Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	The unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC regarding interim financial reporting. Accordingly, certain information and footnotes normally required by accounting principles generally accepted in the United States of America (“GAAP”) for complete financial statements have been condensed or omitted pursuant to those rules and regulations, although Kforce believes that the disclosures made are adequate to make the information not misleading. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in our 2016 Annual Report on Form 10-K. In management’s opinion, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting of only normal recurring adjustments) considered necessary for a fair presentation. The Unaudited Condensed Consolidated Balance Sheet as of December 31, 2016 was derived from our audited Consolidated Balance Sheet as of December 31, 2016, as presented in our 2016 Annual Report on Form 10-K. Our quarterly operating results are affected by the number of billing days in a quarter and the seasonality of our customers’ businesses. In addition, we experience an increase in direct costs of services and a corresponding decrease in gross profit in the first fiscal quarter of each year as a result of certain U.S. state and federal employment tax resets. Thus, the results of operations for any interim period may be impacted by these factors and are not necessarily indicative of, nor comparable to, the results of operations for a full year.
Principles of Consolidation	The unaudited condensed consolidated financial statements include the accounts of Kforce Inc. and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. References in this document to “the Registrant,” “Kforce,” “the Company,” “we,” “the Firm,” “our” or “us” refer to Kforce Inc. and its subsidiaries, except where the context indicates otherwise.
Use of Estimates	The preparation of 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 financial statements and the reported amounts of revenues and expenses during the reporting period. The most important of these estimates and assumptions relate to the following: allowance for doubtful accounts, fallouts and other accounts receivable reserves; accounting for goodwill and identifiable intangible assets; self-insured liabilities for workers’ compensation and health insurance; obligations for pension plans; accounting for income taxes and expected annual commission rates. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates.
Stock-Based Compensation	Kforce accounts for stock-based compensation by measuring the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. The cost is recognized over the requisite service period. Effective January 1, 2017, as a result of our adoption of a recently issued accounting standard, the Firm changed its accounting policy regarding forfeitures and elected to recognize them as they occur.
Income Taxes	Kforce accounts for income taxes using the asset and liability approach to the recognition of deferred tax assets and liabilities for the expected future tax consequences of differences between the financial statement carrying amounts and the tax basis of assets and liabilities. Unless it is more likely than not that a deferred tax asset can be utilized to offset future taxes, a valuation allowance is recorded against that asset. Effective January 1, 2017, as a result of our adoption of a recently issued accounting standard, excess tax benefits or deficiencies of deductions attributable to employees’ vesting of restricted stock are reflected in Income tax expense in the accompanying Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income. Kforce evaluates tax positions that have been taken or are expected to be taken in its tax returns, and records a liability for uncertain tax positions. Kforce uses a two-step approach to recognize and measure uncertain tax positions. First, tax positions are recognized if the weight of available evidence indicates that it is more likely than not that the position will be sustained upon examination, including resolution of related appeals or litigation processes, if any. Second, tax positions are measured as the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon settlement. Kforce recognizes interest and penalties related to unrecognized tax benefits in Income tax expense in the accompanying Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income.
Health Insurance	Except for certain fully insured health insurance lines of coverage, Kforce retains the risk of loss for each health insurance plan participant up to $350 thousand in claims annually. Additionally, for all claim amounts exceeding $350 thousand, Kforce retains the risk of loss up to an aggregate annual loss of those claims of $700 thousand. For its partially self-insured lines of coverage, health insurance costs are accrued using estimates to approximate the liability for reported claims and incurred but not reported claims, which are primarily based upon an evaluation of historical claims experience, actuarially-determined completion factors and a qualitative review of our health insurance exposure including the extent of outstanding claims and expected changes in health insurance costs.
Earnings Per Share	Basic earnings per share is computed as earnings divided by the weighted average number of common shares outstanding (“WASO”) during the period. WASO excludes unvested shares of restricted stock. Diluted earnings per common share is computed by dividing the earnings attributable to common shareholders by diluted WASO. Diluted WASO includes the dilutive effect of stock options and other potentially dilutive securities such as unvested shares of restricted stock using the treasury stock method, except where the effect of including potential common shares would be anti-dilutive.
New Accounting Standards	Recently Adopted Accounting Standards In March 2017, the FASB issued authoritative guidance requiring that an employer disaggregate the service cost component from the other components of net periodic benefit cost for defined benefit pension plans. The amendments also provide explicit guidance on how to present the service cost component and the other components of net periodic benefit cost in the income statement. The guidance is to be applied for annual periods beginning after December 15, 2017, including interim periods within those annual periods, and early adoption is permitted. The guidance should be applied retrospectively for the presentation of the service cost component and the other components of net periodic benefit cost in the income statements. We elected to early adopt this guidance as of January 1, 2017 due to the ease of implementation. The impact of early adoption resulted in a retrospective adjustment to the Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income to reclass the interest cost component of net periodic benefit cost from Selling, general and administrative expenses to Other expense, net. The amount of the reclassification was approximately $0.1 million for the three months ended March 31, 2017 and March 31, 2016, respectively. In January 2017, the FASB issued authoritative guidance simplifying the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. Under this guidance, an entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The guidance is to be applied for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019 and early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The guidance requires companies to apply the requirements prospectively. We elected to early adopt this guidance as of January 1, 2017 in order to simplify our processes. The adoption of this guidance did not have an impact on the Firm’s consolidated financial statements. In March 2016, the FASB issued authoritative guidance regarding the accounting for share-based payment transactions, including income tax consequences, classification of awards as either equity or liability, and classification in the statement of cash flows. This guidance was effective for us on January 1, 2017. The impact of this guidance resulted in the following: •All excess tax benefits and deficiencies will be recognized as income tax benefit or expense in the income statement. Prior to the effective date, they were recognized as a change to additional paid-in capital. The Firm will apply this amendment prospectively. For the three months ended March 31, 2017, the Firm recorded approximately $0.2 million of excess tax benefits as a reduction to Income tax expense in the accompanying Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income. This resulted in a reduction to our quarterly effective tax rate of 2.4% and an increase to our diluted earnings per share of $0.01 for the three months ended March 31, 2017. This accounting standard guidance could continue to create volatility in the Firm’s effective tax rate in the future. •Excess tax benefits and deficiencies will be classified as an operating activity in the statement of cash flows. Prior to the effective date, they were included in financing activities in the statement of cash flows. The Firm elected to apply this amendment retrospectively. This change increased our net cash provided by operating activities by $0.2 million and $0.3 million for the three months ended March 31, 2017 and March 31, 2016, respectively, in the accompanying Unaudited Condensed Consolidated Statements of Cash Flows. •An entity is allowed to make a policy election as to whether they will include an estimate for awards expected to be forfeited or whether they will account for forfeitures as they occur. The Firm elected to change its policy on accounting for forfeitures and to account for them as they occur in order to simplify our processes. This policy election is to be applied using a modified retrospective approach with a cumulative-effect adjustment to retained earnings as of the effective date. The impact to the beginning balance of retained earnings was $0.5 million, which is net of taxes of $0.3 million. In November 2015, the FASB issued authoritative guidance requiring that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. This guidance was effective for us on January 1, 2017. The Firm elected to apply this guidance retrospectively. As a result, $4.8 million of current deferred tax assets, net was reclassified to noncurrent deferred tax assets, net as of December 31, 2016. Accounting Standards Not Yet Adopted In February 2016, the FASB issued authoritative guidance regarding the accounting for leases. The guidance is to be applied for annual periods beginning after December 15, 2018 and interim periods within those annual periods, and early adoption is permitted. The guidance requires companies to apply the requirements retrospectively to all prior periods presented, including interim periods. Kforce elected not to adopt this standard early. The Firm has made progress with assessing contractual arrangements that may be impacted by the new standard. Kforce anticipates that the adoption of this standard will have a significant impact to its consolidated balance sheet as it will result in recording substantially all operating leases as a right-to-use asset and lease obligation. Kforce continues to assess all potential impacts of the standard, especially with respect to our disclosures. In May 2014, the FASB issued authoritative guidance regarding revenue from contracts with customers, which specifies that revenue should be recognized when promised goods or services are transferred to customers in an amount that reflects the consideration which the company expects to be entitled in exchange for those goods or services. In August 2015, the FASB issued authoritative guidance deferring the effective date of the new revenue standard by one year for all entities. The one-year deferral results in the guidance being effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017 and entities are not permitted to adopt the standard earlier than the original effective date. Since May 2014, the FASB has issued additional and amended authoritative guidance regarding revenue from contracts with customers in order to clarify and improve the understanding of the implementation guidance. The guidance permits companies to either apply the requirements retrospectively to all prior periods presented, or apply the requirements in the year of adoption, through a cumulative adjustment. We have selected the modified retrospective transition method. Based on our preliminary assessment, we believe that the timing of our revenue recognition will not be impacted for at least 95% of our revenues. The remainder of our revenues are derived from Government Solutions (“GS”) fixed-price contracts. We are reviewing these contracts in order to determine if there may be any change to the timing. We are continuing to evaluate various items that may impact our revenue transaction prices. Furthermore, we do anticipate an increase in the level of disclosure around our arrangements and resulting revenue recognition.

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.