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Acquisitions - Summary of Fair Value of Aggregate Consideration Paid or Payable (Parenthetical) (Detail) - USD ($) $ in Thousands |  | 6 Months Ended
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Jan. 03, 2019 | Jun. 30, 2019 | Jun. 30, 2018
Business Acquisition [Line Items] |  |  |
Net cash paid |  | $ 238,943 | $ 1,289
SiriusDecisions, Inc [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Cash acquired | $ 7,900 |  |
Net cash paid | $ 238,900 |  |

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- Definition The cash inflow associated with the acquisition of business during the period (for example, cash that was held by the acquired business). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
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