in other comprehensive income — — — Purchases — 5 5 Sales — — — Transfers into Level 3 — — — Transfers out of Level 3 (77 ) — (77 ) Ending balance, June 30, 2017 $ 1 $ 5 $ 6
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	This table summarizes the book value and principal amounts of our long-term debt: (Dollars in millions) Book value Principal amount Interest rate Year of issue June 30, December 31, June 30, December 31, 2018 2017 2018 2017 6.900 % 1998 Senior debentures, due 2028 $ 26 $ 26 $ 28 $ 28 6.920 % 2005 Senior debentures, due 2028 391 391 391 391 6.125 % 2004 Senior notes, due 2034 370 370 374 374 Total $ 787 $ 787 $ 793 $ 793
Fair Value of Life Policy Loans	The following table shows the fair value of our life policy loans included in other invested assets and the fair values of our deferred annuities and structured settlements included in life policy and investment contract reserves: (Dollars in millions) Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Total At June 30, 2018 Life policy loans $ — $ — $ 40 $ 40 Deferred annuities — — 769 769 Structured settlements — 192 — 192 Total $ — $ 192 $ 769 $ 961 At December 31, 2017 Life policy loans $ — $ — $ 41 $ 41 Deferred annuities — — 834 834 Structured settlements — 210 — 210 Total $ — $ 210 $ 834 $ 1,044
Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Values of Deferred Annuities, Structured Settlements and Other Items	The following table shows fair values of our note payable and long-term debt: (Dollars in millions) Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Total At June 30, 2018 Note payable $ — $ 61 $ — $ 61 6.900% senior debentures, due 2028 — 32 — 32 6.920% senior debentures, due 2028 — 478 — 478 6.125% senior notes, due 2034 — 448 — 448 Total $ — $ 1,019 $ — $ 1,019 At December 31, 2017 Note payable $ — $ 24 $ — $ 24 6.900% senior debentures, due 2028 — 34 — 34 6.920% senior debentures, due 2028 — 505 — 505 6.125% senior notes, due 2034 — 477 — 477 Total $ — $ 1,040 $ — $ 1,040

Property Casualty Loss and Lo25

Property Casualty Loss and Loss Expenses (Tables)	6 Months Ended
	Jun. 30, 2018
Premiums Written, Net [Abstract]
Consolidated Property Casualty Loss And Loss Expense Reserves	This table summarizes activity for our consolidated property casualty loss and loss expense reserves: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Gross loss and loss expense reserves, beginning of period $ 5,293 $ 5,128 $ 5,219 $ 5,035 Less reinsurance recoverable 184 297 187 298 Net loss and loss expense reserves, beginning of period 5,109 4,831 5,032 4,737 Net incurred loss and loss expenses related to: Current accident year 852 832 1,691 1,658 Prior accident years (31 ) (38 ) (79 ) (76 ) Total incurred 821 794 1,612 1,582 Net paid loss and loss expenses related to: Current accident year 341 373 536 558 Prior accident years 354 322 873 831 Total paid 695 695 1,409 1,389 Net loss and loss expense reserves, end of period 5,235 4,930 5,235 4,930 Plus reinsurance recoverable 188 283 188 283 Gross loss and loss expense reserves, end of period $ 5,423 $ 5,213 $ 5,423 $ 5,213

Life Policy and Investment Co26

Life Policy and Investment Contract Reserves (Tables)	6 Months Ended
	Jun. 30, 2018
Liability for Future Policy Benefits [Abstract]
Reserve For Losses Loss Adjustment Expenses Table [Text Block]	This table summarizes our life policy and investment contract reserves: (Dollars in millions) June 30, December 31, 2017 Life policy reserves: Ordinary/traditional life $ 1,118 $ 1,080 Other 48 47 Subtotal 1,166 1,127 Investment contract reserves: Deferred annuities 813 835 Universal life 616 601 Structured settlements 159 160 Other 6 6 Subtotal 1,594 1,602 Total life policy and investment contract reserves $ 2,760 $ 2,729

Deferred Acquisition Costs (Ta

Deferred Acquisition Costs (Tables)	6 Months Ended
	Jun. 30, 2018
Deferred Costs [Abstract]
Deferred Policy Acquisition Costs And Asset Reconciliation, Including the Amortized Deferred Policy Acquisition Costs	The table below shows the deferred policy acquisition costs and asset reconciliation. (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Property casualty: Deferred policy acquisition costs asset, beginning of period $ 446 $ 428 $ 438 $ 408 Capitalized deferred policy acquisition costs 251 237 483 463 Amortized deferred policy acquisition costs (225 ) (217 ) (449 ) (423 ) Deferred policy acquisition costs asset, end of period $ 472 $ 448 $ 472 $ 448 Life: Deferred policy acquisition costs asset, beginning of period $ 245 $ 232 $ 232 $ 229 Capitalized deferred policy acquisition costs 15 12 28 25 Amortized deferred policy acquisition costs (11 ) (12 ) (21 ) (20 ) Amortized shadow deferred policy acquisition costs 7 (2 ) 17 (4 ) Deferred policy acquisition costs asset, end of period $ 256 $ 230 $ 256 $ 230 Consolidated: Deferred policy acquisition costs asset, beginning of period $ 691 $ 660 $ 670 $ 637 Capitalized deferred policy acquisition costs 266 249 511 488 Amortized deferred policy acquisition costs (236 ) (229 ) (470 ) (443 ) Amortized shadow deferred policy acquisition costs 7 (2 ) 17 (4 ) Deferred policy acquisition costs asset, end of period $ 728 $ 678 $ 728 $ 678

Accumulated Other Comprehensi28

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2018
Accumulated Other Comprehensive Income [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	(Dollars in millions) Three months ended June 30, 2018 2017 Before tax Income tax Net Before tax Income tax Net Investments: AOCI, beginning of period $ 164 $ 35 $ 129 $ 2,756 $ 954 $ 1,802 OCI before investment gains and losses, net, recognized in net income (78 ) (18 ) (60 ) 211 74 137 Investment gains and losses, net, recognized in net income (2 ) — (2 ) 10 3 7 OCI (80 ) (18 ) (62 ) 221 77 144 AOCI, end of period $ 84 $ 17 $ 67 $ 2,977 $ 1,031 $ 1,946 Pension obligations: AOCI, beginning of period $ (12 ) $ (1 ) $ (11 ) $ (25 ) $ (8 ) $ (17 ) OCI excluding amortization recognized in net income — — — — — — Amortization recognized in net income 1 — 1 — — — OCI 1 — 1 — — — AOCI, end of period $ (11 ) $ (1 ) $ (10 ) $ (25 ) $ (8 ) $ (17 ) Life deferred acquisition costs, life policy reserves and other: AOCI, beginning of period $ (4 ) $ (1 ) $ (3 ) $ (7 ) $ (2 ) $ (5 ) OCI before investment gains and losses, net, recognized in net income — — — — (1 ) 1 Investment gains and losses, net, recognized in net income 2 1 1 1 1 — OCI 2 1 1 1 — 1 AOCI, end of period $ (2 ) $ — $ (2 ) $ (6 ) $ (2 ) $ (4 ) Summary of AOCI: AOCI, beginning of period $ 148 $ 33 $ 115 $ 2,724 $ 944 $ 1,780 Investments OCI (80 ) (18 ) (62 ) 221 77 144 Pension obligations OCI 1 — 1 — — — Life deferred acquisition costs, life policy reserves and other OCI 2 1 1 1 — 1 Total OCI (77 ) (17 ) (60 ) 222 77 145 AOCI, end of period $ 71 $ 16 $ 55 $ 2,946 $ 1,021 $ 1,925 (Dollars in millions) Six months ended June 30, 2018 2017 Before tax Income tax Net Before tax Income tax Net Investments: AOCI, beginning of period $ 3,540 $ 733 $ 2,807 $ 2,625 $ 908 $ 1,717 Cumulative effect of change in accounting for equity securities as of January 1, 2018 (3,155 ) (652 ) (2,503 ) — — — Adjusted AOCI, beginning of period 385 81 304 2,625 908 1,717 OCI before investment gains and losses, net, recognized in net income (295 ) (63 ) (232 ) 501 176 325 Investment gains and losses, net, recognized in net income (6 ) (1 ) (5 ) (149 ) (53 ) (96 ) OCI (301 ) (64 ) (237 ) 352 123 229 AOCI, end of period $ 84 $ 17 $ 67 $ 2,977 $ 1,031 $ 1,946 Pension obligations: AOCI, beginning of period $ (12 ) $ (1 ) $ (11 ) $ (26 ) $ (8 ) $ (18 ) OCI excluding amortization recognized in net income — — — — — — Amortization recognized in net income 1 — 1 1 — 1 OCI 1 — 1 1 — 1 AOCI, end of period $ (11 ) $ (1 ) $ (10 ) $ (25 ) $ (8 ) $ (17 ) Life deferred acquisition costs, life policy reserves and other: AOCI, beginning of period $ (10 ) $ (2 ) $ (8 ) $ (9 ) $ (3 ) $ (6 ) OCI before investment gains and losses, net, recognized in net income 6 1 5 3 1 2 Investment gains and losses, net, recognized in net income 2 1 1 — — — OCI 8 2 6 3 1 2 AOCI, end of period $ (2 ) $ — $ (2 ) $ (6 ) $ (2 ) $ (4 ) Summary of AOCI: AOCI, beginning of period $ 3,518 $ 730 $ 2,788 $ 2,590 $ 897 $ 1,693 Cumulative effect of change in accounting for equity securities as of January 1, 2018 (3,155 ) (652 ) (2,503 ) — — — Adjusted AOCI, beginning of period 363 78 285 2,590 897 1,693 Investments OCI (301 ) (64 ) (237 ) 352 123 229 Pension obligations OCI 1 — 1 1 — 1 Life deferred acquisition costs, life policy reserves and other OCI 8 2 6 3 1 2 Total OCI (292 ) (62 ) (230 ) 356 124 232 AOCI, end of period $ 71 $ 16 $ 55 $ 2,946 $ 1,021 $ 1,925

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2018
Reinsurance Disclosures [Abstract]
Property Casualty Insurance Assumed And Ceded Business	The table below summarizes our consolidated property casualty insurance net written premiums, earned premiums and incurred loss and loss expenses: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Direct written premiums $ 1,336 $ 1,265 $ 2,583 $ 2,491 Assumed written premiums 52 42 101 75 Ceded written premiums (39 ) (36 ) (77 ) (64 ) Net written premiums $ 1,349 $ 1,271 $ 2,607 $ 2,502 Direct earned premiums $ 1,235 $ 1,189 $ 2,442 $ 2,352 Assumed earned premiums 36 33 69 60 Ceded earned premiums (41 ) (41 ) (81 ) (80 ) Earned premiums $ 1,230 $ 1,181 $ 2,430 $ 2,332 Direct incurred loss and loss expenses $ 821 $ 770 $ 1,602 $ 1,558 Assumed incurred loss and loss expenses 13 20 29 35 Ceded incurred loss and loss expenses (13 ) 4 (19 ) (11 ) Incurred loss and loss expenses $ 821 $ 794 $ 1,612 $ 1,582
Life Insurance Assumed and Ceded Business	(Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Direct earned premiums $ 81 $ 77 $ 158 $ 151 Ceded earned premiums (17 ) (17 ) (34 ) (34 ) Earned premiums $ 64 $ 60 $ 124 $ 117 Direct contract holders' benefits incurred 70 87 146 163 Ceded contract holders' benefits incurred (8 ) (27 ) (21 ) (38 ) Contract holders' benefits incurred $ 62 $ 60 $ 125 $ 125

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Differences Between The 35 Percent Statutory Income Tax Rate And Effective Income Tax Rate	The differences between the 21 percent and 35 percent statutory federal income tax rates and our effective income tax rate were as follows: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Tax at statutory rate: $ 56 21.0 % $ 44 35.0 % $ 45 21.0 % $ 141 35.0 % Increase (decrease) resulting from: Tax-exempt income from municipal bonds (5 ) (1.9 ) (9 ) (7.0 ) (10 ) (4.7 ) (18 ) (4.5 ) Dividend received exclusion (5 ) (1.5 ) (9 ) (7.0 ) (8 ) (3.7 ) (17 ) (4.2 ) Other 1 0.2 2 0.9 1 0.5 (3 ) (0.8 ) Provision for income taxes $ 47 17.8 % $ 28 21.9 % $ 28 13.1 % $ 103 25.5 %

Net Income Per Common Share (Ta

Net Income Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Calculations For Basic And Diluted Earnings Per Share	The table shows calculations for basic and diluted earnings per share: (In millions, except per share data) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Numerator: Net income—basic and diluted $ 217 $ 100 $ 186 $ 301 Denominator: Basic weighted-average common shares outstanding 163.2 164.3 163.6 164.4 Effect of share-based awards: Stock options 0.8 1.0 0.9 1.1 Nonvested shares 0.5 0.7 0.5 0.7 Diluted weighted-average shares 164.5 166.0 165.0 166.2 Earnings per share: Basic $ 1.33 $ 0.61 $ 1.13 $ 1.83 Diluted $ 1.32 $ 0.60 $ 1.12 $ 1.81 Number of anti-dilutive share-based awards 1.3 0.6 1.3 0.7

Employee Retirement Benefits (T

Employee Retirement Benefits (Tables)	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures	The following summarizes the components of net periodic benefit cost for our qualified and supplemental pension plans: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Service cost $ 2 $ 2 $ 5 $ 5 Non-service costs (benefit): Interest cost 3 4 6 7 Expected return on plan assets (6 ) (5 ) (11 ) (10 ) Amortization of actuarial loss and prior service cost 1 — 1 1 Total non-service benefit (2 ) (1 ) (4 ) (2 ) Net periodic benefit cost $ — $ 1 $ 1 $ 3

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Information	Segment information is summarized in the following table: (Dollars in millions) Three months ended June 30, Six months ended June 30, 2018 2017 2018 2017 Revenues: Commercial lines insurance Commercial casualty $ 272 $ 271 $ 537 $ 536 Commercial property 231 226 459 449 Commercial auto 166 158 327 313 Workers' compensation 85 86 165 170 Other commercial 58 55 114 109 Commercial lines insurance premiums 812 796 1,602 1,577 Fee revenues — 1 2 2 Total commercial lines insurance 812 797 1,604 1,579 Personal lines insurance Personal auto 153 144 304 285 Homeowner 139 128 275 253 Other personal 39 35 77 69 Personal lines insurance premiums 331 307 656 607 Fee revenues 2 1 3 3 Total personal lines insurance 333 308 659 610 Excess and surplus lines insurance 57 52 113 100 Fee revenues 1 1 1 1 Total excess and surplus lines insurance 58 53 114 101 Life insurance premiums 64 60 124 117 Fee revenues 1 1 2 3 Total life insurance 65 61 126 120 Investments Investment income, net of expenses 154 151 304 300 Investment gains and losses, net 105 (11 ) (86 ) 149 Total investment revenue 259 140 218 449 Other Cincinnati Re insurance premiums 30 26 59 48 Other 1 1 2 2 Total other revenues 31 27 61 50 Total revenues $ 1,558 $ 1,386 $ 2,782 $ 2,909 Income (loss) before income taxes: Insurance underwriting results Commercial lines insurance $ 47 $ 24 $ 62 $ 22 Personal lines insurance (32 ) (24 ) (41 ) (39 ) Excess and surplus lines insurance 13 19 31 37 Life insurance 8 4 10 4 Investments 235 117 170 403 Other (7 ) (12 ) (18 ) (23 ) $ 264 $ 128 $ 214 $ 404 Identifiable assets: June 30, December 31, 2017 Property casualty insurance $ 3,011 $ 2,863 Life insurance 1,406 1,409 Investments 16,972 17,112 Other 371 459 Total $ 21,760 $ 21,843

Accounting Policies (Details)

Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Available-for-sale Equity Securities, Unrealized Gain, After Tax	$ 2,503	$ 0	$ 2,503	$ 0
Net investment gain (loss)	105	(11)	(86)	149
Equity securities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net investment gain (loss)	105	(7)	(90)	142
Unrealized Gain (Loss) on Investments	$ 101	$ 0	$ (97)	$ 0

Investments - Analysis of Cost

Investments - Analysis of Cost or Amortized Cost, Gross Unrealized Gains and Losses and Fair Value for Investments (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	$ 10,552	$ 10,314
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	190	409
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	106	24
Fair Value	10,636	10,699
Debt Securities | Corporate
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	5,625	5,420
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	110	246
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	57	13
Fair Value	5,678	5,653
Debt Securities | States, municipalities and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	4,316	4,316
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	78	155
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	36	6
Fair Value	4,358	4,465
Debt Securities | Commercial mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	283	280
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2	7
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	4	1
Fair Value	281	286
Debt Securities | Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	277	257
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0	1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	8	4
Fair Value	269	254
Debt Securities | United States government
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	41	31
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1	0
Fair Value	40	31
Debt Securities | Foreign government
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	10	10
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Fair Value	$ 10	10
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost		3,094
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		3,169
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		14
Fair Value		6,249
Equity securities | Common equities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost		2,918
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		3,135
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		14
Fair Value		6,039
Equity securities | Nonredeemable preferred equities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost		176
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		34
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		0
Fair Value		210
Fixed Maturities And Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost		13,408
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		3,578
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		38
Fair Value		$ 16,948

Investments - Fair Values and U

Investments - Fair Values and Unrealized Losses by Investment Category and by Duration of Securities' Continuous Unrealized Loss Position (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		$ 809
Less than 12 months Unrealized Losses		20
12 months or more Fair Value		682
12 months or more Unrealized Losses		18
Total Fair Value		1,491
Total Unrealized Losses		38
Fixed maturities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	$ 3,162	580
Less than 12 months Unrealized Losses	66	6
12 months or more Fair Value	749	682
12 months or more Unrealized Losses	40	18
Total Fair Value	3,911	1,262
Total Unrealized Losses	106	24
Fixed maturities | Corporate
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	1,836	330
Less than 12 months Unrealized Losses	39	4
12 months or more Fair Value	283	252
12 months or more Unrealized Losses	18	9
Total Fair Value	2,119	582
Total Unrealized Losses	57	13
Fixed maturities | States, municipalities and political subdivisions
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	1,070	88
Less than 12 months Unrealized Losses	22	1
12 months or more Fair Value	262	264
12 months or more Unrealized Losses	14	5
Total Fair Value	1,332	352
Total Unrealized Losses	36	6
Fixed maturities | Commercial mortgage-backed
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	113	33
Less than 12 months Unrealized Losses	2	0
12 months or more Fair Value	35	36
12 months or more Unrealized Losses	2	1
Total Fair Value	148	69
Total Unrealized Losses	4	1
Fixed maturities | Government-sponsored enterprises
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	110	96
Less than 12 months Unrealized Losses	2	1
12 months or more Fair Value	158	124
12 months or more Unrealized Losses	6	3
Total Fair Value	268	220
Total Unrealized Losses	8	4
Fixed maturities | Foreign government
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	10	10
Less than 12 months Unrealized Losses	0	0
12 months or more Fair Value	0	0
12 months or more Unrealized Losses	0	0
Total Fair Value	10	10
Total Unrealized Losses	0	0
Fixed maturities | United States government
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	23	23
Less than 12 months Unrealized Losses	1	0
12 months or more Fair Value	11	6
12 months or more Unrealized Losses	0	0
Total Fair Value	34	29
Total Unrealized Losses	$ 1	0
Equity securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		229
Less than 12 months Unrealized Losses		14
12 months or more Fair Value		0
12 months or more Unrealized Losses		0
Total Fair Value		229
Total Unrealized Losses		14
Equity securities | Common equities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value		229
Less than 12 months Unrealized Losses		14
12 months or more Fair Value		0
12 months or more Unrealized Losses		0
Total Fair Value		229
Total Unrealized Losses		$ 14

Investments - Schedule of Contr

Investments - Schedule of Contractual Maturities of Investments (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Amortized cost
Due in one year or less	$ 720
Due after one year through five years	2,745
Due after five years through ten years	3,630
Due after ten years	3,457
Total	10,552	$ 10,314
Fair value
Due in one year or less	733
Due after one year through five years	2,781
Due after five years through ten years	3,641
Due after ten years	3,481
Total	$ 10,636	$ 10,699
% of fair value
Due in one year or less	6.90%
Due after one year through five years	26.10%
Due after five years through ten years	34.30%
Due after ten years	32.70%
Total	100.00%

Investments - Realized Investme

Investments - Realized Investment Gains and Losses and Change in Unrealized Investment Gains and Losses and Other Items (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investment income:
Interest	$ 112	$ 111	$ 222	$ 222
Dividends	44	42	86	81
Other	1	1	2	2
Total	157	154	310	305
Less investment expenses	3	3	6	5
Total	154	151	304	300
Gain (Loss) on Sale of Investments			(90)	149
Investment gains and losses, net:
Investment gains and losses, net	105	(11)	(86)	149
Equity securities
Investment income:
Gain (Loss) on Sale of Investments	4	0	7	0
Unrealized Gain (Loss) on Investments	101	0	(97)	0
Investment gains and losses, net:
Gross realized gains	0	6	0	159
Gross realized losses	0	(10)	0	(14)
Other Than Temporary Impairment Losses	0	(3)	0	(3)
Other	(2)	(1)	(2)	0
Investment gains and losses, net	105	(7)	(90)	142
Fixed maturities
Investment gains and losses, net:
Gross realized gains	3	3	7	13
Gross realized losses	(1)	0	(1)	0
Other Than Temporary Impairment Losses	0	(6)	0	(6)
Investment gains and losses, net	$ 2	$ (3)	$ 6	$ 7

