Short-term Investments - Additional Information (Detail)	9 Months Ended
Sep. 30, 2019
Maximum [Member]
Marketable Securities [Line Items]
Debt securities maturity period	1 year

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