Unaudited Consolidated Schedule of Investments - Additional Information (Parenthetical) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024		Dec. 31, 2023
Schedule of Investments [Line Items]
Cost	$ 2,551,299,000		$ 2,535,576,000
Total investments at fair value	$ 2,527,537,000		$ 2,488,715,000
Percent of net assets	208.60%	[1]	208.00%
Non-qualifying assets	29.10%		28.80%
Forward currency contracts	$ 15,833,000
Aerospace and Defense
Schedule of Investments [Line Items]
Total investments at fair value	$ 137,956,000		$ 132,498,000
Percent of net assets	11.40%		11.10%
Automotive
Schedule of Investments [Line Items]
Total investments at fair value	$ 71,897,000		$ 80,828,000
Percent of net assets	5.90%		6.70%
Banking, Finance, Insurance and Real Estate
Schedule of Investments [Line Items]
Total investments at fair value	$ 406,291,000		$ 401,816,000
Percent of net assets	33.50%		33.60%
Beverage, Food and Tobacco
Schedule of Investments [Line Items]
Total investments at fair value	$ 33,518,000		$ 23,135,000
Percent of net assets	2.80%		1.90%
Capital Equipment
Schedule of Investments [Line Items]
Total investments at fair value	$ 136,168,000		$ 128,706,000
Percent of net assets	11.20%		10.80%
Chemicals, Plastics, and Rubber
Schedule of Investments [Line Items]
Total investments at fair value	$ 40,937,000		$ 35,897,000
Percent of net assets	3.40%		3.00%
Construction and Building
Schedule of Investments [Line Items]
Total investments at fair value	$ 30,684,000		$ 30,387,000
Percent of net assets	2.50%		2.50%
Consumer goods: Durable
Schedule of Investments [Line Items]
Total investments at fair value	$ 49,236,000		$ 47,074,000
Percent of net assets	4.10%		3.90%
Consumer goods: Non-durable
Schedule of Investments [Line Items]
Total investments at fair value	$ 36,108,000		$ 28,210,000
Percent of net assets	3.00%		2.40%
Containers, Packaging and Glass
Schedule of Investments [Line Items]
Total investments at fair value	$ 37,542,000		$ 37,524,000
Percent of net assets	3.10%		3.10%
Energy: Electricity
Schedule of Investments [Line Items]
Total investments at fair value	$ 29,079,000		$ 20,874,000
Percent of net assets	2.40%		1.70%
Energy: Oil and Gas
Schedule of Investments [Line Items]
Total investments at fair value	$ 3,236,000		$ 3,240,000
Percent of net assets	0.30%		0.30%
Environmental Industries
Schedule of Investments [Line Items]
Total investments at fair value	$ 51,501,000		$ 53,484,000
Percent of net assets	4.20%		4.50%
Healthcare and Pharmaceuticals
Schedule of Investments [Line Items]
Total investments at fair value	$ 190,321,000		$ 216,952,000
Percent of net assets	15.70%		18.10%
High Tech Industries
Schedule of Investments [Line Items]
Total investments at fair value	$ 304,442,000		$ 303,082,000
Percent of net assets	25.10%		25.40%
Hotel, Gaming and Leisure
Schedule of Investments [Line Items]
Total investments at fair value	$ 55,991,000		$ 54,256,000
Percent of net assets	4.60%		4.50%
Investment Funds and Vehicles
Schedule of Investments [Line Items]
Total investments at fair value	$ 110,694,000		$ 110,066,000
Percent of net assets	9.10%		9.20%
Media: Advertising, Printing and Publishing
Schedule of Investments [Line Items]
Total investments at fair value	$ 38,931,000		$ 39,447,000
Percent of net assets	3.20%		3.30%
Media: Broadcasting and Subscription
Schedule of Investments [Line Items]
Total investments at fair value	$ 13,060,000		$ 13,277,000
Percent of net assets	1.10%		1.10%
Media: Diversified and Production
Schedule of Investments [Line Items]
Total investments at fair value	$ 65,449,000		$ 64,559,000
Percent of net assets	5.40%		5.40%
Metals and Mining
Schedule of Investments [Line Items]
Total investments at fair value	$ 9,015,000		$ 8,993,000
Percent of net assets	0.70%		0.80%
Services: Business
Schedule of Investments [Line Items]
Total investments at fair value	$ 366,291,000		$ 326,762,000
Percent of net assets	30.20%		27.30%
Services: Consumer
Schedule of Investments [Line Items]
Total investments at fair value	$ 61,307,000		$ 61,409,000
Percent of net assets	5.10%		5.10%
Structured products
Schedule of Investments [Line Items]
Total investments at fair value	$ 104,014,000		$ 102,922,000
Percent of net assets	8.60%		8.60%
Telecommunications
Schedule of Investments [Line Items]
Total investments at fair value	$ 27,535,000		$ 27,565,000
Percent of net assets	2.30%		2.30%
Transportation: Cargo
Schedule of Investments [Line Items]
Total investments at fair value	$ 88,075,000		$ 96,450,000
Percent of net assets	7.30%		8.10%
Transportation: Consumer
Schedule of Investments [Line Items]
Total investments at fair value	$ 12,882,000		$ 11,951,000
Percent of net assets	1.10%		1.00%
Utilities: Electric
Schedule of Investments [Line Items]
Total investments at fair value	$ 15,377,000		$ 22,696,000
Percent of net assets	1.30%		1.90%
Utilities: Oil and Gas
Schedule of Investments [Line Items]
Total investments at fair value	$ 0		$ 4,655,000
Percent of net assets	0.00%		0.40%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	100.00%		100.00%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Aerospace and Defense
Schedule of Investments [Line Items]
Percentage of Total Portfolio	5.50%		5.30%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Automotive
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.90%		3.30%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Banking, Finance, Insurance and Real Estate
Schedule of Investments [Line Items]
Percentage of Total Portfolio	16.10%		16.10%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Beverage, Food and Tobacco
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.30%		0.90%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Capital Equipment
Schedule of Investments [Line Items]
Percentage of Total Portfolio	5.40%		5.20%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Chemicals, Plastics, and Rubber
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.60%		1.50%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Construction and Building
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.20%		1.20%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Consumer goods: Durable
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%		1.90%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Consumer goods: Non-durable
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.40%		1.10%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Containers, Packaging and Glass
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.50%		1.50%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Energy: Electricity
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.20%		0.80%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Energy: Oil and Gas
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.10%		0.10%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Environmental Industries
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%		2.10%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Healthcare and Pharmaceuticals
Schedule of Investments [Line Items]
Percentage of Total Portfolio	7.50%		8.70%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | High Tech Industries
Schedule of Investments [Line Items]
Percentage of Total Portfolio	12.00%		12.20%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Hotel, Gaming and Leisure
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.20%		2.20%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Investment Funds and Vehicles
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.40%		4.40%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Media: Advertising, Printing and Publishing
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.50%		1.60%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Media: Broadcasting and Subscription
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.50%		0.50%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Media: Diversified and Production
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.60%		2.60%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Metals and Mining
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.40%		0.40%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Services: Business
Schedule of Investments [Line Items]
Percentage of Total Portfolio	14.50%		13.20%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Services: Consumer
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.40%		2.50%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Structured products
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.10%		4.10%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Telecommunications
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.10%		1.10%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Transportation: Cargo
Schedule of Investments [Line Items]
Percentage of Total Portfolio	3.50%		3.90%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Transportation: Consumer
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.50%		0.50%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Utilities: Electric
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.60%		0.90%
Percentage of Total Portfolio, at Fair Value | Industry Concentration Risk | Utilities: Oil and Gas
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%		0.20%
Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	100.00%		100.00%
Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	100.00%		100.00%
Senior debt and 1st lien notes
Schedule of Investments [Line Items]
Cost	$ 1,699,117,000		$ 1,705,353,000
Total investments at fair value	$ 1,658,742,000		$ 1,670,300,000
Percent of net assets	137.00%		140.00%
Senior debt and 1st lien notes | Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	66.00%		67.00%
Senior debt and 1st lien notes | Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	67.00%		67.00%
Subordinated debt and 2nd lien notes
Schedule of Investments [Line Items]
Cost	$ 260,225,000		$ 256,850,000
Total investments at fair value	$ 246,902,000		$ 238,215,000
Percent of net assets	21.00%		20.00%
Subordinated debt and 2nd lien notes | Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	10.00%		10.00%
Subordinated debt and 2nd lien notes | Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	10.00%		10.00%
Structured products
Schedule of Investments [Line Items]
Cost	$ 105,043,000		$ 107,314,000
Total investments at fair value	$ 95,131,000		$ 93,038,000
Percent of net assets	8.00%		8.00%
Structured products | Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.00%		4.00%
Structured products | Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.00%		4.00%
Equity shares
Schedule of Investments [Line Items]
Cost	$ 343,533,000		$ 320,335,000
Total investments at fair value	$ 413,482,000		$ 374,704,000
Percent of net assets	34.00%		31.00%
Equity shares | Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	16.00%		15.00%
Equity shares | Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	13.00%		13.00%
Equity warrants
Schedule of Investments [Line Items]
Cost	$ 129,000		$ 76,000
Total investments at fair value	$ 2,586,000		$ 2,392,000
Percent of net assets	0.00%		0.00%
Equity warrants | Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%		0.00%
Equity warrants | Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%		0.00%
Investment in joint ventures / PE fund
Schedule of Investments [Line Items]
Cost	$ 143,252,000		$ 145,648,000
Total investments at fair value	$ 110,694,000		$ 110,066,000
Percent of net assets	9.00%		9.00%
Investment in joint ventures / PE fund | Percentage of Total Portfolio, at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.00%		4.00%
Investment in joint ventures / PE fund | Percentage of Total Portfolio, at Cost | Investment Type Concentration Risk
Schedule of Investments [Line Items]
Percentage of Total Portfolio	6.00%		6.00%
MVC Credit Support Agreement
Schedule of Investments [Line Items]
Forward currency contracts	$ 2,450,000		$ 3,700,000
MVC Credit Support Agreement | Barings LLC
Schedule of Investments [Line Items]
Forward currency contracts	2,450,000	[2],[3],[4]	3,700,000	[5],[6],[7]
Notional Amount	23,000,000	[2],[3],[4]	23,000,000	[5],[6],[7]
Sierra Credit Support Agreement
Schedule of Investments [Line Items]
Forward currency contracts	(9,000,000)
Sierra Credit Support Agreement | Barings LLC
Schedule of Investments [Line Items]
Forward currency contracts	(9,000,000)	[8],[9],[10]	(3,900,000)	[11],[12],[13]
Notional Amount	100,000,000	[8],[9],[10]	100,000,000	[11],[12],[13]
MVC Private Equity Fund LP
Schedule of Investments [Line Items]
Cost	8,160,000		8,160,000
Total investments at fair value	511,000		1,005,000
Control investments
Schedule of Investments [Line Items]
Cost	103,553,000		103,163,000
Total investments at fair value	$ 103,116,000		$ 90,920,000
Percent of net assets	8.50%		7.60%
Control investments | MVC Private Equity Fund LP
Schedule of Investments [Line Items]
Total investments at fair value	$ 511,000		$ 1,005,000
February 21, 2019 | Line of Credit
Schedule of Investments [Line Items]
Commitment aggregate amount	$ 1,065,000,000		$ 1,065,000,000

