Servicing - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Transfers And Servicing [Abstract]
Loans serviced for others unpaid principal amount	$ 303.9	$ 289.2
Capitalized service right assets included in other assets	2.6	2.4
Fair market value of the capitalized servicing rights	$ 2.9	$ 3.3
Prepayment rate	14.10%	8.90%
Discount yield	5.42%	6.60%

Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746

Name:	us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration