Investment Holdings, Schedule of Investments [Table Text Block] |
| | December 31, 2022 | | | December 31, 2021 | |
| | Cost | | | Fair Value | | | Cost | | | Fair Value | |
| | (In thousands) | |
Investments | | | | | | | | | | | | | | | | |
Debt | | $ | 701,074 | | | $ | 686,458 | | | $ | 441,885 | | | $ | 437,317 | |
Warrants | | | 14,790 | | | | 29,712 | | | | 10,023 | | | | 20,200 | |
Other | | | 1,200 | | | | 1,300 | | | | 1,450 | | | | 200 | |
Equity | | | 4,184 | | | | 2,556 | | | | 479 | | | | 358 | |
Total investments | | $ | 721,248 | | | $ | 720,026 | | | $ | 453,837 | | | $ | 458,075 | |
| | December 31, 2022 | | | December 31, 2021 | |
| | Cost | | | Fair Value | | | Cost | | | Fair Value | |
| | (In thousands) | |
Life Science | | | | | | | | | | | | | | | | |
Biotechnology | | $ | 193,372 | | | $ | 195,006 | | | $ | 109,899 | | | $ | 107,902 | |
Medical Device | | | 132,803 | | | | 135,960 | | | | 88,681 | | | | 84,567 | |
Technology | | | | | | | | | | | | | | | | |
Communications | | | 22,892 | | | | 26,176 | | | | 22,853 | | | | 25,920 | |
Consumer-Related | | | 121,961 | | | | 114,050 | | | | 92,158 | | | | 93,194 | |
Data Storage | | | 476 | | | | 1,316 | | | | 476 | | | | 1,047 | |
Internet and Media | | | 329 | | | | 1,159 | | | | 569 | | | | 3,305 | |
Networking | | | 11,831 | | | | 11,710 | | | | 17,390 | | | | 17,964 | |
Power Management | | | 1,585 | | | | 2,610 | | | | 1,585 | | | | 2,609 | |
Semiconductors | | | 56 | | | | — | | | | 101 | | | | — | |
Software | | | 120,157 | | | | 118,716 | | | | 60,902 | | | | 60,807 | |
Sustainability | | | | | | | | | | | | | | | | |
Energy Efficiency | | | 8 | | | | 27 | | | | — | | | | — | |
Other Sustainability | | | 84,633 | | | | 85,524 | | | | 46,595 | | | | 47,011 | |
Healthcare Information and Services | | | | | | | | | | | | | | | | |
Diagnostics | | | 9,851 | | | | 9,858 | | | | 12,393 | | | | 12,377 | |
Other | | | 7,559 | | | | 3,870 | | | | 175 | | | | 1,177 | |
Software | | | 13,735 | | | | 14,044 | | | | 60 | | | | 195 | |
Total investments | | $ | 721,248 | | | $ | 720,026 | | | $ | 453,837 | | | $ | 458,075 | |
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