Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2018
Summary of Significant Accounting Policies [Abstract]
Description of Business	Description of Business: Protective Insurance Corporation (formerly Baldwin & Lyons, Inc.) (the "Company"), based in Carmel, Indiana, is a property-casualty insurer specializing in marketing and underwriting property, liability and workers compensation coverage for trucking and public transportation fleets, as well as coverage for trucking industry independent contractors. In addition, the Company offers workers' compensation coverage for a variety of operations outside the transportation industry. The Company operates as one reportable property and casualty insurance segment, offering a range of products and services, the most significant being commercial automobile and workers' compensation insurance products. Effective August 1, 2018, the Company changed its name to Protective Insurance Corporation to better align its operational and market identities to reflect its position within the transportation and workers' compensation insurance industry.
Basis of Presentation	Basis of Presentation: The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and do not include all of the information and notes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for fair presentation have been included. Interim financial statements should be read in conjunction with the Company's annual audited financial statements and other disclosures included in the Company's most recent Annual Report on Form 10-K. Operating results for interim periods are not necessarily indicative of results that may be expected for the year ending December 31, 2018 or any other future period.
Investments	Investments: Carrying amounts for fixed maturity securities represent fair value and are based on quoted market prices, where available, or broker/dealer quotes for specific securities where quoted market prices are not available. Equity securities are carried at quoted market prices (fair value). The Company accounts for investments in limited partnerships using the equity method of accounting, which requires an investor in a limited partnership to record its proportionate share of the limited partnership's net income. To the extent the limited partnerships include both realized and unrealized investment gains or losses in the determination of net income or loss, then the Company would also recognize, through its condensed consolidated statements of operations, its proportionate share of the investee's unrealized, as well as realized, investment gains or losses within net unrealized gains (losses) on equity securities and limited partnership investments. Short-term and other investments are carried at cost, which approximates their fair values. Realized gains and losses on disposals of investments are recorded on the trade date and are determined by the specific identification of the cost of investments sold and are included in income. Fixed maturity securities are considered to be available-for-sale. The related unrealized net gains or losses (net of applicable tax effects) on fixed maturity securities are reflected directly in shareholders' equity. Included within available-for-sale fixed maturity securities are convertible debt securities. A portion of the changes in the fair values of convertible debt securities is reflected as a component of net realized gains on investments, excluding impairment losses within the condensed consolidated statements of operations. Equity securities are recorded at fair value, with unrealized net gains or losses reflected as a component of net unrealized gains (losses) on equity securities and limited partnership investments within the condensed consolidated statements of operations. In accordance with the Financial Accounting Standards Board's ("FASB") other-than-temporary impairment guidance, if a fixed maturity security is in an unrealized loss position and the Company has the intent to sell the fixed maturity security, or it is more likely than not that the Company will have to sell the fixed maturity security before recovery of its amortized cost basis, the decline in value is deemed to be other-than-temporary and is recorded to other-than-temporary impairment losses on investments in the condensed consolidated statements of operations. For impaired fixed maturity securities that the Company does not intend to sell or in cases where it is more likely than not that the Company will not have to sell such securities, but the Company expects that it will not fully recover the amortized cost basis, the credit component of the other-than-temporary impairment is recognized in other-than-temporary impairment losses on investments in the condensed consolidated statements of operations and the non-credit component of the other-than-temporary impairment is recognized directly in shareholders' equity. The credit component of an other-than-temporary impairment is determined by comparing the net present value of projected future cash flows with the amortized cost basis of the fixed maturity security. The net present value is calculated by discounting the Company's best estimate of projected future cash flows at the appropriate effective interest rate.
