Acquisition-Related Amortization and Remeasurement - Components of Acquisition-Related Amortization and Remeasurement (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquisition Related Amortization And Remeasurement [Abstract]
Changes in fair value of contingent consideration	$ (7,300)	$ 29,140	$ 3,069
Amortization of acquired intangibles	6,801	5,072	1,255
Total	$ (499)	$ 34,212	$ 4,324

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e7008-128479

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration