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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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Acquisitions and Divestiture - Disposals (Details) $ in Thousands				12 Months Ended
	Aug. 01, 2018 USD ($)	May 01, 2018 USD ($)	Apr. 03, 2018 USD ($)	Dec. 31, 2018 USD ($) business	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal				$ 45,447	$ 0	$ 0
Held-for-sale \| CEB Talent Assessment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of businesses sold \| business				3
Divestiture, revenue contributed				$ 97,300
Divestiture, operating income (loss)				60,500
Proceeds from divestiture of businesses			$ 375,800
Sale of business, consideration			403,000
Gain on disposal			$ 15,500
Held-for-sale \| CEB Challenger
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses	$ 116,000
Sale of business, consideration	119,100
Gain on disposal	$ 8,300
Held-for-sale \| CEB Workforce Survey and Analytics
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses		$ 26,400
Sale of business, consideration		28,000
Gain on disposal		$ 8,800
Disposed of by Sale \| Other Certain Assets In CEB Transaction [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets				8,600
Gain on sale of assets				$ 12,800