Basis of Presentation of Interim Period Statements	3 Months Ended
Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation of Interim Period Statements	Note 1 - Basis of Presentation of Interim Period Statements The accompanying consolidated financial statements are unaudited and have been prepared by Barrett Business Services, Inc. (“Barrett”, “BBSI”, the “Company”, “our” or “we”), pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures typically included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the interim periods presented. The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results may differ from such estimates and assumptions. The consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s 2014 Annual Report on Form 10-K at pages F1 – F34. The results of operations for an interim period are not necessarily indicative of the results of operations for a full year. Revenue recognition We recognize revenue as services are rendered by our workforce. Professional employer (PEO) services are normally used by organizations to satisfy ongoing needs related to the management of human capital and are governed by the terms of a client services agreement with a minimum term of one year, which cover all employees at a particular work site. Our client services agreements are renewable on an annual basis and typically require 30 days’ written notice to cancel or terminate the contract by either party. Our client services agreements provide for immediate termination upon any default of the client regardless of when notice is given. We report PEO revenues on a net basis because we are not the primary obligor for the services provided by our co-employed clients to their customers pursuant to our client services agreements. Consequently, these service fee revenues represent the gross margin generated from our professional employer services after deducting the amounts invoiced to clients for direct payroll expenses such as salaries, wages, health insurance, employee out-of-pocket expenses incurred incidental to employment, and safety incentives. These amounts are also excluded from cost of revenues. Professional employer service fees also include amounts invoiced to our clients for employer payroll-related taxes and workers’ compensation coverage. Staffing services are engaged by customers to meet short-term and long-term personnel needs. Marketable securities As of March 31, 2015, the Company’s marketable securities consisted of tax-exempt municipal securities, U.S. Treasuries, variable rate demand notes (VRDN) and corporate bonds. The Company classifies municipal securities, U.S. Treasuries, VRDN and corporate bonds as available for sale; they are reported at fair value with unrealized gains and losses, net of taxes, shown as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Management considers available evidence in evaluating potential impairment of investments, including the duration and extent to which fair value is less than cost and the Company’s ability and intent to hold the investments. In the event a loss is determined to be other-than-temporary, the loss will be recognized in the statement of operations. Allowance for doubtful accounts The Company had an allowance for doubtful accounts of $241,000 and $291,000 at March 31, 2015 and December 31, 2014, respectively. The Company must make estimates of the collectability of accounts receivable for services provided to customers. Management analyzes historical bad debts, customer concentrations, customer credit-worthiness, current economic conditions, and changes in customers’ payment trends when evaluating the adequacy of the allowance for doubtful accounts. If the financial condition of our customers deteriorates, resulting in an impairment of their ability to make payments, additional allowances may be required. Workers’ compensation claims The Company is a self-insured employer with respect to workers’ compensation coverage for all of its employees (including employees co-employed through our client service agreements) working in Oregon, Maryland, Delaware and Colorado, except as described below. In the state of Washington, state law allows only the Company’s staffing services and internal management employees to be covered under the Company’s self-insured workers’ compensation program. Additionally, the Company operates a wholly owned fully licensed insurance company, Ecole Insurance Company (“Ecole”), in Arizona to provide workers’ compensation coverage to our employees in Arizona. Effective January 1, 2015, the Company no longer maintains a certificate to self-insure in the state of California and now maintains individual policies with ACE Group (“ACE”) for all California-based clients. The arrangement, typically known as a fronted program, provides BBSI a licensed, admitted insurance carrier in California to issue policies on behalf of BBSI without the intention of transferring any of the workers’ compensation risk for the first $5.0 million per claim. The risk of loss up to the first $5.0 million per claim is retained by BBSI through an indemnity agreement. While this portion of the risk of loss remains with BBSI, ACE assumes credit risk should BBSI be unable to satisfy its indemnification obligations to ACE. ACE also bears the economic burden for all costs in excess of $5.0 million per claim. The agreement is effective through January 2016 with the potential for continued annual renewals thereafter. The Company makes monthly payments into a trust account established between the Company and ACE related to the new ACE fronted insurance program to be set aside for the payment of future claims. The balance in the trust account was $78.0 million and $50.1 million at March 31, 2015 and December 31, 2014, respectively. The trust account balance is included as a component of the current and long-term restricted marketable securities and workers’ compensation deposits in the accompanying consolidated balance sheet. To manage our financial exposure, in the event of catastrophic injuries or fatalities, the Company maintains excess workers’ compensation insurance through our wholly owned captive insurance company, Associated Insurance Company for Excess (“AICE”), with a per occurrence retention of $5.0 million, except in Maryland and Colorado, where our per occurrence retention is $1.0 million and $2.0 million, respectively. AICE maintains excess workers’ compensation insurance coverage with ACE, between $5.0 million and $15.0 million per occurrence, except in Maryland, where coverage with ACE is between $1.0 million and $25.0 million per occurrence, and in Colorado, where the coverage with ACE is between $2.0 million and statutory limits per occurrence. The Company continues to evaluate the financial capacity of its insurers to assess the recoverability of the related insurer receivables. The Company has provided a total of $222.3 million and $216.0 million at March 31, 2015 and December 31, 2014, respectively, as an estimated future liability for unsettled workers’ compensation claims liabilities. The estimated liability for unsettled workers’ compensation claims represents management’s best estimate based upon an actuarial valuation provided by a third party actuary at March 31, 2015 and December 31, 2014. Included in the claims liabilities are case reserve estimates for reported losses, plus additional amounts based on projections for incurred but not reported claims and anticipated increases in case reserve estimates. Also included in these estimates are amounts for unallocated loss adjustment expenses, including legal costs. These estimates are continually reviewed and adjustments to liabilities are reflected in current operating results as they become known. Our workers’ compensation claims liabilities do not represent an exact calculation of liability, but instead represent management’s best estimate, generally utilizing actuarial expertise and projection techniques, at a given accounting date. The process of estimating unpaid claims and claim adjustment expense involves a high degree of judgment and is subject to a number of variables. These variables can be affected by both internal and external events such as changes in claims handling procedures, changes in individuals involved in the reserve estimation process, inflation, legal trends and legislative changes. Safety incentives liability Safety incentives represent cash incentives paid to certain client companies under client service agreements for maintaining safe-work practices in order to minimize workplace injuries. The Company has provided $15.5 million at March 31, 2015 and $14.2 million at December 31, 2014 as an estimate of the liability for unpaid safety incentives. The incentive is based on a percentage of annual payroll and is paid annually to customers who meet predetermined workers’ compensation claims cost objectives. Safety incentive payments are made only after closure of all workers’ compensation claims incurred during the customer’s contract period. The liability is estimated and accrued each month based upon contract year-to-date payroll and the then-current amount of the customer’s estimated workers’ compensation claims reserves as established by us and our third-party administrator, and the expected payout as determined by historical incentive payment trends. Safety incentive expense is netted against professional employer services revenue in our consolidated statements of operations. Statements of cash flows Interest paid during the three months ended March 31, 2015 and 2014 did not materially differ from interest expense. Income taxes received by the Company during the three months ended March 31, 2015 totaled $1.2 million compared to income taxes paid during the three months ended March 31, 2014 of $1.2 million. Accounting estimates The preparation of our consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Estimates are used for carrying values of marketable securities, allowance for doubtful accounts, deferred income taxes, carrying values for goodwill and property and equipment, accrued workers’ compensation liabilities and safety incentive liabilities. Actual results may or may not differ from such estimates.

