Net Assets - Roll forward of Net Assets (Details) - USD ($)
$ in Thousands |
3 Months Ended |
Mar. 31, 2023 |
Mar. 31, 2022 |
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period (in shares) |
100,937,026
|
|
| Beginning of the period |
$ 1,326,191
|
$ 1,342,612
|
| Issuances of common stock |
|
21,572
|
| Offering costs |
(56)
|
(52)
|
| Distributions declared |
(32,453)
|
(33,339)
|
| Net increase (decrease) in net assets resulting from operations |
$ 44,812
|
37,047
|
| End of the period (in shares) |
100,937,026
|
|
| End of the period |
$ 1,338,494
|
1,367,840
|
| Total Net Assets of NMFC |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period |
1,314,473
|
1,321,245
|
| Issuances of common stock |
|
21,572
|
| Offering costs |
(56)
|
(52)
|
| Distributions declared |
(32,300)
|
(29,589)
|
| Net increase (decrease) in net assets resulting from operations |
44,573
|
36,192
|
| End of the period |
$ 1,326,690
|
$ 1,349,368
|
| Common Stock |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period (in shares) |
100,937,026
|
97,907,441
|
| Beginning of the period |
$ 1,009
|
$ 979
|
| Issuances of common stock (in shares) |
|
1,591,121
|
| Issuances of common stock |
|
$ 16
|
| End of the period (in shares) |
100,937,026
|
99,498,562
|
| End of the period |
$ 1,009
|
$ 995
|
| Paid in Capital in Excess of Par |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period |
1,305,945
|
1,272,796
|
| Issuances of common stock |
|
21,556
|
| Offering costs |
(56)
|
(52)
|
| End of the period |
1,305,889
|
1,294,300
|
| Accumulated Net Investment Income |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period |
147,593
|
118,330
|
| Distributions declared |
(32,300)
|
(29,589)
|
| Net increase (decrease) in net assets resulting from operations |
38,113
|
29,573
|
| End of the period |
153,406
|
118,314
|
| Accumulated Net Realized (Losses) Gains |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period |
(68,072)
|
(92,099)
|
| Net increase (decrease) in net assets resulting from operations |
677
|
17,596
|
| End of the period |
(67,395)
|
(74,503)
|
| Net Unrealized Appreciation (Depreciation) |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period |
(72,002)
|
21,239
|
| Net increase (decrease) in net assets resulting from operations |
5,783
|
(10,977)
|
| End of the period |
(66,219)
|
10,262
|
| Non-Controlling Interest in NMNLC |
|
|
| Investment Company, Net Assets [Roll Forward] |
|
|
| Beginning of the period |
11,718
|
21,367
|
| Distributions declared |
(153)
|
(3,750)
|
| Net increase (decrease) in net assets resulting from operations |
239
|
855
|
| End of the period |
$ 11,804
|
$ 18,472
|