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INVESTMENTS - STRS JVs individual Investments (Details)
£ in Thousands, $ in Thousands, $ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2022
USD ($)
Dec. 31, 2021
USD ($)
Sep. 30, 2022
CAD ($)
Sep. 30, 2022
GBP (£)
Dec. 31, 2021
CAD ($)
Dec. 31, 2020
USD ($)
Schedule of Investments [Line Items]            
Investment Owned, at Cost $ 773,406 $ 831,960        
Investment Owned, at Fair Value 764,554 $ 819,208        
Investment, Interest Rate, Paid in Kind   1.50%     1.50%  
STRS JV            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LINCSystemsLLCMember        
Investment Owned, at Cost 285,614 $ 260,472        
Investment Owned, at Fair Value $ 280,877 $ 259,510        
Investment, Interest Rate, Paid in Kind   7.00%     7.00%  
Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 727,213 $ 794,969        
Investment Owned, at Fair Value $ 716,495 $ 781,049        
Advertising            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 9,763          
Investment Owned, at Fair Value $ 9,782          
Advertising | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment Owned, at Cost   $ 9,490        
Investment Owned, at Fair Value   $ 9,488        
Air Freight & Logistics            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 3,531          
Investment Owned, at Fair Value $ 3,557          
Air Freight & Logistics | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 15,655 $ 20,021        
Investment Owned, at Fair Value $ 15,440 $ 20,129        
Application Software            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 13,183 $ 13,247        
Investment Owned, at Fair Value $ 13,411 $ 13,518        
Application Software | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 20,674 $ 22,460        
Investment Owned, at Fair Value $ 18,145 $ 22,590        
Building Products            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 14,125 $ 16,441        
Investment Owned, at Fair Value $ 14,305 $ 16,603        
Building Products | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 26,714 $ 43,653        
Investment Owned, at Fair Value $ 24,714 $ 43,757        
Construction & Engineering            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 8,534 $ 13,626        
Investment Owned, at Fair Value $ 8,625 $ 13,975        
Construction & Engineering | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment Owned, at Cost   $ 10,814        
Investment Owned, at Fair Value   $ 11,086        
Data Processing & Outsourced Services            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 15,497 $ 15,766        
Investment Owned, at Fair Value $ 14,507 $ 16,160        
Data Processing & Outsourced Services | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 39,673 $ 31,301        
Investment Owned, at Fair Value $ 41,019 $ 31,971        
Diversified Support Services            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 12,302 $ 12,773        
Investment Owned, at Fair Value $ 11,741 $ 10,489        
Diversified Support Services | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 11,264 $ 11,459        
Investment Owned, at Fair Value $ 11,165 $ 11,460        
Electronic Equipment & Instruments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 13,564 $ 6,680        
Investment Owned, at Fair Value $ 13,485 $ 6,687        
Electronic Equipment & Instruments | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment Owned, at Cost   $ 6,684        
Investment Owned, at Fair Value   $ 6,687        
Environmental & Facilities Services            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 18,577 $ 6,780        
Investment Owned, at Fair Value $ 18,641 $ 6,872        
Environmental & Facilities Services | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 18,251 $ 32,174        
Investment Owned, at Fair Value $ 18,108 $ 32,173        
Household Appliances            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 8,325          
Investment Owned, at Fair Value $ 7,773          
Household Appliances | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 6,040          
Investment Owned, at Fair Value $ 6,003          
Industrial Machinery            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 15,168 $ 6,727        
Investment Owned, at Fair Value $ 15,276 $ 6,815        
Industrial Machinery | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 7,521          
Investment Owned, at Fair Value $ 7,541          
Internet & Direct Marketing Retail            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 18,901 $ 15,153        
Investment Owned, at Fair Value $ 19,114 $ 15,353        
Internet & Direct Marketing Retail | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 37,285 $ 41,910        
Investment Owned, at Fair Value $ 37,542 $ 42,440        
Investment Banking & Brokerage            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 5,643 $ 9,943        
Investment Owned, at Fair Value $ 5,687 $ 10,054        
Investment Banking & Brokerage | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 12,043 $ 12,674        
Investment Owned, at Fair Value $ 12,077 $ 12,729        
IT Consulting And Other Services            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 34,933 $ 40,384        
Investment Owned, at Fair Value $ 33,342 $ 40,697        
IT Consulting And Other Services | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 13,649 $ 17,679        
Investment Owned, at Fair Value $ 13,653 $ 17,694        
Leisure Products            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 8,945 $ 8,931        
Investment Owned, at Fair Value $ 9,044 $ 8,930        
Leisure Products | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 3,565 $ 6,115        
Investment Owned, at Fair Value $ 3,509 $ 3,072        
Packaged Foods & Meats            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 12,297 $ 26,802        
Investment Owned, at Fair Value $ 11,998 $ 25,606        
Packaged Foods & Meats | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 11,175 $ 11,084        
Investment Owned, at Fair Value $ 10,922 $ 10,862        
Personal Products            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 3,639 $ 4,185        
Investment Owned, at Fair Value $ 3,698 $ 4,273        
Personal Products | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 13,703 $ 12,055        
Investment Owned, at Fair Value $ 13,566 $ 12,260        
Pharmaceuticals            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 15,512 $ 14,955        
Investment Owned, at Fair Value $ 13,706 $ 15,061        
Real Estate Operating Companies            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 10,777 $ 4,781        
Investment Owned, at Fair Value $ 10,722 $ 4,780        
Real Estate Operating Companies | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment Owned, at Cost   $ 5,425        
Investment Owned, at Fair Value   $ 5,431        
Real Estate Services            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment Owned, at Cost $ 8,791          
Investment Owned, at Fair Value $ 8,572          
Research & Consulting Services            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 8,799 $ 8,852        
Investment Owned, at Fair Value $ 8,832 $ 8,901        
Research & Consulting Services | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 22,244 $ 23,987        
Investment Owned, at Fair Value $ 22,316 $ 23,822        
Systems Software            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment Owned, at Cost   $ 9,801        
Investment Owned, at Fair Value   $ 9,898        
Systems Software | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 18,970 $ 19,018        
Investment Owned, at Fair Value $ 17,525 $ 19,160        
Technology Hardware, Storage & Peripherals            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 14,899 $ 14,694        
Investment Owned, at Fair Value $ 14,991 $ 14,725        
Technology Hardware, Storage & Peripherals | Debt Investments            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 16,479 $ 22,717        
Investment Owned, at Fair Value $ 16,809 $ 23,117        
Trading Companies & Distributors            
Schedule of Investments [Line Items]            
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment Owned, at Cost $ 9,909 $ 9,951        
Investment Owned, at Fair Value $ 10,068 $ 10,113        
Investment, Identifier [Axis]: ABB/Con-cise Optical Group LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ABBCon-ciseOpticalGroupLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Health Care Supplies [Member]   Health Care Supplies [Member] Health Care Supplies [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] us-gaap:BaseRateMember   us-gaap:BaseRateMember us-gaap:BaseRateMember    
Investment, Interest Rate, Floor 0.75%   0.75% 0.75%    
Investment, Basis Spread, Variable Rate 6.51%   6.51% 6.51%    
Investment Interest Rate 12.72%   12.72% 12.72%    
Investment, Acquisition Date Feb. 23, 2022          
Investment Maturity Date Feb. 23, 2028   Feb. 23, 2028 Feb. 23, 2028    
Investment Owned, Balance, Principal Amount $ 2,106          
Investment Owned, at Cost 2,058          
Investment Owned, at Fair Value $ 2,073          
Investment, Identifier [Axis]: ABB/Con-cise Optical Group LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ABBCon-ciseOpticalGroupLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Health Care Supplies [Member]   Health Care Supplies [Member] Health Care Supplies [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 0.75%   0.75% 0.75%    
Investment, Basis Spread, Variable Rate 7.50%   7.50% 7.50%    
Investment Interest Rate 10.46%   10.46% 10.46%    
Investment, Acquisition Date Feb. 23, 2022          
Investment Maturity Date Feb. 23, 2028   Feb. 23, 2028 Feb. 23, 2028    
Investment Owned, Balance, Principal Amount $ 21,627          
Investment Owned, at Cost 21,141          
Investment Owned, at Fair Value $ 21,281          
Investment, Identifier [Axis]: ALM Media, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ALMMediaLLCMember whf:ALMMediaLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Research & Consulting Services Research & Consulting Services Research & Consulting Services Research & Consulting Services Research & Consulting Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 7.00% 6.50% 6.50% 7.00%  
Investment Interest Rate 9.31% 8.00% 9.31% 9.31% 8.00%  
Investment, Acquisition Date Nov. 25, 2019 Nov. 25, 2019        
Investment Maturity Date Nov. 25, 2024 Nov. 25, 2024 Nov. 25, 2024 Nov. 25, 2024 Nov. 25, 2024  
Investment Owned, Balance, Principal Amount $ 13,584 $ 14,175        
Investment Owned, at Cost 13,467 14,011        
Investment Owned, at Fair Value $ 13,458 $ 13,996        
Investment, Interest Rate, Paid in Kind   1.00%     1.00%  
Investment, Interest Rate, Paid in Cash   10.25%     10.25%  
Investment, Identifier [Axis]: AST Applications Software Technology LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:ASTApplicationsSoftwareTechnologyLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   IT Consulting And Other Services     IT Consulting And Other Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   8.00%     8.00%  
Investment Interest Rate   9.00%     9.00%  
Investment, Acquisition Date   Jan. 10, 2017        
Investment Maturity Date   Jan. 10, 2023     Jan. 10, 2023  
Investment Owned, Balance, Principal Amount   $ 3,958        
Investment Owned, at Cost   3,943        
Investment Owned, at Fair Value   $ 3,958        
Investment, Interest Rate, Paid in Kind   1.00%     1.00%  
Investment, Interest Rate, Paid in Cash   8.00%     8.00%  
Investment, Identifier [Axis]: ATSG Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ATSGIncMember whf:ATSGIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.42% 7.50% 9.42% 9.42% 7.50%  
Investment, Acquisition Date Nov. 12, 2021 Nov. 12, 2021        
Investment Maturity Date Nov. 12, 2026 Nov. 12, 2026 Nov. 12, 2026 Nov. 12, 2026 Nov. 12, 2026  
Investment Owned, Balance, Principal Amount $ 13,877 $ 14,008        
Investment Owned, at Cost 13,649 13,736        
Investment Owned, at Fair Value $ 13,653 $ 13,736        
Investment, Identifier [Axis]: Access USA Shipping, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AccessUSAShippingLLCMember whf:AccessUSAShippingLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 8.00% 8.00% 8.00% 8.00% 8.00%  
Investment Interest Rate 11.12% 9.50% 11.12% 11.12% 9.50%  
Investment, Acquisition Date Feb. 08, 2019 Feb. 08, 2019        
Investment Maturity Date Feb. 08, 2024 Feb. 08, 2024 Feb. 08, 2024 Feb. 08, 2024 Feb. 08, 2024  
Investment Owned, Balance, Principal Amount $ 4,718 $ 4,937        
Investment Owned, at Cost 4,699 4,906        
Investment Owned, at Fair Value $ 4,718 $ 4,937        
Investment, Identifier [Axis]: Aeyon LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AeyonLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Research & Consulting Services   Research & Consulting Services Research & Consulting Services    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 8.88%   8.88% 8.88%    
Investment Interest Rate 11.62%   11.62% 11.62%    
Investment, Acquisition Date Feb. 10, 2022          
Investment Maturity Date Feb. 10, 2027   Feb. 10, 2027 Feb. 10, 2027    
Investment Owned, Balance, Principal Amount $ 8,933          
Investment Owned, at Cost 8,777          
Investment Owned, at Fair Value $ 8,858          
Investment, Identifier [Axis]: American Crafts, LC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AmericanCraftsLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Office Services And Supplies [Member]   Office Services And Supplies [Member] Office Services And Supplies [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 8.50%   8.50% 8.50%    
Investment Interest Rate 11.62%   11.62% 11.62%    
Investment, Acquisition Date Jan. 25, 2022          
Investment Maturity Date May 28, 2026   May 28, 2026 May 28, 2026    
Investment Owned, Balance, Principal Amount $ 1,367          
Investment Owned, at Cost 1,344          
Investment Owned, at Fair Value $ 1,195          
Investment, Identifier [Axis]: American Crafts, LC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AmericanCraftsLCMember whf:AmericanCraftsLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.50% 8.50% 8.50% 8.50% 8.50%  
Investment Interest Rate 11.62% 9.50% 11.62% 11.62% 9.50%  
Investment, Acquisition Date May 28, 2021 May 28, 2021        
Investment Maturity Date May 28, 2026 May 28, 2026 May 28, 2026 May 28, 2026 May 28, 2026  
Investment Owned, Balance, Principal Amount $ 8,139 $ 8,434        
Investment Owned, at Cost 8,050 8,325        
Investment Owned, at Fair Value $ 7,114 $ 8,325        
Investment, Identifier [Axis]: Arcole Holding Corporation Shares            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ArcoleHoldingCorporationMember whf:ArcoleHoldingCorporationMember        
Investment, Type [Extensible Enumeration] Common Stock [Member] Common Stock [Member] Common Stock [Member] Common Stock [Member] Common Stock [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage  
Investment, Acquisition Date Oct. 01, 2020 Oct. 01, 2020        
Investment Owned, at Cost $ 6,944 $ 6,944        
Investment Owned, at Fair Value $ 6,295 $ 6,874       $ 6,448
Investment, Identifier [Axis]: Arcstor Midco, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ArcstorMidcoLLCMember whf:ArcstorMidcoLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Systems Software Systems Software Systems Software Systems Software Systems Software  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment Interest Rate 10.67% 8.00% 10.67% 10.67% 8.00%  
Investment, Acquisition Date Mar. 16, 2021 Mar. 16, 2021        
Investment Maturity Date Mar. 16, 2027 Mar. 16, 2027 Mar. 16, 2027 Mar. 16, 2027 Mar. 16, 2027  
Investment Owned, Balance, Principal Amount $ 19,256 $ 19,354        
Investment Owned, at Cost 18,970 19,018        
Investment Owned, at Fair Value $ 17,525 $ 19,160        
Investment, Identifier [Axis]: Atlas Purchaser, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AtlasPurchaserIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Application Software   Application Software Application Software    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 0.75%   0.75% 0.75%    
Investment, Basis Spread, Variable Rate 5.25%   5.25% 5.25%    
Investment Interest Rate 8.68%   8.68% 8.68%    
Investment, Acquisition Date Aug. 29, 2022          
Investment Maturity Date May 08, 2028   May 08, 2028 May 08, 2028    
Investment Owned, Balance, Principal Amount $ 3,105          
Investment Owned, at Cost 2,595          
Investment Owned, at Fair Value $ 2,562          
Investment, Identifier [Axis]: Atlas Purchaser, Inc Second Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AtlasPurchaserIncMember whf:AtlasPurchaserIncMember        
Investment, Type [Extensible Enumeration] whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Application Software Application Software Application Software Application Software Application Software  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 0.75% 0.75% 0.75% 0.75% 0.75%  
Investment, Basis Spread, Variable Rate 9.00% 9.00% 9.00% 9.00% 9.00%  
Investment Interest Rate 11.19% 9.75% 11.19% 11.19% 9.75%  
Investment, Acquisition Date May 03, 2021 May 03, 2021        
Investment Maturity Date May 07, 2029 May 07, 2029 May 07, 2029 May 07, 2029 May 07, 2029  
Investment Owned, Balance, Principal Amount $ 15,000 $ 15,000        
Investment Owned, at Cost 14,628 14,586        
Investment Owned, at Fair Value $ 12,197 $ 14,700        
Investment, Identifier [Axis]: Avision Holdings, LLC Class A LLC Interests            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:AvisionHoldingsLLCMember whf:AvisionHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:ClassALLCInterestsMember whf:ClassALLCInterestsMember whf:ClassALLCInterestsMember whf:ClassALLCInterestsMember whf:ClassALLCInterestsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Advertising Advertising Advertising Advertising Advertising  
Investment, Acquisition Date Dec. 15, 2021 Dec. 15, 2021        
Investment Owned, Balance, Principal Amount $ 201 $ 200        
Investment Owned, at Cost 251 250        
Investment Owned, at Fair Value $ 219 $ 250        
Investment, Identifier [Axis]: BBQ Buyer, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BBQBuyerLLCMember whf:BBQBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 10.00% 10.00% 10.00% 10.00% 10.00%  
Investment Interest Rate 13.12% 11.50% 13.12% 13.12% 11.50%  
Investment, Acquisition Date Apr. 29, 2022 Dec. 02, 2021        
Investment Maturity Date Aug. 28, 2025 Aug. 28, 2025 Aug. 28, 2025 Aug. 28, 2025 Aug. 28, 2025  
Investment Owned, Balance, Principal Amount $ 2,593 $ 2,573        
Investment Owned, at Cost 2,553 2,523        
Investment Owned, at Fair Value $ 2,559 $ 2,523        
Investment, Interest Rate, Paid in Kind 2.00% 2.00% 2.00% 2.00% 2.00%  
Investment, Interest Rate, Paid in Cash 11.12% 9.50% 11.12% 11.12% 9.50%  
Investment, Identifier [Axis]: BBQ Buyer, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BBQBuyerLLCMember whf:BBQBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 10.00% 10.00% 10.00% 10.00% 10.00%  
Investment Interest Rate 13.12% 11.50% 13.12% 13.12% 11.50%  
Investment, Acquisition Date Aug. 28, 2020 Aug. 28, 2020        
Investment Maturity Date Aug. 28, 2025 Aug. 28, 2025 Aug. 28, 2025 Aug. 28, 2025 Aug. 28, 2025  
Investment Owned, Balance, Principal Amount $ 12,719 $ 12,623        
Investment Owned, at Cost 12,533 12,388        
Investment Owned, at Fair Value $ 12,616 $ 12,623        
Investment, Interest Rate, Paid in Kind 2.00% 2.00% 2.00% 2.00% 2.00%  
