Revenue Recognition - Summary of Company's Source of Non-interest Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Non-interest income
Increase in bank-owned life insurance	$ 488	$ 652
Net gain (loss) from securities transactions	6	(8)
Other	852	461
Total non-interest income	5,324	4,251
Service Charges and Fees [Member]
Non-interest income
Non-interest income	1,923	1,580
Debit Card Income [Member]
Non-interest income
Non-interest income	1,738	1,253
Mortgage Banking [Member]
Non-interest income
Non-interest income	317	313
Accounting Standards Update 2014-09 [Member]
Non-interest income
Increase in bank-owned life insurance	488	652
Net gain (loss) from securities transactions	6	(8)
Other	852	461
Total non-interest income	5,324	4,251
Accounting Standards Update 2014-09 [Member] | Service Charges and Fees [Member]
Non-interest income
Non-interest income	1,923	1,580
Accounting Standards Update 2014-09 [Member] | Debit Card Income [Member]
Non-interest income
Non-interest income	1,738	1,253
Accounting Standards Update 2014-09 [Member] | Mortgage Banking [Member]
Non-interest income
Non-interest income	$ 317	$ 313