| In millions, except per share items | Jun-30-23 | Mar-31-23 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Sep-30-21 | Jun-30-21 | Mar-31-21 |
| | 10-Q | 10-Q | 10-Q | 10-Q | 10-Q | 10-Q | 10-Q | 10-Q |
| Operating Activities | | | | | | | | |
| Net income | 32.7 | 24.3 | 27.4 | 22.7 | 21.3 | 22.7 | 22.1 | 19.8 |
| |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Amortization and (accretion), net | 2.4 | 2.3 | 2.4 | 2.7 | 3.5 | 2.2 | 2.0 | 2.0 |
| Depreciation of premises and equipment | 1.1 | 1.2 | 1.3 | 1.3 | 1.4 | 1.5 | 1.5 | 1.4 |
| Deferred income tax (benefit) expense | -0.2 | -0.7 | 0.5 | -0.2 | 0.9 | -0.1 | 1.5 | 0.4 |
| Net periodic employee benefit cost | 0.0 | 0.0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.2 |
| Gains on sale of investment securities, net | 0.8 | | | -1.3 | | | | |
| Stock-compensation expense | 0.6 | 1.1 | 0.8 | 0.7 | 1.0 | 0.7 | 0.6 | 1.2 |
| Increase in value of bank-owned life insurance | -3.2 | -0.8 | -0.8 | -1.0 | -2.0 | -0.7 | -0.9 | -1.5 |
| Loans originated for sale | -3.8 | -2.6 | -5.7 | -8.4 | -15.1 | -10.9 | -13.0 | -4.7 |
| Proceeds from the sale of loans originated for sale | 3.8 | 2.7 | 5.9 | 8.4 | 15.1 | 11.3 | 12.6 | 4.7 |
| Gain on sale of loans | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 |
| Change in accrued interest receivable | 0.4 | 0.8 | -0.9 | -0.2 | -0.5 | -0.3 | 0.3 | -0.4 |
| Change in other assets | 6.6 | 3.2 | 0.0 | -9.5 | -1.8 | 3.5 | -11.3 | 1.3 |
| Change in other liabilities | -13.9 | 6.6 | 4.4 | 0.0 | 4.8 | 4.5 | 8.2 | -3.3 |
| Net Cash Provided by Operating Activities | 27.4 | 39.9 | 36.4 | 16.9 | 28.5 | 33.4 | 20.9 | 19.4 |
| |
| Investing Activities | | | | | | | | |
| Net decrease (increase) in loans | -29.2 | 6.1 | -62.7 | -6.9 | -15.7 | 7.1 | 16.4 | 75.8 |
| Purchases | 21.8 | | 125.6 | 204.9 | 157.9 | 122.1 | 250.1 | 66.4 |
| Proceeds from sales of securities available-for-sale | 0.6 | 84.9 | | | | | | |
| Proceeds from maturities and calls | 36.9 | 26.8 | 46.6 | 61.8 | 69.5 | 77.0 | 87.2 | 49.4 |
| Purchases | -5.8 | -0.2 | 0.0 | -0.2 | 0.0 | | -0.1 | 0.0 |
| Proceeds from sales | -0.2 | 0.2 | 0.0 | 0.0 | 0.0 | 1.1 | 3.2 | 0.5 |
| Proceeds from maturities and calls | -26.3 | 26.8 | 46.6 | -69.5 | 69.5 | 77.0 | 87.2 | 49.4 |
| Purchases of premises and equipment | -1.1 | -0.6 | -0.6 | -0.6 | -0.4 | -0.4 | -1.5 | -1.0 |
| Proceeds from the disposals of premises and equipment | 0.3 | | 0.1 | | 0.1 | 0.0 | 0.4 | |
| Proceeds from bank-owned life insurance policies | | 0.2 | 0.0 | 1.1 | 2.5 | 0.0 | 0.4 | 1.7 |
| Payments for low income housing tax credits | -2.4 | -1.7 | -1.3 | -0.3 | -0.5 | -0.1 | -0.3 | -1.2 |
| Acquisition of Citizens Commerce Bancshares, Inc. | 0.5 | 13.5 | | | | | | |
| Net Cash Provided by (Used in) Investing Activities | -21.7 | 129.4 | -143.6 | -150.0 | -102.4 | -37.4 | -144.4 | 58.7 |
| |
| Financing Activities | | | | | | | | |
| Net (decrease) increase in non-interest-bearing deposits | -38.6 | | | 158.5 | | | | |
| Net (decrease) increase in interest-bearing deposits | -73.7 | -41.6 | -23.6 | -31.3 | 89.4 | 100.9 | | |
| Net (decrease) increase in short-term borrowings | -21.5 | -4.2 | -97.6 | 113.9 | -24.0 | -14.7 | -4.7 | 20.0 |
| Purchases of treasury stock | -24.0 | -20.1 | -0.7 | -16.3 | -3.0 | -25.5 | -17.1 | -5.8 |
| Proceeds from exercise of stock options | | | 0.0 | 0.7 | | 0.1 | 0.2 | 0.4 |
| Repayments of Debt and Lease Obligation | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.2 | -0.4 | |
| Dividends paid | -10.0 | -9.6 | -8.9 | -9.1 | -9.0 | -9.0 | -9.1 | -9.2 |
| Net Cash (Used in) Provided by Financing Activities | -77.3 | -66.4 | -291.4 | 232.0 | 37.3 | 33.7 | -23.4 | 150.1 |
| Increase in Cash and Cash Equivalents | 31.3 | | | 62.3 | | | | |
| |
| Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract] | | | | | | | | |
| Supplemental Cash Flow Information: | | | | | | | | |
| Cash paid for interest | 10.8 | 7.7 | 2.0 | 1.5 | 1.8 | 2.3 | 3.0 | 3.9 |
| Cash paid for income taxes | 13.8 | 3.5 | 7.0 | 10.8 | | 3.8 | 10.7 | |
| Goodwill | | | | | | | | |
| Core deposit intangible | | | | | | | | |