Fair Value Measurement - Estimated Fair Values of Financial Instruments that are Reported at Amortized Cost in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial assets:
Cash and due from banks	$ 86,052	$ 77,253
Cash at Federal Reserve and other banks	553,688	592,298
Amortized cost, held to maturity	235,778	284,563
Financial liabilities:
Other borrowings	40,559	26,914
Junior subordinated debt	57,852	57,635
Level 3 | Overdraft Privilege Commitments
Off-balance sheet:
Contract amount, Off-balance sheet	112,993	110,813
Level 3 | Standby letters of credit
Off-balance sheet:
Contract amount, Off-balance sheet	14,112	15,056
Level 3 | Commitments
Off-balance sheet:
Contract amount, Off-balance sheet	1,474,690	1,426,827
Carrying Amount | Level 1
Financial assets:
Cash and due from banks	86,052	77,253
Cash at Federal Reserve and other banks	553,688	592,298
Carrying Amount | Level 2
Financial assets:
Amortized cost, held to maturity	235,778	284,563
Restricted equity securities	17,250	17,250
Financial liabilities:
Deposits	6,992,053	6,505,934
Other borrowings	40,559	26,914
Carrying Amount | Level 3
Financial assets:
Loans, net	4,870,278	4,671,280
Financial liabilities:
Junior subordinated debt	57,852	57,635
Fair Value | Level 1
Financial assets:
Cash and due from banks	86,052	77,253
Cash at Federal Reserve and other banks	553,688	592,298
Fair Value | Level 2
Financial assets:
Amortized cost, held to maturity	247,019	298,726
Financial liabilities:
Deposits	6,998,976	6,507,235
Other borrowings	40,559	26,914
Fair Value | Level 3
Financial assets:
Loans, net	4,875,176	4,753,027
Financial liabilities:
Junior subordinated debt	57,795	56,632
Fair Value | Level 3 | Overdraft Privilege Commitments
Off-balance sheet:
Fair value, Off-balance sheet	1,129	1,108
Fair Value | Level 3 | Standby letters of credit
Off-balance sheet:
Fair value, Off-balance sheet	141	151
Fair Value | Level 3 | Commitments
Off-balance sheet:
Fair value, Off-balance sheet	$ 14,747	$ 14,268