Fair Value Measurement - Additional Information (Detail)	9 Months Ended
Sep. 30, 2019 USD ($) Investmentsecurities
Fair Value Disclosures [Abstract]
Number of investment securities classified as level 3 (in investment securities) \| Investmentsecurities	0
Transfers between level 1 to level 2, Assets	$ 0
Carrying value of loans fully charged-off	$ 0

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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 (bb)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

Name:	us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant