Fair Value Measurements - Estimated Fair Values of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
FINANCIAL ASSETS
Federal funds sold, Carrying Amount	$ 1,209	$ 1,316
Debt securities held for investment, Carrying Amount	1,129	1,190
Loans, net of allowance for credit losses, Carrying Amount	7,684,593	7,559,845
Debt securities held for investment, Fair Value	1,129	1,190
Loans held for sale, Fair Value	5,997	3,489
FINANCIAL LIABILITIES
Deposits, Carrying Amount	10,909,621	10,700,122
Short-term borrowings, Carrying Amount	9,699	3,351
Subordinated debt, Carrying Amount	86,115	86,101
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS
Loan commitments, Fair Value	4,577	4,875
Letters of credit, Fair Value	599	637
Level 2 Inputs [Member]
FINANCIAL ASSETS
Cash and cash equivalents, Carrying Amount	2,525,095	2,397,463
Federal funds sold, Carrying Amount	1,209	1,316
Debt securities held for investment, Carrying Amount	4	5
Loans held for sale, Carrying Amount	5,997	3,489
Cash and cash equivalents, Fair Value	2,525,095	2,397,463
Federal funds sold, Fair Value	1,209	1,316
Debt securities held for investment, Fair Value	4	5
Loans held for sale, Fair Value	5,997	3,489
FINANCIAL LIABILITIES
Deposits, Carrying Amount	10,909,621	10,700,122
Short-term borrowings, Carrying Amount	9,699	3,351
Subordinated debt, Carrying Amount	86,115	86,101
Deposits, Fair Value	10,421,046	10,413,348
Short-term borrowings, Fair Value	9,699	3,351
Subordinated debt, Fair Value	78,255	79,271
Level 3 Inputs [Member]
FINANCIAL ASSETS
Debt securities held for investment, Carrying Amount	1,125	1,185
Loans, net of allowance for credit losses, Carrying Amount	7,684,593	7,559,845
Debt securities held for investment, Fair Value	1,125	1,185
Loans, net of allowance for credit losses, Fair Value	$ 8,436,154	$ 7,356,768