Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Axis] Fixed income securities [Member] Equity Securities [Member] Cash and Cash Equivalents [Member] Statement, Equity Components [Axis] Common Stock [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income, Net of Income Taxes [Member] Non-controlling Interest [Member] Property, Plant and Equipment, Type [Axis] Furniture and Fixtures [Member] Range [Axis] Minimum [Member] Maximum [Member] Major Types Of Debt and Equity Securities [Axis] U.S. Government and agencies [Member] Obligations of states and political subdivisions [Member] Corporate securities [Member] Fair Value, Hierarchy [Axis] Level I [Member] Level II [Member] Level III [Member] Attributable to Non-Controlling Interest [Member] Attributable to NI Holdings, [Member] Segments [Axis] Multi-Peril Crop and Hail [Member] Non Standard Auto [Member] Other property and casualty coverages [Member] Legal Entity [Axis] Battle Creek [Member] Real estate [Member] Electronic data processing equipment [Member] Furniture and fixtures [Member] Automobiles [Member] Residential mortgage-backed securities [Member] Commercial mortgage-backed securities [Member] Asset backed securities [Member] Basic materials [Member] Communications [Member] Consumer, cyclical [Member] Consumer, non-cyclical [Member] Energy [Member] Financial [Member] Industrial [Member] Technology [Member] Related Party [Axis] NDFB [Member] Unearned Employee Stock Ownership Plan Shares [Member] Nodak Insurance [Member] Equity Method Investee, Name [Axis] Treasury Stock [Member] Document and Entity Information [Abstract] Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Document Type Amendment Flag Entity Current Reporting Status Entity Public Float Entity Well-known Seasoned Issuer Document Period End Date Document Fiscal Period Focus Document Fiscal Year Focus Entity Voluntary Filers Statement of Financial Position [Abstract] Assets: Cash and cash equivalents Fixed income securities, at fair value Equity securities, at fair value Other investments Total cash and investments Premiums and agents' balances receivable Deferred policy acquisition costs Reinsurance premiums receivable Reinsurance recoverables on losses Accrued investment income Property and equipment Receivable from Federal Crop Insurance Corporation Goodwill Federal income tax recoverable Other assets Total assets Liabilities: Unpaid losses and loss adjustment expenses Unearned premiums Reinsurance payable Deferred income taxes, net Accrued expenses and other liabilities Commitments and Contingencies Total liabilities Equity: Common stock, $0.01 par value, authorized 25,000,000 shares, issued: 2017 - 23,000,000 shares, 2016 - none; and outstanding: 2017 - 22,313,329 shares, 2016 - none Preferred stock, without par value, authorized 5,000,000 shares, no shares issued or outstanding Additional paid-in capital Unearned employee stock ownership plan shares Retained earnings Accumulated other comprehensive income, net of income taxes Treasury stock, at cost, 2017 - 446,671 shares, 2016 - none Non-controlling interest Total equity Total liabilities and equity Common stock, par value Common stock, shares authorized Common stock, shares issued Common stock, shares outstanding Preferred stock, shares authorized Preferred stock, shares issued Preferred stock, shares outstanding Treasury stock, shares Income Statement [Abstract] Revenues: Net premiums earned Fee and other income Net investment income Net realized capital gain on investments Total revenues Expenses: Losses and loss adjustment expenses Amortization of deferred policy acquisition costs Other underwriting and general expenses Total expenses Income (loss) before income taxes Income taxes Net income (loss) Net income (loss) attributable to non-controlling interest Net income (loss) attributable to NI Holdings, Inc. Earnings per common share: Weighted average shares outstanding Basic and diluted net income (loss) per share Statement [Table] Statement [Line Items] Equity Components [Axis] Net income (loss) Other comprehensive income (loss), before income taxes: Holding gains on investments Reclassification adjustment for net realized capital loss (gain) included in net income Other comprehensive income (loss), before income taxes Income tax benefit (expense) related to items of other comprehensive income Other comprehensive income (loss), net of income taxes Comprehensive income (loss) Beginning Balance Issuance of common stock Net income Dividends paid Other comprehensive income, net of income taxes Purchase of treasury stock Ending Balance Statement of Cash Flows [Abstract] Cash Flows from Operating Activities: Adjustments to reconcile net income to net cash provided by operating activities: Net realized capital gain on investments Deferred income tax expense (benefit) Depreciation of property and equipment Amortization of intangibles Amortization of deferred policy acquisition costs Deferral of policy acquisition costs Net amortization of premiums and discounts on investments Changes in assets and liabilities which provided (used) cash: Premiums and agents' balances receivable Reinsurance premiums receivable Reinsurance recoverables on losses Accrued investment income Receivable from Federal Crop Insurance Corporation Federal income tax recoverable Other assets Unpaid losses and loss adjustment expenses Unearned premiums Reinsurance payables Accrued expenses and other liabilities Net cash used in operating activities Cash flows from investing activities: Proceeds from sales of fixed income securities Proceeds from sales of equity securities Purchases of fixed income securities Purchases of equity securities Purchases of property and equipment, net Other Net cash (used in) provided by investing activities Cash flows from financing activities: Proceeds from issuance of common stock Purchases of treasury stock Loan to employee stock ownership plan Proceeds from bank overdraft Net cash provided by financing activities Net decrease in cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization Basis of Presentation Accounting Policies [Abstract] Summary of Significant Accounting Policies Summary of Recent Accounting Pronouncements Marketable Securities [Abstract] Investments Investments, All Other Investments [Abstract] Fair Value Measurements Reinsurance Disclosures [Abstract] Reinsurance Deferred Policy Acquisition Costs Disclosures [Abstract] Deferred Policy Acquisition Costs Liability for Unpaid Claims and Claims Adjustment Expense, Activity in Liability [Abstract] Unpaid Losses and Loss Adjustment Expenses Property, Plant and Equipment [Abstract] Property and Equipment Earnings Per Share [Abstract] Earnings Per Share Related Party Transactions [Abstract] Related Party Transactions Compensation Related Costs [Abstract] Benefit Plans Debt Disclosure [Abstract] Line of Credit Income Tax Disclosure [Abstract] Income Taxes Leases, Operating [Abstract] Operating Leases Commitments and Contingencies Disclosure [Abstract] Contingencies Segment Reporting [Abstract] Segment Information Subsequent Events [Abstract] Subsequent Events Organization and Business Basis of Consolidation Use of Estimates Variable-Interest Entities Cash and Cash Equivalents Investments Fair Value of Other Financial Instruments Reclassifications Revenue Recognition Policy Acquisition Costs Property and Equipment Losses and Loss Adjustment Expenses Income Taxes Credit Risk Reinsurance Goodwill and Other Intangible Assets Schedule of amortized cost and estimated fair value of securities Schedule of amortized cost and fair value of fixed income securities by contractual maturity Schedule of unrealized loss of securities Schedule of net investment income Schedule of net realized gain (loss) on investments Schedule of Financial Instruments at Fair Value Measured on a Recurring Basis Schedule of Financial Assets and Liabilities at Fair Value Schedule of reconciliation of direct to net premiums on both a written and an earned basis Schedule of reconciliation of direct to net losses and loss adjustment expenses Schedule of deferred policy acquisition costs Schedule of Activity in the liability for unpaid losses and loss adjustment expenses Schedule of Incurred Claims and Allocated Claim Adjustment Expenses, Net of Reinsurance Schedule of reconciliation of the net incurred and paid claims development Schedule of required supplementary information about average historical claims duration Schedule of Property and equipment Schedule of illustrates the impact of consolidating Battle Creek into our consolidated balance sheets prior to intercompany eliminations Schedule of revenue by insurance product line Percentage of shares exchanged Percentage of quota share agreement Investment, Name [Axis] Ownership percentage Other invested assets Federal Deposit Insurance Corporation amount Short-term investment balances in investment that are insured by SIPC Advertising Costs Investment Type [Axis] Investments [Abstract] Fixed income securities with a fair value Impairment of investments Number of securities Percentage of fixed maturities amortized cost values Major Types of Debt and Equity Securities [Axis] Cost or Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost, Due to mature One year or less Amortized Cost, Due to mature After one year through five years Amortized Cost, Due to mature After five years through ten years Amortized Cost, Due to mature After ten years Amortized Cost, Due to mature Mortgage/asset-backed securities Available-for-sale Securities, Debt Maturities, Amortized Cost Fair Value, Due to mature One year or less Fair Value, Due to mature After one year through five years Fair Value, Due to mature After five years through ten years Fair Value, Due to mature After ten years Fair Value, Due to mature Mortgage/asset-backed securities Available-for-sale Securities, Debt Securities, Estimated Fair Value Less than 12 months Fair Value Less than 12 months Unrealized Losses Greater than 12 months Fair Value Greater than 12 months Unrealized Losses Fair Value, Total Unrealized Losses, Total Total gross investment income Investment expenses Net investment income Gross realized gains Gross realized losses, excluding other than temporary impairment losses Other than temporary impairment losses Net realized capital gains on investments Total fixed income securities Total equity securities Total assets at fair value Reinsurance Retention Policy, Amount Retained Reinsurance Retention Policy, Excess Retention, Amount Reinsured Retained risk amount Catastrophic retention amount increased Ceded reinsurance commission percentage Premiums Written Direct premium Assumed premium Ceded premium Net premiums Premiums Earned Direct premium Assumed premium Ceded premium Net premiums Percentage of assumed premium to net earned premium Direct losses and loss adjustment expenses Assumed losses and loss adjustment expenses Ceded losses and loss adjustment expenses Net losses and loss adjustment expenses Balance, beginning of period Deferral of policy acquisition costs Amortization of deferred policy acquisition costs Balance, end of period Liability for unpaid losses and loss adjustment expense Reinsurance ceded Net balance at beginning of year Tri-State Acquisition Liability for unpaid loss and LAE Reinsurance ceded Net liability assumed Incurred related to: Current year Prior years Total Incurred Paid related to: Current year Prior years Total paid Liability for unpaid losses and loss adjustment expense Reinsurance ceded Net balance at end of period Cost: Accumulated depreciation Total property and equipment, net Estimated Useful Life Depreciation expense Average number of common shares outstanding Net common shares outstanding Purchased shares of common stock Repurchased, value Authorized amount Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Line Items] Royalties Accrued royalties Related party revenues Related party expenses Cash and cash equivalents (overdraft) Investments Premiums and agents' balances receivable Reinsurance premiums receivable (eliminated in consolidation) Reinsurance recoverables on losses (eliminated in consolidation) Deferred income tax asset, net Notes payable (eliminated in consolidation) Accrued expenses and other liabilities Company's Total contribution to the money purchase plan Employee contribution in percentage Company's total contributions to the 401(k) plan Funds deposited in deferred compensation Line of credit with Wells Fargo Line of credit expiration date Net operating loss carryover Net capital loss carryovers Net capital loss carryovers expired Expiration date Unrecognized tax benefits Interest and penalties Operating lease expenses Minimum future payments under these non-cancellable leases Lease expiration date Net premium earned Fee and other income Net realized capital gains on investments Total revenues American Life and Security Corporation [Member] American West [Member] Amortized Cost, Due to mature Mortgage/asset-backed securities. Fair Value, Due to mature Mortgage/asset-backed securities. Basic materials [Member] Battle Creek [Member] Bellingham Wash [Member] Capital Reserve Life Insurance Company [Member] Ceded reinsurance commission percentage. Communications [Member] Consumer, cyclical [Member] Consumer, non-cyclical [Member] David Elmore [Member] Elimination Of TPA Fees [Member] Energy [Member] Fee and other income. Financial [Member] First Wyoming Life Insurance Company [Member] Great Plains Financial Corporation [Member] Hot Dot, Inc [Member] Hot Dot [Member] Income tax expense related to items of other comprehensive income. Industrial [Member] Intra State Offering [Member] Investment Grade [Member] Investment Income Less Investment Expenses Net liability assumed. Reinsurance ceded. Life Insurance Force [Member] Longview Washington Refunding Taxable [Member] Losses and loss adjustment expenses policy. Represents information pertaining to Maricopa County Arizona School District No. 31 . Memphis Tenn [Member] Multi-peril crop and hail [Member] New York State Taxable Series [Member] Non-Investment Grade [Member] Non-standard auto [Member] NDFB [Member] Represents information pertaining to Northern Plains. Northstar Financial Corporation [Member] Old Reliance [Member] Optimum Reinsurance Company [Member] Organization and business policy. Other Long Term Investments [Member] Other property and casualty coverages [Member] Other Property and Casualty [Member] Represents information pertaining to Pacific Northwest Capital Corporation. Percentage of fixed maturities amortized cost values. Philadelphia PA Auth For Indl Dev City Svc Agreementl [Member] Philadelphia Pa Authority For Industrial [Member] Primero [Member] Riviera Beach FLA Pub Impt Rev [Member] Sagicor Life Insurance Company [Member] Tabular disclosure of reconciliation of direct to net losses and loss adjustment expenses. Security Capital Corporation [Member] Security National Life Insurance Company [Member] States and Political Subdivisions General Obligations [Member] States and Political Subdivisions Special Revenue [Member] Stock Subscription Receivable Member Surplus Notes [Member] Represents information pertaining to surplus note one. Represents information pertaining to surplus note two. Technology [Member] Tri-State, Ltd. [Member] Unearned Employee Stock Ownership Plan Shares [Member] Increase decrease in Reinsurance receivables. Nodak Insurance [Member] Percentage of shares exchanged. Percentage of quota share agreement. Retained risk amount. Catastrophic retention amount increased. Funds deposited in deferred compensation. The amount of depreciation or (credit) during the period for property, plant and equipment. Reinsurance recoverables on losses. The value of cash and cash equivalents or overdraft as of the reporting date. The cash outflow during the period for a loan to the employee stock ownership plan. Amount of written premiums ceded to other entities, includes both credits and debits. Investments and Cash Assets Liabilities Unearned ESOP Shares Treasury Stock, Value Stockholders' Equity Attributable to Parent Liabilities and Equity Operating Expenses Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Net Income (Loss) Attributable to Parent Gain (Loss) on Investments, Excluding Other than Temporary Impairments Increase (Decrease) in Deferred Income Taxes Deferred Policy Acquisition Costs, Amortization Expense Accretion (Amortization) of Discounts and Premiums, Investments Increase (Decrease) in Receivables Increase (Decrease) in Reinsurance Recoverable ReinsuranceRecoverablesOnLosses Increase (Decrease) in Accrued Investment Income Receivable IncreaseDecreaseInReinsuranceReceivables Increase (Decrease) in Income Taxes Receivable Increase (Decrease) in Other Operating Assets Increase (Decrease) in Liability for Claims and Claims Adjustment Expense Reserve Increase (Decrease) in Unearned Premiums Increase (Decrease) in Accrued Liabilities and Other Operating Liabilities Net Cash Provided by (Used in) Operating Activities Payments to Acquire Available-for-sale Securities, Debt Payments to Acquire Available-for-sale Securities, Equity Payments to Acquire Property, Plant, and Equipment Payments for (Proceeds from) Other Investing Activities Net Cash Provided by (Used in) Investing Activities Payments for Repurchase of Equity LoanCreditFromEmployeeStockOwnershipPlan Net Cash Provided by (Used in) Financing Activities Cash and Cash Equivalents, Period Increase (Decrease) Investment, Policy [Policy Text Block] Property, Plant and Equipment, Policy [Policy Text Block] Income Tax, Policy [Policy Text Block] Reinsurance Accounting Policy [Policy Text Block] Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale Debt Securities, Amortized Cost Basis Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Investment Income Less Investment Expenses Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments Premiums Written, Net Direct Premiums Earned Assumed Premiums Earned Ceded Premiums Earned Policyholder Benefits and Claims Incurred, Ceded Liability for Claims and Claims Adjustment Expense Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Liability for Unpaid Claims and Claims Adjustment Expense, Net Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment CashAndCashEquivalentsOverdraft Investments [Default Label] Premiums Receivable, Gross Accrued Liabilities and Other Liabilities Pacific Northwest Capital Corporation [Member]