Document And Entity Information Research and development Note To Financial Statement Details Textual statementsignificantaccountingpoliciespolicies Operating expenses: statementnote2inventoriestables statementnote3restructuringtables statementnote4commitmentsandcontingentliabilitiestables statementnote5earningslosspersharetables statementnote7shareholdersequitytables us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue Stock based compensation expense related to restricted stock Amendment Flag us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements statementnote8businesssegmentstables statementnote2inventoriessummaryofinventoriesdetails statementnote3restructuringrestructuringchargesincludedinconsolidatedstatementsofoperationsdetails statementnote4commitmentsandcontingentliabilitieschangeswarrantyliabilitydetails statementnote5earningslosspersharereconciliationofbasicweightedaveragecommonsharesoutstandingtodilutedweightedaveragesharesoutstandingdetails statementnote7shareholdersequitysummaryofstockrepurchasedandretireddetails statementnote8businesssegmentssegmentreportinginformationdetails Notes To Financial Statements Notes To Financial Statements [Abstract] Document Fiscal Year Focus Document Fiscal Period Focus Document Period End Date Selling, general and administrative Credit Facility [Axis] Current Fiscal Year End Date Accruals for warranty Decrease (increase) in operating assets: Deferred income taxes, net us-gaap_EffectiveIncomeTaxRateContinuingOperations Effective Income Tax Rate Reconciliation, Percent Share-based Goods and Nonemployee Services Transaction, Supplier [Domain] Document Information [Line Items] Supplier [Axis] Document Information [Table] Wells Fargo, JPMorgan Chase Bank, N.A.and PNC Bank [Member] The lender party consisting of the following: Wells Fargo, JPMorgan Chase Bank, N.A. and PNC Bank. Entity Current Reporting Status Deposits from customers Entity Voluntary Filers Entity Filer Category Document Type us-gaap_DividendsCommonStock Dividends declared and paid ($0.05 per share) Swing Line Loans [Member] A contractual arrangement with a lender, classified as a swing line loan, under which borrowing can be made up to a specific amount at any point in time, and under which borrowings outstanding may be either short-term or long-term, depending upon the particulars. Series B Senior Note [Member] The bond classified as Series B that takes priority over other debt securities sold by the issuer. spar_LineOfCreditFacilityTermOfSuccessivePeriodsInRenewalOption Line of Credit Facility, Term of Successive Periods in Renewal Option The length of each successive period to which the reporting entity may renew a credit facility. spar_LineOfCreditFacilityNumberOfSuccessivePeriodsInRenewalOption Line of Credit Facility, Number of Successive Periods in Renewal Option The number of each successive period to which the reporting entity may renew a credit facility. Common stock, shares outstanding (in shares) us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash used in investing activities us-gaap_StockholdersEquity Total Spartan Motors, Inc. shareholders’ equity Entity Well-known Seasoned Issuer Cash flows from financing activities: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest Income (loss) before taxes us-gaap_InterestExpenseDebt Interest expense Dividends declared (in dollars per share) Statement of Financial Position [Abstract] us-gaap_LineOfCredit Long-term Line of Credit Aftermarket Parts and Accessories Sales [Member] Represents sales related to aftermarket parts and accessories. Fleet Vehicle Sales [Member] Represents sales related to fleet vehicles. April, 2016 [Member] Represents the share repurchase program authorized in April, 2016. Interest and other income (expense) Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities and of income (expense) related to nonoperating activities, classified as other. Campaign and Recalls Outside Programs [Member] Represents the change in pre-existing warrants on campaigns and recalls outside of normal warranty programs. October, 2011 [Member] Represents the share repurchased program authorized in October, 2011. us-gaap_IncreaseDecreaseInInventories Inventories Change in Esitmated Liability [Member] Represents the estimated change in pre-existing warranties. us-gaap_InventoryRecallExpense Inventory Recall Expense Revolving Credit Facility [Member] us-gaap_TableTextBlock Notes Tables Reclassification from Current Deferred Tax Assets to Noncurrent Deferred Tax Assets [Member] Represents the reclassification of current deferred tax assets to noncurrent deferred tax assets. Reclassification from Deferred Tax Liabilities to Noncurrent Deferred Tax Assets [Member] Represents the reclassification of deferred tax liabilities to noncurrent deferred tax assets. Statement [Table] Credit Facility [Domain] us-gaap_IncreaseDecreaseInIncomeTaxesReceivable Income taxes receivable Segments [Axis] Segments [Domain] Year Ended December 31, 2015 [Member] Represents the year ended December 31, 2015. Other Segments [Member] spar_IncreaseDecreaseInCurrentAssets Increase (Decrease) in Current Assets The amount of increase (decrease) in current assets. Restructuring charges, general and admininstrative Restructuring charges spar_IncreaseDecreaseInOtherAssets Increase (Decrease) in Other Assets The amount of increase (decrease) in assets classified as other. Statement of Stockholders' Equity [Abstract] Impairment of assets Income Statement [Abstract] us-gaap_IncreaseDecreaseInAccountsReceivable Accounts receivable Statement of Cash Flows [Abstract] Long-term Debt, Type [Domain] Long-term Debt, Type [Axis] us-gaap_IncreaseDecreaseInOperatingAssets Increase (Decrease) in Operating Assets us-gaap_IncreaseDecreaseInOtherOperatingAssets Other assets Diluted net earnings (loss) per share (in dollars per share) Increase (decrease) in operating liabilities: Basic net earnings (loss) per share (in dollars per share) Basic weighted average common shares outstanding (in shares) Anti-dilutive stock awards (in shares) Diluted weighted average common shares outstanding (in shares) Schedule of Product Warranty Liability [Table Text Block] us-gaap_RepaymentsOfLongTermDebt Payments on long-term debt us-gaap_OperatingExpenses Total operating expenses us-gaap_RepaymentsOfUnsecuredDebt Repayments of Unsecured Debt Long-term debt, less current portion Retained earnings us-gaap_LiabilitiesAndStockholdersEquity TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Revenues Warranties issued during the period Products and Services [Axis] Changes in liability for pre-existing warranties during the period, including expirations Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties Products and Services [Domain] us-gaap_ProductWarrantyAccrualPayments Cash settlements made during the period Legal Entity [Axis] us-gaap_IncreaseDecreaseInAccruedSalaries Accrued compensation and related taxes Entity Registrant Name Entity Central Index Key Entity [Domain] us-gaap_IncreaseDecreaseInAccountsPayable Accounts payable us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation Issuance of common stock and the tax impact of stock incentive plan transactions Proceeds from long-term debt Entity Common Stock, Shares Outstanding (in shares) us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures Issuance of restricted stock, net of cancellation us-gaap_LettersOfCreditOutstandingAmount Letters of Credit Outstanding, Amount us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation Issuance of common stock and the tax impact of stock incentive plan transactions (in shares) Fair Value by Liability Class [Domain] Liability Class [Axis] us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures Issuance of restricted stock, net of cancellation (in shares) us-gaap_IncreaseDecreaseInOperatingLiabilities Increase (Decrease) in Operating Liabilities us-gaap_IncreaseDecreaseInOtherOperatingLiabilities Other current liabilities and accrued expenses Segment Reporting Disclosure [Text Block] Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Trading Symbol Taxes on income us-gaap_RepaymentsOfLinesOfCredit Payments on credit facilities Other non-current liabilities spar_IncreaseDecreaseInAccruedStandardProductWarrantyLiability Cash paid for warranty repairs The increase (decrease) during the reporting period of the obligations incurred through that date and payable for the standard product warranty liability for the period. Does not include increases or decreases in an extended warranty liability. us-gaap_IncreaseDecreaseInCustomerDeposits Deposits from customers Purchase and retirement of common stock Borrowings under credit facilities spar_ExcessTaxBenefitExpenseFromSharebasedCompensationOperatingActivities Tax benefit related to stock incentive plan transactions Amount of cash outflow (inflow) for realized tax benefit (expense) related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes. Net cash used in the exercise, vesting or cancellation of stock incentive awards The total cash inflow (outflow) associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately. Shares purchased (in shares) Purchase and retirement of common stock (in shares) us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Financial Statement Filing Date [Domain] Report Date [Axis] Total restructuring Total restructuring charges included in Statements of Operations. Common Stock [Member] Manufacturing Process Reengineering [Member] Represents manufacturing process re-engineering. Current assets: Production Relocation Costs [Member] Represents information pertaining to production relocation costs. Equity Component [Domain] Inventory Impairment [Member] Represents information pertaining to inventory impairment. Equity Components [Axis] Other Specialty Vehicles [Member] Information pertaining to the other specialty vehicles segment. Motorhome Chassis [Member] Information pertaining to the motorhome chassis segment. us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease Net increase (decrease) in cash and cash equivalents Net income (loss) Net income (loss) Additional Paid-in Capital [Member] Schedule of Weighted Average Number of Shares [Table Text Block] Retained Earnings [Member] Taxes Accounts receivable, less allowance of $412 and $130 Emergency Response Vehicles [Member] Information pertaining to the emergency response vehicles segment. Delivery And Service Vehicles [Member] Delivery and service vehicles segment. Class of Stock [Axis] Specialty Chassis and Vehicles [Member] Information pertaining to the specialty chassis and vehicles segment. Accounts receivable, allowance Accrued compensation and related taxes Commitments and Contingencies Disclosure [Text Block] Noncontrolling Interest [Member] Non-controlling interest Schedule of Common Stock Repurchased and Retired [Table Text Block] Tabular disclosure for all common stock repurchased and retired during the period. Accounts payable us-gaap_PriorPeriodReclassificationAdjustment Prior Period Reclassification Adjustment Variable Rate [Domain] Variable Rate [Axis] Common stock, par