Investments - Additional Inform

Investments - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)security	Jun. 30, 2017USD ($)security	Jun. 30, 2018USD ($)security	Jun. 30, 2017USD ($)security	Dec. 31, 2017USD ($)security
Gain (Loss) on Investments [Line Items]
Largest Single Common Stock Holding	$ 259,000,000		$ 259,000,000
Largest equity holdings to total equity portfolio	4.30%		4.30%
Largest equity holdings to total portfolio	1.50%		1.50%
Unrealized losses 12 months or more (equity investment less than $500,000)					$ (18,000,000)
Fixed maturity investments, Percentage of amortized costs			70.00%		70.00%
Fixed maturities
Gain (Loss) on Investments [Line Items]
Number Of Securities Other Than Temporary Impairment Losses1 | security	0	1	0	1
Provision for Other Credit Losses	$ 0	$ 0	$ 0	$ 0
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months | security	263		263		249
Unrealized losses 12 months or more (equity investment less than $500,000)	$ (40,000,000)		$ (40,000,000)		$ (18,000,000)
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months and Below 70 Percent of Amortized Cost	0		0		0
Equity securities
Gain (Loss) on Investments [Line Items]
Number Of Securities Other Than Temporary Impairment Losses1 | security		5		5
Number Of Securities Continuous Unrealized Loss Position More Than Twelve Months					0
Unrealized losses 12 months or more (equity investment less than $500,000)					$ 0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Hierarchy for Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	$ 10,636	$ 10,699
Equity securities, at fair value	6,200	6,249
Separate accounts	792	806
Top Hat savings plan mutual funds and common equity (included in Other assets)	33	31
Fair value of asset	17,650	17,774
Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	10,636	10,699
Debt Securities | Corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	5,678	5,653
Debt Securities | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	4,358	4,465
Debt Securities | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	281	286
Debt Securities | Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	269	254
Debt Securities | United States government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	40	31
Debt Securities | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	10	10
Equity securities | Common equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	6,008	6,039
Equity securities | Nonredeemable preferred equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	192	210
Taxable Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate accounts	781	795
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Top Hat savings plan mutual funds and common equity (included in Other assets)	33	31
Fair value of asset	6,081	6,101
Quoted prices in active markets for identical assets (Level 1) | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	40	31
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | United States government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	40	31
Quoted prices in active markets for identical assets (Level 1) | Debt Securities | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Equity securities | Common equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	6,008	6,039
Quoted prices in active markets for identical assets (Level 1) | Equity securities | Nonredeemable preferred equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	0	0
Quoted prices in active markets for identical assets (Level 1) | Taxable Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate accounts	0	0
Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Top Hat savings plan mutual funds and common equity (included in Other assets)	0	0
Fair value of asset	11,564	11,667
Significant other observable inputs (Level 2) | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	10,591	10,662
Significant other observable inputs (Level 2) | Debt Securities | Corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	5,677	5,652
Significant other observable inputs (Level 2) | Debt Securities | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	4,354	4,460
Significant other observable inputs (Level 2) | Debt Securities | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	281	286
Significant other observable inputs (Level 2) | Debt Securities | Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	269	254
Significant other observable inputs (Level 2) | Debt Securities | United States government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Significant other observable inputs (Level 2) | Debt Securities | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	10	10
Significant other observable inputs (Level 2) | Equity securities | Common equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	0	0
Significant other observable inputs (Level 2) | Equity securities | Nonredeemable preferred equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	192	210
Significant other observable inputs (Level 2) | Taxable Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate accounts	781	795
Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Top Hat savings plan mutual funds and common equity (included in Other assets)	0	0
Fair value of asset	5	6
Significant unobservable inputs (Level 3) | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	5	6
Significant unobservable inputs (Level 3) | Debt Securities | Corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	1	1
Significant unobservable inputs (Level 3) | Debt Securities | States, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	4	5
Significant unobservable inputs (Level 3) | Debt Securities | Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | United States government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Debt Securities | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	0	0
Significant unobservable inputs (Level 3) | Equity securities | Common equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	0	0
Significant unobservable inputs (Level 3) | Equity securities | Nonredeemable preferred equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value	0	0
Significant unobservable inputs (Level 3) | Taxable Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate accounts	$ 0	$ 0

Fair Value Measurements - Chang

Fair Value Measurements - Change in Level 3 Assets (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 5	$ 1	$ 6	$ 78
Total gains or losses (realized/unrealized):
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	(1)	0
Purchases	0	0	0	5
Sales	0	0	0	0
Transfers into Level 3	0	5	0	0
Transfers out of Level 3	0	0	0	(77)
Ending balance	5	6	5	6
Corporate Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1	1	1	78
Total gains or losses (realized/unrealized):
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	(77)
Ending balance	1	1	1	1
States, Municipalities And Political Subdivisions Fixed Maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	4	0	5	0
Total gains or losses (realized/unrealized):
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	(1)	0
Purchases	0	0	0	5
Sales	0	0	0	0
Transfers into Level 3	0	5	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	$ 4	$ 5	$ 4	$ 5

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Book Value and Principal Amounts of Long-Term Debt (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Book value	$ 787	$ 787
Principal amount of debt	$ 793	$ 793
Senior Debentures 6.900% Due 2028
Debt Instrument [Line Items]
Interest rate	6.90%	6.90%
Debt issuance year	1,998	1,998
Book value	$ 26	$ 26
Principal amount of debt	$ 28	$ 28
Senior Debentures 6.920% Due 2028
Debt Instrument [Line Items]
Interest rate	6.92%	6.92%
Debt issuance year	2,005	2,005
Book value	$ 391	$ 391
Principal amount of debt	$ 391	$ 391
Senior Notes 6.125% Due 2034
Debt Instrument [Line Items]
Interest rate	6.125%	6.125%
Debt issuance year	2,004	2,004
Book value	$ 370	$ 370
Principal amount of debt	$ 374	$ 374

Fair Value Measurements - Fai43

Fair Value Measurements - Fair Values of Note Payable and Long-Term Debt (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of note payable	$ 61	$ 24
Total	1,019	1,040
Finance receivable	$ 66	$ 61
Senior Debentures 6.900 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	6.90%	6.90%
Debt instrument, year of maturity	2,028	2,028
Fair value of senior debt	$ 32	$ 34
Senior Debentures 6.920 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	6.92%	6.92%
Debt instrument, year of maturity	2,028	2,028
Fair value of senior debt	$ 478	$ 505
Senior Notes 6.125 % Due 2034
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	6.125%	6.125%
Debt instrument, year of maturity	2,034	2,034
Fair value of senior debt	$ 448	$ 477
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of note payable	0	0
Total	0	0
Quoted prices in active markets for identical assets (Level 1) | Senior Debentures 6.900 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	0	0
Quoted prices in active markets for identical assets (Level 1) | Senior Debentures 6.920 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	0	0
Quoted prices in active markets for identical assets (Level 1) | Senior Notes 6.125 % Due 2034
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	0	0
Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of note payable	61	24
Total	1,019	1,040
Significant other observable inputs (Level 2) | Senior Debentures 6.900 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	32	34
Significant other observable inputs (Level 2) | Senior Debentures 6.920 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	478	505
Significant other observable inputs (Level 2) | Senior Notes 6.125 % Due 2034
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	448	477
Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of note payable	0	0
Total	0	0
Significant unobservable inputs (Level 3) | Senior Debentures 6.900 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	0	0
Significant unobservable inputs (Level 3) | Senior Debentures 6.920 % Due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	0	0
Significant unobservable inputs (Level 3) | Senior Notes 6.125 % Due 2034
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of senior debt	0	0
Policy Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivable	$ 32	$ 31

Fair Value Measurements - Fai44

Fair Value Measurements - Fair Value of Life Policy Loans, Deferred Annuities, and Structured Settlements (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivable	$ 66	$ 61
Fair value of life policy loans	40	41
Liabilities Related to Investment Contracts, Fair Value Disclosure	961	1,044
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of life policy loans	0	0
Liabilities Related to Investment Contracts, Fair Value Disclosure	0	0
Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of life policy loans	0	0
Liabilities Related to Investment Contracts, Fair Value Disclosure	192	210
Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of life policy loans	40	41
Liabilities Related to Investment Contracts, Fair Value Disclosure	769	834
Policy Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivable	32	31
Deferred annuities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	769	834
Deferred annuities | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	0	0
Deferred annuities | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	0	0
Deferred annuities | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	769	834
Structured Finance [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	192	210
Structured Finance [Member] | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	0	0
Structured Finance [Member] | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	192	210
Structured Finance [Member] | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities Related to Investment Contracts, Fair Value Disclosure	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivable	$ 66	$ 61
Loss and loss expense reserves	5,468	5,273
Life Policy Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivable	32	31
Deferred annuities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss and loss expense reserves	813	835
Structured Finance [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss and loss expense reserves	$ 159	$ 161
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage Of Level 3 Assets To Total Financial Instruments Measured At Fair Value	1.00%

Property Casualty Loss and Lo46

Property Casualty Loss and Loss Expenses - Consolidated Property Casualty Loss and Loss Expense Reserves (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Summary of Consolidated Property Casualty Loss and Loss Expense Reserves [Roll Forward]
Gross loss and loss expense reserves, beginning of period	$ 5,293	$ 5,128	$ 5,219	$ 5,035
Less reinsurance recoverable	184	297	187	298
Net loss and loss expense reserves, beginning of period	5,109	4,831	5,032	4,737
Current accident year	852	832	1,691	1,658
Prior accident years	(31)	(38)	(79)	(76)
Total incurred	821	794	1,612	1,582
Current accident year	341	373	536	558
Prior accident years	354	322	873	831
Total paid	695	695	1,409	1,389
Net loss and loss expense reserves, end of period	5,235	4,930	5,235	4,930
Plus reinsurance recoverable	188	283	188	283
Gross loss and loss expense reserves, end of period	$ 5,423	$ 5,213	$ 5,423	$ 5,213

Property Casualty Loss and Lo47

Property Casualty Loss and Loss Expenses - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Reserve for loss and loss expenses	$ 5,423	$ 5,213	$ 5,423	$ 5,213	$ 5,293	$ 5,219	$ 5,128	$ 5,035
Prior accident years	(31)	(38)	(79)	(76)
Life and Health Loss Reserves
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Reserve for loss and loss expenses	45	68	45	68
Commercial Lines
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	(42)	(26)	(77)	(37)
Commercial Lines | Workers' Compensation
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	(18)	(12)	(31)	(31)
Commercial Lines | Commercial Casualty Segment [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	(14)	(7)	(10)	8
Commercial Lines | Other Commercial Lines [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	(8)	(11)	(12)	(19)
Commercial Lines | Commercial Auto
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	5	9	4	20
Commercial Lines | Commercial Property Segment [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	(7)	(5)	(28)	(15)
Personal Lines
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	17	(3)	16	(13)
Personal Lines | Homeowner [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	14		17
Excess and Surplus Lines Insurance
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	(4)	(9)	(14)	(22)
Reinsurance assumed and other non segment [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years	$ (2)		(4)	(4)
Consolidated Property and Casualty Insurance Entity | Catastrophe Development
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Prior accident years		$ (3)	$ (7)	$ (14)

Reserves in Addition to Account

Reserves in Addition to Account Balance, Based on Expected No-Lapse Guarantee Benefits and Expected Policy Assessments (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	$ 2,760	$ 2,729
Life policy reserves:
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	1,166	1,127
Life policy reserves: | Ordinary/traditional life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	1,118	1,080
Life policy reserves: | Other
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	48	47
Investment contract reserves:
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	1,594	1,602
Investment contract reserves: | Deferred annuities
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	813	835
Investment contract reserves: | Universal life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	616	601
Investment contract reserves: | Structured Settlement Annuity [Member]
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	159	160
Investment contract reserves: | Other
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	$ 6	$ 6

Deferred Acquisition Costs - De

Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	$ 691	$ 660	$ 670	$ 637
Capitalized deferred policy acquisition costs	266	249	511	488
Deferred Policy Acquisition Costs, Amortization Expense	(236)	(229)	(470)	(443)
Deferred Policy Acquisition Cost, Amortization Expense, Other	7	(2)	17	(4)
Deferred policy acquisition costs asset, end of period	728	678	728	678
Life Insurance Product Line [Member]
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	245	232	232	229
Capitalized deferred policy acquisition costs	15	12	28	25
Deferred Policy Acquisition Costs, Amortization Expense	(11)	(12)	(21)	(20)
Deferred Policy Acquisition Cost, Amortization Expense, Other	7	(2)	17	(4)
Deferred policy acquisition costs asset, end of period	256	230	256	230
Consolidated Property and Casualty Insurance Entity
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	446	428	438	408
Capitalized deferred policy acquisition costs	251	237	483	463
Deferred Policy Acquisition Costs, Amortization Expense	(225)	(217)	(449)	(423)
Deferred policy acquisition costs asset, end of period	$ 472	$ 448	$ 472	$ 448

