Fair Value Measurements - Carrying Amounts and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair values of defined benefit pension plan assets by category of the firm
Securities available for sale, at fair value	$ 1,290,613	$ 1,250,777
Loans held for sale	318,272	411,427
Mortgage servicing rights	53,208	48,230	$ 39,339
Derivative instruments	61	1,620
Financial liabilities
Derivative instruments	9,974	6,768
Level 1
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	414,930	569,111
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	8,052,536	7,765,773
Short-term borrowings	489,091	387,706
Other long-term borrowings		53
Federal Home Loan Bank advances	0	0
Junior subordinated debentures	0	0
Subordinated notes	0	0
Derivative instruments	0	0
Level 2
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	0	0
Securities available for sale, at fair value	1,280,627	1,240,144
Loans held for sale	318,272	219,848
Loans, net	0	0
Mortgage servicing rights	0	0
Derivative instruments	8,498	6,519
Financial liabilities
Deposits	2,158,431	2,337,334
Short-term borrowings	0	0
Other long-term borrowings		0
Federal Home Loan Bank advances	152,321	6,751
Junior subordinated debentures	104,480	109,766
Subordinated notes	117,963	148,875
Derivative instruments	10,000	8,388
Level 3
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	0	0
Securities available for sale, at fair value	9,986	10,633
Loans held for sale	0	191,579
Loans, net	9,321,039	8,818,039
Mortgage servicing rights	53,208	61,111
Derivative instruments	0	0
Financial liabilities
Deposits	0	0
Short-term borrowings	0	0
Other long-term borrowings		0
Federal Home Loan Bank advances	0	0
Junior subordinated debentures	0	0
Subordinated notes	0	0
Derivative instruments	0	0
Carrying Value
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	414,930	569,111
Securities available for sale, at fair value	1,290,613	1,250,777
Loans held for sale	318,272	411,427
Loans, net	9,637,476	9,034,103
Mortgage servicing rights	53,208	48,230
Derivative instruments	8,498	6,519
Financial liabilities
Deposits	10,213,168	10,128,557
Short-term borrowings	489,091	387,706
Other long-term borrowings		53
Federal Home Loan Bank advances	152,337	6,690
Junior subordinated debentures	110,215	109,636
Subordinated notes	113,955	147,239
Derivative instruments	10,000	8,388
Fair Value
Fair values of defined benefit pension plan assets by category of the firm
Cash and cash equivalents	414,930	569,111
Securities available for sale, at fair value	1,290,613	1,250,777
Loans held for sale	318,272	411,427
Loans, net	9,321,039	8,818,039
Mortgage servicing rights	53,208	61,111
Derivative instruments	8,498	6,519
Financial liabilities
Deposits	10,210,967	10,103,107
Short-term borrowings	489,091	387,706
Other long-term borrowings		53
Federal Home Loan Bank advances	152,321	6,751
Junior subordinated debentures	104,480	109,766
Subordinated notes	117,963	148,875
Derivative instruments	$ 10,000	$ 8,388

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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Amount after allowance and 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 and loans held for sale.

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Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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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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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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