Employee Benefits - Additional Information (Detail) - USD ($)	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	$ 0
Accounting Standards Update 2017-07 [Member]
Defined Benefit Plan Disclosure [Line Items]
Reclassification from salaries and employee benefits to other expenses	$ 1,506,000	$ 507,000

Amount of contributions received and expected to be received by defined benefit plan from employer in current fiscal year.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920

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