Accelerated cash payment. Accelerated Cash Payment Accelerated cash payment Accelerated cash payment remaining amount. Accelerated Cash Payment Remaining Amount Accelerated cash payment, remaining amount Accounting Changes and Error Corrections [Abstract] Accounting Changes and Error Corrections [Abstract] Accounts Payable, Current Accounts payable Accounts Receivable, Net, Current Trade accounts receivable, net Accrued Income Taxes, Current Income taxes payable Accrued payroll, payroll taxes and related benefits liabilities current. Accrued Payroll Payroll Taxes And Related Benefits Liabilities Current Accrued payroll, payroll taxes and related benefits Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less accumulated depreciation and amortization Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) Accumulated other comprehensive loss AOCI Attributable to Parent [Member] Accumulated Other Comprehensive (Loss) Income [Member] Ace Group [Member] Ace Group [Member] ACE Group [Member] Additional Paid in Capital Additional paid-in capital Additional Paid in Capital, Common Stock Additional paid-in capital Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Adjustments for Error Correction [Domain] Adjustments for Error Correction [Domain] Adjustments Related to Tax Withholding for Share-based Compensation Common stock repurchased on vesting of restricted stock units Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Share based compensation expense Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Reconciliations of net income (loss) to net cash provided by operating activities: Reconciliations of net income to net cash provided by operating activities: Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Excess tax benefits from share-based compensation Age to participate in the savings plan. Age To Participate In Savings Plan Age to participate in the savings plan Air Transportation Equipment [Member] Aircraft [Member] Allocated Share-based Compensation Expense Stock-based compensation expense included in selling, general and administrative expenses Allocated Share-based Compensation Expense, Net of Tax Stock-based compensation expense related to stock options and restricted stock units, net of tax Allowance for Doubtful Accounts Receivable Allowance for doubtful accounts, ending balance Allowance for doubtful accounts, beginning balance Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Write-offs Write-offs of uncollectible accounts, net of recoveries Alternative Minimum Tax Credits [Member] Alternative Minimum Tax Credits [Member] Alternative Minimum Tax Credit Carry Forward [Member] Amendment Flag Amendment Flag Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Anti-dilutive common shares excluded from calculation of diluted loss per share Assets Total assets Total assets Assets [Abstract] ASSETS Assets, Current Total current assets Total current assets Assets, Current [Abstract] Current assets: Associated Insurance Company Excess [Member] Associated Insurance Company Excess [Member] AICE [Member] Available For Sale Restricted [Member] Available For Sale Restricted [Member] Available For Sale Restricted [Member] Available-for-sale Securities Marketable securities Available-for-sale Securities, Current Marketable securities Available-for-sale Securities [Member] Available-for-sale Securities [Member] Available-for-sale Securities, Noncurrent Marketable securities Available For Sale Unrestricted [Member] Available For Sale Unrestricted [Member] Available For Sale Unrestricted [Member] Award Type [Axis] Award Type [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Barrett Business Services Inc [Member] Barrett Business Services Inc [Member] Barrett Business Services Inc [Member] Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Basis of Presentation of Interim Period Statements [Line Items] Basis Of Presentation Of Interim Period Statements [Line Items] Basis Of Presentation Of Interim Period Statements [Line Items] Basis of Presentation of Interim Period Statements [Table] Basis Of Presentation Of Interim Period Statements [Table] Basis Of Presentation Of Interim Period Statements [Table] Building [Member] Buildings [Member] Business Combinations Policy [Policy Text Block] Business combinations CALIFORNIA California [Member] Capital Loss Carryforward [Member] Capital Loss Carry Forward [Member] Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents, end of year Cash and cash equivalents, beginning of year Cash and cash equivalents Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Cash And Cash Equivalents Maximum Maturity Period Cash And Cash Equivalents Maximum Maturity Period Cash and cash equivalents, maturity term Cash and Cash Equivalents [Member] Cash and Cash Equivalents [Member] Cash and Cash Equivalents, Period Increase (Decrease) Net decrease in cash and cash equivalents Net increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Cash and cash equivalents Cash flow information. Cash Flow Information Policy [Text Block] Statements of cash flows Certificates of Deposit [Member] Certificate of Deposit [Member] Changes in state tax benefit. Changes In State Tax Benefit Increase (decrease) in state tax benefit Claim payments. Claim Payments [Abstract] Claim payments related to: Claim payments prior period. Claim Payments Prior Period Prior years Claims expense accrual. Claims Expense Accrual [Abstract] Claims expense accrual: COLORADO Colorado [Member] Commitments and Contingencies Commitments and contingencies Commitments and contingencies (Notes 7, 9 and 13) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments Disclosure [Text Block] Commitments Common Stock, Capital Shares Reserved for Future Issuance Number of shares of common stock reserved for issuance under the 2015 Plan Common Stock, Dividends, Per Share, Cash Paid Cash dividends per common share Common Stock Market Prices [Abstract] Common Stock Market Prices [Abstract] Common stock market prices: Common stock market prices high. Common Stock Market Prices High High Common stock market prices low. Common Stock Market Prices Low Low Common Stock [Member] Common Stock [Member] Common Stock, Par or Stated Value Per Share Common stock, par value Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock, Value, Issued Common stock, $.01 par value; 20,500 shares authorized, 7,203 and 7,126 shares issued and outstanding Common stock, $.01 par value Common stock, $.01 par value; 20,500 shares authorized, 7,126 shares issued and outstanding Compensation and Retirement Disclosure [Abstract] Compensation and Retirement Disclosure [Abstract] Components of Deferred Tax Assets [Abstract] Gross deferred income tax assets: Components of Deferred Tax Liabilities [Abstract] Gross deferred income tax liabilities: Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive (loss) income Comprehensive income (loss) Comprehensive Income, Policy [Policy Text Block] Comprehensive income (loss) Computer Equipment [Member] Computer Hardware and Software [Member] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration Risk, Percentage Percentage of revenue attributable to geographic area Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Consecutive period of service following initial date of employment for saving plan valuation. Consecutive Period Of Service Following Initial Date Of Employment For Saving Plan Valuation Consecutive period to participate in the savings plan Consolidation, Policy [Policy Text Block] Principles of consolidation Corporate Bond Securities [Member] Corporate Bonds [Member] Cost of Revenue Cost of revenues Total cost of revenues Total cost of revenues Cost of Revenue [Abstract] Cost of revenues: Cost of Sales, Policy [Policy Text Block] Cost of revenues Cost of Services, Direct Labor Direct payroll costs Cost of Services, Direct Taxes and Licenses Costs Payroll taxes and benefits Cost of services workers compensation. Cost Of Services Workers Compensation Workers' compensation Workers' compensation expense Credit Agreement [Member] Credit Agreement [Member] Agreement [Member] Credit Concentration Risk [Member] Credit Concentration Risk [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Current Assets [Member] Current Assets [Member] Current Assets [Member] Current Federal Tax Expense (Benefit) Federal Current Fiscal Year End Date Current Fiscal Year End Date Current Income Tax Expense (Benefit) Current income tax expense Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current: Current State and Local Tax Expense (Benefit) State The noncurrent portion of money or property received from customers that is to be returned upon satisfactory contract completion or as partial prepayment for goods or services to be provided in the future and Aggregate carrying amount, as of the balance sheet date, of noncurrent obligations not separately disclosed in the balance sheet. Noncurrent liabilities are expected to be paid after one year (or the normal operating cycle, if longer). Customer Deposits And Other Long Term Liabilities Customer deposits and other long-term liabilities Customer deposits. Customer Deposits Policy [Text Block] Customer deposits Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Text Block] Revolving Credit Facility and Long-Term Debt Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Basis Spread on Variable Rate LIBOR plus rate Long-term Debt, Gross Outstanding balance on term loan and revolving credit facility Debt Instrument, Convertible, Conversion Ratio Funded debt to EBITDA ratio Debt Instrument Covenant Maximum Capital Expenditure Threshold Year One Debt Instrument Covenant Maximum Capital Expenditure Threshold Year One Maximum amount of capital expenditures in 2015 Debt Instrument Covenant Maximum Capital Expenditure Threshold Year Two Debt Instrument Covenant Maximum Capital Expenditure Threshold Year Two Maximum amount of capital expenditures in 2016 Debt Instrument Fair Value Carrying Value [Abstract] Debt Instrument Fair Value Carrying Value [Abstract] Debt Instrument Fair Value Carrying Value [Abstract] Debt Instrument, Interest Rate Terms Term loan from Bank, Interest rate description Debt Instrument Maturities Period Debt Instrument Maturities Period Restricted marketable securities maturity period Debt Instrument, Maturity Date Term loan maturity date Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Debt Instrument, Periodic Payment, Principal Term loan payment Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period One [Member] Due On June 30, 2016 [Member] Debt Instrument, Redemption, Period Three [Member] Due On December 31, 2016 [Member] Debt Instrument, Redemption, Period Two [Member] Due On September 30, 2016 [Member] Deferred Federal Income Tax Expense (Benefit) Federal Deferred Income Tax Expense (Benefit) Deferred income taxes Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Deferred: Deferred income tax expense benefit including other comprehensive income tax adjustments. Deferred Income Tax Expense Benefit Including Other Comprehensive Income Tax Adjustments Deferred income taxes Deferred Tax Liabilities, Gross Deferred Tax Liabilities, gross total Deferred State and Local Income Tax Expense (Benefit) State Deferred Tax Assets, Gross Deferred tax assets, gross total Deferred Tax Assets, Net Net deferred income tax assets Deferred Tax Assets, Net, Current Deferred income taxes Deferred tax assets medical cost containment fees accruals. Deferred Tax Assets Medical Cost Containment Fees Accruals MCC accrual Deferred Tax Assets, Net of Valuation Allowance Deferred tax assets, net total Deferred Tax Assets, Operating Loss Carryforwards, State and Local State loss carryforward Deferred Tax Assets, Other Other Deferred Tax Assets, Tax Credit Carryforwards State credit carryforward Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax Alternative minimum tax credit carryforward Deferred Tax Assets, Tax Credit Carryforwards, General Business Workers' opportunity tax credit and EZ credit carryforward Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Equity based compensation Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts Allowance for doubtful accounts Deferred tax assets tax deferred expense reserves and accruals safety incentives payable. Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Safety Incentives Payable Safety incentives payable Deferred tax assets tax deferred expense reserves and accruals workers compensation claims. Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Workers Compensation Claims Workers' compensation claims liabilities Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross Tax effect of unrealized losses, net Deferred Tax Assets, Valuation Allowance Less valuation allowance Valuation allowance of state tax benefits not expected to be utilized Deferred Tax Liabilities, Goodwill Tax amortization of goodwill Deferred Tax Liabilities, Net, Noncurrent Deferred income taxes Deferred Tax Liabilities, Other Other Deferred Tax Liabilities, Property, Plant and Equipment Tax depreciation in excess of book depreciation Defined contribution employee contribution percent. Defined Contribution Employee Contribution Percent Employee's contributions Defined Contribution Plan, Employer Discretionary Contribution Amount Discretionary Company contributions Defined contribution plan employer matching contribution amount. Defined Contribution Plan Employer Matching Contribution Amount Matching contributions Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Contributions by management Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Percentage of each participating employee annual compensation Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock Incentive Plans Dividends, Common Stock, Cash Cash dividends on common stock Dividends Payable, Amount Per Share Cash dividend Document and Entity Information [Abstract] Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Period End Date Document Period End Date Document Type Document Type Earnings Per Share, Basic Basic earnings (loss) per common share Basic (loss) earnings per common share Basic (loss) earnings per share Earnings Per Share, Diluted Diluted earnings (loss) per common share Diluted (loss) earnings per common share Diluted (loss) earnings per share Earnings Per Share, Policy [Policy Text Block] Basic and diluted earnings per share Ecole insurance company. Ecole Insurance Company [Member] Ecole Insurance Company [Member] Effective Income Tax Rate Reconciliation, Percent Total Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Statutory federal tax rate Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Valuation allowance on capital loss carryforward and state tax credit carryforward Effective income tax rate reconciliation non deductible expenses and other net. Effective Income Tax Rate Reconciliation Non Deductible Expenses And Other Net Nondeductible expenses and other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Adjustment for final positions on filed returns Effective income tax rate reconciliation state taxes net of federal benefit. Effective Income Tax Rate Reconciliation State Taxes Net Of Federal Benefit State taxes, net of federal benefit Effective income tax rate reconciliation, tax credit, other adjustments. Effective Income Tax Rate Reconciliation, Tax Credit, Other Adjustments Other, net Effective Income Tax Rate Reconciliation, Tax Credit, Percent Federal and state tax credits Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent Federal tax-exempt interest income Effect of Fourth Quarter Events [Line Items] Effect of Fourth Quarter Events [Line Items] Employee contribution portion of annual compensation. Employee Contribution Portion Of Annual Compensation Additional annual compensation Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unrecognized compensation expense related to stock options and restricted stock units Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Weighted average period Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options Deferred income taxes Entity Central Index Key Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Current Reporting Status Entity Current Reporting Status Entity [Domain] Entity [Domain] Entity Filer Category Entity Filer Category Entity Public Float Entity Public Float