Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2017
Summary of Significant Accounting Policies [Abstract]
Description of Business	Description of Business: Baldwin & Lyons, Inc. (the "Company"), based in Carmel, Indiana, is a specialty property-casualty insurer providing property, liability and workers compensation coverage for trucking and public transportation fleets, as well as coverage for trucking industry independent contractors. In addition, B&L 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. The Company determined that its business constituted one reportable property and casualty insurance segment as of January 1, 2017. During 2016 and prior years, the Company had two reportable segments – property and casualty insurance and reinsurance. The Company moved to a single reportable segment based on how its operating results are regularly reviewed by the Company's chief operating decision maker to make decisions about resources to be allocated to the segment and to assess its performance. The prior year segment information throughout this Annual Report on Form 10-K was updated to conform to the current year presentation.
Basis of Presentation	Basis of Presentation: The consolidated financial statements include the accounts of the Company and its wholly- owned subsidiaries. Inter-company transactions and accounts have been eliminated in consolidation.
Use of Estimates	Use of Estimates: Preparation of the consolidated financial statements requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results will differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents: The Company considers investments in money market funds to be cash equivalents. Carrying amounts for these instruments approximate their fair values.
Investments	Investments: Carrying amounts for fixed maturity securities represent fair value and are based on quoted market prices, when available, or broker/dealer quotes for specific securities when 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 that a limited partnership includes both realized and unrealized investment gains or losses in its determination of net income or loss, then the Company would also recognize, through its statements of operations, its proportionate share of the limited partnership's unrealized as well as realized investment gains or losses. 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, are determined by specific identification of cost of investments sold and are included in income. All fixed maturity and equity securities are considered to be available for sale; the related unrealized net gains or losses (net of applicable tax effect) are reflected directly in shareholders' equity. Included within available for sale fixed maturity securities are convertible debt securities. Portions of the changes in fair values of convertible debt securities are reflected as a component of net realized gains (losses) on investments. In accordance with the Financial Accounting Standard 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 net realized losses on investments in the 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 net realized losses on investments in the consolidated statements of operations and the non-credit component of the other-than-temporary impairment is recognized directly in shareholders' equity (accumulated other comprehensive income). 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. The unrealized net gains or losses (net of applicable tax effect) related to equity securities are reflected directly in shareholders' equity, unless a decline in value is determined to be other-than-temporary, in which case the loss is charged to income. In determining if and when a decline in market value below cost is other-than-temporary, an objective analysis is made of each individual security where current market value is less than cost. For any equity security where the unrealized loss exceeds 20% of original or adjusted cost, and where that decline has existed for six months, the decline is treated as an other-than-temporary impairment. Additionally, for any equity security where the decline has existed for a period of at least one year, the decline is treated as an other-than-temporary impairment. Additionally, the Company takes into account any known subjective information in evaluating for impairment, without consideration of the Company's quantitative criteria defined above, as well as the Company's intent and ability to retain the equity security for a period of time sufficient to allow for such recovery in fair value.
Property and Equipment	Property and Equipment: Property and equipment are carried at cost, less accumulated depreciation. Depreciation is computed principally by the straight-line method.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets: Goodwill is not amortized. Rather, it is tested for impairment in accordance with FASB guidance, at the reporting-unit level. Goodwill is tested annually (during the fourth quarter) or more often if events or circumstances, such as adverse changes in the business climate, indicate there may be impairment. No impairment was noted as a result of the 2017 impairment evaluation. Intangible assets determined to have finite lives, such as customer relationships and employment agreements, are amortized over their estimated useful lives in a manner that best reflects the economic benefits of the intangible asset. In addition, impairment testing is performed on these amortizing intangible assets if impairment indicators are noted.
Reserves for Losses and Loss Expenses	Reserves for Losses and Loss Expenses: The reserves for losses and loss expenses are determined using case basis evaluations and statistical analyses and represent estimates of the ultimate cost of all reported and unreported losses which are unpaid at year end. These reserves include estimates of future trends in claim severity and frequency and other factors which could vary as the losses are ultimately settled. While actual results will differ from such estimates, management believes that the reserves for losses and loss expenses are adequate. The estimates are continually reviewed and as adjustments to these reserves become necessary, such adjustments are reflected in current operations.
Recognition of Revenue and Costs	Recognition of Revenue and Costs: Premiums are earned over the period for which insurance protection is provided. A reserve for unearned premiums, computed by the daily pro-rata method, is established to reflect amounts applicable to subsequent accounting periods. Commissions to unaffiliated companies and premium taxes applicable to unearned premiums are deferred and expensed as the related premiums are earned. The Company does not defer acquisition costs, which are not directly variable with the production of premium. If it is determined that expected losses and deferred expenses will likely exceed the related unearned premiums, the asset representing deferred policy acquisition costs is reduced and an expense is charged against current operations to reflect any such premium deficiency. In the event that the expected premium deficiency exceeds deferred policy acquisition costs, an additional liability would be recorded with a corresponding expense to current operations for the amount of the excess premium deficiency. Anticipated investment income is considered in determining recoverability of deferred acquisition costs.
