Loans - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($) Loan	Dec. 31, 2019 USD ($)
Loans outstanding	$ 5.4	$ 5.2
Short Term Loan Modification Program [Member]
Loans, deferral payment period	90 days
Loans, deferral extended payment period	90 days
Loans, deferral maximum payment period	180 days
Temporary payment relief provided for number of loans | Loan	134
Aggregate outstanding principal balance provided for temporary payment relief	$ 50.3
Short Term Loan Modification Program [Member] | Commercial Loans [Member]
Temporary payment relief provided for number of loans | Loan	55
Aggregate outstanding principal balance provided for temporary payment relief	$ 34.3
Short Term Loan Modification Program [Member] | Residential Loans [Member]
Temporary payment relief provided for number of loans | Loan	79
Aggregate outstanding principal balance provided for temporary payment relief	$ 16.0
PPP Loans [Member]
CARES Act number of guaranteed loans | Loan	269
CARES Act aggregate guaranteed outstanding loans	$ 32.7