Disclosures About Fair Value of Financial Instruments - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Carrying Amount	$ 404,465	$ 518,032
Cash and cash equivalents, Estimated Fair Value	404,465	518,032
Debt securities, available for sale	2,918,830	3,791,575
Debt securities, held to maturity	886,294
Investment securities held to maturity	854,737
Loans held for sale	5,224	16,254
Total loans and leases receivable, net of allowance for credit losses on loans and leases	15,201,267	14,414,827
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	14,905,661	14,207,811
FHLB, Federal Reserve Bank and other restricted stock, Carrying Amount	64,112	64,584
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	64,112	64,584
Derivative assets	46,451	27,295
Deposits held	17,522,438	16,777,924
Deposits, Estimated Fair Value	17,502,691	16,777,236
Federal funds purchased, Carrying Amount	365,000	75,000
Federal funds purchased, Estimated Fair Value	365,000	75,000
FHLB advances, Carrying Amount	500,000	700,000
FHLB advances, Estimated Fair Value	480,319	700,000
Other borrowings, Carrying Amount	123,515	223,086
Other borrowings, Estimated Fair Value	120,888	226,585
Subordinated debt, Carrying Amount	181,882	181,673
Subordinated debt, Estimated Fair Value	171,722	204,782
Derivative liabilities	43,727	26,544
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Estimated Fair Value	404,465	518,032
Debt securities, available for sale	0	0
Investment securities held to maturity	0
Loans held for sale	0	0
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	0	0
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	0	0
Derivative assets	0	0
Deposits, Estimated Fair Value	15,624,425	16,270,586
Federal funds purchased, Estimated Fair Value	365,000	75,000
FHLB advances, Estimated Fair Value	0	0
Other borrowings, Estimated Fair Value	0	0
Subordinated debt, Estimated Fair Value	0	0
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Estimated Fair Value	0	0
Debt securities, available for sale	2,830,944	3,648,690
Investment securities held to maturity	454,736
Loans held for sale	609	15,747
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	1,569,090	2,284,325
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	64,112	64,584
Derivative assets	46,410	27,116
Deposits, Estimated Fair Value	1,878,266	506,650
Federal funds purchased, Estimated Fair Value	0	0
FHLB advances, Estimated Fair Value	480,319	700,000
Other borrowings, Estimated Fair Value	120,888	226,585
Subordinated debt, Estimated Fair Value	171,722	204,782
Derivative liabilities	43,727	26,544
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Estimated Fair Value	0	0
Debt securities, available for sale	87,886	142,885
Investment securities held to maturity	400,001
Loans held for sale	4,615	507
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	13,336,571	11,923,486
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	0	0
Derivative assets	41	179
Deposits, Estimated Fair Value	0	0
Federal funds purchased, Estimated Fair Value	0	0
FHLB advances, Estimated Fair Value	0	0
Other borrowings, Estimated Fair Value	0	0
Subordinated debt, Estimated Fair Value	0	0
Derivative liabilities	$ 0	$ 0