| 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 |
| Cash flows from operating activities: | | | | | | | | |
| Net increase (decrease) in net assets resulting from operations | 4.7 | 77.7 | 8.2 | | | | | |
| Adjustments to reconcile net increase (decrease) in net assets resulting from operations to net cash from (used in) operating activities: | | | | | | | | |
| Loan origination and other fees received | 20.1 | 30.5 | 19.2 | | | | | |
| Net realized (gain) loss on investments | 11.0 | -2.6 | 38.3 | | | | | |
| Net realized (gain) loss on foreign currency transactions | -23.9 | 6.0 | 0.0 | | | | | |
| Net unrealized (appreciation) depreciation of CSAs | 6.7 | -1.8 | | | | | | |
| Net unrealized (appreciation) depreciation on foreign currency transactions | -7.9 | -17.3 | 10.2 | | | | | |
| Payment-in-kind interest / dividends | -12.3 | -10.8 | -1.3 | | | | | |
| Amortization of deferred financing fees | -8.5 | -7.8 | -1.2 | | | | | |
| Accretion of loan origination and other fees | -8.5 | -7.8 | -1.2 | | | | | |
| Amortization / accretion of purchased loan premium / discount | -2.3 | -4.6 | -1.8 | | | | | |
| Payments for derivative contracts | -5.6 | -2.4 | 0.0 | | | | | |
| Proceeds from derivative contracts | 30.8 | 2.0 | 0.2 | | | | | |
| Changes in operating assets and liabilities: | | | | | | | | |
| Interest and fees receivable | -14.6 | -14.5 | -4.2 | | | | | |
| Prepaid expenses and other assets | -3.2 | -2.2 | 0.0 | | | | | |
| Accounts payable and accrued liabilities | -7.8 | 2.4 | 3.9 | | | | | |
| Interest payable | 1.9 | 3.5 | -1.4 | | | | | |
| Net cash provided by (used in) operating activities | 86.3 | -396.6 | -218.1 | | | | | |
| |
| Cash flows from financing activities: | | | | | | | | |
| Borrowings under credit facilities | 244.7 | 455.7 | 636.7 | | | | | |
| Financing fees paid | -1.9 | -7.3 | -0.8 | | | | | |
| Purchases of shares in repurchase plan | -32.1 | | -7.1 | | | | | |
| Cash dividends / distributions paid | -93.7 | -53.6 | -31.3 | | | | | |
| Net cash provided by (used in) financing activities | -31.1 | 388.3 | 288.6 | | | | | |
| Net increase (decrease) in cash and foreign currencies | 55.2 | -8.2 | 70.5 | | | | | |
| |
| Supplemental Information: | | | | | | | | |
| Cash paid for interest | 50.6 | 27.2 | 16.7 | | | | | |
| Excise taxes paid during the period | | 0.1 | 0.1 | | | | | |
| Supplemental non-cash information | | | | | | | | |
| Acquisitions (See Note 9): | | | | | | | | |
| Fair value of net assets acquired, net of cash | -435.8 | | 171.2 | | | | | |
| Transaction costs | | | | | | | | |
| Common stock issued in acquisition of net assets | 499.4 | | 160.4 | | | | | |
| Credit support agreement (See Note 2) | -44.4 | | -13.6 | | | | | |
| Deemed contribution - from Adviser | 27.7 | | 3.3 | | | | | |
| Deemed contributions - CSA | 44.4 | | 13.6 | | | | | |