Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2018
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 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 2017 Annual Report on Form 10-K. In management’s opinion, the accompanying unaudited condensed consolidated financial statements reflect all adjustments considered necessary for a fair presentation. The Unaudited Condensed Consolidated Balance Sheet as of December 31, 2017 was derived from our audited Consolidated Balance Sheet as of December 31, 2017, as presented in our 2017 Annual Report on Form 10-K.
Principles of Consolidation	The unaudited condensed consolidated financial statements include the accounts of Kforce Inc. and its subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. References in this document to “Kforce,” “the Company,” “we,” “the Firm,” “management,” “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: revenue transaction prices; allowance for doubtful accounts; income taxes; self-insured liabilities for workers’ compensation and health insurance; obligations for pension plans and goodwill and any related impairment. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates.
Earnings per Share	Basic earnings per share is computed as net income divided by the weighted average number of common shares outstanding (“WASO”) during the period. WASO excludes unvested shares of restricted stock. Diluted earnings per share is computed by dividing net income by diluted WASO. Diluted WASO includes the dilutive effect of 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 May 2014, the FASB issued authoritative guidance regarding revenue from contracts with customers, which specifies that revenue should be recognized when control of the promised goods or services is transferred to our customers at an amount that reflects the consideration to which we expect to be entitled to in exchange for those goods or services. The amended guidance (“Topic 606”) is effective for annual and interim reporting periods beginning after December 15, 2017. We adopted this new standard effective January 1, 2018, using the modified retrospective transition method with a cumulative adjustment to the opening balance of retained earnings. The comparative information continues to be reported under the accounting standards in effect for the period presented ("Topic 605"). Refer to Note C - "Revenue Recognition" for additional accounting policy and transition disclosures. Accounting Standards Not Yet Adopted In August 2018, the FASB issued authoritative guidance regarding customer's accounting for implementation costs incurred in a cloud computing arrangement that is a service contract. These amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The guidance is effective for fiscal periods beginning after December 15, 2019. We are currently evaluating the potential impact on our consolidated financial statements. In August 2018, the FASB issued authoritative guidance regarding changes to the disclosure requirement for defined benefit plans including additions and deletions to certain disclosure requirements for employers that sponsor defined benefit pension or other post-retirement plans. The guidance is effective for fiscal periods beginning after December 15, 2020. The adoption of this guidance will modify our disclosures but is not expected to have a material effect on our consolidated financial statements. In August 2018, the FASB issued authoritative guidance regarding changes to the disclosure requirements for fair value measurement. The amendments on changes in unrealized gains and losses, the weighted average and range of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The guidance is effective for fiscal periods beginning after December 15, 2019. The adoption of this guidance will modify our disclosures but is not expected to have a material effect on our consolidated financial statements. In February 2018, the FASB issued authoritative guidance regarding the reclassification of certain stranded tax effects from accumulated other comprehensive income to retained earnings as a result of the change in tax rates related to the Tax Cuts and Jobs Act. The guidance is effective for fiscal periods beginning after December 15, 2018 and should be applied either in the period of adoption or retrospectively. Kforce will adopt on January 1, 2019. This guidance is not expected to have a material impact on the consolidated financial statements. In August 2017, the FASB issued authoritative guidance targeting improvements to accounting for hedging activities by simplifying the rules around hedge accounting and improving the disclosure requirements. The guidance is effective for annual periods beginning after December 15, 2018. The hedge accounting guidance should be implemented using a modified retrospective approach for any hedges that exist on the date of adoption, while the presentation and disclosure requirements must be applied prospectively. The adoption of this guidance will modify our disclosures but is not expected to have a material effect on our consolidated financial statements. In June 2016, the FASB issued authoritative guidance on accounting for credit losses on financial instruments, including trade receivables. The guidance requires the application of a current expected credit loss model, which measures credit losses based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts. The guidance is effective for annual periods beginning after December 15, 2019. The guidance requires companies to apply the requirements using a modified retrospective approach. We are currently evaluating the potential impact on our consolidated financial statements, especially with respect our disclosures. In February 2016, the FASB issued authoritative guidance regarding the accounting for leases, and has since issued subsequent updates to the initial guidance. The guidance requires the recognition of assets and liabilities for operating leases with terms longer than 12 months. The guidance is effective for annual periods beginning after December 15, 2018 and we expect to utilize the optional transition method in the period of adoption without retrospective application to previous periods. We continue to make progress with our implementation procedures, including upgrading our lease accounting software, assessing accounting policy elections, evaluating the impact on internal controls and analyzing our vendor contracts to determine the appropriate accounting treatment. While we are continuing to assess the effect of adoption, we currently believe the most significant changes include the recognition of right-of-use assets and lease liabilities on our balance sheets for real estate and office equipment operating leases as well as the related financial statement disclosures.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2018

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 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 2017 Annual Report on Form 10-K. In management’s opinion, the accompanying unaudited condensed consolidated financial statements reflect all adjustments considered necessary for a fair presentation. The Unaudited Condensed Consolidated Balance Sheet as of December 31, 2017 was derived from our audited Consolidated Balance Sheet as of December 31, 2017, as presented in our 2017 Annual Report on Form 10-K.

