Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Loans	$ 60,307	$ 71,210
OREO, net	5,148	3,029
Total	65,455	74,239
Level 1
Assets
Loans	0	0
OREO, net	0	0
Total	0	0
Level 2
Assets
Loans	0	0
OREO, net	0	0
Total	0	0
Level 3
Assets
Loans	60,307	71,210
OREO, net	5,148	3,029
Total	$ 65,455	$ 74,239

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant