Fair Value Measurements - Fair value measurements of investments and foreign currency forward contracts, by major class according to the fair value hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value Measurements
Total investments	$ 483,766	$ 502,980
Recurring
Fair Value Measurements
Total investments	518,284	541,040
Foreign currency forward contracts asset (liability)		1,507
Recurring | Senior Secured Loans
Fair Value Measurements
Total investments	416,316	434,023
Recurring | Unitranche Secured Loans
Fair Value Measurements
Total investments	13,548	20,633
Recurring | Junior Secured Loans
Fair Value Measurements
Total investments	27,425	22,193
Recurring | Equity Securities
Fair Value Measurements
Total investments	27,726	28,682
Recurring | Level 1
Fair Value Measurements
Total investments	229	294
Recurring | Level 1 | Equity Securities
Fair Value Measurements
Total investments	229	294
Recurring | Level 2
Fair Value Measurements
Foreign currency forward contracts asset (liability)		1,507
Recurring | Level 3
Fair Value Measurements
Total investments	484,786	505,237
Recurring | Level 3 | Senior Secured Loans
Fair Value Measurements
Total investments	416,316	434,023
Recurring | Level 3 | Unitranche Secured Loans
Fair Value Measurements
Total investments	13,548	20,633
Recurring | Level 3 | Junior Secured Loans
Fair Value Measurements
Total investments	27,425	22,193
Recurring | Level 3 | Equity Securities
Fair Value Measurements
Total investments	27,497	28,388
Recurring | Measured at NAV
Fair Value Measurements
Total investments	$ 33,269	$ 35,509