Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets
Cash and due from banks	$ 378.2	$ 349.2
Federal funds sold	199.7	521.2
Interest bearing deposits in banks	0.1	0.1
Total cash and cash equivalents	578.0	870.5
Investment securities:
Available-for-sale	5,841.5	6,946.1
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss	3,207.9	3,451.8
Investments, Total	9,049.4	10,397.9
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	223.2	198.6
Loans Held for Sale (Table)	47.4	79.9
Loans and Leases Receivable, Net of Deferred Income	18,279.6	18,099.2
Less allowance for loan losses	(227.7)	(220.1)
Net loans	18,051.9	17,879.1
Goodwill	1,100.9	1,100.9
Company-owned life insurance	502.4	497.9
Premises and equipment, net of accumulated depreciation	444.3	444.7
Other intangibles, net of accumulated amortization	81.4	97.0
Accrued interest receivable	129.1	118.3
Mortgage servicing rights, net of accumulated amortization and impairment reserve	28.3	31.1
Other real estate owned	16.5	12.7
Deferred Income Tax Assets, Net	150.0	210.5
Other assets	268.4	348.7
Total assets	30,671.2	32,287.8
Deposits:
Non-interest bearing	6,029.6	7,560.0
Interest bearing	17,293.5	17,513.6
Total deposits	23,323.1	25,073.6
Securities sold under repurchase agreements	782.7	1,052.9
Accounts payable and accrued expenses	380.4	445.9
Accrued interest payable	52.2	14.5
Long-term debt	120.8	120.8
Other borrowings	2,603.0	2,327.0
Allowance for credit losses on off-balance sheet credit exposures	18.4	16.2
Subordinated debentures held by subsidiary trusts	163.1	163.1
Total liabilities	$ 27,443.7	$ 29,214.0
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Preferred Stock, No Par Value	$ 0	$ 0
Preferred Stock, Shares Authorized	100,000	100,000
Common Stock, Shares, Issued	103,941,626	104,442,023
Common stock, shares, outstanding	103,941,626	104,442,023
Common Stock, Par or Stated Value Per Share	$ 0.00001	$ 0.00001
Stockholders’ equity:
Nonvoting noncumulative preferred stock without par value; authorized 100,000 shares; no shares issued or outstanding as of December 31, 2019 and 2018	$ 0.0	$ 0.0
Common stock	2,448.9	2,478.2
Retained earnings	1,135.1	1,072.7
Accumulated other comprehensive income (loss), net	(356.5)	(477.1)
Total stockholders’ equity	3,227.5	3,073.8
Total liabilities and stockholders’ equity	$ 30,671.2	$ 32,287.8
Common stock, shares authorized	150,000,000