Revenue Recognition - Summary of Company's Source of Non-interest Income (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Non-interest income
Increase in bank-owned life insurance		$ 482	$ 488
Net gain (loss) from securities transactions		8	6
Other
Total non-interest income		5,306	5,324
Service Charges and Fees [Member]
Non-interest income
Non-interest income		2,026	1,923
Other
Non-interest income		2,026	1,923
Debit Card Income [Member]
Non-interest income
Non-interest income		2,043	1,738
Other
Non-interest income		2,043	1,738
Mortgage Banking [Member]
Non-interest income
Non-interest income	[1]	590	317
Accounting Standards Update 2014-09 [Member]
Non-interest income
Increase in bank-owned life insurance	[1]	482	488
Net gain (loss) from securities transactions	[1]	8	6
Other
Total non-interest income		5,306	5,324
Recovery on zero-basis purchased loans(a)	[1]	14	46
Income from equity method investments(a)	[1]	(5)	(3)
Other non-interest income not related to loans and deposits(a)	[1]	21	7
Total other non-interest income		157	852
Accounting Standards Update 2014-09 [Member] | Service Charges and Fees [Member]
Non-interest income
Non-interest income		2,026	1,923
Other
Non-interest income		2,026	1,923
Accounting Standards Update 2014-09 [Member] | Debit Card Income [Member]
Non-interest income
Non-interest income		2,043	1,738
Other
Non-interest income		2,043	1,738
Accounting Standards Update 2014-09 [Member] | Investment Referral Income [Member]
Non-interest income
Non-interest income		166	175
Other
Non-interest income		166	175
Accounting Standards Update 2014-09 [Member] | Trust Income [Member]
Non-interest income
Non-interest income		71	61
Other
Non-interest income		71	61
Accounting Standards Update 2014-09 [Member] | Insurance Sales Commissions [Member]
Non-interest income
Non-interest income		18	30
Other
Non-interest income		18	30
Accounting Standards Update 2014-09 [Member] | Other Non Interest Income Related To Loans and Deposits [Member]
Non-interest income
Non-interest income		(128)	536
Other
Non-interest income		$ (128)	$ 536

[1] (a) Not within the scope of ASC 606.