Revenue Recognition	Revenue Recognition: For our non-fully-insured contracts, we had no material contract assets, contract liabilities or deferred contract costs recorded on our condensed consolidated balance sheet at September 30, 2018. For the three and nine months ended September 30, 2018, revenue recognized from performance obligations related to prior periods, such as due to changes in transaction price, was not material. For contracts that have an original expected duration of greater than one year, revenue expected to be recognized in future periods related to unfulfilled contractual performance obligations and contracts with variable consideration related to undelivered performance obligations was not material as of September 30, 2018.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements: In May 2014, the FASB issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (Topic 606), or ASU 2014-09, as amended by subsequently issued ASUs, to clarify the principles for recognizing revenue. While insurance contracts are not within the scope of this updated guidance, the Company's commission and fee income, other than that directly associated with insurance contracts, is subject to this updated guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The following steps are applied in the updated guidance: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which deferred the effective date of ASU 2014-09 to the first quarter of 2018. The Company adopted the new guidance as of January 1, 2018. The adoption of the new guidance did not have a material impact on the Company's condensed consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, or ASU 2016-01. The amendments in ASU 2016-01 changed the accounting for non-consolidated equity investments that are not accounted for under the equity method of accounting by requiring changes in fair value to be recognized in income. Previously, the Company's equity securities were classified as available-for-sale and changes in fair value were recognized in accumulated other comprehensive income (loss) as a component of shareholders' equity. ASU 2016-01 became effective for interim and annual reporting periods beginning after December 15, 2017. The Company adopted the new guidance as of January 1, 2018 using the modified retrospective approach and recorded a cumulative-effect adjustment to reclassify unrealized gains on equity securities of $71,012 ($46,157, net of tax) from other comprehensive income (loss) to retained earnings within the current period condensed consolidated balance sheet. Going forward, unrealized gains or losses on equity securities will be recognized in the condensed consolidated statements of operations within net unrealized gains (losses) on equity securities and limited partnership investments. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, or ASU 2016-15. This update addresses the presentation and classification on the statement of cash flows for eight specific items, with the objective of reducing existing diversity in practice in how certain cash receipts and cash payments are presented and classified. ASU 2016-15 became effective for interim and annual reporting periods beginning after December 15, 2017. The Company adopted the new guidance as of January 1, 2018. The adoption of the new guidance did not have a material impact on the Company's condensed consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. This update amends Accounting Standards Codification ("ASC") Topic 230 to add and clarify guidance on the classification and presentation of restricted cash in the statement of cash flows. The guidance requires entities to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The guidance was applied retrospectively and is effective for annual periods beginning after December 15, 2017, and interim periods within those years. The Company adopted the new guidance as of January 1, 2018 and reclassified $4.0 million of restricted cash as of December 31, 2017 to the beginning cash balance within the condensed consolidated statement of cash flows. The adoption of the new guidance did not have a material impact on the Company's condensed consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220). This ASU allows for the option to reclassify, from accumulated other comprehensive income (loss) to retained earnings, stranded tax effects resulting from the newly enacted federal corporate income tax rate in the Tax Cuts and Jobs Act of 2017 (the "U.S. Tax Act"), which was enacted on December 22, 2017. The legislation included a reduction to the corporate income tax rate from 35 percent to 21 percent effective January 1, 2018. The amount of the reclassification would be the difference between the historical corporate income tax rate and the newly enacted 21 percent corporate income tax rate. ASU 2018-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company adopted the new guidance in the first quarter of 2018 and recorded a cumulative-effect adjustment to reclassify the tax effects on fixed maturity investments of $117 from other comprehensive income (loss) to retained earnings within the current period condensed consolidated balance sheet.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements: In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), or ASU 2016-02. Upon the effective date, ASU 2016-02 will supersede the current lease guidance in ASC Topic 840, Leases. Under the new guidance, lessees will be required to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee's obligation to make lease payments arising from a lease, measured on a discounted basis. Concurrently, lessees will be required to recognize a right-of-use asset, which is an asset that represents the lessee's right to use, or control the use of, a specified asset for the lease term. The guidance provides for a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative periods presented in the financial statements. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements, which provides adopters an additional transition method by allowing entities to initially apply ASU 2016-02, and subsequent related standards, at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. These ASUs are effective for interim and annual reporting periods beginning after December 15, 2018, with early adoption permitted. The Company does not expect the adoption of ASU 2016-02 to have a material impact on the Company's consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, or ASU 2016-13. This update introduces a current expected credit loss model for measuring expected credit losses for certain types of financial instruments held at the reporting date based on historical experience, current conditions and reasonable supportable forecasts. ASU 2016-13 replaces the current incurred loss model for measuring expected credit losses, requires expected losses on available-for-sale debt securities to be recognized through an allowance for credit losses rather than as reductions in the amortized cost of the securities, and provides for additional disclosure requirements. ASU 2016-13 is effective for interim and annual reporting periods beginning after December 15, 2019, with early adoption permitted for interim and annual reporting periods beginning after December 15, 2018. The Company is currently evaluating the effects the adoption of ASU 2016-13 will have on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, or ASU 2017-04. This amendment removes Step 2 of the goodwill impairment test under current guidance. The new guidance requires an impairment charge to be recognized for the amount by which the carrying amount exceeds the reporting unit's fair value. ASU 2017-04 is effective for interim and annual reporting periods beginning after December 15, 2020, with early adoption permitted. The Company does not expect the adoption of ASU 2017-04 to have a material impact on its consolidated financial statements. In July 2018, the FASB issued ASU No. 2018-09, Codification Improvements. This update provides clarification, corrects errors in and makes minor improvements to the ASC within various ASC topics. Many of the amendments in this update have transition guidance with effective dates for annual periods beginning after December 15, 2018 and some amendments in this update do not require transition guidance and are effective upon issuance of this update. The Company will adopt amendments as they become applicable. The Company has determined the impact of these improvements will not be material to its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, or ASU 2018-13. This update removes the disclosure requirements for the amounts of and the reasons for transfers between Level 1 and Level 2 and disclosure of the policy for timing of transfers between levels. This update also removes disclosure requirements for the valuation processes for Level 3 fair value measurements. Additionally, this update adds disclosure requirements for the changes in unrealized gains and losses for recurring Level 3 fair value measurements and quantitative information for certain unobservable inputs in Level 3 fair value measurements. ASU 2018-13 is effective for interim and annual reporting periods beginning after December 15, 2019. The Company is currently evaluating the effects the adoption of ASU 2018-13 will have on its consolidated financial statements.

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.