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 |
Revenues [Abstract] | | | | | | | | |
|
Interest income from cash | | | | | | | | |
Total investment income | 219.1 | 135.3 | 71.0 | | | | | |
|
Operating expenses: | | | | | | | | |
Interest and other financing fees | 56.9 | 33.0 | 19.8 | | | | | |
Base management fee (Note 2) | 29.5 | 19.5 | 14.3 | | | | | |
Incentive management fees (Note 2) | 6.6 | 14.7 | | | | | | |
General and administrative expenses (Note 2) | 9.9 | 9.1 | 5.8 | 6.4 | 16.2 | 5.4 | 4.4 | 3.9 |
Total operating expenses | 102.9 | 76.4 | 40.0 | | | | | |
Net investment income before taxes | 116.3 | 59.0 | 31.1 | | | 72.2 | 58.9 | 71.6 |
|
Net realized gains (losses): | | | | | | | | |
Net realized gains (losses) on investments | 0.1 | -0.1 | -38.3 | | | | | -27.5 |
Foreign currency transactions | 23.9 | -6.0 | 0.0 | | | | | |
|
Net unrealized appreciation (depreciation): | | | | | | | | |
Credit support agreements | -6.7 | 1.8 | | | | | | |
|
Foreign currency transactions | | | | | | | | |
Net unrealized appreciation (depreciation) | | | | | | | | |
Net realized gains (losses) and unrealized appreciation (depreciation) on investments, credit support agreements and foreign currency transactions | | | | | | | | |
Benefit from (provision for) income taxes | | | | | | | | |
Net increase (decrease) in net assets resulting from operations | | | | | | | | |
Net investment income per share—basic (in dollars per share) | $1.12 | $0.90 | $0.64 | | | | | |
Net investment income per share—diluted (in dollars per share) | $1.12 | $0.90 | $0.64 | | | | | |
|
Dividends/distributions per share: | | | | | | | | |
Total dividends/distributions per share, declared (in dollars per share) | $0.95 | $0.82 | $0.65 | | | | | |
Total dividends/distributions per share, paid (in dollars per share) | $0.95 | $0.82 | $0.65 | | | | | |
|
Weighted average shares outstanding—basic (in shares) | 102.9 | 65.3 | 48.6 | | | | | 33.2 |
Weighted average shares outstanding—diluted (in shares) | 102.9 | 65.3 | 48.6 | | | | | |