| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Operating activities: | | | | | | | | |
| Net income | 125.4 | 117.7 | 64.8 | 92.1 | 68.3 | 40.6 | 44.8 | |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Depreciation of premises and equipment, and amortization | 12.3 | 6.4 | 6.5 | 6.9 | 7.0 | 6.8 | 6.5 | 5.9 |
| Amortization of intangible assets | 6.3 | 5.5 | 5.7 | 5.7 | 3.5 | 1.4 | 1.4 | 1.2 |
| Amortization of investment securities premium, net | 6.6 | 6.7 | 2.7 | 2.5 | 2.5 | 3.2 | 4.9 | 3.5 |
| Loss on sale of investment securities | | | 0.0 | -0.1 | -0.2 | -1.0 | | |
| Originations of loans for resale | -71.6 | -217.2 | -227.8 | -131.1 | -84.2 | -114.1 | -142.6 | -111.6 |
| Proceeds from sale of loans originated for resale | 74.9 | 227.9 | 234.4 | 131.7 | 87.0 | 114.8 | 144.1 | 115.5 |
| Gain on sale of loans | -2.3 | -9.6 | -9.1 | -3.3 | -2.4 | -3.1 | -4.0 | -3.1 |
| Change in market value of mortgage servicing rights | -0.3 | 0.9 | 2.6 | 1.8 | 0.1 | 0.7 | 2.2 | 0.7 |
| Provision for losses on foreclosed assets | 17.9 | -7.2 | 42.2 | -1.7 | 2.6 | | 0.1 | 0.5 |
| Loss (gain) on disposal of fixed assets | -1.1 | -0.4 | 0.1 | 0.1 | 0.2 | 0.1 | 0.9 | 0.1 |
| Increase in cash value of life insurance | -2.9 | -2.8 | -2.9 | -3.0 | -2.7 | -2.7 | -2.7 | -2.8 |
| Equity compensation vesting expense | 3.9 | 2.6 | 2.0 | 1.7 | 1.5 | 1.6 | 1.5 | 1.4 |
| Change in: | | | | | | | | |
| Interest receivable | -9.2 | 0.7 | -1.1 | 0.5 | -5.6 | -1.7 | -1.2 | -1.5 |
| Interest payable | -0.3 | -0.4 | -1.0 | 0.4 | 1.1 | 0.1 | 0.0 | -0.2 |
| Other assets and liabilities, net | 17.1 | 2.4 | 9.6 | -1.2 | 10.1 | -3.2 | -4.1 | 3.8 |
| Net cash from operating activities | 162.9 | 132.2 | 114.8 | 102.8 | 91.1 | 55.4 | 48.2 | 54.8 |
| |
| Investing activities: | | | | | | | | |
| Proceeds from maturities of securities available for sale | 267.8 | 371.6 | 167.5 | 98.0 | 73.0 | 150.3 | 193.4 | 127.3 |
| Proceeds from maturities of securities held to maturity | 38.4 | 83.9 | 89.9 | 68.3 | 68.9 | | | |
| Proceeds from sale of available for sale securities | | | 0.2 | 127.1 | 293.3 | 25.8 | | 0.0 |
| Purchases of securities available for sale | -699.0 | -1,190.7 | -617.6 | -37.3 | -436.7 | -265.8 | -247.7 | -341.3 |
| Loan origination and principal collections, net | -739.0 | -45.8 | -415.4 | -286.3 | -173.8 | -259.4 | -251.5 | -244.0 |
| Proceeds from sale of premises and equipment | 6.7 | 2.7 | | | | 3.3 | 1.7 | 0.0 |
| Purchases of premises and equipment | -3.6 | -3.2 | -2.8 | -4.3 | -7.4 | -15.2 | -10.9 | -5.5 |
| Net cash from (used by) investing activities | -723.2 | -883.8 | -816.3 | -29.8 | -142.0 | -357.4 | -139.4 | -604.3 |
| |
| Financing activities: | | | | | | | | |
| Net change in deposits | -253.6 | 861.2 | 1,138.9 | 0.5 | 365.4 | 113.6 | 103.1 | 250.8 |
| Net change in other borrowings | 214.5 | 23.2 | 8.5 | 2.6 | -271.3 | 104.7 | 5.2 | 3.1 |
| Repurchase of common stock, net of option exercises | -27.1 | -4.3 | -26.7 | -2.2 | -2.5 | -1.6 | -1.9 | -0.4 |
| Dividends paid | -35.8 | -29.7 | -26.3 | -25.0 | -18.8 | -15.1 | -13.7 | |
| Exercise of stock options | 1.2 | 0.1 | 0.2 | 0.0 | 0.2 | 0.4 | 0.5 | 0.7 |
| Net cash (used by) from financing activities | -100.9 | 850.5 | 1,094.6 | -24.0 | 73.0 | 201.9 | 93.3 | 242.2 |
| Net change in cash and cash equivalents | -661.2 | 98.9 | 393.0 | 49.0 | 22.1 | -100.2 | 2.2 | |
| |
| Supplemental disclosure of noncash activities: | | | | | | | | |
| Unrealized gain (loss) on securities available for sale | -290.2 | -19.6 | 15.8 | | | | | |
| Market value of shares tendered in-lieu of cash to pay for exercise of options and/or related taxes | 2.5 | 2.1 | 0.7 | 5.1 | 1.5 | 2.2 | 6.0 | 2.9 |
| Loans transferred to foreclosed assets | 1.3 | 1.1 | 0.8 | 1.2 | | | | |
| Supplemental disclosure of cash flow activity: | | | | | | | | |
| Cash paid for interest expense | 9.3 | 5.9 | 10.5 | 15.0 | 11.8 | 5.6 | 5.7 | 5.6 |
| Cash paid for income taxes | 41.0 | 46.3 | 29.5 | 35.1 | 14.5 | 21.2 | 27.6 | |
| Business combination | | | | | | | | |