Accumulated Other Comprehensi50

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax					$ 2,503			$ 0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 55		$ 55		55		$ 2,788
Accumulated other comprehensive income, net of tax, end of period	55		55
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	164	$ 2,756	385	$ 2,625
Cumulative effect of change in accounting for equity securities, before tax							(3,155)			$ 0
Other comprehensive income before reclassification, before tax	(78)	211	(295)	501
Reclassification adjustment, before tax	(2)	10	(6)	(149)
Effect on other comprehensive income, before tax	(80)	221	(301)	352
Accumulated other comprehensive income, before tax, end of period	84	2,977	84	2,977
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	35	954	81	908
Cumulative effect of change in accounting for equity securities, tax							(652)			0
Other comprehensive income before reclassification, tax	(18)	74	(63)	176
Reclassification adjustment, tax	0	3	(1)	(53)
Effect on other comprehensive income, tax	(18)	77	(64)	123
Accumulated other comprehensive income, tax, end of period	17	1,031	17	1,031
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax							(2,503)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	67	1,946	67	1,946	67	$ 129	304	1,946	$ 1,802	1,717
Cumulative effect of change in accounting for equity securities, net										0
Other comprehensive income before reclassification, net of tax	(60)	137	(232)	325
Reclassification adjustment, net of tax	(2)	7	(5)	(96)
Effect on other comprehensive income, net of tax	(62)	144	(237)	229
Accumulated other comprehensive income, net of tax, end of period	67	1,946	67	1,946
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(12)	(25)	(12)	(26)
Other comprehensive income before reclassification, before tax	0	0	0	0
Reclassification adjustment, before tax	1	0	1	1
Effect on other comprehensive income, before tax	1	0	1	1
Accumulated other comprehensive income, before tax, end of period	(11)	(25)	(11)	(25)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	(1)	(8)	(1)	(8)
Other comprehensive income before reclassification, tax	0	0	0	0
Reclassification adjustment, tax	0	0	0	0
Effect on other comprehensive income, tax	0	0	0	0
Accumulated other comprehensive income, tax, end of period	(1)	(8)	(1)	(8)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(10)	(17)	(10)	(17)	(10)	(11)	(11)	(17)	(17)	(18)
Other comprehensive income before reclassification, net of tax	0	0	0	0
Reclassification adjustment, net of tax	1	0	1	1
Effect on other comprehensive income, net of tax	1	0	1	1
Accumulated other comprehensive income, net of tax, end of period	(10)	(17)	(10)	(17)
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(4)	(7)	(10)	(9)
Other comprehensive income before reclassification, before tax	0	0	6	3
Reclassification adjustment, before tax	2	1	2	0
Effect on other comprehensive income, before tax	2	1	8	3
Accumulated other comprehensive income, before tax, end of period	(2)	(6)	(2)	(6)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	(1)	(2)	(2)	(3)
Other comprehensive income before reclassification, tax	0	(1)	1	1
Reclassification adjustment, tax	1	1	1	0
Effect on other comprehensive income, tax	1	0	2	1
Accumulated other comprehensive income, tax, end of period	0	(2)	0	(2)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(2)	(4)	(2)	(4)	(2)	(3)	(8)	(4)	(5)	(6)
Other comprehensive income before reclassification, net of tax	0	1	5	2
Reclassification adjustment, net of tax	1	0	1	0
Effect on other comprehensive income, net of tax	1	1	6	2
Accumulated other comprehensive income, net of tax, end of period	(2)	(4)	(2)	(4)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	148	2,724	363	2,590
Cumulative effect of change in accounting for equity securities, before tax							(3,155)			0
Change in unrealized gains, net, on investments available for sale, before tax	(80)	221	(301)	352
Change in pension obligations, before tax	1	0	1	1
Change in life deferred acquisition costs, life policy reserves and other, before tax	2	1	8	3
Effect on other comprehensive income, before tax	(77)	222	(292)	356
Accumulated other comprehensive income, before tax, end of period	71	2,946	71	2,946
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	33	944	78	897
Cumulative effect of change in accounting for equity securities, tax							(652)			0
Change in unrealized gains, net, on investments available for sale, tax	(18)	77	(64)	123
Change in pension obligations, tax	0	0	0	0
Change in life deferred acquisition costs, life policy reserves and other, tax	1	0	2	1
Effect on other comprehensive income, tax	(17)	77	(62)	124
Accumulated other comprehensive income, tax, end of period	16	1,021	16	1,021
Unrealized gains reclassified to retained earnings for ASU 2016-01, after tax					(2,503)		(2,503)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	55	1,925	55	1,925	$ 55	$ 115	285	$ 1,925	$ 1,780	1,693
Cumulative effect of change in accounting for equity securities, net										0
Change in unrealized gains, net, on investments available for sale, net of tax	(62)	144	(237)	229
Change in pension obligations, net of tax	1	0	1	1
Change in life deferred acquisition costs, life policy reserves and other, net of tax	1	1	6	2
Effect on other comprehensive income, net of tax	(60)	145	(230)	232
Accumulated other comprehensive income, net of tax, end of period	$ 55	$ 1,925	55	1,925
Previously Reported | Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period			3,540	2,625
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period			733	908
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period							2,807			1,717
Previously Reported | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period			3,518	2,590
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period			$ 730	$ 897
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period							$ 2,788			$ 1,693

Reinsurance - Consolidated Prop

Reinsurance - Consolidated Property Casualty Insurance Assumed and Ceded Business (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property Casualty Insurance Assumed And Ceded Business [Line Items]
Incurred loss and loss expenses	$ 883	$ 854	$ 1,737	$ 1,707
Consolidated Property and Casualty Insurance Entity
Property Casualty Insurance Assumed And Ceded Business [Line Items]
Direct written premiums	1,336	1,265	2,583	2,491
Assumed written premiums	52	42	101	75
Ceded written premiums	(39)	(36)	(77)	(64)
Net written premiums	1,349	1,271	2,607	2,502
Direct earned premiums	1,235	1,189	2,442	2,352
Assumed earned premiums	36	33	69	60
Ceded earned premiums	(41)	(41)	(81)	(80)
Earned premiums	1,230	1,181	2,430	2,332
Direct incurred loss and loss expenses	821	770	1,602	1,558
Assumed incurred loss and loss expenses	13	20	29	35
Ceded incurred loss and loss expenses	(13)	4	(19)	(11)
Incurred loss and loss expenses	$ 821	$ 794	$ 1,612	$ 1,582

Reinsurance - Life Insurance Ce

Reinsurance - Life Insurance Ceded Business (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reinsurance for Insurance Companies, by Product Segment [Line Items]
Insurance losses and contract holders' benefits	$ 883	$ 854	$ 1,737	$ 1,707
Life Insurance Segment
Reinsurance for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	81	77	158	151
Ceded earned premiums	(17)	(17)	(34)	(34)
Earned premiums	64	60	124	117
Direct contract holders' benefits incurred	70	87	146	163
Ceded contract holders' benefits incurred	(8)	(27)	(21)	(38)
Insurance losses and contract holders' benefits	$ 62	$ 60	$ 125	$ 125

