Fair Value Measurements - Carrying Amounts and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair values of defined benefit pension plan assets by category of the firm
Securities held to maturity	$ 415,552
Securities available for sale, at fair value	2,386,052	$ 1,343,457
Loans held for sale	453,533	417,771
Loans, net	9,856,743	10,757,503
Mortgage servicing rights	89,018	62,994	$ 53,208
Derivative instruments	8,007	3,866
Financial liabilities
Derivative instruments	13,436	21,107
Carrying Value
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	1,877,965	633,203
Securities held to maturity	416,357
Securities available for sale, at fair value	2,386,052	1,343,457
Loans held for sale	453,533	417,771
Loans, net	9,856,743	10,757,503
Mortgage servicing rights	89,018	62,994
Derivative instruments	17,698	33,574
Financial liabilities
Deposits	13,905,724	12,059,081
Short-term borrowings	13,947	21,340
Federal Home Loan Bank advances	417	152,167
Junior subordinated debentures	111,373	110,794
Subordinated notes	359,419	212,009
Derivative instruments	13,803	21,107
Fair Value
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	1,877,965	633,203
Securities held to maturity	415,552
Securities available for sale, at fair value	2,386,052	1,343,457
Loans held for sale	453,533	417,771
Loans, net	9,690,604	10,668,625
Mortgage servicing rights	99,425	62,994
Derivative instruments	17,698	33,574
Financial liabilities
Deposits	13,902,739	12,069,198
Short-term borrowings	13,947	21,340
Federal Home Loan Bank advances	422	158,914
Junior subordinated debentures	106,682	93,092
Subordinated notes	373,950	217,575
Derivative instruments	13,803	21,107
Fair Value \| Level 1
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	1,877,965	633,203
Securities held to maturity	0
Securities available for sale, at fair value	0	0
Loans held for sale	0	0
Loans, net	0	0
Mortgage servicing rights	0	0
Derivative instruments	0	0
Financial liabilities
Deposits	12,494,342	10,363,193
Short-term borrowings	13,947	21,340
Federal Home Loan Bank advances	0	0
Junior subordinated debentures	0	0
Subordinated notes	0	0
Derivative instruments	0	0
Fair Value \| Level 2
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	0	0
Securities held to maturity	415,552
Securities available for sale, at fair value	2,386,052	1,334,445
Loans held for sale	453,533	417,771
Loans, net	0	0
Mortgage servicing rights	0	0
Derivative instruments	17,698	33,574
Financial liabilities
Deposits	1,408,397	1,706,005
Short-term borrowings	0	0
Federal Home Loan Bank advances	422	158,914
Junior subordinated debentures	106,682	93,092
Subordinated notes	373,950	217,575
Derivative instruments	13,803	21,107
Fair Value \| Level 3
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	0	0
Securities held to maturity	0
Securities available for sale, at fair value	0	9,012
Loans held for sale	0	0
Loans, net	9,690,604	10,668,625
Mortgage servicing rights	99,425	62,994
Derivative instruments	0	0
Financial liabilities
Deposits	0	0
Short-term borrowings	0	0
Federal Home Loan Bank advances	0	0
Junior subordinated debentures	0	0
Subordinated notes	0	0
Derivative instruments	$ 0	$ 0

Junior Subordinated Debt Obligations, Fair Value Disclosure

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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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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Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity 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. This item represents the amount of short-term debt existing as of the balance sheet date.

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