New Accounting Pronouncements - Additional Information (Detail) $ in Millions	9 Months Ended
Sep. 30, 2017 USD ($)
ASU No. 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fee income	$ 0.6

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