value (in dollars per share) Federal Funds Effective Swap Rate [Member] Adjustments for New Accounting Pronouncements [Axis] Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Accrued warranty New Accounting Pronouncements, Policy [Policy Text Block] Type of Adoption [Domain] Preferred stock, shares issued (in shares) Work in process Raw materials and purchased components us-gaap_InventoryValuationReserves Reserve for slow-moving inventory Preferred stock, no par value: 2,000 shares authorized (none issued) Finished goods Preferred stock, par value (in dollars per share) us-gaap_OtherInventoryDemo Other Inventory, Demo, Gross Preferred stock, shares authorized (in shares) Other income (expense): Other current liabilities and accrued expenses Operating income (loss) Operating income (loss) us-gaap_GrossProfit Gross profit Accounting Standards Update 2015-17 [Member] us-gaap_LiabilitiesCurrent Total current liabilities us-gaap_PaymentsForRepurchaseOfCommonStock Purchase and retirement of common stock Common stock, $0.01 par value; 40,000 shares authorized; 34,419 and 34,271 outstanding us-gaap_DebtInstrumentTerm Debt Instrument, Term Less: net loss attributable to non-controlling interest us-gaap_InventoryWriteDown Inventory Write-down Restructuring charges Common stock, shares authorized (in shares) Accounting Policies [Abstract] Subsequent Event Type [Domain] Subsequent Event Type [Axis] us-gaap_PaymentsOfDividends Payment of dividends Share Repurchase Program [Domain] us-gaap_NonoperatingIncomeExpense Total other income (expense) spar_LineOfCreditFacilityPotentialIncreaseBorrowingCapacity Line of Credit Facility, Potential Increase Borrowing Capacity The potential increase in borrowing capacity under a credit facility. Statement [Line Items] Share Repurchase Program [Axis] Subsequent Event [Member] Subsequent Events [Text Block] us-gaap_PolicyTextBlockAbstract Accounting Policies One Month Adjusted LIBOR [Member] Variable rate for one month adjusted LIBOR. Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares) Stock Repurchase Program, Number of Shares Authorized to be Repurchased Cash flows from investing activities: us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash provided by (used in) operating activities us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities Total adjustments Cash flows from operating activities: Adjustments for Error Corrections [Axis] Scenario, Unspecified [Domain] Current portion of long-term debt Adjustments for Error Correction [Domain] Scenario [Axis] us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash used in financing activities spar_ExcesstaxbenefitPaymentFromForShareBasedCompensationFinancingActivities Cash related to tax impact of stock incentive plan transactions Amount of cash inflow or outflow from or for realized tax benefit related to deductible compensation cost reported on the entity's tax return for those instruments recognized for financial reporting purposes. Lender Name [Axis] Line of Credit Facility, Lender [Domain] Property, plant and equipment, net Goodwill Other assets Inventory Disclosure [Text Block] Effect of dilutive stock options (in shares) Schedule of Inventory, Current [Table Text Block] us-gaap_SharesIssued Balance (in shares) Balance (in shares) Income Tax Disclosure [Text Block] Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: Business Description and Accounting Policies [Text Block] Restructuring and Related Activities Disclosure [Text Block] Type of Restructuring [Domain] Restructuring Type [Axis] Stockholders' Equity Note Disclosure [Text Block] us-gaap_ProductWarrantyAccrual Balance of accrued warranty Balance of accrued warranty Depreciation and amortization us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges Gain on disposal of assets us-gaap_NetIncomeLoss Net income (loss) attributable to Spartan Motors Inc. us-gaap_Liabilities Total liabilities Cost of products sold Commitments and contingencies Inventories, net Total inventory us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest Balance Balance Total shareholders’ equity Segment assets TOTAL ASSETS Current liabilities: Restricted Stock [Member] Other current assets Antidilutive Securities, Name [Domain] Stock based compensation related to stock awards Employee Stock Option [Member] Antidilutive Securities [Axis] Additional paid in capital spar_IncreaseDecreaseInOtherOperatingLiabilitiesCustomerRebates Accrued customer rebates The net change during the reporting period in accrued customer rebates. GM [Member] Chassis bailment inventory agreement with General Motors Company (GM). Capital expenditures Purchases of property, plant and equipment Letter of Credit [Member] Income taxes receivable spar_PaymentsForPreviousAcquisitionFinancingActivities Payment of contingent consideration on acquisition Cash outflow representing an adjustment to the purchase price of a previous acquisition classified as financing activities. us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity us-gaap_LineOfCreditFacilityCapacityAvailableForTradePurchases Line of Credit Facility, Capacity Available for Trade Purchases Schedule of Segment Reporting Information, by Segment [Table Text Block] us-gaap_NumberOfReportableSegments Number of Reportable Segments Accrued customer rebates Aggregate carrying amount of rebates due to customers. us-gaap_AssetsCurrent Total current assets Shareholders' equity: Earnings Per Share [Text Block] Deferred income taxes Intangible assets, net Proceeds from sale of property, plant and equipment