Discontinued Operations - Narrative (Details) - Discontinued Operations, Disposed of by Sale - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash provided by (used in) operating activities for discontinued operations		$ 5.1
Cash provided by (used in) investing activities for discontinued operations		$ 118.5
Kforce Government Solutions, Inc.("KGS")
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense related to revised estimate on tax obligation on sale	$ 0.6

Amount of cash inflow (outflow) of investing activities of discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of tax (expense) benefit on (gain) loss recognized for the (reversal of write-down) write-down to fair value, less cost to sell, of a discontinued operation.

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