[1] Fair value as a percentage of net assets.

[2] (a) The MVC Credit Support Agreement (as defined in “Note 2. Agreements and Related Party Transactions”) covers all of the investments acquired by Barings BDC, Inc. (the “Company”) from MVC Capital, Inc. (“MVC”) in connection with the MVC Acquisition (as defined in “Note 2. Agreements and Related Party Transactions”) and any investments received by the Company in connection with the restructuring, amendment, extension or other modification (including the issuance of new securities) of any of the investments acquired by the Company from MVC in connection with the MVC Acquisition (collectively, the “MVC Reference Portfolio”). Each investment that is included in the MVC Reference Portfolio is denoted in the above Schedule of Investments with footnote (28).

[3] (b)      The Company and Barings LLC (“Barings” or the “Adviser”) entered into the MVC Credit Support Agreement pursuant to which Barings agreed to provide credit support to the Company in the amount of up to $23.0 million.

[4] (c) Settlement Date means the earlier of (1) January 1, 2031 or (2) the date on which the entire MVC Reference Portfolio has been realized or written off.

[5] Settlement Date means the earlier of (1) January 1, 2031 or (2) the date on which the entire MVC Reference Portfolio has been realized or written off.

[6] The Company and Barings entered into the MVC Credit Support Agreement pursuant to which Barings agreed to provide credit support to the Company in the amount of up to $23.0 million.

[7] The MVC Credit Support Agreement covers all of the investments acquired by the Company from MVC in connection with the MVC Acquisition and any investments received by the Company in connection with the restructuring, amendment, extension or other modification (including the issuance of new securities) of any of the MVC Reference Portfolio. Each investment that is included in the MVC Reference Portfolio is denoted in the above Schedule of Investments with footnote (28).

[8] (d) See “Note 2. Agreements and Related Party Transactions” for additional information regarding the Credit Support Agreements.

[9] (e)     The Sierra Credit Support Agreement (as defined in “Note 2. Agreements and Related Party Transactions”) covers all of the investments acquired by the Company from Sierra Income Corporation (“Sierra”) in connection with the Sierra Merger (as defined in “Note 2. Agreements and Related Party Transactions”) and any investments received by the Company in connection with the restructuring, amendment, extension or other modification (including the issuance of new securities) of any of the investments acquired by the Company from Sierra in connection with the Sierra Merger (collectively, the “Sierra Reference Portfolio”). Each investment that is included in the Sierra Reference Portfolio is denoted in the above Schedule of Investments with footnote (29).

[10] (f)      The Company and Barings entered into the Sierra Credit Support Agreement pursuant to which Barings agreed to provide credit support to the Company in the amount of up to $100.0 million.

[11] Settlement Date means the earlier of (1) April 1, 2032 or (2) the date on which the entire Sierra Reference Portfolio has been realized or written off.

[12] The Company and Barings entered into the Sierra Credit Support Agreement pursuant to which Barings agreed to provide credit support to the Company in the amount of up to $100.0 million.

[13] The Sierra Credit Support Agreement covers all of the investments acquired by the Company from Sierra in connection with the Sierra Merger and any investments received by the Company in connection with the restructuring, amendment, extension or other modification (including the issuance of new securities) of any of the Sierra Reference Portfolio. Each investment that is included in the Sierra Reference Portfolio is denoted in the above Schedule of Investments with footnote (29).