Fair Value Measurements - Summary of Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 1,658,486	$ 3,758,170
Securities available for sale	4,812,704	4,042,699
Securities held to maturity	1,002	1,001
Other securities	246,399	239,645
Loans held for sale	220,689	504,416
Net loans	18,970,395	18,023,648
Deposits	23,026,649	23,350,263
Derivative financial liabilities		0
Mortgage servicing rights	22,593	23,144
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,658,486	3,758,170
Securities available for sale	4,812,704	4,042,699
Securities held to maturity	1,002	1,001
Other securities	246,399	239,645
Loans held for sale	220,689	504,416
Net loans	18,756,666	17,807,632
Derivative financial assets	62,261	32,265
Deposits	23,026,649	23,350,263
Short-term borrowings	128,242	128,844
Long-term borrowings	796,961	817,394
Derivative financial liabilities	1,922	3,728
Mortgage servicing rights	22,593	23,144
Carrying Amount [Member] \| Marketable Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities	13,513	12,404
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,658,486	3,758,170
Securities available for sale	4,812,704	4,042,699
Securities held to maturity	1,020	1,020
Other securities	234,079	227,663
Loans held for sale	220,689	504,416
Net loans	17,828,197	17,119,202
Derivative financial assets	62,261	32,265
Deposits	22,999,148	23,334,431
Short-term borrowings	128,242	128,844
Long-term borrowings	757,969	773,291
Derivative financial liabilities	1,922	3,728
Mortgage servicing rights	41,748	27,355
Fair Value [Member] \| Marketable Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities	13,513	12,404
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Securities available for sale	5,540	5,758
Securities held to maturity	0	0
Other securities	0	0
Loans held for sale	0	0
Net loans	0	0
Derivative financial assets	0	0
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Derivative financial liabilities	0	0
Mortgage servicing rights	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Marketable Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities	13,513	12,404
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,658,486	3,758,170
Securities available for sale	4,807,164	4,036,941
Securities held to maturity	0	0
Other securities	0	0
Loans held for sale	17,590	40,307
Net loans	0	0
Derivative financial assets	58,397	22,760
Deposits	22,999,148	23,334,431
Short-term borrowings	128,242	128,844
Long-term borrowings	757,969	773,291
Derivative financial liabilities	0	3,197
Mortgage servicing rights	0	0
Significant Other Observable Inputs (Level 2) [Member] \| Marketable Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Securities available for sale	0	0
Securities held to maturity	1,020	1,020
Other securities	234,079	227,663
Loans held for sale	203,099	464,109
Net loans	17,828,197	17,119,202
Derivative financial assets	3,864	9,505
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Derivative financial liabilities	1,922	531
Mortgage servicing rights	41,748	27,355
Significant Unobservable Inputs (Level 3) [Member] \| Marketable Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities	$ 0	$ 0

The sum of cash and cash equivalents plus Federal Funds Sold. Cash and cash equivalents consist of short term, highly liquid investments that are readily convertible to known amounts of cash and are so near their maturity that they present negligible risk of changes in value due to changes in interest rates -- usually with an original maturity less than 90 days.

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Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Amount of investments classified as other.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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