Contingent Put Option - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Option Indexed to Issuer's Equity [Line Items]
Fair value changes in the contingent put option	$ (26,265)	$ (19,240)	$ 7,100
Redeemable Preferred Stock
Option Indexed to Issuer's Equity [Line Items]
Fair value changes in the contingent put option			7,100
Changes in fair value			$ 7,100

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

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

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration