Leases - Schedule of Weighted Average Remaining Lease Terms and Weighted Average Discount Rates (Detail)	Sep. 30, 2020	Dec. 31, 2019
USD
Weighted average remaining lease term (in years)
Operating leases with functional currency	2 years 7 months 6 days	2 years 7 months 6 days
Weighted average discount rate
Operating leases with functional currency	4.50%	4.02%
Euro
Weighted average remaining lease term (in years)
Operating leases with functional currency	3 years 9 months 18 days	4 years 4 months 24 days
Weighted average discount rate
Operating leases with functional currency	1.81%	1.84%

Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Name:	us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant