Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Acquisitions - Summary of Allocation of Purchase Price to Fair Value of Assets Acquired and Liabilities Assumed (Parenthetical) (Detail) - USD ($) $ in Thousands			12 Months Ended
	Jan. 03, 2019	Jul. 06, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Amortization of intangible assets			$ 22,619	$ 1,162	$ 781
SiriusDecisions, Inc [Member]
Business Acquisition [Line Items]
Intangible assets	$ 115,000
Intangible assets, Useful life	8 years 4 months 24 days
Amortization of intangible assets			$ 21,800
SiriusDecisions, Inc [Member] \| Technology Asset Class [Member]
Business Acquisition [Line Items]
Intangible assets	$ 13,000
Intangible assets, Useful life	3 years 2 months 12 days
SiriusDecisions, Inc [Member] \| Technology Asset Class [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Intangible assets, Useful life	1 year
SiriusDecisions, Inc [Member] \| Technology Asset Class [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Intangible assets, Useful life	8 years
SiriusDecisions, Inc [Member] \| Backlog [Member]
Business Acquisition [Line Items]
Intangible assets	$ 13,000
Intangible assets, Useful life	2 years
SiriusDecisions, Inc [Member] \| Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets	$ 77,000
Intangible assets, Useful life	9 years 3 months
SiriusDecisions, Inc [Member] \| Trademarks [Member]
Business Acquisition [Line Items]
Intangible assets	$ 12,000
Intangible assets, Useful life	15 years 6 months
FeedbackNow [Member]
Business Acquisition [Line Items]
Intangible assets		$ 4,780
Intangible assets, Useful life		4 years 9 months 18 days
FeedbackNow [Member] \| Technology Asset Class [Member]
Business Acquisition [Line Items]
Intangible assets		$ 3,000
Intangible assets, Useful life		6 years 6 months
FeedbackNow [Member] \| Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets		$ 1,300
Intangible assets, Useful life		6 years 1 month 6 days
FeedbackNow [Member] \| Customer Relationships [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Intangible assets, Useful life		4 years 6 months
FeedbackNow [Member] \| Customer Relationships [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Intangible assets, Useful life		7 years 6 months
FeedbackNow [Member] \| Trademarks [Member]
Business Acquisition [Line Items]
Intangible assets		$ 500
Intangible assets, Useful life		8 years 6 months