Note 1 - Basis of Presentation of Interim Period Statements

The accompanying consolidated financial statements are unaudited and have been prepared by Barrett Business Services, Inc. (“Barrett”, “BBSI”, the “Company”, “our” or “we”), pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures typically included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the interim periods presented. The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results may differ from such estimates and assumptions. The consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s 2014 Annual Report on Form 10-K at pages F1 – F34. The results of operations for an interim period are not necessarily indicative of the results of operations for a full year.

Revenue recognition

We recognize revenue as services are rendered by our workforce. Professional employer (PEO) services are normally used by organizations to satisfy ongoing needs related to the management of human capital and are governed by the terms of a client services agreement with a minimum term of one year, which cover all employees at a particular work site. Our client services agreements are renewable on an annual basis and typically require 30 days’ written notice to cancel or terminate the contract by either party. Our client services agreements provide for immediate termination upon any default of the client regardless of when notice is given. We report PEO revenues on a net basis because we are not the primary obligor for the services provided by our co-employed clients to their customers pursuant to our client services agreements. Consequently, these service fee revenues represent the gross margin generated from our professional employer services after deducting the amounts invoiced to clients for direct payroll expenses such as salaries, wages, health insurance, employee out-of-pocket expenses incurred incidental to employment, and safety incentives. These amounts are also excluded from cost of revenues. Professional employer service fees also include amounts invoiced to our clients for employer payroll-related taxes and workers’ compensation coverage. Staffing services are engaged by customers to meet short-term and long-term personnel needs.

Marketable securities

As of March 31, 2015, the Company’s marketable securities consisted of tax-exempt municipal securities, U.S. Treasuries, variable rate demand notes (VRDN) and corporate bonds. The Company classifies municipal securities, U.S. Treasuries, VRDN and corporate bonds as available for sale; they are reported at fair value with unrealized gains and losses, net of taxes, shown as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Management considers available evidence in evaluating potential impairment of investments, including the duration and extent to which fair value is less than cost and the Company’s ability and intent to hold the investments. In the event a loss is determined to be other-than-temporary, the loss will be recognized in the statement of operations.

Allowance for doubtful accounts

The Company had an allowance for doubtful accounts of $241,000 and $291,000 at March 31, 2015 and December 31, 2014, respectively. The Company must make estimates of the collectability of accounts receivable for services provided to customers. Management analyzes historical bad debts, customer concentrations, customer credit-worthiness, current economic conditions, and changes in customers’ payment trends when evaluating the adequacy of the allowance for doubtful accounts. If the financial condition of our customers deteriorates, resulting in an impairment of their ability to make payments, additional allowances may be required.

