Accounting Policies	9 Months Ended
Sep. 30, 2017
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 September 30, 2017, 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 2016 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 2016-07, Investments - Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-07, Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting. ASU 2016-07 eliminates the requirement to retroactively adjust an investment, results of operations, and retained earnings once an investment qualifies for use of the equity method. It requires the equity method investor to add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting without retroactive adjustment. The effective date of ASU 2016-07 was for interim and annual reporting periods beginning after December 15, 2016, and was applied prospectively. The company adopted this ASU effective January 1, 2017, and it did not have a material impact on our company's consolidated financial position, cash flows or results of operations. ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued ASU 2016-09, Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The effective date of ASU 2016-09 was for interim and annual reporting periods beginning after December 15, 2016. The recognition and classification of the excess tax benefit provisions were applied prospectively in the results of operations and statement of cash flows. This adoption resulted in excess tax benefits of an immaterial amount for the three months ended September 30, 2017, and $7 million for the nine months ended September 30, 2017, which reduced our current provision for income taxes in our results of operations. The statutory tax withholding classification, which are cash payments made to taxing authorities for shares withheld, were applied retrospectively and reclassified the statutory tax withholding requirements in the statement of cash flows from Other liabilities in operating activities to Other in financing activities. This statutory tax withholding reclassification resulted in $13 million and $11 million being included in financing activities for the nine months ended September 30, 2017 and 2016, respectively. There were no cumulative effect adjustments upon adoption of this ASU. Pending Accounting Updates ASU 2014-09 Revenue from Contracts with Customers In May 2014, the FASB issued 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 is for interim and annual reporting periods beginning after December 15, 2017. The ASU has not yet been adopted and will not have a material impact on our company’s 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 revises 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. Our results of operations will be impacted as changes in fair value of equity securities will be reported in net income instead of reported in other comprehensive income. The effective date of ASU 2016-01 is for interim and annual reporting periods beginning after December 15, 2017, and will be applied prospectively. The ASU has not yet been adopted. Had we adopted this ASU on September 30, 2017, $1.795 billion of after-tax unrealized gains on equity securities would have been reclassified from accumulated other comprehensive income to retained earnings. The actual amount reclassified upon adoption will vary depending on the future changes in fair value of our equity portfolio. 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. Management is currently evaluating the impact on our company’s consolidated financial position, cash flows and 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 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 ASU has not yet been adopted; however, it will 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. The effective date of ASU 2017-07 is for interim and annual reporting periods beginning after December 15, 2017. The ASU has not yet been adopted; however, it will not have a material 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 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 amendment should be applied on a prospective basis. The effective date of ASU 2017-09 is for interim and annual reporting periods, beginning after December 15, 2017. The ASU has not yet been adopted; however, it will not have a material impact on our company's consolidated financial position, cash flows or results of operations upon adoption.

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 September 30, 2017, 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 2016 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 2016-07, Investments - Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting

In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-07, Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting. ASU 2016-07 eliminates the requirement to retroactively adjust an investment, results of operations, and retained earnings once an investment qualifies for use of the equity method. It requires the equity method investor to add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting without retroactive adjustment. The effective date of ASU 2016-07 was for interim and annual reporting periods beginning after December 15, 2016, and was applied prospectively. The company adopted this ASU effective January 1, 2017, and it did not have a material impact on our company's consolidated financial position, cash flows or results of operations.

ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting

In March 2016, the FASB issued ASU 2016-09, Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The effective date of ASU 2016-09 was for interim and annual reporting periods beginning after December 15, 2016. The recognition and classification of the excess tax benefit provisions were applied prospectively in the results of operations and statement of cash flows. This adoption resulted in excess tax benefits of an immaterial amount for the three months ended September 30, 2017, and

$7 million for the nine months ended September 30, 2017, which reduced our current provision for income taxes in our results of operations. The statutory tax withholding classification, which are cash payments made to taxing authorities for shares withheld, were applied retrospectively and reclassified the statutory tax withholding requirements in the statement of cash flows from Other liabilities in operating activities to Other in financing activities. This statutory tax withholding reclassification resulted in $13 million and $11 million being included in financing activities for the nine months ended September 30, 2017 and 2016, respectively. There were no cumulative effect adjustments upon adoption of this ASU.

Pending Accounting Updates

ASU 2014-09 Revenue from Contracts with Customers

In May 2014, the FASB issued 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 is for interim and annual reporting periods beginning after December 15, 2017. The ASU has not yet been adopted and will not have a material impact on our company’s 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 revises 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. Our results of operations will be impacted as changes in fair value of equity securities will be reported in net income instead of reported in other comprehensive income. The effective date of ASU 2016-01 is for interim and annual reporting periods beginning after December 15, 2017, and will be applied prospectively. The ASU has not yet been adopted. Had we adopted this ASU on September 30, 2017, $1.795 billion of after-tax unrealized gains on equity securities would have been reclassified from accumulated other comprehensive income to retained earnings. The actual amount reclassified upon adoption will vary depending on the future changes in fair value of our equity portfolio.

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. Management is currently evaluating the impact on our company’s consolidated financial position, cash flows and 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 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 ASU has not yet been adopted; however, it will 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. The effective date of ASU 2017-07 is for interim and annual reporting periods beginning after December 15, 2017. The ASU has not yet been adopted; however, it will not have a material 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 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 amendment should be applied on a prospective basis. The effective date of ASU 2017-09 is for interim and annual reporting periods, beginning after December 15, 2017. The ASU has not yet been adopted; however, it will not have a material impact on our company's consolidated financial position, cash flows or results of operations upon adoption.