New Accounting Pronouncements - Additional Information (Detail) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($)
ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in assets and liabilities related to operating leases	$ 20

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