Commitments and Contingencies - Additional Information (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Indemnification Agreement [Member]
Other Commitments [Line Items]
Indemnification obligations accrued	$ 0	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_OtherCommitmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration