Non-interest Income and Expense - Components of Non-Interest Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule Of Other Noninterest Income And Expense [Line Items]
Total service charges and fees	$ 9,126	$ 9,070
Increase in cash value of life insurance	720	775
Asset management and commission income	916	642
Gain on sale of loans	891	412
Lease brokerage income	193	220
Sale of customer checks	124	140
Gain on sale of investment securities	0	0
Gain on marketable equity securities	47	36
Other	(197)	508
Total other non-interest income	2,694	2,733
Total non-interest income	11,820	11,803
ATM and Interchange Fees
Schedule Of Other Noninterest Income And Expense [Line Items]
Total service charges and fees	5,111	4,581
Service Charges on Deposit Accounts
Schedule Of Other Noninterest Income And Expense [Line Items]
Total service charges and fees	4,046	3,880
Other Service Fees
Schedule Of Other Noninterest Income And Expense [Line Items]
Total service charges and fees	758	771
Mortgage Banking Service Fees
Schedule Of Other Noninterest Income And Expense [Line Items]
Total service charges and fees	469	483
Change in Value of Mortgage Servicing Rights
Schedule Of Other Noninterest Income And Expense [Line Items]
Total service charges and fees	$ (1,258)	$ (645)