Leases - Additional Information (Detail) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Topic 842 [Member] \| SiriusDecisions, Inc [Member] \| Facility Lease [Member]
Lessee Lease Description [Line Items]
Operating lease right-of-use asset impairments	$ 0.4

Amount of loss from impairment of right-of-use asset from operating lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 25
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=77888369&loc=SL77918431-209957

Name:	us-gaap_OperatingLeaseImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration