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Fair Value Measurements - Schedule of roll-forward of fair value of earn-out consideration categorized as level 3 in fair value hierarchy (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest payment on earn-out consideration, cash flows from operating activities		$ 0		$ 0
Interest payment on earn-out consideration, revenue	$ 440,000		$ 440,000
Business Acquisition Contingent Consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening balance	5,716,000	21,935,000	8,272,000	22,184,000
Payments made on earn-out consideration	0	0	(2,556,000)	0
Change in fair value of earn out consideration	0	(3,773,000)	0	(4,452,000)
Others	440,000	0	440,000	430,000
Closing balance	$ 6,156,000	$ 18,162,000	$ 6,156,000	$ 18,162,000

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- Definition

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+ References

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- Definition

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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