Workers’ compensation claims

The Company is a self-insured employer with respect to workers’ compensation coverage for all of its employees (including employees co-employed through our client service agreements) working in Oregon, Maryland, Delaware and Colorado, except as described below. In the state of Washington, state law allows only the Company’s staffing services and internal management employees to be covered under the Company’s self-insured workers’ compensation program. Additionally, the Company operates a wholly owned fully licensed insurance company, Ecole Insurance Company (“Ecole”), in Arizona to provide workers’ compensation coverage to our employees in Arizona.

Effective January 1, 2015, the Company no longer maintains a certificate to self-insure in the state of California and now maintains individual policies with ACE Group (“ACE”) for all California-based clients. The arrangement, typically known as a fronted program, provides BBSI a licensed, admitted insurance carrier in California to issue policies on behalf of BBSI without the intention of transferring any of the workers’ compensation risk for the first $5.0 million per claim. The risk of loss up to the first $5.0 million per claim is retained by BBSI through an indemnity agreement. While this portion of the risk of loss remains with BBSI, ACE assumes credit risk should BBSI be unable to satisfy its indemnification obligations to ACE. ACE also bears the economic burden for all costs in excess of $5.0 million per claim. The agreement is effective through January 2016 with the potential for continued annual renewals thereafter.

The Company makes monthly payments into a trust account established between the Company and ACE related to the new ACE fronted insurance program to be set aside for the payment of future claims. The balance in the trust account was $78.0 million and $50.1 million at March 31, 2015 and December 31, 2014, respectively. The trust account balance is included as a component of the current and long-term restricted marketable securities and workers’ compensation deposits in the accompanying consolidated balance sheet.

To manage our financial exposure, in the event of catastrophic injuries or fatalities, the Company maintains excess workers’ compensation insurance through our wholly owned captive insurance company, Associated Insurance Company for Excess (“AICE”), with a per occurrence retention of $5.0 million, except in Maryland and Colorado, where our per occurrence retention is $1.0 million and $2.0 million, respectively. AICE maintains excess workers’ compensation insurance coverage with ACE, between $5.0 million and $15.0 million per occurrence, except in Maryland, where coverage with ACE is between $1.0 million and $25.0 million per occurrence, and in Colorado, where the coverage with ACE is between $2.0 million and statutory limits per occurrence. The Company continues to evaluate the financial capacity of its insurers to assess the recoverability of the related insurer receivables.

The Company has provided a total of $222.3 million and $216.0 million at March 31, 2015 and December 31, 2014, respectively, as an estimated future liability for unsettled workers’ compensation claims liabilities. The estimated liability for unsettled workers’ compensation claims represents management’s best estimate based upon an actuarial valuation provided by a third party actuary at March 31, 2015 and December 31, 2014. Included in the claims liabilities are case reserve estimates for reported losses, plus additional amounts based on projections for incurred but not reported claims and anticipated increases in case reserve estimates. Also included in these estimates are amounts for unallocated loss adjustment expenses, including legal costs. These estimates are continually reviewed and adjustments to liabilities are reflected in current operating results as they become known.

Our workers’ compensation claims liabilities do not represent an exact calculation of liability, but instead represent management’s best estimate, generally utilizing actuarial expertise and projection techniques, at a given accounting date. The process of estimating unpaid claims and claim adjustment expense involves a high degree of judgment and is subject to a number of variables. These variables can be affected by both internal and external events such as changes in claims handling procedures, changes in individuals involved in the reserve estimation process, inflation, legal trends and legislative changes.

Safety incentives liability

Safety incentives represent cash incentives paid to certain client companies under client service agreements for maintaining safe-work practices in order to minimize workplace injuries. The Company has provided $15.5 million at March 31, 2015 and $14.2 million at December 31, 2014 as an estimate of the liability for unpaid safety incentives. The incentive is based on a percentage of annual payroll and is paid annually to customers who meet predetermined workers’ compensation claims cost objectives. Safety incentive payments are made only after closure of all workers’ compensation claims incurred during the customer’s contract period. The liability is estimated and accrued each month based upon contract year-to-date payroll and the then-current amount of the customer’s estimated workers’ compensation claims reserves as established by us and our third-party administrator, and the expected payout as determined by historical incentive payment trends. Safety incentive expense is netted against professional employer services revenue in our consolidated statements of operations.

Statements of cash flows

Interest paid during the three months ended March 31, 2015 and 2014 did not materially differ from interest expense. Income taxes received by the Company during the three months ended March 31, 2015 totaled $1.2 million compared to income taxes paid during the three months ended March 31, 2014 of $1.2 million.

Accounting estimates

The preparation of our consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Estimates are used for carrying values of marketable securities, allowance for doubtful accounts, deferred income taxes, carrying values for goodwill and property and equipment, accrued workers’ compensation liabilities and safety incentive liabilities. Actual results may or may not differ from such estimates.