Business Combinations	3 Months Ended
Business Combinations	Mar. 31, 2021
Business Combinations [Abstract]
Business Combinations	BUSINESS COMBINATIONS Our acquisition strategy focuses on businesses with a leadership team that is committed to best in class culture, extraordinary client service and cross-serving potential. CBIZ has a long history of acquiring businesses that share common cultural values with us and provide value-added services to the small and midsize business market. The valuation of any business is a subjective process and includes industry, geography, profit margins, expected cash flows, client retention, nature of recurring or non-recurring project-based work, growth rate assumptions and competitive market conditions. During the three months ended March 31, 2021, we completed the following acquisition: •Effective January 1, 2021, we acquired substantially all the assets of Middle Market Advisory Group (“MMA”). MMA, based in Englewood, CO, is a provider of tax compliance and consulting services to middle market companies and family groups in the real estate, automotive, technology and SAAS, construction, and manufacturing industries. Operating results will be reported in the Financial Services practice group. Aggregate consideration for the acquisition consisted of approximately $1.9 million in cash and $1.6 million in contingent consideration. Under the terms of the acquisition agreement, a portion of the purchase price is contingent on future performance of the business acquired. The maximum potential undiscounted amount of all future payments for the 2021 acquisition that we could be required to make under the contingent arrangements is $1.7 million. As of March 31, 2021, the aggregated fair value of contingent consideration related to this acquisition was $1.6 million, of which $0.6 million was recorded in Contingent purchase price liability – current and $1.0 million was recorded in Contingent purchase price liability – non-current in the accompanying Condensed Consolidated Balance Sheets at March 31, 2021. Refer to Note 7. Fair Value Measurements, for additional information regarding contingent purchase price liability fair value and fair value adjustments. Annualized revenue from the acquired business is estimated to be approximately $3.6 million. Pro forma results of operations for this acquisition has not been presented because the effects of the acquisitions were not significant to our Income from continuing operations before income taxes. During the three months ended March 31, 2020, we have acquired substantially all of the assets of the following businesses: •Effective February 1, 2020, we acquired substantially all the assets of Alliance Insurance Services, Inc., a provider of insurance and advisory services based in Washington, DC. Operating results will be reported in the Benefits and Insurance Services practice group. •Effective February 1, 2020, we acquired substantially all the assets of Pension Dynamics Company, LLC, a full-service retirement and benefits plan advisor based in Pleasant Hill, California. Operating results will be reported in the Benefits and Insurance Services practice group. •Effective February 1, 2020, we acquired substantially all the assets of Sunshine Systems, a payroll solutions provider based in Massachusetts. Operating results will be reported in the Benefits and Insurance Services practice group. Aggregated consideration for these acquisitions consisted of approximately $9.4 million in cash, $0.9 million in our common stock, and $4.8 million in contingent considerations. Under the terms of the acquisition agreements, a portion of the purchase price is contingent on future performance of the business acquired. The maximum potential undiscounted amount of all future payments that we could be required to make under the contingent arrangements is $6.2 million. As of March 31, 2020, the aggregated fair value of the contingent considerations related to these acquisitions was $4.7 million, of which $2.0 million was recorded in "Contingent purchase price liability – current" and $2.7 million was recorded in "Contingent purchase price liability – non-current" in the accompanying Condensed Consolidated Balance Sheets at March 31, 2020. Refer to Note 7. Fair Value Measurements, for additional information regarding contingent purchase price liability fair value and fair value adjustments. Annualized revenue from the acquired businesses is estimated to be approximately $6.1 million. Pro forma results of operations for these acquisitions have not been presented because the effects of these acquisitions were not material to our "Income from continuing operations before income taxes." The goodwill of $1.5 million and $11.2 million arising from the acquisitions for the three months ended March 31, 2021 and 2020, respectively, primarily results from expected future earnings and cash flows from the existing management team, as well as the synergies created by the integration of the new business within our organization, including cross-selling opportunities expected with our Financial Services practice group and the Benefits and Insurance Services practice group, to help strengthen our existing service offerings and expand our market position. All of the goodwill is deductible for income tax purposes. Acquisition of Client Lists - During the three months ended March 31, 2021, we purchased one client list reported in the Benefits and Insurance Services practice group for $0.2 million, of which $0.1 million is contingent. During the three months ended March 31, 2020, we purchased two client lists, reported in the Benefits and Insurance Services practice group, for total consideration of $0.5 million, of which $0.3 million is contingent. Change in Contingent Purchase Price Liability for Previous Acquisitions - During the three months ended March 31, 2021 and 2020, the fair value of the contingent purchase price liability related to prior acquisitions increased by $0.7 million and decreased by $0.7 million, respectively. The change in fair value during the three months ended March 31, 2021 is mostly attributable to the change in stock price related to the mark-to-market adjustment of future common stock issuances and net present value adjustments. The change in fair value during the three months ended March 31, 2020 is due to the change in stock price related to the mark-to-market adjustment of future common stock issuances offset by net present value adjustments. These adjustments are included in "Other income (expense), net" in the accompanying Condensed Consolidated Statements of Comprehensive Income. Contingent Payments for Previous Business Acquisitions and Client Lists - We paid $1.5 million in cash and issued approximately 0.1 million shares of our common stock during the three months ended March 31, 2021 for previous acquisitions. For the same period in 2020, we paid $2.4 million in cash and issued approximately 0.1 million shares of our common stock for previous acquisitions. During the three months ended March 31, 2021 and 2020, we paid approximately $0.1 million and $0.3 million, respectively, in cash for previous client list purchases.