Reinsurance	Reinsurance: Reinsurance premiums, commissions, expense reimbursements and reserves related to the Company's reinsured business are accounted for on bases consistent with those used in accounting for the original policies issued and the terms of the reinsurance contracts. Premiums ceded to other insurers have been reported as a reduction of premium earned. Amounts applicable to reinsurance ceded for unearned premium and claim loss reserves have been reported as reinsurance recoverable assets. Certain reinsurance contracts provide for additional or return premiums and commissions based upon profits or losses to the reinsurer over prescribed periods. Estimates of additional or return premiums and commissions are adjusted quarterly to recognize actual loss experience to date, as well as projected loss experience applicable to the various contract periods. Estimates of reinstatement premiums on reinsurance contracts covering catastrophic events are, to the extent reasonably determinable, recorded concurrently with the related loss. Should impairment in the ability of a reinsurer to satisfy its obligations to the Company be determined to exist, current year operations would be charged in amounts sufficient to provide for the Company's additional liability. Such charges, when incurred, are included in other operating expenses, rather than losses and loss expenses incurred, since the inability of the Company to collect from reinsurers is a credit risk rather than a deficiency associated with the loss reserving process. The Company accounts for foreign and domestic reinsurance using the periodic method. Under the periodic method, premiums are recognized as revenue ratably over the contract term, and claims, including an estimate of claims incurred but not reported, are recognized as they occur.
Deferred Taxes	Deferred Taxes: Deferred income tax assets and liabilities are recognized for temporary differences between the financial statement and tax return bases of assets and liabilities based on enacted tax rates and laws. The deferred tax benefits of the deferred tax assets are recognized to the extent realization of such benefits is more likely than not. Deferred income tax expense or benefit generally represents the net change in deferred income tax assets and liabilities during the year. Current income tax expense represents the tax liability associated with revenues and expenses currently taxable or deductible on various income tax returns for the year reported.
Restricted Stock	Restricted Stock: Shares of restricted stock vest over the vesting period from the date of grant and certain shares of restricted stock are accelerated for retirement eligible recipients in accordance with the non-substantive, post-grant date vesting clause of Accounting Standards Codification ("ASC") Topic 715, Compensation-Retirement Benefits. Restricted stock is valued based on the closing price of the stock on the day the award is granted. Non-vested shares of restricted stock will be forfeited should an executive's employment terminate for any reason other than death, disability, or retirement as defined by the Compensation Committee (the "Compensation Committee") of the Board of Directors (the "Board") of the Company.
Earnings Per Share	Earnings Per Share: Diluted earnings per share of common stock are based on the average number of shares of Class A and Class B common stock outstanding during the year, adjusted for the dilutive effect, if any, of restricted stock awards outstanding. Basic earnings per share are presented exclusive of the effect of share-based awards outstanding.
Comprehensive Income	Comprehensive Income: The Company records accumulated other comprehensive income from unrealized gains and losses on available-for-sale securities and from foreign exchange adjustments as a separate component of shareholders' equity. A reclassification adjustment to other comprehensive income is made for gains or losses during the period included in net income.
Fair Value Measurements	Fair Value Measurements: The Company provides disclosures related to recurring and non-recurring fair value measurements with separate disclosures for the amounts of significant transfers in and out of Level 1 and Level 2 fair value measurements, along with an explanation for the transfers. Additionally, separate disclosures are provided for purchases, sales, issuances and settlements on a gross basis for Level 3 fair value measurements as well as additional clarification for both the level of disaggregation reported for each class of assets or liabilities and disclosures of inputs and valuation techniques used to measure fair value for both recurring and non-recurring fair value measurements for assets and liabilities categorized as Level 2 or Level 3.
Recent Accounting Pronouncements	Recent 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 quarter ending March 31, 2018. The Company will use the modified retrospective method upon adoption in 2018. The Company has completed its evaluation of the impact this guidance will have on its consolidated financial statements and has performed a technical assessment of material customer contracts and has concluded the adoption of ASU 2014-09 will not result in any material adjustments and it will not have a material impact on the Company's 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 change 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. Under current guidance, changes in fair value for investments of this nature were recognized in accumulated other comprehensive income as a component of shareholders' equity. Additionally, ASU 2016-01 simplifies the impairment assessment of equity investments without readily determinable fair values; requires entities to use the exit price when estimating the fair value of financial instruments; and modifies various presentation disclosure requirements for financial instruments. ASU 2016-01 became effective for interim and annual reporting periods beginning after December 15, 2017. The effect of this guidance will be dependent on the unrealized gains or losses associated with the Company's equity investments. Such unrealized gains or losses will be recognized upon adoption as a cumulative-effect adjustment to retained earnings with future unrealized gains or losses recognized in the statement of income. Refer to Note B for a discussion of unrealized gains and losses (before income taxes) on non-consolidated equity investments of $71,012 currently recognized in other comprehensive income (loss). 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. ASU 2016-02 is effective for interim and annual reporting periods beginning after December 15, 2018, with early adoption permitted. The guidance is required to be applied using 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. 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 August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. 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 is effective for interim and annual reporting periods beginning after December 15, 2017, with early adoption permitted. We are currently evaluating the effects the adoption of ASU 2016-15 will have on our consolidated statements of cash flows, if any. The Company does not expect ASU 2016-18 to impact our consolidated balance sheet or consolidated statement of income. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. This update amends 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 will be applied retrospectively and is effective for annual periods beginning after December 15, 2017, and interim periods within those years, with early adoption permitted. We are currently evaluating the effects the adoption of ASU 2016-18 will have on our consolidated statements of cash flows. The Company does not expect ASU 2016-18 to impact our consolidated balance sheet or consolidated statement of income. 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 guidance to have a material impact on its 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 ("AOCI") to retained earnings for 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. The Company is still evaluating the impacts of this standard on its consolidated financial statements but intends to make this reclassification.