Fair Value Measurement - Estimates Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Financial Assets
Cash and due from banks	$ 1,157,030	$ 568,137
Equity securities	29,538	13,427
Available-for-sale debt securities	3,222,819	2,246,072
Net held-to-maturity debt securities	1,137,782	1,152,906
Net loans	18,604,760	12,517,663
Loans held for sale	123,019	18,695
Accrued interest receivable	106,410	78,324
Financial Liabilities
Deposits	21,154,556	14,133,717
Federal Home Loan Bank borrowings	1,750,000	1,000,000
Other borrowings	103,666	192,073
Subordinated debt and junior subordinated debt	357,762	279,308
Accrued interest payable	25,967	14,228
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial Assets
Cash and due from banks	1,157,030	568,137
Equity securities	29,538	13,427
Accrued interest receivable	106,410	78,324
Financial Liabilities
Deposits	18,211,369	12,406,785
Other borrowings	99,771	180,372
Accrued interest payable	25,967	14,228
Significant Other Observable Inputs (Level 2) [Member]
Financial Assets
Available-for-sale debt securities	3,220,866	2,244,988
Net held-to-maturity debt securities	1,005,941	1,006,617
Loans held for sale	123,019	18,695
Other assets - interest rate derivatives	64,943	72,343
Financial Liabilities
Deposits	2,924,934	1,714,530
Federal Home Loan Bank borrowings	1,750,833	1,000,371
Subordinated debt and junior subordinated debt	339,114	262,101
Other liabilities - interest rate derivatives	66,526	72,204
Significant Unobservable Inputs (Level 3) [Member]
Financial Assets
Available-for-sale debt securities	1,953	1,084
Net held-to-maturity debt securities	169	200
Net loans	18,111,962	12,042,064
Carrying Amount [Member]
Financial Assets
Cash and due from banks	1,157,030	568,137
Equity securities	29,538	13,427
Available-for-sale debt securities	3,222,819	2,246,072
Net held-to-maturity debt securities	1,137,604	1,152,760
Net loans	18,604,760	12,517,663
Loans held for sale	123,019	18,695
Other assets - interest rate derivatives	64,943	72,343
Accrued interest receivable	106,410	78,324
Financial Liabilities
Deposits	21,154,556	14,133,717
Federal Home Loan Bank borrowings	1,750,000	1,000,000
Other borrowings	103,666	192,073
Subordinated debt and junior subordinated debt	357,762	279,308
Other liabilities - interest rate derivatives	66,526	72,204
Accrued interest payable	25,967	14,228
Fair Value Estimate [Member]
Financial Assets
Cash and due from banks	1,157,030	568,137
Equity securities	29,538	13,427
Available-for-sale debt securities	3,222,819	2,246,072
Net held-to-maturity debt securities	1,006,110	1,006,817
Net loans	18,111,962	12,042,064
Loans held for sale	123,019	18,695
Other assets - interest rate derivatives	64,943	72,343
Accrued interest receivable	106,410	78,324
Financial Liabilities
Deposits	21,136,303	14,121,315
Federal Home Loan Bank borrowings	1,750,833	1,000,371
Other borrowings	99,771	180,372
Subordinated debt and junior subordinated debt	339,114	262,101
Other liabilities - interest rate derivatives	66,526	72,204
Accrued interest payable	$ 25,967	$ 14,228