Income Taxes - Differences Betw

Income Taxes - Differences Between Statutory Income Tax Rate and Effective Income Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ 56	$ 44	$ 45	$ 141
Increase (decrease) resulting from:
Tax-exempt income from municipal bonds	(5)	(9)	(10)	(18)
Dividend received exclusion	(5)	(9)	(8)	(17)
Other	1	2	1	(3)
Total provision for income taxes	$ 47	$ 28	$ 28	$ 103
Tax at statutory rate	21.00%	35.00%	21.00%	35.00%
Increase (decrease) resulting from:
Tax-exempt income from municipal bonds	(1.90%)	(7.00%)	(4.70%)	(4.50%)
Dividend received exclusion	(1.50%)	(7.00%)	(3.70%)	(4.20%)
Other	0.20%	0.90%	0.50%	(0.80%)
Provision for income taxes	17.80%	21.90%	13.10%	25.50%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Tax at statutory rate, percentage	21.00%	35.00%	21.00%	35.00%

Net Income Per Common Share - C

Net Income Per Common Share - Calculations for Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net income—basic and diluted	$ 217	$ 100	$ 186	$ 301
Denominator:
Basic weighted-average common shares outstanding (in shares)	163.2	164.3	163.6	164.4
Diluted weighted-average shares	164.5	166	165	166.2
Earnings per share:
Basic (in USD per share)	$ 1.33	$ 0.61	$ 1.13	$ 1.83
Diluted (in USD per share)	$ 1.32	$ 0.60	$ 1.12	$ 1.81
Number of anti-dilutive stock-based awards (in shares)	1.3	0.6	1.3	0.7
Stock Options
Denominator:
Effect of stock-based awards (in shares)	0.8	1	0.9	1.1
Nonvested shares
Denominator:
Effect of stock-based awards (in shares)	0.5	0.7	0.5	0.7

Employee Retirement Benefits -

Employee Retirement Benefits - Components of Net Periodic Costs for Qualified and Supplemental Pension Plans (Detail) - Qualified Pension Plans [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 5	$ 5
Interest cost	3	4	6	7
Expected return on plan assets	(6)	(5)	(11)	(10)
Amortization of actuarial loss and prior service cost	1	0	1	1
Net periodic benefit cost	$ 0	$ 1	$ 1	$ 3

Employee Retirement Benefits 57

Employee Retirement Benefits - Defined Contribution Plan (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Matching contributions to 401(k) and Top Hat plans	$ 4	$ 3	$ 10	$ 9
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension contributions			$ 5

Segment Information (Detail)

Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Earned premiums	$ 1,294	$ 1,241	$ 2,554	$ 2,449
Fee revenues	4	4	8	9
Investment income, net of expenses	154	151	304	300
Investment gains and losses, net	105	(11)	(86)	149
Other	1	1	2	2
Total revenues	1,558	1,386	2,782	2,909
Income (loss) before income taxes	264	128	214	404
Identifiable assets	21,760		21,760		$ 21,843
Consolidated Property and Casualty Insurance Entity
Segment Reporting Information [Line Items]
Identifiable assets	3,011		3,011		2,863
Life Insurance Segment
Segment Reporting Information [Line Items]
Identifiable assets	1,406		1,406		1,409
Investments Segment
Segment Reporting Information [Line Items]
Identifiable assets	16,972		16,972		17,112
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Other	1	1	2	2
Total revenues	31	27	61	50
Income (loss) before income taxes	(7)	(12)	(18)	(23)
Identifiable assets	371		371		$ 459
Corporate, Non-Segment [Member] | Reinsurance assumed and other non segment [Member]
Segment Reporting Information [Line Items]
Earned premiums	30	26	59	48
Operating Segments | Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums	812	796	1,602	1,577
Fee revenues	0	1	2	2
Total revenues	812	797	1,604	1,579
Income (loss) before income taxes	47	24	62	22
Operating Segments | Personal Lines
Segment Reporting Information [Line Items]
Earned premiums	331	307	656	607
Fee revenues	2	1	3	3
Total revenues	333	308	659	610
Income (loss) before income taxes	(32)	(24)	(41)	(39)
Operating Segments | Excess and Surplus Lines Insurance
Segment Reporting Information [Line Items]
Earned premiums	57	52	113	100
Fee revenues	1	1	1	1
Total revenues	58	53	114	101
Income (loss) before income taxes	13	19	31	37
Operating Segments | Life Insurance Segment
Segment Reporting Information [Line Items]
Earned premiums	64	60	124	117
Fee revenues	1	1	2	3
Total revenues	65	61	126	120
Income (loss) before income taxes	8	4	10	4
Operating Segments | Investments Segment
Segment Reporting Information [Line Items]
Investment income, net of expenses	154	151	304	300
Investment gains and losses, net	105	(11)	(86)	149
Total revenues	259	140	218	449
Income (loss) before income taxes	235	117	170	403
Commercial Casualty | Operating Segments | Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums	272	271	537	536
Commercial Property | Operating Segments | Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums	231	226	459	449
Commercial Auto | Operating Segments | Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums	166	158	327	313
Workers' Compensation | Operating Segments | Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums	85	86	165	170
Other Commercial Lines | Operating Segments | Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums	58	55	114	109
Personal Auto | Operating Segments | Personal Lines
Segment Reporting Information [Line Items]
Earned premiums	153	144	304	285
Home Owner Segment | Operating Segments | Personal Lines
Segment Reporting Information [Line Items]
Earned premiums	139	128	275	253
Other Personal Lines | Operating Segments | Personal Lines
Segment Reporting Information [Line Items]
Earned premiums	$ 39	$ 35	$ 77	$ 69

Segment Information - Narrative

Segment Information - Narrative (Details)	6 Months Ended
	Jun. 30, 2018segmentindustry
Segment Reporting [Abstract]
Number of Industries Operating In | industry	2
Number of Reportable Segments | segment	5