Borrowings (Tables)
 9 Months Ended
Sep. 30, 2023
Debt Disclosure [Abstract]  
Schedule of Information Related to Borrowings
The following table summarizes the interest expense, non-usage fees and amortization of financing costs incurred on the Holdings Credit Facility for the three and nine months ended September 30, 2023 and September 30, 2022:
 Three Months EndedNine Months Ended
 September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense$10,340 $6,734 $31,345 $13,937 
Non-usage fee$209 $154 $473 $558 
Amortization of financing costs$475 $807 $1,408 $2,395 
Weighted average interest rate7.2 %4.4 %6.9 %3.2 %
Effective interest rate7.8 %5.0 %7.4 %3.9 %
Average debt outstanding$563,470 $607,585 $603,154 $580,699 
The following table summarizes the interest expense, non-usage fees and amortization of financing costs incurred on the NMFC Credit Facility for the three and nine months ended September 30, 2023 and September 30, 2022:
 Three Months EndedNine Months Ended
 September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense$2,680 $1,872 $5,481 $3,798 
Non-usage fee$55 $25 $269 $118 
Amortization of financing costs$56 $60 $162 $175 
Weighted average interest rate7.4 %4.3 %7.0 %3.2 %
Effective interest rate7.8 %4.5 %7.6 %3.5 %
Average debt outstanding$141,764 $171,850 $104,227 $156,303 
The following table summarizes the interest expense, non-usage fees and amortization of financing costs incurred on the DB Credit Facility for the three and nine months ended September 30, 2023 and September 30, 2022:
 Three Months EndedNine Months Ended
 September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense(1)$3,864 $2,682 $11,062 $6,555 
Non-usage fee(1)$120 $103 $355 $236 
Amortization of financing costs$277 $272 $814 $809 
Weighted average interest rate8.1 %5.3 %7.8 %4.0 %
Effective interest rate9.1 %6.1 %8.8 %4.7 %
Average debt outstanding$186,487 $199,442 $186,429 $217,817 
(1)Interest expense includes the portion of the facility agent fee applicable to the drawn portion of the DB Credit Facility and non-usage fee includes the portion of the facility agent fee applicable to the undrawn portion of the DB Credit Facility.
The following table summarizes the interest expense, non-usage fees and amortization of financing costs incurred on the NMNLC Credit Facility II for the three and nine months ended September 30, 2023 and September 30, 2022:
Three Months EndedNine Months Ended
September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense$40 $25 $136 $225 
Non-usage fee$— $1 $1 $2 
Amortization of financing costs$21 $5 $66 $40 
Weighted average interest rate7.5 %5.0 %7.1 %3.4 %
Effective interest rate11.7 %6.1 %10.9 %4.0 %
Average debt outstanding$2,091 $2,013 $2,480 $8,939 
The following table summarizes the interest expense and amortization of financing costs incurred on the Unsecured Notes for the three and nine months ended September 30, 2023 and September 30, 2022:
 Three Months EndedNine Months Ended
 September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense$4,644 $6,512 $15,602 $18,624 
Amortization of financing costs$143 $202 $524 $607 
Weighted average interest rate4.7 %4.8 %4.8 %4.7 %
Effective interest rate4.9 %5.0 %5.0 %4.9 %
Average debt outstanding$391,500 $539,870 $433,661 $525,456 
The following table summarizes the Company’s SBA-guaranteed debentures as of September 30, 2023:
Issuance DateMaturity DateDebenture AmountInterest RateSBA Annual Charge
Fixed SBA-guaranteed debentures(1):    
March 25, 2015March 1, 2025$37,500 2.517 %0.355 %
September 23, 2015September 1, 202537,500 2.829 %0.355 %
September 23, 2015September 1, 202528,795 2.829 %0.742 %
March 23, 2016March 1, 202613,950 2.507 %0.742 %
September 21, 2016September 1, 20264,000 2.051 %0.742 %
September 20, 2017September 1, 202713,000 2.518 %0.742 %
March 21, 2018March 1, 202815,255 3.187 %0.742 %
Fixed SBA-guaranteed debentures(2):
September 19, 2018September 1, 202815,000 3.548 %0.222 %
September 25, 2019September 1, 202919,000 2.283 %0.222 %
March 25, 2020March 1, 203041,000 2.078 %0.222 %
March 25, 2020March 1, 203024,000 2.078 %0.275 %
September 23, 2020September 1, 203051,000 1.034 %0.275 %
Total SBA-guaranteed debentures $300,000   
(1)SBA-guaranteed debentures are held by SBIC I.
(2)SBA-guaranteed debentures are held by SBIC II.
The following table summarizes the interest expense and amortization of financing costs incurred on the SBA-guaranteed debentures for the three and nine months ended September 30, 2023 and September 30, 2022:
 Three Months EndedNine Months Ended
September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense$2,042 $2,042 $6,061 $6,061 
Amortization of financing costs$253 $253 $750 $750 
Weighted average interest rate2.7 %2.7 %2.7 %2.7 %
Effective interest rate3.0 %3.0 %3.0 %3.0 %
Average debt outstanding$300,000 $300,000 $300,000 $300,000 
Schedule of Information Related to Convertible Notes
The following table summarizes certain key terms related to the convertible features of the Company’s 2022 Convertible Notes as of September 30, 2023:
2022 Convertible Notes
Initial conversion premium(1)14.7 %
Initial conversion rate(2)70.4225 
Initial conversion price$14.20 
Conversion rate at September 30, 2023(1)(2)71.2860 
Conversion price at September 30, 2023(2)(3)$14.03 
Last conversion price calculation dateSeptember 15, 2023
(1)Conversion rates denominated in shares of common stock per $1 principal amount of the 2022 Convertible Notes converted.
(2)Represents conversion rate and conversion price, as applicable, taking into account certain de minimis adjustments that will be made on the conversion date.
(3)The conversion price in effect at September 30, 2023 on the 2022 Convertible Notes was calculated on September 15, 2023.
The following table summarizes the interest expense, amortization of financing costs and amortization of premium incurred on the 2018 and 2022 Convertible Notes (together, the "Convertible Notes") for the three and nine months ended September 30, 2023 and September 30, 2022:
 Three Months EndedNine Months Ended
 September 30, 2023September 30, 2022September 30, 2023September 30, 2022
Interest expense$5,696 $2,893 $17,892 $8,679 
Amortization of financing costs$447 $100 $1,276 $296 
Amortization of premium$(52)$(26)$(101)$(77)
Weighted average interest rate7.2 %5.8 %7.0 %5.8 %
Effective interest rate7.7 %5.9 %7.5 %5.9 %
Average debt outstanding$317,138 $201,250 $340,881 $201,250