Fair Value Measurements - Estimated Fair Values of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
FINANCIAL ASSETS
Federal funds sold, Carrying Amount	$ 3,489	$ 800
Debt securities held for investment, Carrying Amount	2,917	2,977
Loans, net of allowance for credit losses, Carrying Amount	6,407,101	6,085,506
Debt securities held for investment, Fair Value	2,917	2,978
Loans held for sale, Fair Value	10,137	24,776
FINANCIAL LIABILITIES
Deposits, Carrying Amount	11,250,971	8,091,914
Short-term borrowings, Carrying Amount	3,300	0
Subordinated debt, Carrying Amount	86,001	85,987
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS
Loan commitments, Fair Value	3,958	3,648
Letters of credit, Fair Value	522	621
Level 2 Inputs [Member]
FINANCIAL ASSETS
Cash and cash equivalents, Carrying Amount	4,091,404	2,050,022
Federal funds sold, Carrying Amount	3,489	800
Debt securities held for investment, Carrying Amount	27	32
Loans held for sale, Carrying Amount	10,137	24,776
Cash and cash equivalents, Fair Value	4,091,404	2,050,022
Federal funds sold, Fair Value	3,489	800
Debt securities held for investment, Fair Value	27	33
Loans held for sale, Fair Value	10,137	24,776
FINANCIAL LIABILITIES
Deposits, Carrying Amount	11,250,971	8,091,914
Short-term borrowings, Carrying Amount	3,300
Subordinated debt, Carrying Amount	86,001	85,987
Deposits, Fair Value	11,258,118	8,161,553
Short-term borrowings, Fair Value	3,300
Subordinated debt, Fair Value	85,736	90,391
Level 3 Inputs [Member]
FINANCIAL ASSETS
Debt securities held for investment, Carrying Amount	2,890	2,945
Loans, net of allowance for credit losses, Carrying Amount	6,407,101	6,085,506
Debt securities held for investment, Fair Value	2,890	2,945
Loans, net of allowance for credit losses, Fair Value	$ 6,276,465	$ 6,059,716