Principles of Consolidation

The unaudited condensed consolidated financial statements include the accounts of Kforce Inc. and its subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. References in this document to “Kforce,” “the Company,” “we,” “the Firm,” “management,” “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: revenue transaction prices; allowance for doubtful accounts; income taxes; self-insured liabilities for workers’ compensation and health insurance; obligations for pension plans and goodwill and any related impairment. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates.

Earnings per Share

Basic earnings per share is computed as net income divided by the weighted average number of common shares outstanding (“WASO”) during the period. WASO excludes unvested shares of restricted stock. Diluted earnings per share is computed by dividing net income by diluted WASO. Diluted WASO includes the dilutive effect of 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 May 2014, the FASB issued authoritative guidance regarding revenue from contracts with customers, which specifies that revenue should be recognized when control of the promised goods or services is transferred to our customers at an amount that reflects the consideration to which we expect to be entitled to in exchange for those goods or services. The amended guidance (“Topic 606”) is effective for annual and interim reporting periods beginning after December 15, 2017. We adopted this new standard effective January 1, 2018, using the modified retrospective transition method with a cumulative adjustment to the opening balance of retained earnings. The comparative information continues to be reported under the accounting standards in effect for the period presented ("Topic 605"). Refer to Note C - "Revenue Recognition" for additional accounting policy and transition disclosures.

Accounting Standards Not Yet Adopted

In August 2018, the FASB issued authoritative guidance regarding customer's accounting for implementation costs incurred in a cloud computing arrangement that is a service contract. These amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The guidance is effective for fiscal periods beginning after December 15, 2019. We are currently evaluating the potential impact on our consolidated financial statements.

In August 2018, the FASB issued authoritative guidance regarding changes to the disclosure requirement for defined benefit plans including additions and deletions to certain disclosure requirements for employers that sponsor defined benefit pension or other post-retirement plans. The guidance is effective for fiscal periods beginning after December 15, 2020. The adoption of this guidance will modify our disclosures but is not expected to have a material effect on our consolidated financial statements.

In August 2018, the FASB issued authoritative guidance regarding changes to the disclosure requirements for fair value measurement. The amendments on changes in unrealized gains and losses, the weighted average and range of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The guidance is effective for fiscal periods beginning after December 15, 2019. The adoption of this guidance will modify our disclosures but is not expected to have a material effect on our consolidated financial statements.

In February 2018, the FASB issued authoritative guidance regarding the reclassification of certain stranded tax effects from accumulated other comprehensive income to retained earnings as a result of the change in tax rates related to the Tax Cuts and Jobs Act. The guidance is effective for fiscal periods beginning after December 15, 2018 and should be applied either in the period of adoption or retrospectively. Kforce will adopt on January 1, 2019. This guidance is not expected to have a material impact on the consolidated financial statements.

In August 2017, the FASB issued authoritative guidance targeting improvements to accounting for hedging activities by simplifying the rules around hedge accounting and improving the disclosure requirements. The guidance is effective for annual periods beginning after December 15, 2018. The hedge accounting guidance should be implemented using a modified retrospective approach for any hedges that exist on the date of adoption, while the presentation and disclosure requirements must be applied prospectively. The adoption of this guidance will modify our disclosures but is not expected to have a material effect on our consolidated financial statements.

In June 2016, the FASB issued authoritative guidance on accounting for credit losses on financial instruments, including trade receivables. The guidance requires the application of a current expected credit loss model, which measures credit losses based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts. The guidance is effective for annual periods beginning after December 15, 2019. The guidance requires companies to apply the requirements using a modified retrospective approach. We are currently evaluating the potential impact on our consolidated financial statements, especially with respect our disclosures.

In February 2016, the FASB issued authoritative guidance regarding the accounting for leases, and has since issued subsequent updates to the initial guidance. The guidance requires the recognition of assets and liabilities for operating leases with terms longer than 12 months. The guidance is effective for annual periods beginning after December 15, 2018 and we expect to utilize the optional transition method in the period of adoption without retrospective application to previous periods. We continue to make progress with our implementation procedures, including upgrading our lease accounting software, assessing accounting policy elections, evaluating the impact on internal controls and analyzing our vendor contracts to determine the appropriate accounting treatment. While we are continuing to assess the effect of adoption, we currently believe the most significant changes include the recognition of right-of-use assets and lease liabilities on our balance sheets for real estate and office equipment operating leases as well as the related financial statement disclosures.