Investment, Interest Rate, Paid in Cash 11.12% 9.50% 11.12% 11.12% 9.50%  
Investment, Identifier [Axis]: BBQ Buyer, LLC Shares            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BBQBuyerLLCMember whf:BBQBuyerLLCMember        
Investment, Type [Extensible Enumeration] Common Stock [Member] Common Stock [Member] Common Stock [Member] Common Stock [Member] Common Stock [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Acquisition Date Aug. 28, 2020 Aug. 28, 2020        
Investment Owned, Balance, Principal Amount $ 1,100 $ 1,100        
Investment Owned, at Cost 1,100 1,100        
Investment Owned, at Fair Value $ 1,954 $ 2,442        
Investment, Identifier [Axis]: BL Products Parent, LP Class A Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BLProductsParentLPMember          
Investment, Type [Extensible Enumeration] whf:ClassAUnitsMember   whf:ClassAUnitsMember whf:ClassAUnitsMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Industrial Machinery   Industrial Machinery Industrial Machinery    
Investment, Acquisition Date Feb. 01, 2022          
Investment Owned, Balance, Principal Amount $ 667          
Investment Owned, at Cost 667          
Investment Owned, at Fair Value $ 668          
Investment, Identifier [Axis]: BLP Buyer, Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.44%, Due 2/1/27            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BLProductsParentLPMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Industrial Machinery   Industrial Machinery Industrial Machinery    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 9.00%   9.00% 9.00%    
Investment, Acquisition Date Feb. 18, 2022          
Investment Maturity Date Feb. 01, 2027   Feb. 01, 2027 Feb. 01, 2027    
Investment Owned, Balance, Principal Amount $ 274          
Investment Owned, at Cost 269          
Investment Owned, at Fair Value $ 271          
Investment, Identifier [Axis]: BLP Buyer, Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.54%, Due 2/1/27            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BLProductsParentLPMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Industrial Machinery   Industrial Machinery Industrial Machinery    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 9.03%   9.03% 9.03%    
Investment, Acquisition Date Feb. 18, 2022          
Investment Maturity Date Feb. 01, 2027   Feb. 01, 2027 Feb. 01, 2027    
Investment Owned, Balance, Principal Amount $ 8,209          
Investment Owned, at Cost 8,066          
Investment Owned, at Fair Value $ 8,080          
Investment, Identifier [Axis]: BPII-JL Group Holdings LP Class A Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BPII-JLGroupHoldingsLPMember whf:BPII-JLGroupHoldingsLPMember        
Investment, Type [Extensible Enumeration] whf:ClassAUnitsMember whf:ClassAUnitsMember whf:ClassAUnitsMember whf:ClassAUnitsMember whf:ClassAUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services  
Investment, Acquisition Date Dec. 29, 2021 Dec. 29, 2021        
Investment Owned, Balance, Principal Amount $ 83 $ 83        
Investment Owned, at Cost 825 825        
Investment Owned, at Fair Value $ 661 $ 825        
Investment, Identifier [Axis]: Bridgepoint Healthcare, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BridgepointHealthcareLLCMember whf:BridgepointHealthcareLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.75% 7.75% 7.75% 7.75% 7.75%  
Investment Interest Rate 10.51% 8.75% 10.51% 10.51% 8.75%  
Investment, Acquisition Date Oct. 05, 2021 Oct. 05, 2021        
Investment Maturity Date Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026  
Investment Owned, at Fair Value $ (11)          
Investment, Identifier [Axis]: Bridgepoint Healthcare, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BridgepointHealthcareLLCMember whf:BridgepointHealthcareLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.75% 7.75% 7.75% 7.75% 7.75%  
Investment Interest Rate 10.51% 8.75% 10.51% 10.51% 8.75%  
Investment, Acquisition Date Oct. 05, 2021 Oct. 05, 2021        
Investment Maturity Date Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026  
Investment Owned, at Fair Value $ (8)          
Investment, Identifier [Axis]: Bridgepoint Healthcare, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BridgepointHealthcareLLCMember whf:BridgepointHealthcareLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member] Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.75% 7.75% 7.75% 7.75% 7.75%  
Investment Interest Rate 10.51% 8.75% 10.51% 10.51% 8.75%  
Investment, Acquisition Date Oct. 05, 2021 Oct. 05, 2021        
Investment Maturity Date Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026 Oct. 05, 2026  
Investment Owned, Balance, Principal Amount $ 10,562 $ 10,979        
Investment Owned, at Cost 10,392 10,770        
Investment Owned, at Fair Value $ 10,337 $ 10,769        
Investment, Identifier [Axis]: Bulk Midco, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:BulkMidcoLLCMember whf:BulkMidcoLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Cable And Satellite [Member] Cable And Satellite [Member] Cable And Satellite [Member] Cable And Satellite [Member] Cable And Satellite [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.25% 7.24% 5.25% 5.25% 7.24%  
Investment Interest Rate 11.50% 8.24% 11.50% 11.50% 8.24%  
Investment, Acquisition Date Jun. 08, 2018 Jun. 08, 2018        
Investment Maturity Date Jun. 08, 2023 Jun. 08, 2023 Jun. 08, 2023 Jun. 08, 2023 Jun. 08, 2023  
Investment Owned, Balance, Principal Amount $ 14,922 $ 15,000        
Investment Owned, at Cost 14,891 14,936        
Investment Owned, at Fair Value $ 14,323 $ 14,526        
Investment, Identifier [Axis]: CHS Therapy, LLC First Lien Secured Term Loan A            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CHSTherapyLLCMember whf:CHSTherapyLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 9.00% 9.00% 9.00% 9.00% 9.00%  
Investment Interest Rate 12.67% 10.50% 12.67% 12.67% 10.50%  
Investment, Acquisition Date Jun. 14, 2019 Jun. 14, 2019        
Investment Maturity Date Jun. 14, 2024 Jun. 14, 2024 Jun. 14, 2024 Jun. 14, 2024 Jun. 14, 2024  
Investment Owned, Balance, Principal Amount $ 7,125 $ 7,242        
Investment Owned, at Cost 7,079 7,175        
Investment Owned, at Fair Value $ 7,125 $ 7,242        
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 12.17% 10.00% 12.17% 12.17% 10.00%  
Investment, Identifier [Axis]: CHS Therapy, LLC First Lien Secured Term Loan C            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CHSTherapyLLCMember whf:CHSTherapyLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 9.00% 9.00% 9.00% 9.00% 9.00%  
Investment Interest Rate 12.67% 10.50% 12.67% 12.67% 10.50%  
Investment, Acquisition Date Oct. 07, 2020 Oct. 07, 2020        
Investment Maturity Date Jun. 14, 2024 Jun. 14, 2024 Jun. 14, 2024 Jun. 14, 2024 Jun. 14, 2024  
Investment Owned, Balance, Principal Amount $ 877 $ 891        
Investment Owned, at Cost 869 879        
Investment Owned, at Fair Value $ 877 $ 891        
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 12.17% 10.00% 12.17% 12.17% 10.00%  
Investment, Identifier [Axis]: CX Holdco LLC Common Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CXHoldcoLLCMember whf:CXHoldcoLLCMember        
Investment, Type [Extensible Enumeration] whf:CommonUnitsMember whf:CommonUnitsMember whf:CommonUnitsMember whf:CommonUnitsMember whf:CommonUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Acquisition Date May 04, 2021 May 04, 2021        
Investment Owned, Balance, Principal Amount $ 972 $ 972        
Investment Owned, at Cost 972 972        
Investment Owned, at Fair Value $ 1,457 $ 972        
Investment, Identifier [Axis]: Camp Facility Services Holdings, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CampFacilityServicesHoldingsLLCMember whf:CampFacilityServicesHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.55% 7.50% 9.55% 9.55% 7.50%  
Investment, Acquisition Date Nov. 16, 2021 Nov. 16, 2021        
Investment Maturity Date Nov. 16, 2027 Nov. 16, 2027 Nov. 16, 2027 Nov. 16, 2027 Nov. 16, 2027  
Investment Owned, at Fair Value $ (24) $ (1)        
Investment, Identifier [Axis]: Camp Facility Services Holdings, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:CampFacilityServicesHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Specialized Consumer Services [Member]     Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Nov. 16, 2021        
Investment Maturity Date   Nov. 16, 2027     Nov. 16, 2027  
Investment, Identifier [Axis]: Camp Facility Services Holdings, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CampFacilityServicesHoldingsLLCMember whf:CampFacilityServicesHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.55% 7.50% 9.55% 9.55% 7.50%  
Investment, Acquisition Date Nov. 16, 2021 Nov. 16, 2021        
Investment Maturity Date Nov. 16, 2027 Nov. 16, 2027 Nov. 16, 2027 Nov. 16, 2027 Nov. 16, 2027  
Investment Owned, Balance, Principal Amount $ 11,830 $ 13,000        
Investment Owned, at Cost 11,628 12,745        
Investment Owned, at Fair Value $ 11,558 $ 12,742        
Investment, Identifier [Axis]: Camp Facility Services Parent, LLC Preferred Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CampFacilityServicesParentLLCMember whf:CampFacilityServicesParentLLCMember        
Investment, Type [Extensible Enumeration] whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Basis Spread, Variable Rate 10.00% 10.00% 10.00% 10.00% 10.00%  
Investment, Acquisition Date Nov. 16, 2021 Nov. 16, 2021        
Investment Owned, Balance, Principal Amount $ 15 $ 15        
Investment Owned, at Cost 840 840        
Investment Owned, at Fair Value $ 853 $ 840        
Investment, Interest Rate, Paid in Kind 10.00% 10.00% 10.00% 10.00% 10.00%  
Investment, Identifier [Axis]: Cennox Holdings Limited, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 5/4/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CennoxHoldingsLimitedMember whf:CennoxHoldingsLimitedMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 7.69% 7.00% 7.69% 7.69% 7.00%  
Investment, Acquisition Date Jul. 16, 2021 Jul. 16, 2021        
Investment Maturity Date May 04, 2026 May 04, 2026 May 04, 2026 May 04, 2026 May 04, 2026  
Investment Owned, Balance, Principal Amount $ 2,844 $ 2,866        
Investment Owned, at Cost 3,868 3,889        
Investment Owned, at Fair Value $ 3,140 $ 3,877        
Investment, Identifier [Axis]: Cennox Holdings Limited, First lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 5/4/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CennoxHoldingsLimitedMember whf:CennoxHoldingsLimitedMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.00% 6.25% 6.25% 6.00%  
Investment Interest Rate 9.78% 7.00% 9.78% 9.78% 7.00%  
Investment, Acquisition Date Jun. 28, 2022 Jul. 16, 2021        
Investment Maturity Date May 04, 2026 May 04, 2026 May 04, 2026 May 04, 2026 May 04, 2026  
Investment Owned, Balance, Principal Amount $ 9,482 $ 864        
Investment Owned, at Cost 9,845 1,173        
Investment Owned, at Fair Value $ 9,205 $ 1,169        
Investment, Identifier [Axis]: Cennox, Inc., First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 5/4/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:CennoxInc.Member        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   IT Consulting And Other Services     IT Consulting And Other Services  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Jun. 28, 2021        
Investment Maturity Date   May 04, 2026     May 04, 2026  
Investment Owned, Balance, Principal Amount   $ 8,915        
Investment Owned, at Cost   8,755        
Investment Owned, at Fair Value   $ 8,915        
Investment, Identifier [Axis]: Cennox, Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 5/4/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CennoxHoldingsLimitedMember whf:CennoxInc.Member        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 8.03% 7.00% 8.03% 8.03% 7.00%  
Investment, Acquisition Date Jul. 16, 2021 Jun. 28, 2021        
Investment Maturity Date May 04, 2026 May 04, 2026 May 04, 2026 May 04, 2026 May 04, 2026  
Investment Owned, Balance, Principal Amount $ 450 $ 561        
Investment Owned, at Cost 680 551        
Investment Owned, at Fair Value $ 502 $ 569        
Investment, Identifier [Axis]: Cennox, Inc., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 5/4/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:CennoxInc.Member        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   IT Consulting And Other Services     IT Consulting And Other Services  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Jun. 28, 2021        
Investment Maturity Date   May 04, 2026     May 04, 2026  
Investment Owned, Balance, Principal Amount   $ 8,525        
Investment Owned, at Cost   8,365        
Investment Owned, at Fair Value   $ 8,438        
Investment, Identifier [Axis]: Claridge Products and Equipment, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ClaridgeProductsandEquipmentLLCMember whf:ClaridgeProductsandEquipmentLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Construction Materials [Member] Construction Materials [Member] Construction Materials [Member] Construction Materials [Member] Construction Materials [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] us-gaap:BaseRateMember us-gaap:PrimeRateMember us-gaap:BaseRateMember us-gaap:BaseRateMember us-gaap:PrimeRateMember  
Investment, Interest Rate, Floor 1.00% 3.25% 1.00% 1.00% 3.25%  
Investment, Basis Spread, Variable Rate 5.72% 5.50% 5.72% 5.72% 5.50%  
Investment Interest Rate 11.84% 8.75% 11.84% 11.84% 8.75%  
Investment, Acquisition Date Dec. 30, 2020 Dec. 30, 2020        
Investment Maturity Date Dec. 29, 2025 Dec. 29, 2025 Dec. 29, 2025 Dec. 29, 2025 Dec. 29, 2025  
Investment Owned, Balance, Principal Amount $ 926 $ 211        
Investment Owned, at Cost 918 207        
Investment Owned, at Fair Value $ 888 $ 204        
Investment, Identifier [Axis]: Claridge Products and Equipment, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ClaridgeProductsandEquipmentLLCMember whf:ClaridgeProductsandEquipmentLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Construction Materials [Member] Construction Materials [Member] Construction Materials [Member] Construction Materials [Member] Construction Materials [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 10.17% 7.50% 10.17% 10.17% 7.50%  
Investment, Acquisition Date Dec. 30, 2020 Dec. 30, 2020        
Investment Maturity Date Dec. 29, 2025 Dec. 29, 2025 Dec. 29, 2025 Dec. 29, 2025 Dec. 29, 2025  
Investment Owned, Balance, Principal Amount $ 7,582 $ 7,640        
Investment Owned, at Cost 7,484 7,518        
Investment Owned, at Fair Value $ 7,280 $ 7,469        
Investment, Identifier [Axis]: CleanChoice Energy, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CleanChoiceEnergyIncMember whf:CleanChoiceEnergyIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Electric Utilities [Member] Electric Utilities [Member] Electric Utilities [Member] Electric Utilities [Member] Electric Utilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.25% 7.25% 7.25% 7.25% 7.25%  
Investment Interest Rate 9.76% 8.25% 9.76% 9.76% 8.25%  
Investment, Acquisition Date Oct. 12, 2021 Oct. 12, 2021        
Investment Maturity Date Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026  
Investment Owned, Balance, Principal Amount $ 10,500 $ 10,500        
Investment Owned, at Cost 10,331 10,299        
Investment Owned, at Fair Value $ 10,408 $ 10,296        
Investment, Identifier [Axis]: Coastal Television Broadcasting Group LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CoastalTelevisionBroadcastingGroupLLCMember whf:CoastalTelevisionBroadcastingGroupLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Broadcasting [Member] Broadcasting [Member] Broadcasting [Member] Broadcasting [Member] Broadcasting [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] whf:SecuredOvernightFinancingRateMember Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] whf:SecuredOvernightFinancingRateMember  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.48% 7.50% 9.48% 9.48% 7.50%  
Investment, Acquisition Date Dec. 30, 2021 Dec. 30, 2021        
Investment Maturity Date Dec. 30, 2026 Dec. 30, 2026 Dec. 30, 2026 Dec. 30, 2026 Dec. 30, 2026  
Investment Owned, at Fair Value $ (4)          
Investment, Identifier [Axis]: Coastal Television Broadcasting Group LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CoastalTelevisionBroadcastingGroupLLCMember whf:CoastalTelevisionBroadcastingGroupLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Broadcasting [Member] Broadcasting [Member] Broadcasting [Member] Broadcasting [Member] Broadcasting [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] whf:SecuredOvernightFinancingRateMember Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] whf:SecuredOvernightFinancingRateMember  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.48% 7.50% 9.48% 9.48% 7.50%  
Investment, Acquisition Date Dec. 30, 2021 Dec. 30, 2021        
Investment Maturity Date Dec. 30, 2026 Dec. 30, 2026 Dec. 30, 2026 Dec. 30, 2026 Dec. 30, 2026  
Investment Owned, Balance, Principal Amount $ 8,191 $ 8,191        
Investment Owned, at Cost 8,052 8,027        
Investment Owned, at Fair Value $ 7,946 $ 8,027        
Investment, Identifier [Axis]: Crown Brands LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CrownBrandsLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Distributors [Member]   Distributors [Member] Distributors [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 10.00%   10.00% 10.00%    
Investment Interest Rate 12.95%   12.95% 12.95%    
Investment, Acquisition Date Apr. 22, 2022          
Investment Maturity Date Dec. 09, 2025   Dec. 09, 2025 Dec. 09, 2025    
Investment Owned, Balance, Principal Amount $ 357          
Investment Owned, at Cost 357          
Investment Owned, at Fair Value $ 344          
Investment, Identifier [Axis]: Crown Brands LLC Second Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CrownBrandsLLCMember whf:CrownBrandsLLCMember        
Investment, Type [Extensible Enumeration] whf:SecondLienSecuredDelayedDrawLoanMember whf:SecondLienSecuredDelayedDrawLoanMember whf:SecondLienSecuredDelayedDrawLoanMember whf:SecondLienSecuredDelayedDrawLoanMember whf:SecondLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Distributors [Member] Distributors [Member] Distributors [Member] Distributors [Member] Distributors [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 10.50% 10.50% 10.50% 10.50% 10.50%  
Investment Interest Rate 13.74% 12.00% 13.74% 13.74% 12.00%  
Investment, Acquisition Date Dec. 15, 2020 Dec. 15, 2020        
Investment Maturity Date Jan. 08, 2026 Jan. 08, 2026 Jan. 08, 2026 Jan. 08, 2026 Jan. 08, 2026  
Investment Owned, Balance, Principal Amount $ 651 $ 650        
Investment Owned, at Cost 651 650        
Investment Owned, at Fair Value $ 423 $ 520        
Investment, Identifier [Axis]: Crown Brands LLC Second Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:CrownBrandsLLCMember whf:CrownBrandsLLCMember        
Investment, Type [Extensible Enumeration] whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Distributors [Member] Distributors [Member] Distributors [Member] Distributors [Member] Distributors [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 10.50% 10.50% 10.50% 10.50% 10.50%  
Investment Interest Rate 13.62% 12.00% 13.62% 13.62% 12.00%  
Investment, Acquisition Date Dec. 15, 2020 Dec. 15, 2020        
Investment Maturity Date Jan. 08, 2026 Jan. 08, 2026 Jan. 08, 2026 Jan. 08, 2026 Jan. 08, 2026  
Investment Owned, Balance, Principal Amount $ 4,386 $ 4,382        
Investment Owned, at Cost 4,318 4,299        
Investment Owned, at Fair Value $ 2,851 $ 3,505        
Investment, Identifier [Axis]: DCA Investment Holding, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:DCAInvestmentHoldingLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Services [Member]     Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   0.75%     0.75%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Mar. 12, 2021        
Investment Maturity Date   Mar. 12, 2027     Mar. 12, 2027  
Investment Owned, Balance, Principal Amount   $ 678        
Investment Owned, at Cost   672        
Investment Owned, at Fair Value   $ 688        
Investment, Identifier [Axis]: DCA Investment Holding, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:DCAInvestmentHoldingLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Services [Member]     Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   0.75%     0.75%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Mar. 12, 2021        
Investment Maturity Date   Mar. 12, 2027     Mar. 12, 2027  
Investment Owned, Balance, Principal Amount   $ 7,025        
Investment Owned, at Cost   6,933        
Investment Owned, at Fair Value   $ 6,988        
Investment, Identifier [Axis]: Drew Foam Companies Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:DrewFoamCompaniesIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Nov. 05, 2020        
Investment Maturity Date   Nov. 05, 2025     Nov. 05, 2025  
Investment Owned, Balance, Principal Amount   $ 7,207        
Investment Owned, at Cost   7,094        
Investment Owned, at Fair Value   $ 7,183        
Investment, Identifier [Axis]: Drew Foam Companies Inc, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 11/5/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:DrewFoamCompaniesIncMember whf:DrewFoamCompaniesIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Building Products Building Products Building Products Building Products Building Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 9.67% 7.00% 9.67% 9.67% 7.00%  
Investment, Acquisition Date Nov. 09, 2020 Nov. 09, 2020        
Investment Maturity Date Nov. 05, 2025 Nov. 05, 2025 Nov. 05, 2025 Nov. 05, 2025 Nov. 05, 2025  
Investment Owned, Balance, Principal Amount $ 14,305 $ 7,207        
Investment Owned, at Cost 14,125 7,096        
Investment Owned, at Fair Value $ 14,305 $ 7,183        
Investment, Identifier [Axis]: E-Phoenix Acquisition Co. Inc., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 5.75%, Rate 6.75%, Due 6/23/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:E-PhoenixAcquisitionCo.Inc.Member whf:E-PhoenixAcquisitionCo.Inc.Member        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Research & Consulting Services Research & Consulting Services Research & Consulting Services Research & Consulting Services Research & Consulting Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.75% 5.75% 5.75% 5.75% 5.75%  
Investment Interest Rate 9.42% 6.75% 9.42% 9.42% 6.75%  
Investment, Acquisition Date Jul. 15, 2021 Jul. 15, 2021        
Investment Maturity Date Jun. 23, 2027 Jun. 23, 2027 Jun. 23, 2027 Jun. 23, 2027 Jun. 23, 2027  
Investment Owned, Balance, Principal Amount $ 8,888 $ 8,955        
Investment Owned, at Cost 8,799 8,852        
Investment Owned, at Fair Value $ 8,832 $ 8,901        
Investment, Identifier [Axis]: Eddy Acquisitions, LLC Preferred Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EddyAcquisitionsLLCMember whf:EddyAcquisitionsLLCMember        
Investment, Type [Extensible Enumeration] whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member]  
Investment, Basis Spread, Variable Rate 12.00% 12.00% 12.00% 12.00% 12.00%  
Investment Interest Rate 12.00% 12.00% 12.00% 12.00% 12.00%  
Investment, Acquisition Date Sep. 15, 2021 Sep. 15, 2021        
Investment Owned, Balance, Principal Amount $ 167 $ 167        
Investment Owned, at Cost 167 167        
Investment Owned, at Fair Value $ 118 $ 167        
Investment, Identifier [Axis]: Education Networks of America, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:EducationNetworksofAmericaIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Application Software     Application Software  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   6.50%     6.50%  
Investment, Acquisition Date   Nov. 30, 2021        
Investment Maturity Date   Oct. 27, 2026     Oct. 27, 2026  
Investment Owned, Balance, Principal Amount   $ 4,719        
Investment Owned, at Cost   4,511        
Investment Owned, at Fair Value   $ 4,508        
Investment, Identifier [Axis]: EducationDynamics, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EducationDynamicsLLCMember whf:EducationDynamicsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment Interest Rate 10.05% 8.00% 10.05% 10.05% 8.00%  
Investment, Acquisition Date Sep. 15, 2021 Sep. 15, 2021        
Investment Maturity Date Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026  
Investment Owned, at Fair Value $ (3)          
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 9.55% 7.50% 9.55% 9.55% 7.50%  
Investment, Identifier [Axis]: EducationDynamics, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EducationDynamicsLLCMember whf:EducationDynamicsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] us-gaap:PrimeRateMember London Interbank Offered Rate (LIBOR) [Member] us-gaap:PrimeRateMember us-gaap:PrimeRateMember London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.50% 7.00% 5.50% 5.50% 7.00%  
Investment Interest Rate 11.75% 8.00% 11.75% 11.75% 8.00%  
Investment, Acquisition Date Sep. 15, 2021 Sep. 15, 2021        
Investment Maturity Date Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026  
Investment Owned, Balance, Principal Amount $ 240          
Investment Owned, at Cost 236          
Investment Owned, at Fair Value $ 234          
Investment, Interest Rate, Paid in Kind   0.50%     0.50%  
Investment, Interest Rate, Paid in Cash   7.50%     7.50%  
Investment, Identifier [Axis]: EducationDynamics, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EducationDynamicsLLCMember whf:EducationDynamicsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment Interest Rate 10.05% 8.00% 10.05% 10.05% 8.00%  
Investment, Acquisition Date Sep. 15, 2021 Sep. 15, 2021        
Investment Maturity Date Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026 Sep. 15, 2026  
Investment Owned, Balance, Principal Amount $ 13,119 $ 13,318        
Investment Owned, at Cost 12,912 13,068        
Investment Owned, at Fair Value $ 12,887 $ 13,064        
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 9.55% 7.50% 9.55% 9.55% 7.50%  
Investment, Identifier [Axis]: EducationDynamics, LLC Subordinated Unsecured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EducationDynamicsLLCMember whf:EducationDynamicsLLCMember        
Investment, Type [Extensible Enumeration] whf:SubordinatedUnsecuredTermLoanMember whf:SubordinatedUnsecuredTermLoanMember whf:SubordinatedUnsecuredTermLoanMember whf:SubordinatedUnsecuredTermLoanMember whf:SubordinatedUnsecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member] Education Services [Member]  
Investment, Basis Spread, Variable Rate 4.00% 4.00% 4.00% 4.00% 4.00%  
Investment Interest Rate 4.00% 4.00% 4.00% 4.00% 4.00%  
Investment, Acquisition Date Sep. 15, 2021 Sep. 15, 2021        
Investment Maturity Date Mar. 15, 2027 Mar. 15, 2027 Mar. 15, 2027 Mar. 15, 2027 Mar. 15, 2027  
Investment Owned, Balance, Principal Amount $ 167 $ 167        
Investment Owned, at Cost 167 167        
Investment Owned, at Fair Value $ 167 $ 167        
Investment, Identifier [Axis]: Empire Office, Inc First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EmpireOfficeIncMember whf:EmpireOfficeIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 6.50% 6.75% 6.50% 6.50% 6.75%  
Investment Interest Rate 9.62% 8.25% 9.62% 9.62% 8.25%  
Investment, Acquisition Date Aug. 17, 2021 Aug. 17, 2021        
Investment Maturity Date Apr. 12, 2024 Apr. 12, 2024 Apr. 12, 2024 Apr. 12, 2024 Apr. 12, 2024  
Investment Owned, Balance, Principal Amount $ 4,864          
Investment Owned, at Cost 4,792          
Investment Owned, at Fair Value $ 4,820 $ 7        
Investment, Identifier [Axis]: Empire Office, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EmpireOfficeIncMember whf:EmpireOfficeIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member] Office Services And Supplies [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 6.50% 6.75% 6.50% 6.50% 6.75%  
Investment Interest Rate 9.62% 8.25% 9.62% 9.62% 8.25%  
Investment, Acquisition Date Apr. 12, 2019 Apr. 12, 2019        
Investment Maturity Date Apr. 12, 2024 Apr. 12, 2024 Apr. 12, 2024 Apr. 12, 2024 Apr. 12, 2024  
Investment Owned, Balance, Principal Amount $ 12,019 $ 12,656        
Investment Owned, at Cost 11,923 12,507        
Investment Owned, at Fair Value $ 11,910 $ 12,589        
Investment, Identifier [Axis]: Epiphany Business Services, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:EpiphanyBusinessServicesLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   7.50%     7.50%  
Investment Interest Rate   8.50%     8.50%  
Investment, Acquisition Date   Dec. 04, 2020        
Investment Maturity Date   Jun. 22, 2023     Jun. 22, 2023  
Investment Owned, Balance, Principal Amount   $ 3,052        
Investment Owned, at Cost   3,008        
Investment Owned, at Fair Value   $ 3,027        
Investment, Identifier [Axis]: Epiphany Business Services, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:EpiphanyBusinessServicesLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   7.50%     7.50%  
Investment Interest Rate   8.50%     8.50%  
Investment, Acquisition Date   Dec. 04, 2020        
Investment Maturity Date   Jun. 22, 2023     Jun. 22, 2023  
Investment Owned, at Fair Value   $ 3        
Investment, Identifier [Axis]: Epiphany Business Services, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:EpiphanyBusinessServicesLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   7.50%     7.50%  
Investment Interest Rate   8.50%     8.50%  
Investment, Acquisition Date   Dec. 04, 2020        
Investment Maturity Date   Jun. 22, 2023     Jun. 22, 2023  
Investment Owned, Balance, Principal Amount   $ 4,278        
Investment Owned, at Cost   4,214        
Investment Owned, at Fair Value   $ 4,235        
Investment, Identifier [Axis]: Escalon Services Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EscalonServicesIncMember whf:EscalonServicesIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 10.31% 13.50% 10.31% 10.31% 13.50%  
Investment Interest Rate 13.22% 14.50% 13.22% 13.22% 14.50%  
Investment, Acquisition Date Dec. 04, 2020 Dec. 04, 2020        
Investment Maturity Date Dec. 04, 2025 Dec. 04, 2025 Dec. 04, 2025 Dec. 04, 2025 Dec. 04, 2025  
Investment Owned, Balance, Principal Amount $ 17,278 $ 8,046        
Investment Owned, at Cost 16,599 7,490        
Investment Owned, at Fair Value $ 17,797 $ 8,046        
Investment, Interest Rate, Paid in Kind 1.50%   1.50% 1.50%    
Investment, Interest Rate, Paid in Cash 11.72% 13.00% 11.72% 11.72% 13.00%  
Investment, Identifier [Axis]: Escalon Services Inc Warrants            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:EscalonServicesIncMember whf:EscalonServicesIncMember        
Investment, Type [Extensible Enumeration] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services  
Investment, Acquisition Date Dec. 04, 2020 Dec. 04, 2020        
Investment Owned, Balance, Principal Amount $ 709 $ 709        
Investment Owned, at Cost 476 476        
Investment Owned, at Fair Value $ 2,368 $ 893        
Investment, Identifier [Axis]: FR Flow Control CB LLC, First Lien Secured Term Loan B, Floor 1.00%, Spread L plus 5.50%, Rate 6.50%, Due 6/28/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:FRFlowControlCBLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanBMember     whf:FirstLienSecuredTermLoanBMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Industrial Machinery     Industrial Machinery  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   6.50%     6.50%  
Investment, Acquisition Date   Jul. 19, 2019        
Investment Maturity Date   Jun. 28, 2026     Jun. 28, 2026  
Investment Owned, Balance, Principal Amount   $ 6,815        
Investment Owned, at Cost   6,727        
Investment Owned, at Fair Value   $ 6,815        
Investment, Identifier [Axis]: Flexitallic Group SAS First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:FlexitallicGroupSASMember whf:FlexitallicGroupSASMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Commodity Chemicals [Member] Commodity Chemicals [Member] Commodity Chemicals [Member] Commodity Chemicals [Member] Commodity Chemicals [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.50% 7.50% 7.50% 7.50% 7.50%  
Investment Interest Rate 11.20% 8.50% 11.20% 11.20% 8.50%  
Investment, Acquisition Date Oct. 28, 2019 Oct. 28, 2019        
Investment Maturity Date Oct. 29, 2026 Oct. 29, 2026 Oct. 29, 2026 Oct. 29, 2026 Oct. 29, 2026  
Investment Owned, Balance, Principal Amount $ 16,371 $ 15,722        
Investment Owned, at Cost 15,777 15,047        
Investment Owned, at Fair Value $ 16,003 $ 15,172        
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 10.70% 8.00% 10.70% 10.70% 8.00%  
Investment, Identifier [Axis]: Future Payment Technologies, LP First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:FuturePaymentTechnologiesLPMember whf:FuturePaymentTechnologiesLPMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.25% 8.25% 8.25% 8.25% 8.25%  
Investment Interest Rate 10.81% 9.25% 10.81% 10.81% 9.25%  
Investment, Acquisition Date Dec. 23, 2016 Dec. 23, 2016        
Investment Maturity Date Jun. 07, 2024 Jun. 07, 2024 Jun. 07, 2024 Jun. 07, 2024 Jun. 07, 2024  
Investment Owned, Balance, Principal Amount $ 23,222 $ 24,000        
Investment Owned, at Cost 23,074 23,811        
Investment Owned, at Fair Value $ 23,222 $ 23,925        
Investment, Identifier [Axis]: Geo Logic Systems Ltd., First Lien Secured Revolving Loan, Floor 1.00%, Spread C plus 6.50%, Rate 7.50%, Due 12/19/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:GeoLogicSystemsLtdMember whf:GeoLogicSystemsLtdMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 10.67% 7.50% 10.67% 10.67% 7.50%  
Investment, Acquisition Date Jan. 22, 2020 Jan. 22, 2020        
Investment Maturity Date Dec. 19, 2024 Dec. 19, 2024 Dec. 19, 2024 Dec. 19, 2024 Dec. 19, 2024  
Investment Owned, at Fair Value $ 2 $ 4        
Investment, Identifier [Axis]: Geo Logic Systems Ltd., First Lien Secured Term Loan, Floor 1.00%, Spread C plus 6.50%, Rate 7.50%, Due 12/19/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:GeoLogicSystemsLtdMember whf:GeoLogicSystemsLtdMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services Data Processing & Outsourced Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 10.67% 7.50% 10.67% 10.67% 7.50%  
Investment, Acquisition Date Jan. 22, 2020 Jan. 22, 2020        
Investment Maturity Date Dec. 19, 2024 Dec. 19, 2024 Dec. 19, 2024 Dec. 19, 2024 Dec. 19, 2024  
Investment Owned, Balance, Principal Amount $ 20,225 $ 20,632        
Investment Owned, at Cost 15,497 15,766        
Investment Owned, at Fair Value $ 14,505 $ 16,156        
Investment, Identifier [Axis]: Grupo HIMA San Pablo, Inc Amended Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:GrupoHIMASanPabloIncMember        
Investment, Type [Extensible Enumeration]   whf:AmendedTermLoanMember     whf:AmendedTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Interest Rate, Floor   1.50%     1.50%  
Investment, Basis Spread, Variable Rate   9.00%     9.00%  
Investment Interest Rate   10.50%     10.50%  
Investment, Acquisition Date   Nov. 24, 2021        
Investment Maturity Date   Nov. 24, 2023     Nov. 24, 2023  
Investment Owned, Balance, Principal Amount   $ 1,708        
Investment Owned, at Cost   1,704        
Investment Owned, at Fair Value   $ 1,708        
Investment, Interest Rate, Paid in Kind   10.50%     10.50%  
Investment, Interest Rate, Paid in Cash   0.00%     0.00%  
Investment, Identifier [Axis]: Grupo HIMA San Pablo, Inc First Lien Secured Term Loan A            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:GrupoHIMASanPabloIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanAMember     whf:FirstLienSecuredTermLoanAMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Basis Spread, Variable Rate   9.00%     9.00%  
Investment Interest Rate   9.13%     9.13%  
Investment, Acquisition Date   May 05, 2019        
Investment Maturity Date   Apr. 30, 2019     Apr. 30, 2019  
Investment Owned, Balance, Principal Amount   $ 3,476        
Investment Owned, at Cost   3,476        
Investment Owned, at Fair Value   $ 1,169        
Investment, Identifier [Axis]: Grupo HIMA San Pablo, Inc First Lien Secured Term Loan B            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:GrupoHIMASanPabloIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanBMember     whf:FirstLienSecuredTermLoanBMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.50%     1.50%  
Investment, Basis Spread, Variable Rate   9.00%     9.00%  
Investment Interest Rate   10.50%     10.50%  
Investment, Acquisition Date   Feb. 01, 2013        
Investment Maturity Date   Apr. 30, 2019     Apr. 30, 2019  
Investment Owned, Balance, Principal Amount   $ 12,185        
Investment Owned, at Cost   12,185        
Investment Owned, at Fair Value   $ 4,097        
Investment, Interest Rate, Paid in Kind   2.00%     2.00%  
Investment, Interest Rate, Paid in Cash   13.75%     13.75%  
Investment, Identifier [Axis]: Grupo HIMA San Pablo, Inc Second Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:GrupoHIMASanPabloIncMember        
Investment, Type [Extensible Enumeration]   whf:SecondLienSecuredTermLoanMember     whf:SecondLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Basis Spread, Variable Rate   15.75%     15.75%  
Investment Interest Rate   15.75%     15.75%  
Investment, Acquisition Date   Feb. 01, 2013        
Investment Maturity Date   Jul. 31, 2018     Jul. 31, 2018  
Investment Owned, Balance, Principal Amount   $ 1,028        
Investment Owned, at Cost   $ 1,024        
Investment, Identifier [Axis]: Grupo HIMA San Pablo, Inc Superpriority Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:GrupoHIMASanPabloIncMember        
Investment, Type [Extensible Enumeration]   whf:SuperpriorityDelayedDrawLoanMember     whf:SuperpriorityDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Facilities [Member]     Health Care Facilities [Member]  
Investment, Basis Spread, Variable Rate   12.00%     12.00%  
Investment Interest Rate   12.00%     12.00%  
Investment, Acquisition Date   Nov. 24, 2021        
Investment Maturity Date   Nov. 24, 2023     Nov. 24, 2023  
Investment Owned, Balance, Principal Amount   $ 568        
Investment Owned, at Cost   568        
Investment Owned, at Fair Value   $ 568        
Investment, Identifier [Axis]: HC Salon Holdings, Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:HCSalonHoldingsIncMember whf:HCSalonHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.00% 8.00% 8.00% 8.00% 8.00%  
Investment Interest Rate 11.67% 9.00% 11.67% 11.67% 9.00%  
Investment, Acquisition Date Sep. 30, 2021 Sep. 30, 2021        
Investment Maturity Date Sep. 30, 2026 Sep. 30, 2026 Sep. 30, 2026 Sep. 30, 2026 Sep. 30, 2026  
Investment Owned, at Fair Value $ 11          
Investment, Identifier [Axis]: HC Salon Holdings, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:HCSalonHoldingsIncMember whf:HCSalonHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.00% 8.00% 8.00% 8.00% 8.00%  
Investment Interest Rate 11.67% 9.00% 11.67% 11.67% 9.00%  
Investment, Acquisition Date Sep. 30, 2021 Sep. 30, 2021        
Investment Maturity Date Sep. 30, 2026 Sep. 30, 2026 Sep. 30, 2026 Sep. 30, 2026 Sep. 30, 2026  
Investment Owned, Balance, Principal Amount $ 11,550 $ 11,638        
Investment Owned, at Cost 11,365 11,417        
Investment Owned, at Fair Value $ 11,550 $ 11,416        
Investment, Identifier [Axis]: HRG Management, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:HRGManagementLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Real Estate Operating Companies     Real Estate Operating Companies  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Oct. 19, 2021        
Investment Maturity Date   Oct. 19, 2026     Oct. 19, 2026  
Investment Owned, Balance, Principal Amount   $ 653        
Investment Owned, at Cost   644        
Investment Owned, at Fair Value   $ 651        
Investment, Identifier [Axis]: HRG Management, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:HRGManagementLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Real Estate Operating Companies     Real Estate Operating Companies  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Oct. 19, 2021        
Investment Maturity Date   Oct. 19, 2026     Oct. 19, 2026  
Investment, Identifier [Axis]: HRG Management, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:HRGManagementLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Real Estate Operating Companies     Real Estate Operating Companies  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Oct. 19, 2021        
Investment Maturity Date   Oct. 19, 2026     Oct. 19, 2026  
Investment Owned, Balance, Principal Amount   $ 4,875        
Investment Owned, at Cost   4,781        
Investment Owned, at Fair Value   $ 4,780        
Investment, Identifier [Axis]: HRG Management, LLC, First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.29%, Due 10/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] HRG Management, LLC HomeRiver Group, LLC [Member]          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Real Estate Operating Companies   Real Estate Operating Companies Real Estate Operating Companies    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 8.99%   8.99% 8.99%    
Investment, Acquisition Date Feb. 18, 2022          
Investment Maturity Date Oct. 19, 2026   Oct. 19, 2026 Oct. 19, 2026    
Investment Owned, Balance, Principal Amount $ 1,273          
Investment Owned, at Cost 1,257          
Investment Owned, at Fair Value $ 1,242          
Investment, Identifier [Axis]: HRG Management, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.29%, Due 10/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] HRG Management, LLC HomeRiver Group, LLC [Member]          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Real Estate Operating Companies   Real Estate Operating Companies Real Estate Operating Companies    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 8.99%   8.99% 8.99%    
Investment, Acquisition Date Feb. 18, 2022          
Investment Maturity Date Oct. 19, 2026   Oct. 19, 2026 Oct. 19, 2026    
Investment Owned, at Fair Value $ (4)          
Investment, Identifier [Axis]: HRG Management, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.25%, Due 10/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   HRG Management, LLC HomeRiver Group, LLC [Member]        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Real Estate Operating Companies     Real Estate Operating Companies  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Dec. 28, 2021        
Investment Maturity Date   Oct. 19, 2026     Oct. 19, 2026  
Investment Owned, Balance, Principal Amount   $ 4,875        
Investment Owned, at Cost   4,781        
Investment Owned, at Fair Value   $ 4,780        
Investment, Identifier [Axis]: HRG Management, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.29%, Due 10/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] HRG Management, LLC HomeRiver Group, LLC [Member]          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Real Estate Operating Companies   Real Estate Operating Companies Real Estate Operating Companies    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 8.99%   8.99% 8.99%    
Investment, Acquisition Date Dec. 28, 2021          
Investment Maturity Date Oct. 19, 2026   Oct. 19, 2026 Oct. 19, 2026    
Investment Owned, Balance, Principal Amount $ 9,677          
Investment Owned, at Cost 9,520          
Investment Owned, at Fair Value $ 9,484          
Investment, Identifier [Axis]: Hollander Intermediate LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:HollanderIntermediateLlcMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Home Furnishings [Member]   Home Furnishings [Member] Home Furnishings [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 2.00%   2.00% 2.00%    
Investment, Basis Spread, Variable Rate 8.75%   8.75% 8.75%    
Investment Interest Rate 11.79%   11.79% 11.79%    
Investment, Acquisition Date Sep. 19, 2022          
Investment Maturity Date Sep. 21, 2026   Sep. 21, 2026 Sep. 21, 2026    
Investment Owned, Balance, Principal Amount $ 4,891          
Investment Owned, at Cost 4,849          
Investment Owned, at Fair Value $ 4,671          
Investment, Identifier [Axis]: Honors Holdings, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:HonorsHoldingsLLCMember whf:HonorsHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.46% 7.58% 7.46% 7.46% 7.58%  
Investment Interest Rate 10.80% 8.58% 10.80% 10.80% 8.58%  
Investment, Acquisition Date Sep. 06, 2019 Sep. 06, 2019        
Investment Maturity Date Sep. 06, 2024 Sep. 06, 2024 Sep. 06, 2024 Sep. 06, 2024 Sep. 06, 2024  
Investment Owned, Balance, Principal Amount $ 4,649 $ 4,649        
Investment Owned, at Cost 4,618 4,611        
Investment Owned, at Fair Value $ 4,603 $ 4,578        
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 10.30% 8.08% 10.30% 10.30% 8.08%  
Investment, Identifier [Axis]: Honors Holdings, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:HonorsHoldingsLLCMember whf:HonorsHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.56% 7.96% 7.56% 7.56% 7.96%  
Investment Interest Rate 10.73% 8.96% 10.73% 10.73% 8.96%  
Investment, Acquisition Date Sep. 06, 2019 Sep. 06, 2019        
Investment Maturity Date Sep. 06, 2024 Sep. 06, 2024 Sep. 06, 2024 Sep. 06, 2024 Sep. 06, 2024  
Investment Owned, Balance, Principal Amount $ 9,440 $ 9,440        
Investment Owned, at Cost 9,337 9,315        
Investment Owned, at Fair Value $ 9,346 $ 9,296        
Investment, Interest Rate, Paid in Kind 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Interest Rate, Paid in Cash 10.23% 8.46% 10.23% 10.23% 8.46%  
Investment, Identifier [Axis]: I And I Sales Group, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IAndISalesGroupLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Advertising     Advertising  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 15, 2021        
Investment Maturity Date   Dec. 15, 2026     Dec. 15, 2026  
Investment Owned, Balance, Principal Amount   $ 396        
Investment Owned, at Cost   388        
Investment Owned, at Fair Value   $ 388        
Investment, Identifier [Axis]: I And I Sales Group, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IAndISalesGroupLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Advertising     Advertising  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 15, 2021        
Investment Maturity Date   Dec. 15, 2026     Dec. 15, 2026  
Investment, Identifier [Axis]: I And I Sales Group, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IAndISalesGroupLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Advertising     Advertising  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 15, 2021        
Investment Maturity Date   Dec. 15, 2026     Dec. 15, 2026  
Investment Owned, Balance, Principal Amount   $ 9,286        
Investment Owned, at Cost   9,102        
Investment Owned, at Fair Value   $ 9,100        
Investment, Identifier [Axis]: I&I Sales Group, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:IAndISalesGroupLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Advertising   Advertising Advertising    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 5.75%   5.75% 5.75%    
Investment Interest Rate 9.00%   9.00% 9.00%    
Investment, Acquisition Date Mar. 11, 2022          
Investment Maturity Date Dec. 15, 2026   Dec. 15, 2026 Dec. 15, 2026    
Investment Owned, Balance, Principal Amount $ 714          
Investment Owned, at Cost 702          
Investment Owned, at Fair Value $ 707          
Investment, Identifier [Axis]: I&I Sales Group, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:IAndISalesGroupLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Advertising   Advertising Advertising    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 5.75%   5.75% 5.75%    
Investment Interest Rate 9.42%   9.42% 9.42%    
Investment, Acquisition Date Feb. 18, 2022          
Investment Maturity Date Dec. 15, 2026   Dec. 15, 2026 Dec. 15, 2026    
Investment Owned, at Fair Value $ 1          
Investment, Identifier [Axis]: I&I Sales Group, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:IAndISalesGroupLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Advertising   Advertising Advertising    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 5.75%   5.75% 5.75%    
Investment Interest Rate 9.42%   9.42% 9.42%    
Investment, Acquisition Date Feb. 18, 2022          
Investment Maturity Date Dec. 15, 2026   Dec. 15, 2026 Dec. 15, 2026    
Investment Owned, Balance, Principal Amount $ 9,216          
Investment Owned, at Cost 9,061          
Investment Owned, at Fair Value $ 9,074          
Investment, Identifier [Axis]: IDIG Parent, LLC, First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/15/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IDIGParentLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Systems Software     Systems Software  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Sep. 21, 2021        
Investment Maturity Date   Dec. 15, 2026     Dec. 15, 2026  
Investment Owned, Balance, Principal Amount   $ 1,411        
Investment Owned, at Cost   1,397        
Investment Owned, at Fair Value   $ 1,411        
Investment, Identifier [Axis]: IDIG Parent, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/15/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IDIGParentLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Systems Software     Systems Software  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Jun. 25, 2021        
Investment Maturity Date   Dec. 15, 2026     Dec. 15, 2026  
Investment Owned, at Fair Value   $ 5        
Investment, Identifier [Axis]: IDIG Parent, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/15/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IDIGParentLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Systems Software     Systems Software  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Jun. 25, 2021        
Investment Maturity Date   Dec. 15, 2026     Dec. 15, 2026  
Investment Owned, Balance, Principal Amount   $ 8,482        
Investment Owned, at Cost   8,404        
Investment Owned, at Fair Value   $ 8,482        
Investment, Identifier [Axis]: ITS Buyer Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:ITSBuyerIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Air Freight & Logistics     Air Freight & Logistics  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 22, 2021        
Investment Maturity Date   Jun. 15, 2026     Jun. 15, 2026  
Investment, Identifier [Axis]: ITS Buyer Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:ITSBuyerIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Air Freight & Logistics     Air Freight & Logistics  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 22, 2021        
Investment Maturity Date   Jun. 15, 2026     Jun. 15, 2026  
Investment Owned, Balance, Principal Amount   $ 3,612        
Investment Owned, at Cost   3,540        
Investment Owned, at Fair Value   $ 3,539        
Investment, Identifier [Axis]: ITS Buyer Inc. First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ITSBuyerIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Air Freight & Logistics   Air Freight & Logistics Air Freight & Logistics    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.67%   9.67% 9.67%    
Investment, Acquisition Date Feb. 17, 2022          
Investment Maturity Date Jun. 15, 2026   Jun. 15, 2026 Jun. 15, 2026    
Investment Owned, at Fair Value $ 4          
Investment, Identifier [Axis]: ITS Buyer Inc. First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ITSBuyerIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Air Freight & Logistics   Air Freight & Logistics Air Freight & Logistics    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.67%   9.67% 9.67%    
Investment, Acquisition Date Feb. 17, 2022          
Investment Maturity Date Jun. 15, 2026   Jun. 15, 2026 Jun. 15, 2026    
Investment Owned, Balance, Principal Amount $ 3,589          
Investment Owned, at Cost 3,531          
Investment Owned, at Fair Value $ 3,553          
Investment, Identifier [Axis]: ImageOne Industries, LLC Common A Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ImageOneIndustriesLLCMember whf:ImageOneIndustriesLLCMember        
Investment, Type [Extensible Enumeration] whf:CommonAUnitsMember whf:CommonAUnitsMember whf:CommonAUnitsMember whf:CommonAUnitsMember whf:CommonAUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services  
Investment, Acquisition Date Sep. 20, 2019 Sep. 20, 2019        
Investment Owned, Balance, Principal Amount $ 227 $ 225        
Investment Owned, at Cost 2          
Investment Owned, at Fair Value $ 84 $ 158        
Investment, Identifier [Axis]: Industrial Specialty Services USA LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:IndustrialSpecialtyServicesUSALLCMember whf:IndustrialSpecialtyServicesUSALLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.18% 7.25% 9.18% 9.18% 7.25%  
Investment, Acquisition Date Dec. 31, 2021 Dec. 31, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, Balance, Principal Amount $ 886          
Investment Owned, at Cost 871          
Investment Owned, at Fair Value $ 861          
Investment, Identifier [Axis]: Industrial Specialty Services USA LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:IndustrialSpecialtyServicesUSALLCMember whf:IndustrialSpecialtyServicesUSALLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.92% 7.25% 9.92% 9.92% 7.25%  
Investment, Acquisition Date Dec. 31, 2021 Dec. 31, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, Balance, Principal Amount $ 11,917 $ 12,007        
Investment Owned, at Cost 11,715 11,767        
Investment Owned, at Fair Value $ 11,612 $ 11,767        
Investment, Identifier [Axis]: Inspired Beauty Brands, Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:InspiredBeautyBrandsIncMember whf:InspiredBeautyBrandsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Personal Products Personal Products Personal Products Personal Products Personal Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment Interest Rate 9.91% 8.00% 9.91% 9.91% 8.00%  
Investment, Acquisition Date Dec. 30, 2020 Dec. 30, 2020        
Investment Maturity Date Dec. 30, 2025 Dec. 30, 2025 Dec. 30, 2025 Dec. 30, 2025 Dec. 30, 2025  
Investment Owned, at Fair Value $ (6) $ 8        
Investment, Identifier [Axis]: Inspired Beauty Brands, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:InspiredBeautyBrandsIncMember whf:InspiredBeautyBrandsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Personal Products Personal Products Personal Products Personal Products Personal Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment Interest Rate 9.91% 8.00% 9.91% 9.91% 8.00%  
Investment, Acquisition Date Dec. 30, 2020 Dec. 30, 2020        
Investment Maturity Date Dec. 30, 2025 Dec. 30, 2025 Dec. 30, 2025 Dec. 30, 2025 Dec. 30, 2025  
Investment Owned, Balance, Principal Amount $ 11,804 $ 12,252        
Investment Owned, at Cost 11,650 12,055        
Investment Owned, at Fair Value $ 11,509 $ 12,252        
Investment, Identifier [Axis]: IvyRehab Intermediate II, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IvyRehabIntermediateIILLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Services [Member]     Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Dec. 04, 2020        
Investment Maturity Date   Dec. 04, 2024     Dec. 04, 2024  
Investment Owned, Balance, Principal Amount   $ 2,550        
Investment Owned, at Cost   2,517        
Investment Owned, at Fair Value   $ 2,534        
Investment, Identifier [Axis]: IvyRehab Intermediate II, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IvyRehabIntermediateIILLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Services [Member]     Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   us-gaap:PrimeRateMember     us-gaap:PrimeRateMember  
Investment, Interest Rate, Floor   3.25%     3.25%  
Investment, Basis Spread, Variable Rate   5.75%     5.75%  
Investment Interest Rate   9.00%     9.00%  
Investment, Acquisition Date   Dec. 04, 2020        
Investment Maturity Date   Dec. 04, 2024     Dec. 04, 2024  
Investment Owned, Balance, Principal Amount   $ 142        
Investment Owned, at Cost   139        
Investment Owned, at Fair Value   $ 147        
Investment, Identifier [Axis]: IvyRehab Intermediate II, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:IvyRehabIntermediateIILLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Services [Member]     Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Dec. 04, 2020        
Investment Maturity Date   Dec. 04, 2024     Dec. 04, 2024  
Investment Owned, Balance, Principal Amount   $ 17,366        
Investment Owned, at Cost   17,121        
Investment Owned, at Fair Value   $ 17,366        
Investment, Identifier [Axis]: JVMC Holdings Corp First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JVMCHoldingsCorpMember whf:JVMCHoldingsCorpMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.75% 6.50% 6.50% 6.75%  
Investment Interest Rate 9.62% 7.75% 9.62% 9.62% 7.75%  
Investment, Acquisition Date Feb. 28, 2019 Feb. 28, 2019        
Investment Maturity Date Feb. 28, 2024 Feb. 28, 2024 Feb. 28, 2024 Feb. 28, 2024 Feb. 28, 2024  
Investment Owned, Balance, Principal Amount $ 12,077 $ 12,729        
Investment Owned, at Cost 12,043 12,674        
Investment Owned, at Fair Value $ 12,077 $ 12,729        
Investment, Identifier [Axis]: JZ Capital Partners Ltd First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JZCapitalPartnersLtdMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Asset Management And Custody Banks [Member]   Asset Management And Custody Banks [Member] Asset Management And Custody Banks [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 7.00%   7.00% 7.00%    
Investment Interest Rate 9.77%   9.77% 9.77%    
Investment, Acquisition Date Jan. 26, 2022          
Investment Maturity Date Jan. 26, 2027   Jan. 26, 2027 Jan. 26, 2027    
Investment Owned, at Fair Value $ 22          
Investment, Identifier [Axis]: JZ Capital Partners Ltd First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JZCapitalPartnersLtdMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Asset Management And Custody Banks [Member]   Asset Management And Custody Banks [Member] Asset Management And Custody Banks [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 7.00%   7.00% 7.00%    
Investment Interest Rate 9.77%   9.77% 9.77%    
Investment, Acquisition Date Jan. 26, 2022          
Investment Maturity Date Jan. 26, 2027   Jan. 26, 2027 Jan. 26, 2027    
Investment Owned, Balance, Principal Amount $ 10,286          
Investment Owned, at Cost 10,108          
Investment Owned, at Fair Value $ 10,147          
Investment, Identifier [Axis]: Juniper Landscaping Holdings LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:JuniperLandscapingHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Environmental & Facilities Services     Environmental & Facilities Services  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 29, 2021        
Investment Maturity Date   Dec. 29, 2026     Dec. 29, 2026  
Investment, Identifier [Axis]: Juniper Landscaping Holdings LLC First Lien Secured Delayed Draw Loan Due 12/29/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JuniperLandscapingHoldingsLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.67%   9.67% 9.67%    
Investment, Acquisition Date Mar. 01, 2022          
Investment Maturity Date Dec. 29, 2026   Dec. 29, 2026 Dec. 29, 2026    
Investment Owned, at Fair Value $ (3)          
Investment, Identifier [Axis]: Juniper Landscaping Holdings LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:JuniperLandscapingHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Environmental & Facilities Services     Environmental & Facilities Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 29, 2021        
Investment Maturity Date   Dec. 29, 2026     Dec. 29, 2026  
Investment Owned, Balance, Principal Amount   $ 597        
Investment Owned, at Cost   586        
Investment Owned, at Fair Value   $ 586        
Investment, Identifier [Axis]: Juniper Landscaping Holdings LLC First Lien Secured Revolving Loan Due 12/29/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JuniperLandscapingHoldingsLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.67%   9.67% 9.67%    
Investment, Acquisition Date Mar. 01, 2022          
Investment Maturity Date Dec. 29, 2026   Dec. 29, 2026 Dec. 29, 2026    
Investment Owned, at Fair Value $ (1)          
Investment, Identifier [Axis]: Juniper Landscaping Holdings LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:JuniperLandscapingHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Environmental & Facilities Services     Environmental & Facilities Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Dec. 29, 2021        
Investment Maturity Date   Dec. 29, 2026     Dec. 29, 2026  
Investment Owned, Balance, Principal Amount   $ 11,420        
Investment Owned, at Cost   11,221        
Investment Owned, at Fair Value   $ 11,220        
Investment, Identifier [Axis]: Juniper Landscaping Holdings LLC First Lien Secured Term Loan Due 12/29/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JuniperLandscapingHoldingsLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.67%   9.67% 9.67%    
Investment, Acquisition Date Mar. 01, 2022          
Investment Maturity Date Dec. 29, 2026   Dec. 29, 2026 Dec. 29, 2026    
Investment Owned, Balance, Principal Amount $ 11,334          
Investment Owned, at Cost 11,165          
Investment Owned, at Fair Value $ 11,151          
Investment, Identifier [Axis]: Keras Holdings, LLC Shares            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:KerasHoldingsLLCMember whf:KerasHoldingsLLCMember        
Investment, Type [Extensible Enumeration] Common Stock [Member] Common Stock [Member] Common Stock [Member] Common Stock [Member] Common Stock [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Acquisition Date Dec. 31, 2020 Dec. 31, 2020        
Investment Owned, Balance, Principal Amount $ 496 $ 496        
Investment Owned, at Cost 496 496        
Investment Owned, at Fair Value $ 361 $ 496        
Investment, Identifier [Axis]: LHS Borrower, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LHSBorrowerLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Sep. 30, 2020        
Investment Maturity Date   Sep. 30, 2025     Sep. 30, 2025  
Investment Owned, at Fair Value   $ 4        
Investment, Identifier [Axis]: LHS Borrower, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LHSBorrowerLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Sep. 30, 2020        
Investment Maturity Date   Sep. 30, 2025     Sep. 30, 2025  
Investment Owned, Balance, Principal Amount   $ 9,506        
Investment Owned, at Cost   9,346        
Investment Owned, at Fair Value   $ 9,416        
Investment, Identifier [Axis]: LHS Borrower, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.75%, Rate 7.75%, Due 9/30/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LHSBorrowerLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Oct. 09, 2020        
Investment Maturity Date   Sep. 30, 2025     Sep. 30, 2025  
Investment Owned, at Fair Value   $ 4        
Investment, Identifier [Axis]: LHS Borrower, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.75%, Rate 7.75%, Due 9/30/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LHSBorrowerLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Oct. 09, 2020        
Investment Maturity Date   Sep. 30, 2025     Sep. 30, 2025  
Investment Owned, Balance, Principal Amount   $ 9,506        
Investment Owned, at Cost   9,345        
Investment Owned, at Fair Value   $ 9,416        
Investment, Identifier [Axis]: LINC Systems LLC First Lien Secured Revolving Loan Floor 1.00 Libor Plus 6.25 Rate Due 2242026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LINCSystemsLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Trading Companies & Distributors   Trading Companies & Distributors Trading Companies & Distributors    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 10.33%   10.33% 10.33%    
Investment, Acquisition Date Jun. 22, 2021          
Investment Maturity Date Feb. 24, 2026   Feb. 24, 2026 Feb. 24, 2026    
Investment Owned, at Fair Value $ 10          
Investment, Identifier [Axis]: LINC Systems LLC First Lien Secured Term Loan Floor 1.00 Libor Plus 6.25 Rate Due 2242026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LINCSystemsLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Trading Companies & Distributors   Trading Companies & Distributors Trading Companies & Distributors    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 10.33%   10.33% 10.33%    
Investment, Acquisition Date Jun. 22, 2021          
Investment Maturity Date Feb. 24, 2026   Feb. 24, 2026 Feb. 24, 2026    
Investment Owned, Balance, Principal Amount $ 10,058          
Investment Owned, at Cost 9,909          
Investment Owned, at Fair Value $ 10,058          
Investment, Identifier [Axis]: LINC Systems, LLC, First Lien Secured Delayed Draw Loan, Floor 1.50%, Spread L plus 6.25%, Rate 7.25%, Due 2/24/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LINCSystemsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Technology Hardware, Storage & Peripherals     Technology Hardware, Storage & Peripherals  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Jun. 22, 2021        
Investment Maturity Date   Feb. 24, 2026     Feb. 24, 2026  
Investment Owned, Balance, Principal Amount   $ 10,135        
Investment Owned, at Cost   9,951        
Investment Owned, at Fair Value   $ 10,101        
Investment, Identifier [Axis]: LINC Systems, LLC, First Lien Secured Revolving Loan, Floor 1.50%, Spread L plus 6.25%, Rate 7.25%, Due 2/24/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LINCSystemsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Technology Hardware, Storage & Peripherals     Technology Hardware, Storage & Peripherals  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Jun. 22, 2021        
Investment Maturity Date   Feb. 24, 2026     Feb. 24, 2026  
Investment Owned, at Fair Value   $ 12        
Investment, Identifier [Axis]: LMG Holdings, Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LMGHoldingsIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Electronic Equipment & Instruments     Electronic Equipment & Instruments  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Apr. 30, 2021        
Investment Maturity Date   Apr. 30, 2026     Apr. 30, 2026  
Investment, Identifier [Axis]: LMG Holdings, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LMGHoldingsIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Electronic Equipment & Instruments     Electronic Equipment & Instruments  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Apr. 30, 2021        
Investment Maturity Date   Apr. 30, 2026     Apr. 30, 2026  
Investment Owned, Balance, Principal Amount   $ 6,802        
Investment Owned, at Cost   6,684        
Investment Owned, at Fair Value   $ 6,687        
Investment, Identifier [Axis]: LMG Holdings, Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 4/30/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LMGHoldingsIncMember whf:LMGHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Electronic Equipment & Instruments Electronic Equipment & Instruments Electronic Equipment & Instruments Electronic Equipment & Instruments Electronic Equipment & Instruments  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 6.50% 7.00% 7.00% 6.50%  
Investment Interest Rate 10.09% 7.50% 10.09% 10.09% 7.50%  
Investment, Acquisition Date Jun. 28, 2021 Jun. 28, 2021        
Investment Maturity Date Apr. 30, 2026 Apr. 30, 2026 Apr. 30, 2026 Apr. 30, 2026 Apr. 30, 2026  
Investment Owned, Balance, Principal Amount $ 265          
Investment Owned, at Cost 261          
Investment Owned, at Fair Value $ 256          
Investment, Identifier [Axis]: LMG Holdings, Inc., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 4/30/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LMGHoldingsIncMember whf:LMGHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Electronic Equipment & Instruments Electronic Equipment & Instruments Electronic Equipment & Instruments Electronic Equipment & Instruments Electronic Equipment & Instruments  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 6.50% 7.00% 7.00% 6.50%  
Investment Interest Rate 10.67% 7.50% 10.67% 10.67% 7.50%  
Investment, Acquisition Date Jun. 28, 2021 Jun. 28, 2021        
Investment Maturity Date Apr. 30, 2026 Apr. 30, 2026 Apr. 30, 2026 Apr. 30, 2026 Apr. 30, 2026  
Investment Owned, Balance, Principal Amount $ 13,501 $ 6,802        
Investment Owned, at Cost 13,303 6,680        
Investment Owned, at Fair Value $ 13,229 $ 6,687        
Investment, Identifier [Axis]: LSCS Holdings, Inc Second Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LSCSHoldingsIncMember whf:LSCSHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember whf:SecondLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Life Sciences Tools And Services [Member] Life Sciences Tools And Services [Member] Life Sciences Tools And Services [Member] Life Sciences Tools And Services [Member] Life Sciences Tools And Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 0.50% 0.50% 0.50% 0.50% 0.50%  
Investment, Basis Spread, Variable Rate 8.00% 8.00% 8.00% 8.00% 8.00%  
Investment Interest Rate 11.67% 8.50% 11.67% 11.67% 8.50%  
Investment, Acquisition Date Nov. 23, 2021 Nov. 23, 2021        
Investment Maturity Date Dec. 16, 2029 Dec. 16, 2029 Dec. 16, 2029 Dec. 16, 2029 Dec. 16, 2029  
Investment Owned, Balance, Principal Amount $ 5,000 $ 5,000        
Investment Owned, at Cost 4,932 4,925        
Investment Owned, at Fair Value $ 4,912 $ 4,925        
Investment, Identifier [Axis]: Lab Logistics, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LabLogisticsLLCMember whf:LabLogisticsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.25% 7.25% 7.25% 7.25% 7.25%  
Investment Interest Rate 10.20% 8.25% 10.20% 10.20% 8.25%  
Investment, Acquisition Date Oct. 16, 2019 Oct. 16, 2019        
Investment Maturity Date Sep. 25, 2023 Sep. 25, 2023 Sep. 25, 2023 Sep. 25, 2023 Sep. 25, 2023  
Investment Owned, Balance, Principal Amount $ 5,144 $ 5,183        
Investment Owned, at Cost 5,135 5,166        
Investment Owned, at Fair Value $ 5,144 $ 5,183        
Investment, Identifier [Axis]: Lab Logistics, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LabLogisticsLLCMember whf:LabLogisticsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.25% 7.25% 7.25% 7.25% 7.25%  
Investment Interest Rate 10.16% 8.25% 10.16% 10.16% 8.25%  
Investment, Acquisition Date Oct. 16, 2019 Oct. 16, 2019        
Investment Maturity Date Sep. 25, 2023 Sep. 25, 2023 Sep. 25, 2023 Sep. 25, 2023 Sep. 25, 2023  
Investment Owned, Balance, Principal Amount $ 5,501 $ 1,155        
Investment Owned, at Cost 5,446 1,140        
Investment Owned, at Fair Value $ 5,495 $ 1,155        
Investment, Identifier [Axis]: Lab Logistics, LLC Preferred Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:LabLogisticsLLCMember        
Investment, Type [Extensible Enumeration]   whf:PreferredUnitsMember     whf:PreferredUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Health Care Services [Member]     Health Care Services [Member]  
Investment, Basis Spread, Variable Rate   14.00%     14.00%  
Investment, Acquisition Date   Oct. 29, 2019        
Investment Owned, Balance, Principal Amount   $ 2        
Investment Owned, at Cost   857        
Investment Owned, at Fair Value   $ 1,018        
Investment, Interest Rate, Paid in Kind   14.00%     14.00%  
Investment, Identifier [Axis]: Lenny & Larry's, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LennyLarrysLLCMember whf:LennyLarrysLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.92% 8.40% 8.92% 8.92% 8.40%  
Investment Interest Rate 11.74% 9.40% 11.74% 11.74% 9.40%  
Investment, Acquisition Date May 15, 2018 May 15, 2018        
Investment Maturity Date May 15, 2023 May 15, 2023 May 15, 2023 May 15, 2023 May 15, 2023  
Investment Owned, Balance, Principal Amount $ 11,201 $ 11,142        
Investment Owned, at Cost 11,175 11,084        
Investment Owned, at Fair Value $ 10,922 $ 10,862        
Investment, Interest Rate, Paid in Kind 1.71% 1.72% 1.71% 1.71% 1.72%  
Investment, Interest Rate, Paid in Cash 10.03% 7.68% 10.03% 10.03% 7.68%  
Investment, Identifier [Axis]: Lift Brands, Inc First Lien Secured Term Loan A            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LiftBrandsIncMember whf:LiftBrandsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember whf:FirstLienSecuredTermLoanAMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.50% 7.50% 7.50% 7.50% 7.50%  
Investment Interest Rate 10.62% 8.50% 10.62% 10.62% 8.50%  
Investment, Acquisition Date Jun. 29, 2020 Jun. 29, 2020        
Investment Maturity Date Jun. 29, 2025 Jun. 29, 2025 Jun. 29, 2025 Jun. 29, 2025 Jun. 29, 2025  
Investment Owned, Balance, Principal Amount $ 5,588 $ 5,631        
Investment Owned, at Cost 5,541 5,570        
Investment Owned, at Fair Value $ 5,533 $ 5,546        
Investment, Identifier [Axis]: Lift Brands, Inc First Lien Secured Term Loan B            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LiftBrandsIncMember whf:LiftBrandsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanBMember whf:FirstLienSecuredTermLoanBMember whf:FirstLienSecuredTermLoanBMember whf:FirstLienSecuredTermLoanBMember whf:FirstLienSecuredTermLoanBMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Basis Spread, Variable Rate 9.50% 9.50% 9.50% 9.50% 9.50%  
Investment Interest Rate 9.50% 9.50% 9.50% 9.50% 9.50%  
Investment, Acquisition Date Jun. 29, 2020 Jun. 29, 2020        
Investment Maturity Date Jun. 29, 2025 Jun. 29, 2025 Jun. 29, 2025 Jun. 29, 2025 Jun. 29, 2025  
Investment Owned, Balance, Principal Amount $ 1,330 $ 1,279        
Investment Owned, at Cost 1,314 1,259        
Investment Owned, at Fair Value $ 1,302 $ 1,239        
Investment, Interest Rate, Paid in Kind 9.50% 9.50% 9.50% 9.50% 9.50%  
Investment, Interest Rate, Paid in Cash 0.00% 0.00% 0.00% 0.00% 0.00%  
Investment, Identifier [Axis]: Luxury Brand Holdings, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LuxuryBrandHoldingsIncMember whf:LuxuryBrandHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.31% 7.50% 9.31% 9.31% 7.50%  
Investment, Acquisition Date Dec. 04, 2020 Dec. 04, 2020        
Investment Maturity Date Jun. 04, 2026 Jun. 04, 2026 Jun. 04, 2026 Jun. 04, 2026 Jun. 04, 2026  
Investment Owned, Balance, Principal Amount $ 5,895 $ 5,940        
Investment Owned, at Cost 5,816 5,844        
Investment Owned, at Fair Value $ 5,854 $ 5,940        
Investment, Identifier [Axis]: MEP-TS Midco, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/31/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MEP-TSMidcoLLCMember whf:MEP-TSMidcoLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Application Software Application Software Application Software Application Software Application Software  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 8.88% 7.00% 8.88% 8.88% 7.00%  
Investment, Acquisition Date Jan. 21, 2021 Jan. 21, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, at Fair Value $ 24 $ 28        
Investment, Identifier [Axis]: MEP-TS Midco, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/31/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MEP-TSMidcoLLCMember whf:MEP-TSMidcoLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Application Software Application Software Application Software Application Software Application Software  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 8.88% 7.00% 8.88% 8.88% 7.00%  
Investment, Acquisition Date Jan. 21, 2021 Jan. 21, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, Balance, Principal Amount $ 13,387 $ 13,490        
Investment Owned, at Cost 13,183 13,247        
Investment Owned, at Fair Value $ 13,387 $ 13,490        
Investment, Identifier [Axis]: MSI Information Services, Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MSIInformationServicesIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Interactive Media And Services [Member]   Interactive Media And Services [Member] Interactive Media And Services [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] us-gaap:BaseRateMember   us-gaap:BaseRateMember us-gaap:BaseRateMember    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.75%   6.75% 6.75%    
Investment Interest Rate 13.00%   13.00% 13.00%    
Investment, Acquisition Date Apr. 25, 2022          
Investment Maturity Date Apr. 24, 2026   Apr. 24, 2026 Apr. 24, 2026    
Investment Owned, Balance, Principal Amount $ 300          
Investment Owned, at Cost 295          
Investment Owned, at Fair Value $ 286          
Investment, Identifier [Axis]: MSI Information Services, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MSIInformationServicesIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Interactive Media And Services [Member]   Interactive Media And Services [Member] Interactive Media And Services [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 7.75%   7.75% 7.75%    
Investment Interest Rate 10.88%   10.88% 10.88%    
Investment, Acquisition Date Apr. 25, 2022          
Investment Maturity Date Apr. 24, 2026   Apr. 24, 2026 Apr. 24, 2026    
Investment Owned, Balance, Principal Amount $ 7,851          
Investment Owned, at Cost 7,711          
Investment Owned, at Fair Value $ 7,647          
Investment, Identifier [Axis]: Manchester Acquisition Sub LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ManchesterAcquisitionSubLLCMember whf:ManchesterAcquisitionSubLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Chemicals [Member] Diversified Chemicals [Member] Diversified Chemicals [Member] Diversified Chemicals [Member] Diversified Chemicals [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] whf:SecuredOvernightFinancingRateMember Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] whf:SecuredOvernightFinancingRateMember  
Investment, Interest Rate, Floor 0.75% 0.75% 0.75% 0.75% 0.75%  
Investment, Basis Spread, Variable Rate 5.75% 5.75% 5.75% 5.75% 5.75%  
Investment Interest Rate 8.85% 6.50% 8.85% 8.85% 6.50%  
Investment, Acquisition Date Nov. 16, 2021 Nov. 16, 2021        
Investment Maturity Date Nov. 16, 2026 Nov. 16, 2026 Nov. 16, 2026 Nov. 16, 2026 Nov. 16, 2026  
Investment Owned, Balance, Principal Amount $ 7,940 $ 12,000        
Investment Owned, at Cost 7,575 11,348        
Investment Owned, at Fair Value $ 7,246 $ 11,340        
Investment, Identifier [Axis]: Marlin DTC-LS Midco 2, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:MarlinDTC-LSMidco2LLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Internet & Direct Marketing Retail     Internet & Direct Marketing Retail  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Aug. 06, 2021        
Investment Maturity Date   Jul. 01, 2025     Jul. 01, 2025  
Investment Owned, Balance, Principal Amount   $ 4,277        
Investment Owned, at Cost   4,200        
Investment Owned, at Fair Value   $ 4,206        
Investment, Identifier [Axis]: Marlin DTC-LS Midco 2, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 7/1/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MarlinDTC-LSMidco2LLCMember whf:MarlinDTC-LSMidco2LLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.57% 7.50% 9.57% 9.57% 7.50%  
Investment, Acquisition Date Jul. 19, 2019 Jul. 19, 2019        
Investment Maturity Date Jul. 01, 2025 Jul. 01, 2025 Jul. 01, 2025 Jul. 01, 2025 Jul. 01, 2025  
Investment Owned, at Fair Value $ 9 $ 11        
Investment, Identifier [Axis]: Marlin DTC-LS Midco 2, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 7/1/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MarlinDTC-LSMidco2LLCMember whf:MarlinDTC-LSMidco2LLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.57% 7.50% 9.57% 9.57% 7.50%  
Investment, Acquisition Date Jul. 19, 2019 Jul. 19, 2019        
Investment Maturity Date Jul. 01, 2025 Jul. 01, 2025 Jul. 01, 2025 Jul. 01, 2025 Jul. 01, 2025  
Investment Owned, Balance, Principal Amount $ 19,105 $ 15,342        
Investment Owned, at Cost 18,901 15,153        
Investment Owned, at Fair Value $ 19,105 $ 15,342        
Investment, Identifier [Axis]: Max Solutions Inc. Common Stock            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Max Solutions Inc          
Investment, Type [Extensible Enumeration] Common Stock [Member]   Common Stock [Member] Common Stock [Member]    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Paper Packaging   Paper Packaging Paper Packaging    
Investment, Acquisition Date Sep. 29, 2022          
Investment Owned, Balance, Principal Amount $ 4          
Investment Owned, at Cost 400          
Investment Owned, at Fair Value $ 400          
Investment, Identifier [Axis]: Max Solutions Inc. First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LennyLarrysLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Paper Packaging   Paper Packaging Paper Packaging    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.50%   6.50% 6.50%    
Investment Interest Rate 10.21%   10.21% 10.21%    
Investment, Acquisition Date Sep. 29, 2022          
Investment Maturity Date Sep. 29, 2028   Sep. 29, 2028 Sep. 29, 2028    
Investment, Identifier [Axis]: Max Solutions Inc. First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LennyLarrysLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Paper Packaging   Paper Packaging Paper Packaging    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.50%   6.50% 6.50%    
Investment Interest Rate 10.21%   10.21% 10.21%    
Investment, Acquisition Date Sep. 29, 2022          
Investment Maturity Date Sep. 29, 2028   Sep. 29, 2028 Sep. 29, 2028    
Investment, Identifier [Axis]: Max Solutions Inc. First Lien Secured Revolving Loan CAD            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LennyLarrysLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Paper Packaging   Paper Packaging Paper Packaging    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.50%   6.50% 6.50%    
Investment Interest Rate 10.21%   10.21% 10.21%    
Investment, Acquisition Date Sep. 29, 2022          
Investment Maturity Date Sep. 29, 2028   Sep. 29, 2028 Sep. 29, 2028    
Investment, Identifier [Axis]: Max Solutions Inc. First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:LennyLarrysLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Industry Sector [Extensible Enumeration] Paper Packaging   Paper Packaging Paper Packaging    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.50%   6.50% 6.50%    
Investment Interest Rate 10.21%   10.21% 10.21%    
Investment, Acquisition Date Sep. 29, 2022          
Investment Maturity Date Sep. 29, 2028   Sep. 29, 2028 Sep. 29, 2028    
Investment Owned, Balance, Principal Amount $ 8,264          
Investment Owned, at Cost 8,099          
Investment Owned, at Fair Value $ 8,099          
Investment, Identifier [Axis]: Maxitransfers Blocker Corp First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:MaxitransfersBlockerCorpMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Consumer Finance [Member]     Consumer Finance [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   8.50%     8.50%  
Investment Interest Rate   9.50%     9.50%  
Investment, Acquisition Date   Oct. 07, 2020        
Investment Maturity Date   Oct. 07, 2025     Oct. 07, 2025  
Investment Owned, Balance, Principal Amount   $ 1,038        
Investment Owned, at Cost   1,019        
Investment Owned, at Fair Value   $ 1,038        
Investment, Identifier [Axis]: Maxitransfers Blocker Corp First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:MaxitransfersBlockerCorpMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Consumer Finance [Member]     Consumer Finance [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   8.50%     8.50%  
Investment Interest Rate   9.50%     9.50%  
Investment, Acquisition Date   Oct. 07, 2020        
Investment Maturity Date   Oct. 07, 2025     Oct. 07, 2025  
Investment Owned, Balance, Principal Amount   $ 8,590        
Investment Owned, at Cost   8,436        
Investment Owned, at Fair Value   $ 8,590        
Investment, Identifier [Axis]: Meta Buyer LLC, First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.97%, Due 11/1/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MetaBuyerLLCMember whf:MetaBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Pharmaceuticals Personal Products Pharmaceuticals Pharmaceuticals Personal Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 9.52% 7.00% 9.52% 9.52% 7.00%  
Investment, Acquisition Date Dec. 16, 2021 Dec. 16, 2021        
Investment Maturity Date Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027  
Investment Owned, Balance, Principal Amount $ 897          
Investment Owned, at Cost 881          
Investment Owned, at Fair Value $ 885          
Investment, Identifier [Axis]: Meta Buyer LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.97%, Due 11/1/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MetaBuyerLLCMember whf:MetaBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Pharmaceuticals Personal Products Pharmaceuticals Pharmaceuticals Personal Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 8.80% 7.00% 8.80% 8.80% 7.00%  
Investment, Acquisition Date Dec. 16, 2021 Dec. 16, 2021        
Investment Maturity Date Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027  
Investment Owned, Balance, Principal Amount   $ 251        
Investment Owned, at Cost   246        
Investment Owned, at Fair Value $ 6 $ 246        
Investment, Identifier [Axis]: Meta Buyer LLC, First lien Secured Term Loan, Floor 1.00%, Spread E plus 6.00%, Rate 7.00%, Due 11/1/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MetaBuyerLLCMember whf:MetaBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Pharmaceuticals Personal Products Pharmaceuticals Pharmaceuticals Personal Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment, Acquisition Date Dec. 16, 2021 Dec. 16, 2021        
Investment Maturity Date Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027  
Investment Owned, Balance, Principal Amount $ 12,318 $ 12,411        
Investment Owned, at Cost 13,664 13,737        
Investment Owned, at Fair Value $ 11,844 $ 13,843        
Investment, Identifier [Axis]: Meta Buyer LLC, First lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.33%, Due 11/1/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MetaBuyerLLCMember whf:MetaBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Pharmaceuticals Personal Products Pharmaceuticals Pharmaceuticals Personal Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 8.80% 7.00% 8.80% 8.80% 7.00%  
Investment, Acquisition Date Dec. 16, 2021 Dec. 16, 2021        
Investment Maturity Date Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027 Nov. 01, 2027  
Investment Owned, Balance, Principal Amount $ 984 $ 991        
Investment Owned, at Cost 967 972        
Investment Owned, at Fair Value $ 971 $ 972        
Investment, Identifier [Axis]: Mikawaya Holdings, LLC, First Lien Secured Term Loan, Floor 1.25%, Spread L plus 5.50%, Rate 6.75%, Due 1/29/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:MikawayaHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Packaged Foods & Meats     Packaged Foods & Meats  
Investment, Interest Rate, Floor   1.25%     1.25%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   6.75%     6.75%  
Investment, Acquisition Date   Feb. 18, 2020        
Investment Maturity Date   Jan. 29, 2025     Jan. 29, 2025  
Investment Owned, Balance, Principal Amount   $ 3,026        
Investment Owned, at Cost   2,988        
Investment Owned, at Fair Value   $ 3,026        
Investment, Identifier [Axis]: Mills Fleet Farm Group, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:MillsFleetFarmGroupLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Department Stores [Member]     Department Stores [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Oct. 24, 2018        
Investment Maturity Date   Oct. 24, 2024     Oct. 24, 2024  
Investment Owned, Balance, Principal Amount   $ 13,538        
Investment Owned, at Cost   13,331        
Investment Owned, at Fair Value   $ 13,538        
Investment, Identifier [Axis]: Motivational CIV, LLC Class B Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MotivationalCIVLLCMember whf:MotivationalCIVLLCMember        
Investment, Type [Extensible Enumeration] whf:ClassBUnitsMember whf:ClassBUnitsMember whf:ClassBUnitsMember whf:ClassBUnitsMember whf:ClassBUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics  
Investment, Acquisition Date Jul. 12, 2021 Jul. 12, 2021        
Investment Owned, Balance, Principal Amount $ 1,250 $ 1,250        
Investment Owned, at Cost 1,250 1,250        
Investment Owned, at Fair Value $ 606 $ 1,250        
Investment, Identifier [Axis]: Motivational Marketing, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MotivationalMarketingLLCMember whf:MotivationalMarketingLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.07% 7.25% 9.07% 9.07% 7.25%  
Investment, Acquisition Date Jul. 12, 2021 Jul. 12, 2021        
Investment Maturity Date Jul. 12, 2026 Jul. 12, 2026 Jul. 12, 2026 Jul. 12, 2026 Jul. 12, 2026  
Investment Owned, at Fair Value $ (22) $ 7        
Investment, Identifier [Axis]: Motivational Marketing, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:MotivationalMarketingLLCMember whf:MotivationalMarketingLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics Air Freight & Logistics  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.07% 7.25% 9.07% 9.07% 7.25%  
Investment, Acquisition Date Jul. 12, 2021 Jul. 12, 2021        
Investment Maturity Date Jul. 12, 2026 Jul. 12, 2026 Jul. 12, 2026 Jul. 12, 2026 Jul. 12, 2026  
Investment Owned, Balance, Principal Amount $ 11,124 $ 11,789        
Investment Owned, at Cost 10,956 11,575        
Investment Owned, at Fair Value $ 10,744 $ 11,646        
Investment, Identifier [Axis]: NMFC Senior Loan Program I LLC Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:ArcoleHoldingCorporationMember        
Investment, Type [Extensible Enumeration]   Equity Investments     Equity Investments  
Investment Owned, at Fair Value           9,269
Investment, Identifier [Axis]: NNA Services, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:NNAServicesLLCMember whf:NNAServicesLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.75% 6.75% 6.75% 6.75% 6.75%  
Investment Interest Rate 10.42% 7.75% 10.42% 10.42% 7.75%  
Investment, Acquisition Date Aug. 27, 2021 Aug. 27, 2021        
Investment Maturity Date Aug. 27, 2026 Aug. 27, 2026 Aug. 27, 2026 Aug. 27, 2026 Aug. 27, 2026  
Investment Owned, Balance, Principal Amount $ 11,375 $ 11,594        
Investment Owned, at Cost 11,264 11,459        
Investment Owned, at Fair Value $ 11,165 $ 11,460        
Investment, Identifier [Axis]: NPAV Lessor Corp., First Lien Secured Revolving Loan, Floor 1.00%, Spread SF plus 6.00%, Rate 7.60%, Due 1/21/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:NPAVLessorCorp.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] us-gaap:RealEstateSectorMember   us-gaap:RealEstateSectorMember us-gaap:RealEstateSectorMember    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.16%   9.16% 9.16%    
Investment, Acquisition Date Mar. 01, 2022          
Investment Maturity Date Jan. 21, 2027   Jan. 21, 2027 Jan. 21, 2027    
Investment Owned, at Fair Value $ (16)          
Investment, Identifier [Axis]: NPAV Lessor Corp., First Lien Secured Term Loan, Floor 1.00%, Spread SF plus 6.00%, Rate 7.60%, Due 1/21/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:NPAVLessorCorp.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] us-gaap:RealEstateSectorMember   us-gaap:RealEstateSectorMember us-gaap:RealEstateSectorMember    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.16%   9.16% 9.16%    
Investment, Acquisition Date Mar. 01, 2022          
Investment Maturity Date Jan. 21, 2027   Jan. 21, 2027 Jan. 21, 2027    
Investment Owned, Balance, Principal Amount $ 8,946          
Investment Owned, at Cost 8,791          
Investment Owned, at Fair Value $ 8,588          
Investment, Identifier [Axis]: Naviga Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:NavigaIncMember whf:NavigaIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Application Software Application Software Application Software Application Software Application Software  
Investment, Variable Interest Rate, Type [Extensible Enumeration] us-gaap:BaseRateMember London Interbank Offered Rate (LIBOR) [Member] us-gaap:BaseRateMember us-gaap:BaseRateMember London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.92% 7.00% 6.92% 6.92% 7.00%  
Investment Interest Rate 10.28% 8.00% 10.28% 10.28% 8.00%  
Investment, Acquisition Date Jun. 14, 2019 Jun. 14, 2019        
Investment Maturity Date Dec. 29, 2022 Dec. 29, 2022 Dec. 29, 2022 Dec. 29, 2022 Dec. 29, 2022  
Investment Owned, Balance, Principal Amount $ 267 $ 169        
Investment Owned, at Cost 267 168        
Investment Owned, at Fair Value $ 261 $ 169        
Investment, Identifier [Axis]: Naviga Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:NavigaIncMember whf:NavigaIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Application Software Application Software Application Software Application Software Application Software  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 7.00% 7.00% 7.00% 7.00%  
Investment Interest Rate 10.67% 8.00% 10.67% 10.67% 8.00%  
Investment, Acquisition Date Jun. 14, 2019 Jun. 14, 2019        
Investment Maturity Date Dec. 29, 2022 Dec. 29, 2022 Dec. 29, 2022 Dec. 29, 2022 Dec. 29, 2022  
Investment Owned, Balance, Principal Amount $ 3,189 $ 3,213        
Investment Owned, at Cost 3,184 3,195        
Investment Owned, at Fair Value $ 3,125 $ 3,213        
Investment, Identifier [Axis]: Nelson Worldwide, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:NelsonWorldwideLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Research & Consulting Services     Research & Consulting Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   10.25%     10.25%  
Investment Interest Rate   11.25%     11.25%  
Investment, Acquisition Date   Jan. 09, 2018        
Investment Maturity Date   Jan. 09, 2023     Jan. 09, 2023  
Investment Owned, Balance, Principal Amount   $ 10,027        
Investment Owned, at Cost   9,976        
Investment Owned, at Fair Value   $ 9,826        
Investment, Identifier [Axis]: PFB Holdco, Inc Class A Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PFBHoldcoIncMember whf:PFBHoldcoIncMember        
Investment, Type [Extensible Enumeration] whf:ClassAUnitsMember whf:ClassAUnitsMember whf:ClassAUnitsMember whf:ClassAUnitsMember whf:ClassAUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Building Products Data Processing & Outsourced Services Building Products Building Products Data Processing & Outsourced Services  
Investment, Acquisition Date Dec. 17, 2021 Dec. 17, 2021        
Investment Owned, Balance, Principal Amount   $ 1 $ 1      
Investment Owned, at Cost $ 423 $ 423        
Investment Owned, at Fair Value $ 603       $ 427  
Investment, Identifier [Axis]: PFB Holdco, Inc First Lien Secured Revolving Loan Floor 2.45            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:PFBHoldcoIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   whf:CanadaPrimeRateMember     whf:CanadaPrimeRateMember  
Investment, Interest Rate, Floor   2.45%     2.45%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   7.95%     7.95%  
Investment, Acquisition Date   Dec. 17, 2021        
Investment Maturity Date   Dec. 17, 2026     Dec. 17, 2026  
Investment, Identifier [Axis]: PFB Holdco, Inc First Lien Secured Revolving Loan Floor 3.25            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:PFBHoldcoIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   us-gaap:PrimeRateMember     us-gaap:PrimeRateMember  
Investment, Interest Rate, Floor   3.25%     3.25%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   8.75%     8.75%  
Investment, Acquisition Date   Dec. 17, 2021        
Investment Maturity Date   Dec. 17, 2026     Dec. 17, 2026  
Investment, Identifier [Axis]: PFB Holdco, Inc First Lien Secured Term Loan CDOR            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PFBHoldcoIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Building Products   Building Products Building Products    
Investment, Variable Interest Rate, Type [Extensible Enumeration] CanadianDollarOfferedRateMember   CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 8.71%   8.71% 8.71%    
Investment, Acquisition Date Dec. 17, 2021          
Investment Maturity Date Dec. 17, 2026   Dec. 17, 2026 Dec. 17, 2026    
Investment Owned, Balance, Principal Amount     $ 8,959      
Investment Owned, at Cost $ 6,889          
Investment Owned, at Fair Value $ 6,382          
Investment, Identifier [Axis]: PFB Holdco, Inc First Lien Secured Term Loan Floor 2.45            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:PFBHoldcoIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   whf:CanadaPrimeRateMember     whf:CanadaPrimeRateMember  
Investment, Interest Rate, Floor   2.45%     2.45%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   7.95%     7.95%  
Investment, Acquisition Date   Dec. 17, 2021        
Investment Maturity Date   Dec. 17, 2026     Dec. 17, 2026  
Investment Owned, Balance, Principal Amount   $ 9,027        
Investment Owned, at Cost   6,923        
Investment Owned, at Fair Value   $ 6,998        
Investment, Identifier [Axis]: PFB Holdco, Inc First Lien Secured Term Loan Floor 3.25            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:PFBHoldcoIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   us-gaap:PrimeRateMember     us-gaap:PrimeRateMember  
Investment, Interest Rate, Floor   3.25%     3.25%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   8.75%     8.75%  
Investment, Acquisition Date   Dec. 17, 2021        
Investment Maturity Date   Dec. 17, 2026     Dec. 17, 2026  
Investment Owned, Balance, Principal Amount   $ 2,198        
Investment Owned, at Cost   2,154        
Investment Owned, at Fair Value   $ 2,154        
Investment, Identifier [Axis]: PFB Holdco, Inc. First Lien Secured Revolving Loan CDOR            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PFBHoldcoIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Building Products   Building Products Building Products    
Investment, Variable Interest Rate, Type [Extensible Enumeration] CanadianDollarOfferedRateMember   CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 8.71%   8.71% 8.71%    
Investment, Acquisition Date Dec. 17, 2021          
Investment Maturity Date Dec. 17, 2026   Dec. 17, 2026 Dec. 17, 2026    
Investment Owned, at Fair Value $ 2          
Investment, Identifier [Axis]: PFB Holdco, Inc. First Lien Secured Revolving Loan LIBOR            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PFBHoldcoIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Building Products   Building Products Building Products    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 8.28%   8.28% 8.28%    
Investment, Acquisition Date Dec. 17, 2021          
Investment Maturity Date Dec. 17, 2026   Dec. 17, 2026 Dec. 17, 2026    
Investment Owned, at Fair Value $ 1          
Investment, Identifier [Axis]: PFB Holdco, Inc. First Lien Secured Term Loan LIBOR            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PFBHoldcoIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Building Products   Building Products Building Products    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 8.28%   8.28% 8.28%    
Investment, Acquisition Date Dec. 17, 2021          
Investment Maturity Date Dec. 17, 2026   Dec. 17, 2026 Dec. 17, 2026    
Investment Owned, Balance, Principal Amount $ 2,182          
Investment Owned, at Cost 2,144          
Investment Owned, at Fair Value $ 2,154          
Investment, Identifier [Axis]: PG Dental New Jersey Parent, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PGDentalNewJerseyParentLLCMember whf:PGDentalNewJerseyParentLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 9.75% 9.25% 9.75% 9.75% 9.25%  
Investment Interest Rate 12.57% 10.25% 12.57% 12.57% 10.25%  
Investment, Acquisition Date Nov. 25, 2020 Nov. 25, 2020        
Investment Maturity Date Nov. 25, 2025 Nov. 25, 2025 Nov. 25, 2025 Nov. 25, 2025 Nov. 25, 2025  
Investment Owned, Balance, Principal Amount $ 352 $ 702        
Investment Owned, at Cost 347 689        
Investment Owned, at Fair Value $ 308 $ 631        
Investment, Interest Rate, Paid in Kind 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Interest Rate, Paid in Cash 11.07% 8.75% 11.07% 11.07% 8.75%  
Investment, Identifier [Axis]: PG Dental New Jersey Parent, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PGDentalNewJerseyParentLLCMember whf:PGDentalNewJerseyParentLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member] Health Care Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 9.75% 9.25% 9.75% 9.75% 9.25%  
Investment Interest Rate 12.57% 10.25% 12.57% 12.57% 10.25%  
Investment, Acquisition Date Nov. 25, 2020 Nov. 25, 2020        
Investment Maturity Date Nov. 25, 2025 Nov. 25, 2025 Nov. 25, 2025 Nov. 25, 2025 Nov. 25, 2025  
Investment Owned, Balance, Principal Amount $ 14,845 $ 15,448        
Investment Owned, at Cost 14,640 15,178        
Investment Owned, at Fair Value $ 13,807 $ 14,212        
Investment, Interest Rate, Paid in Kind 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Interest Rate, Paid in Cash 11.07% 8.75% 11.07% 11.07% 8.75%  
Investment, Identifier [Axis]: PPS CR Acquisition, Inc First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PPSCRAcquisitionIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Heavy Electrical Equipment [Member]   Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member]    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 9.92%   9.92% 9.92%    
Investment, Acquisition Date Jul. 11, 2022          
Investment Maturity Date Jun. 25, 2026   Jun. 25, 2026 Jun. 25, 2026    
Investment Owned, at Fair Value $ (1)          
Investment, Identifier [Axis]: PPS CR Acquisition, Inc First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PPSCRAcquisitionIncMember whf:PPSCRAcquisitionIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.92% 7.25% 9.92% 9.92% 7.25%  
Investment, Acquisition Date Jun. 25, 2021 Jun. 25, 2021        
Investment Maturity Date Jun. 25, 2024 Jun. 25, 2024 Jun. 25, 2024 Jun. 25, 2024 Jun. 25, 2024  
Investment Owned, Balance, Principal Amount $ 104 $ 104        
Investment Owned, at Cost 103 103        
Investment Owned, at Fair Value $ 63 $ 113        
Investment, Identifier [Axis]: PPS CR Acquisition, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PPSCRAcquisitionIncMember whf:PPSCRAcquisitionIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member] Heavy Electrical Equipment [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.92% 7.25% 9.92% 9.92% 7.25%  
Investment, Acquisition Date Jun. 25, 2021 Jun. 25, 2021        
Investment Maturity Date Jun. 25, 2026 Jun. 25, 2026 Jun. 25, 2026 Jun. 25, 2026 Jun. 25, 2026  
Investment Owned, Balance, Principal Amount $ 14,166 $ 11,123        
Investment Owned, at Cost 13,942 10,924        
Investment Owned, at Fair Value $ 13,835 $ 10,975        
Investment, Identifier [Axis]: PS Lightwave, Inc., First Lien Secured Delayed Draw Loan, Floor 1.50%, Spread L plus 6.75%, Rate 8.25%, Due 3/10/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:PSLightwaveInc.Member        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Technology Hardware, Storage & Peripherals     Technology Hardware, Storage & Peripherals  
Investment, Interest Rate, Floor   1.50%     1.50%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   8.25%     8.25%  
Investment, Acquisition Date   May 19, 2020        
Investment Maturity Date   Mar. 10, 2025     Mar. 10, 2025  
Investment Owned, at Fair Value   $ 5        
Investment, Identifier [Axis]: PS Lightwave, Inc., First Lien Secured Term Loan, Floor 1.50%, Spread L plus 6.75%, Rate 8.25%, Due 3/10/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:PSLightwaveInc.Member        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Technology Hardware, Storage & Peripherals     Technology Hardware, Storage & Peripherals  
Investment, Interest Rate, Floor   1.50%     1.50%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   8.25%     8.25%  
Investment, Acquisition Date   May 19, 2020        
Investment Maturity Date   Mar. 10, 2025     Mar. 10, 2025  
Investment Owned, Balance, Principal Amount   $ 7,304        
Investment Owned, at Cost   7,207        
Investment Owned, at Fair Value   $ 7,230        
Investment, Identifier [Axis]: Patagonia Hold co Llc First Lien Secured Term Loans            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PatagoniaHoldcoLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Alternative Carriers   Alternative Carriers Alternative Carriers    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 5.75%   5.75% 5.75%    
Investment Interest Rate 8.39%   8.39% 8.39%    
Investment, Acquisition Date Aug. 05, 2022          
Investment Maturity Date Aug. 01, 2029   Aug. 01, 2029 Aug. 01, 2029    
Investment Owned, Balance, Principal Amount $ 14,625          
Investment Owned, at Cost 12,040          
Investment Owned, at Fair Value $ 11,993          
Investment, Identifier [Axis]: Pennsylvania Machine Works, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread SF plus 6.25%, Rate 8.57%, Due 3/8/27            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PennsylvaniaMachineWorksLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Industrial Machinery   Industrial Machinery Industrial Machinery    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 10.06%   10.06% 10.06%    
Investment, Acquisition Date Mar. 25, 2022          
Investment Maturity Date Mar. 08, 2027   Mar. 08, 2027 Mar. 08, 2027    
Investment Owned, Balance, Principal Amount $ 6,925          
Investment Owned, at Cost 6,833          
Investment Owned, at Fair Value $ 6,925          
Investment, Identifier [Axis]: PlayMonster LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   PlayMonster LLC [Member].        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Leisure Products     Leisure Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Jun. 07, 2021        
Investment Maturity Date   Jun. 07, 2026     Jun. 07, 2026  
Investment Owned, Balance, Principal Amount   $ 224        
Investment Owned, at Cost   221        
Investment Owned, at Fair Value   $ (828)        
Investment, Identifier [Axis]: PlayMonster LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] PlayMonster LLC [Member]. PlayMonster LLC [Member].        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Leisure Products     Leisure Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.00%     6.00%  
Investment Interest Rate   7.00%     7.00%  
Investment, Acquisition Date   Jun. 07, 2021        
Investment Maturity Date   Jun. 07, 2026     Jun. 07, 2026  
Investment Owned, Balance, Principal Amount   $ 6,000        
Investment Owned, at Cost   5,894        
Investment Owned, at Fair Value   $ 3,900        
Investment, Identifier [Axis]: Playmonster Group Equity Inc Common Equity            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PlaymonsterGroupLLCMember          
Investment, Type [Extensible Enumeration] Common Stock [Member]   Common Stock [Member] Common Stock [Member]    
Investment, Identifier [Axis]: Playmonster Group Equity Inc Preferred Equity            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PlaymonsterGroupLLCMember          
Investment, Type [Extensible Enumeration] us-gaap:PreferredStockMember   us-gaap:PreferredStockMember us-gaap:PreferredStockMember    
Investment Owned, at Fair Value $ 2,099          
Investment, Identifier [Axis]: Playmonster Group Equity, Inc Common Stock            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PlaymonsterGroupEquityIncMember          
Investment, Type [Extensible Enumeration] Common Stock [Member]   Common Stock [Member] Common Stock [Member]    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Leisure Products   Leisure Products Leisure Products    
Investment, Acquisition Date Jan. 24, 2022          
Investment Owned, Balance, Principal Amount $ 72          
Investment Owned, at Cost $ 460          
Investment, Identifier [Axis]: Playmonster Group Equity, Inc. Preferred Stock            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PlaymonsterGroupEquityIncMember          
Investment, Type [Extensible Enumeration] us-gaap:PreferredStockMember   us-gaap:PreferredStockMember us-gaap:PreferredStockMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Leisure Products   Leisure Products Leisure Products    
Investment, Basis Spread, Variable Rate 14.00%   14.00% 14.00%    
Investment, Acquisition Date Jan. 24, 2022          
Investment Owned, Balance, Principal Amount $ 36          
Investment Owned, at Cost 3,600          
Investment Owned, at Fair Value $ 2,099          
Investment, Interest Rate, Paid in Kind 14.00%   14.00% 14.00%    
Investment, Identifier [Axis]: Playmonster Group LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PlaymonsterGroupLLCMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Leisure Products   Leisure Products Leisure Products    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 8.00%   8.00% 8.00%    
Investment Interest Rate 10.78%   10.78% 10.78%    
Investment, Acquisition Date Jan. 24, 2022          
Investment Maturity Date Jun. 08, 2026   Jun. 08, 2026 Jun. 08, 2026    
Investment Owned, Balance, Principal Amount $ 3,565          
Investment Owned, at Cost 3,565          
Investment Owned, at Fair Value $ 3,509          
Investment, Interest Rate, Paid in Kind 8.00%   8.00% 8.00%    
Investment, Interest Rate, Paid in Cash 2.78%   2.78% 2.78%    
Investment, Identifier [Axis]: Potpourri Group, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PotpourriGroupIncMember whf:PotpourriGroupIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Basis Spread, Variable Rate 8.25% 8.25% 8.25% 8.25% 8.25%  
Investment Interest Rate 9.75% 9.75% 9.75% 9.75% 9.75%  
Investment, Acquisition Date Jul. 03, 2019 Jul. 03, 2019        
Investment Maturity Date Jul. 03, 2024 Jul. 03, 2024 Jul. 03, 2024 Jul. 03, 2024 Jul. 03, 2024  
Investment Owned, Balance, Principal Amount $ 16,513 $ 17,148        
Investment Owned, at Cost 16,383 16,955        
Investment Owned, at Fair Value $ 16,513 $ 17,148        
Investment, Identifier [Axis]: Poultry Holdings LLC (HPP), First Lien Secured Term Loan, Floor 1.00%, Spread L plus 7.25%, Rate 8.25% (6.75% Cash + 1.50% PIK), Due 6/28/225            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:PoultryHoldingsLLCMember whf:PoultryHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.25% 7.25% 7.25% 7.25% 7.25%  
Investment Interest Rate 10.38% 8.25% 10.38% 10.38% 8.25%  
Investment, Acquisition Date Oct. 21, 2019 Oct. 21, 2019        
Investment Maturity Date Jun. 28, 2025 Jun. 28, 2025 Jun. 28, 2025 Jun. 28, 2025 Jun. 28, 2025  
Investment Owned, Balance, Principal Amount $ 7,183 $ 7,770        
Investment Owned, at Cost 7,117 7,676        
Investment Owned, at Fair Value $ 6,914 $ 6,993        
Investment, Interest Rate, Paid in Kind 1.50% 1.50% 1.50% 1.50% 1.50%  
Investment, Interest Rate, Paid in Cash 8.88% 6.75% 8.88% 8.88% 6.75%  
Investment, Identifier [Axis]: Project Castle, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:ProjectCastleIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Industrial Machinery   Industrial Machinery Industrial Machinery    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 5.50%   5.50% 5.50%    
Investment Interest Rate 9.05%   9.05% 9.05%    
Investment, Acquisition Date Jun. 09, 2022          
Investment Maturity Date Jun. 01, 2029   Jun. 01, 2029 Jun. 01, 2029    
Investment Owned, Balance, Principal Amount $ 8,376          
Investment Owned, at Cost 7,521          
Investment Owned, at Fair Value $ 7,541          
Investment, Identifier [Axis]: Quest Events, LLC Preferred Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:QuestEventsLLCMember whf:QuestEventsLLCMember        
Investment, Type [Extensible Enumeration] whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services  
Investment, Acquisition Date Dec. 28, 2018 Dec. 28, 2018        
Investment Maturity Date Dec. 08, 2025 Dec. 08, 2025 Dec. 08, 2025 Dec. 08, 2025 Dec. 08, 2025  
Investment Owned, Balance, Principal Amount $ 331 $ 317        
Investment Owned, at Cost 331 $ 317        
Investment Owned, at Fair Value $ 60          
Investment, Identifier [Axis]: Quest Events, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/28/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:QuestEventsLLCMember whf:QuestEventsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 9.67% 7.00% 9.67% 9.67% 7.00%  
Investment, Acquisition Date Jul. 19, 2019 Jul. 19, 2019        
Investment Maturity Date Dec. 28, 2024 Dec. 28, 2024 Dec. 28, 2024 Dec. 28, 2024 Dec. 28, 2024  
Investment Owned, Balance, Principal Amount $ 468 $ 935        
Investment Owned, at Cost 464 925        
Investment Owned, at Fair Value $ 424 $ 760        
Investment, Identifier [Axis]: Quest Events, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/28/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:QuestEventsLLCMember whf:QuestEventsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services Diversified Support Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 9.67% 7.00% 9.67% 9.67% 7.00%  
Investment, Acquisition Date Jul. 19, 2019 Jul. 19, 2019        
Investment Maturity Date Dec. 28, 2024 Dec. 28, 2024 Dec. 28, 2024 Dec. 28, 2024 Dec. 28, 2024  
Investment Owned, Balance, Principal Amount $ 11,926 $ 11,966        
Investment Owned, at Cost 11,838 11,848        
Investment Owned, at Fair Value $ 11,317 $ 9,729        
Investment, Identifier [Axis]: RCKC Acquisitions LLC , First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.25%, Due 12/31/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:RCKCAcquisitionsLLCMember whf:RCKCAcquisitionsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.04% 7.25% 9.04% 9.04% 7.25%  
Investment, Acquisition Date Jan. 27, 2021 Jan. 27, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, Balance, Principal Amount $ 3,014          
Investment Owned, at Cost 2,967          
Investment Owned, at Fair Value $ 2,969 $ (5)        
Investment, Identifier [Axis]: RCKC Acquisitions LLC , First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.25%, Due 12/31/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:RCKCAcquisitionsLLCMember whf:RCKCAcquisitionsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.20% 7.25% 9.20% 9.20% 7.25%  
Investment, Acquisition Date Jan. 27, 2021 Jan. 27, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, Balance, Principal Amount $ 533 $ 818        
Investment Owned, at Cost 526 804        
Investment Owned, at Fair Value $ 525 $ 814        
Investment, Identifier [Axis]: RCKC Acquisitions LLC , First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.25%, Rate 7.25%, Due 12/312026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:RCKCAcquisitionsLLCMember whf:RCKCAcquisitionsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.25% 6.25% 6.25% 6.25% 6.25%  
Investment Interest Rate 9.92% 7.25% 9.92% 9.92% 7.25%  
Investment, Acquisition Date Jan. 27, 2021 Jan. 27, 2021        
Investment Maturity Date Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026 Dec. 31, 2026  
Investment Owned, Balance, Principal Amount $ 11,179 $ 11,264        
Investment Owned, at Cost 11,018 11,074        
Investment Owned, at Fair Value $ 11,011 $ 11,151        
Investment, Identifier [Axis]: RLJ Pro-Vac, Inc. First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:RLJPro-VacInc.Member        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Environmental & Facilities Services     Environmental & Facilities Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Dec. 31, 2021        
Investment Maturity Date   Dec. 31, 2026     Dec. 31, 2026  
Investment Owned, Balance, Principal Amount   $ 8,775        
Investment Owned, at Cost   8,600        
Investment Owned, at Fair Value   $ 8,600        
Investment, Identifier [Axis]: RLJ Pro-Vac, Inc. First Lien Secured Term Loan First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:RLJPro-VacInc.Member        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Environmental & Facilities Services     Environmental & Facilities Services  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.25%     6.25%  
Investment Interest Rate   7.25%     7.25%  
Investment, Acquisition Date   Dec. 31, 2021        
Investment Maturity Date   Dec. 31, 2026     Dec. 31, 2026  
Investment, Identifier [Axis]: Road Safety Services, First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:RoadSafetyServicesIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Construction & Engineering     Construction & Engineering  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Dec. 30, 2021        
Investment Maturity Date   Mar. 18, 2025     Mar. 18, 2025  
Investment Owned, Balance, Principal Amount   $ 4,099        
Investment Owned, at Cost   4,017        
Investment Owned, at Fair Value   $ 4,017        
Investment, Identifier [Axis]: Road Safety Services, Inc., First Lien Secured Revolving Loan, Floor 3.25%, Spread P plus 5.50%, Rate 8.75%, Due 9/18/2023            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:RoadSafetyServicesIncMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Construction & Engineering     Construction & Engineering  
Investment, Interest Rate, Floor   3.25%     3.25%  
Investment, Basis Spread, Variable Rate   5.50%     5.50%  
Investment Interest Rate   8.75%     8.75%  
Investment, Acquisition Date   Dec. 31, 2019        
Investment Maturity Date   Sep. 18, 2023     Sep. 18, 2023  
Investment Owned, Balance, Principal Amount   $ 496        
Investment Owned, at Cost   489        
Investment Owned, at Fair Value   $ 501        
Investment, Identifier [Axis]: Road Safety Services, Inc., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 3/18/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:RoadSafetyServicesIncMember whf:RoadSafetyServicesIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Construction & Engineering Construction & Engineering Construction & Engineering Construction & Engineering Construction & Engineering  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.63% 7.50% 9.63% 9.63% 7.50%  
Investment, Acquisition Date Dec. 31, 2019 Dec. 31, 2019        
Investment Maturity Date Mar. 18, 2025 Mar. 18, 2025 Mar. 18, 2025 Mar. 18, 2025 Mar. 18, 2025  
Investment Owned, Balance, Principal Amount $ 8,625 $ 6,427        
Investment Owned, at Cost 8,534 6,340        
Investment Owned, at Fair Value $ 8,625 $ 6,405        
Investment, Identifier [Axis]: Ross-Simons Topco, LP Preferred Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:Ross-SimonsTopcoLPMember whf:Ross-SimonsTopcoLPMember        
Investment, Type [Extensible Enumeration] whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember whf:PreferredUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail Internet & Direct Marketing Retail  
Investment, Basis Spread, Variable Rate 8.00% 8.00% 8.00% 8.00% 8.00%  
Investment, Acquisition Date Dec. 04, 2020 Dec. 04, 2020        
Investment Owned, Balance, Principal Amount $ 600 $ 600        
Investment Owned, at Cost 514 600        
Investment Owned, at Fair Value $ 816 $ 786        
Investment, Interest Rate, Paid in Kind 8.00% 8.00% 8.00% 8.00% 8.00%  
Investment, Identifier [Axis]: SFS Global Holding Company Warrants            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SFSGlobalHoldingCompanyMember whf:SFSGlobalHoldingCompanyMember        
Investment, Type [Extensible Enumeration] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member]  
Investment, Acquisition Date Jun. 28, 2018 Jun. 28, 2018        
Investment Maturity Date Dec. 28, 2025 Dec. 28, 2025 Dec. 28, 2025 Dec. 28, 2025 Dec. 28, 2025  
Investment, Identifier [Axis]: Sigue Corporation Warrants            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SigueCorporationMember whf:SigueCorporationMember        
Investment, Type [Extensible Enumeration] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member] Other Diversified Financial Services [Member]  
Investment, Acquisition Date Jun. 28, 2018 Jun. 28, 2018        
Investment Maturity Date Dec. 28, 2025 Dec. 28, 2025 Dec. 28, 2025 Dec. 28, 2025 Dec. 28, 2025  
Investment Owned, Balance, Principal Amount $ 22 $ 22        
Investment Owned, at Cost 2,890 2,890        
Investment Owned, at Fair Value $ 3,823 $ 3,492        
Investment, Identifier [Axis]: Sklar Holdings, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SklarHoldingsIncMember whf:SklarHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Diversified Chemicals [Member] Diversified Chemicals [Member] Diversified Chemicals [Member] Diversified Chemicals [Member] Diversified Chemicals [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 9.75% 7.75% 9.75% 9.75% 7.75%  
Investment Interest Rate 10.75% 8.75% 10.75% 10.75% 8.75%  
Investment, Acquisition Date Nov. 13, 2019 Nov. 13, 2019        
Investment Maturity Date May 13, 2023 May 13, 2023 May 13, 2023 May 13, 2023 May 13, 2023  
Investment Owned, Balance, Principal Amount $ 7,353 $ 7,389        
Investment Owned, at Cost 7,292 7,295        
Investment Owned, at Fair Value $ 6,695 $ 7,020        
Investment, Interest Rate, Paid in Kind 2.00%   2.00% 2.00%    
Investment, Interest Rate, Paid in Cash 8.75%   8.75% 8.75%    
Investment, Identifier [Axis]: Sleep OpCo LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SleepOpCoLLCMember whf:SleepOpCoLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Home Furnishings [Member] Home Furnishings [Member] Home Furnishings [Member] Home Furnishings [Member] Home Furnishings [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 8.92% 7.50% 8.92% 8.92% 7.50%  
Investment, Acquisition Date Oct. 12, 2021 Oct. 12, 2021        
Investment Maturity Date Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026  
Investment Owned, at Fair Value $ 10          
Investment, Identifier [Axis]: Sleep OpCo LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SleepOpCoLLCMember whf:SleepOpCoLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Home Furnishings [Member] Home Furnishings [Member] Home Furnishings [Member] Home Furnishings [Member] Home Furnishings [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 8.92% 7.50% 8.92% 8.92% 7.50%  
Investment, Acquisition Date Oct. 12, 2021 Oct. 12, 2021        
Investment Maturity Date Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026 Oct. 12, 2026  
Investment Owned, Balance, Principal Amount $ 20,895 $ 20,034        
Investment Owned, at Cost 20,555 19,651        
Investment Owned, at Fair Value $ 20,630 $ 19,645        
Investment, Identifier [Axis]: Smalto Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread E plus 6.00%, Rate 7.25%, Due 4/29/27            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SmaltoInc.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Household Appliances   Household Appliances Household Appliances    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 7.25%   7.25% 7.25%    
Investment, Acquisition Date May 04, 2022          
Investment Maturity Date Apr. 29, 2027   Apr. 29, 2027 Apr. 29, 2027    
Investment Owned, Balance, Principal Amount $ 419          
Investment Owned, at Cost 437          
Investment Owned, at Fair Value $ 396          
Investment, Identifier [Axis]: Smalto Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread SF plus 6.00%, Rate 7.25%, Due 4/29/27            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SmaltoInc.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember   whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Household Appliances   Household Appliances Household Appliances    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 8.68%   8.68% 8.68%    
Investment, Acquisition Date May 04, 2022          
Investment Maturity Date Apr. 29, 2027   Apr. 29, 2027 Apr. 29, 2027    
Investment Owned, Balance, Principal Amount $ 17          
Investment Owned, at Cost 17          
Investment Owned, at Fair Value $ 17          
Investment, Identifier [Axis]: Smalto Inc., First Lien Secured Term Loan, Floor 1.00%, Spread E plus 6.25%, Rate 7.25%, Due 4/28/28            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SmaltoInc.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Household Appliances   Household Appliances Household Appliances    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.25%   6.25% 6.25%    
Investment Interest Rate 7.25%   7.25% 7.25%    
Investment, Acquisition Date May 04, 2022          
Investment Maturity Date Apr. 28, 2028   Apr. 28, 2028 Apr. 28, 2028    
Investment Owned, Balance, Principal Amount $ 6,659          
Investment Owned, at Cost 6,876          
Investment Owned, at Fair Value $ 6,364          
Investment, Identifier [Axis]: Smalto Inc., First Lien Secured Term Loan, Floor 1.00%, Spread SF plus 6.00%, Rate 7.18%, Due 4/28/28            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SmaltoInc.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Household Appliances   Household Appliances Household Appliances    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.19%   9.19% 9.19%    
Investment, Acquisition Date May 04, 2022          
Investment Maturity Date Apr. 28, 2028   Apr. 28, 2028 Apr. 28, 2028    
Investment Owned, Balance, Principal Amount $ 1,014          
Investment Owned, at Cost 995          
Investment Owned, at Fair Value $ 996          
Investment, Identifier [Axis]: Snap Fitness Holdings, Inc Class A Common Stock            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SnapFitnessHoldingsIncMember whf:SnapFitnessHoldingsIncMember        
Investment, Type [Extensible Enumeration] us-gaap:CommonClassAMember us-gaap:CommonClassAMember us-gaap:CommonClassAMember us-gaap:CommonClassAMember us-gaap:CommonClassAMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Acquisition Date Jun. 29, 2020 Jun. 29, 2020        
Investment Owned, Balance, Principal Amount $ 2 $ 2        
Investment Owned, at Cost 1,941 1,941        
Investment Owned, at Fair Value $ 157 $ 188        
Investment, Identifier [Axis]: Snap Fitness Holdings, Inc First Lien Secured Term Loan C            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SnapFitnessHoldingsIncMember whf:SnapFitnessHoldingsIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember whf:FirstLienSecuredTermLoanCMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Basis Spread, Variable Rate 9.50% 9.50% 9.50% 9.50% 9.50%  
Investment Interest Rate 9.50% 9.50% 9.50% 9.50% 9.50%  
Investment, Acquisition Date Jun. 29, 2020 Jun. 29, 2020        
Investment Owned, Balance, Principal Amount $ 1,268 $ 1,268        
Investment Owned, at Cost 1,265 1,265        
Investment Owned, at Fair Value $ 1,084 $ 1,219        
Investment, Interest Rate, Paid in Kind 9.50% 9.50% 9.50% 9.50% 9.50%  
Investment, Interest Rate, Paid in Cash 0.00% 0.00% 0.00% 0.00% 0.00%  
Investment, Identifier [Axis]: Snap Fitness Holdings, Inc Warrants            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SnapFitnessHoldingsIncMember whf:SnapFitnessHoldingsIncMember        
Investment, Type [Extensible Enumeration] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member] Warrant [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member] Leisure Facilities [Member]  
Investment, Acquisition Date Jun. 29, 2020 Jun. 29, 2020        
Investment Maturity Date Jun. 28, 2028 Jun. 28, 2028 Jun. 28, 2028 Jun. 28, 2028 Jun. 28, 2028  
Investment Owned, Balance, Principal Amount $ 1 $ 1        
Investment Owned, at Cost 793 793        
Investment Owned, at Fair Value $ 64 $ 76        
Investment, Identifier [Axis]: Solar Holdings Bidco Limited First Lien Secured Delayed Draw Loan Interest Rate 8.94            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Solar Holdings Bidco Limited          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 6.75%   6.75% 6.75%    
Investment Interest Rate 9.74%   9.74% 9.74%    
Investment, Acquisition Date Sep. 30, 2022          
Investment Maturity Date Sep. 28, 2029   Sep. 28, 2029 Sep. 28, 2029    
Investment Owned, at Fair Value $ (10)          
Investment, Identifier [Axis]: Solar Holdings Bidco Limited First Lien Secured Delayed Draw Loan Interest Rate 9.74            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Solar Holdings Bidco Limited          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 6.75%   6.75% 6.75%    
Investment Interest Rate 9.74%   9.74% 9.74%    
Investment, Acquisition Date Sep. 30, 2022          
Investment Maturity Date Sep. 28, 2029   Sep. 28, 2029 Sep. 28, 2029    
Investment Owned, Balance, Principal Amount $ 53          
Investment Owned, at Cost 51          
Investment Owned, at Fair Value $ 51          
Investment, Identifier [Axis]: Solar Holdings Bidco Limited First Lien Secured Term Loan CDOR            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Solar Holdings Bidco Limited          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Variable Interest Rate, Type [Extensible Enumeration] CanadianDollarOfferedRateMember   CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 6.75%   6.75% 6.75%    
Investment Interest Rate 10.92%   10.92% 10.92%    
Investment, Acquisition Date Sep. 30, 2022          
Investment Maturity Date Sep. 28, 2029   Sep. 28, 2029 Sep. 28, 2029    
Investment Owned, Balance, Principal Amount     $ 3,839      
Investment Owned, at Cost $ 2,726          
Investment Owned, at Fair Value $ 2,704          
Investment, Identifier [Axis]: Solar Holdings Bidco Limited First Lien Secured Term Loan SF            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Solar Holdings Bidco Limited          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 6.75%   6.75% 6.75%    
Investment Interest Rate 9.74%   9.74% 9.74%    
Investment, Acquisition Date Sep. 30, 2022          
Investment Maturity Date Sep. 28, 2029   Sep. 28, 2029 Sep. 28, 2029    
Investment Owned, Balance, Principal Amount $ 2,783          
Investment Owned, at Cost 2,706          
Investment Owned, at Fair Value $ 2,706          
Investment, Identifier [Axis]: Solar Holdings Bidco Limited First Lien Secured Term Loan SONIA            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Solar Holdings Bidco Limited          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services   Environmental & Facilities Services Environmental & Facilities Services    
Investment, Variable Interest Rate, Type [Extensible Enumeration] whf:SterlingOvernightIndexAverageMember   whf:SterlingOvernightIndexAverageMember whf:SterlingOvernightIndexAverageMember    
Investment, Interest Rate, Floor 0.00%   0.00% 0.00%    
Investment, Basis Spread, Variable Rate 6.75%   6.75% 6.75%    
Investment Interest Rate 8.94%   8.94% 8.94%    
Investment, Acquisition Date Sep. 30, 2022          
Investment Maturity Date Sep. 28, 2029   Sep. 28, 2029 Sep. 28, 2029    
Investment Owned, Balance, Principal Amount | £       £ 169    
Investment Owned, at Cost $ 182          
Investment Owned, at Fair Value $ 184          
Investment, Identifier [Axis]: Source Code Holdings, LLC , First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 7/30/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:SourceCodeHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredDelayedDrawLoanMember     whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Technology Hardware, Storage & Peripherals     Technology Hardware, Storage & Peripherals  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Aug. 10, 2021        
Investment Maturity Date   Jul. 30, 2027     Jul. 30, 2027  
Investment Owned, at Fair Value   $ 1        
Investment, Identifier [Axis]: Source Code Holdings, LLC , First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 7/30/2027            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:SourceCodeHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Technology Hardware, Storage & Peripherals     Technology Hardware, Storage & Peripherals  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Aug. 10, 2021        
Investment Maturity Date   Jul. 30, 2027     Jul. 30, 2027  
Investment Owned, Balance, Principal Amount   $ 7,629        
Investment Owned, at Cost   7,487        
Investment Owned, at Fair Value   $ 7,489        
Investment, Identifier [Axis]: Source Code Holdings, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SourceCodeHoldingsLLCMember whf:SourceCodeHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.63% 7.50% 9.63% 9.63% 7.50%  
Investment, Acquisition Date Aug. 10, 2021 Jul. 30, 2021        
Investment Maturity Date Jul. 30, 2027 Jul. 30, 2027 Jul. 30, 2027 Jul. 30, 2027 Jul. 30, 2027  
Investment Owned, at Fair Value $ 21          
Investment, Identifier [Axis]: Source Code Holdings, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SourceCodeHoldingsLLCMember whf:SourceCodeHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.63% 7.50% 9.63% 9.63% 7.50%  
Investment, Acquisition Date Aug. 10, 2021 Jul. 30, 2021        
Investment Maturity Date Jul. 30, 2027 Jul. 30, 2027 Jul. 30, 2027 Jul. 30, 2027 Jul. 30, 2027  
Investment Owned, Balance, Principal Amount $ 15,143 $ 7,629        
Investment Owned, at Cost 14,899 7,487        
Investment Owned, at Fair Value $ 14,970 $ 7,489        
Investment, Identifier [Axis]: Stella and Chewy's LLC, First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.75%, Rate 7.75%, Due 12/16/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:StellaandChewysLLCMember whf:StellaandChewysLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.75% 6.75% 8.75% 8.75% 6.75%  
Investment Interest Rate 11.92% 7.75% 11.92% 11.92% 7.75%  
Investment, Acquisition Date Mar. 26, 2021 Dec. 29, 2020        
Investment Maturity Date Dec. 16, 2025 Dec. 16, 2025 Dec. 16, 2025 Dec. 16, 2025 Dec. 16, 2025  
Investment Owned, Balance, Principal Amount $ 1,367 $ 1,893        
Investment Owned, at Cost 1,354 1,877        
Investment Owned, at Fair Value $ 1,326 $ 1,697        
Investment, Interest Rate, Paid in Kind 2.00%   2.00% 2.00%    
Investment, Interest Rate, Paid in Cash 9.92%   9.92% 9.92%    
Investment, Identifier [Axis]: Stella and Chewy's LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.75%, Rate 7.75%, Due 12/16/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:StellaandChewysLLCMember whf:StellaandChewysLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats Packaged Foods & Meats  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 8.75% 6.75% 8.75% 8.75% 6.75%  
Investment Interest Rate 12.24% 7.75% 12.24% 12.24% 7.75%  
Investment, Acquisition Date Dec. 29, 2020 Dec. 29, 2020        
Investment Maturity Date Dec. 16, 2025 Dec. 16, 2025 Dec. 16, 2025 Dec. 16, 2025 Dec. 16, 2025  
Investment Owned, Balance, Principal Amount $ 3,874 $ 5,313        
Investment Owned, at Cost 3,826 5,228        
Investment Owned, at Fair Value $ 3,758 $ 4,967        
Investment, Interest Rate, Paid in Kind 2.00%   2.00% 2.00%    
Investment, Interest Rate, Paid in Cash 10.24%   10.24% 10.24%    
Investment, Identifier [Axis]: Sunless, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SunlessInc.Member          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Personal Products   Personal Products Personal Products    
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member]   London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 6.50%   6.50% 6.50%    
Investment Interest Rate 10.17%   10.17% 10.17%    
Investment, Acquisition Date Jun. 30, 2022          
Investment Maturity Date Aug. 13, 2025   Aug. 13, 2025 Aug. 13, 2025    
Investment Owned, Balance, Principal Amount $ 2,092          
Investment Owned, at Cost 2,053          
Investment Owned, at Fair Value $ 2,063          
Investment, Identifier [Axis]: Sunless, Inc., First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 8/13/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SunlessInc.Member whf:SunlessIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Personal Products Personal Products Personal Products Personal Products Personal Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.00% 6.50% 6.50% 6.00%  
Investment Interest Rate 10.17% 7.00% 10.17% 10.17% 7.00%  
Investment, Acquisition Date Oct. 21, 2019 Oct. 21, 2019        
Investment Maturity Date Aug. 13, 2025 Aug. 13, 2024 Aug. 13, 2025 Aug. 13, 2025 Aug. 13, 2024  
Investment Owned, at Fair Value $ 7 $ 14        
Investment, Identifier [Axis]: Sunless, Inc., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 8/13/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:SunlessInc.Member whf:SunlessIncMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Personal Products Personal Products Personal Products Personal Products Personal Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.00% 6.50% 6.50% 6.00%  
Investment Interest Rate 10.17% 7.00% 10.17% 10.17% 7.00%  
Investment, Acquisition Date Oct. 21, 2019 Oct. 21, 2019        
Investment Maturity Date Aug. 13, 2025 Aug. 13, 2024 Aug. 13, 2025 Aug. 13, 2025 Aug. 13, 2024  
Investment Owned, Balance, Principal Amount $ 3,691 $ 4,259        
Investment Owned, at Cost 3,639 4,185        
Investment Owned, at Fair Value $ 3,691 $ 4,259        
Investment, Identifier [Axis]: Sure Fit Home Products, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:SureFitHomeProductsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Home Furnishings [Member]     Home Furnishings [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   9.75%     9.75%  
Investment Interest Rate   10.75%     10.75%  
Investment, Acquisition Date   Apr. 12, 2021        
Investment Maturity Date   Jul. 13, 2023     Jul. 13, 2023  
Investment Owned, Balance, Principal Amount   $ 4,912        
Investment Owned, at Cost   4,828        
Investment Owned, at Fair Value   $ 4,372        
Investment, Identifier [Axis]: TOUR Intermediate Holdings, LLC, First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 5/15/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TOURIntermediateHoldingsLLCMember whf:TOURIntermediateHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.62% 7.50% 9.62% 9.62% 7.50%  
Investment, Acquisition Date May 19, 2020 May 19, 2020        
Investment Maturity Date May 15, 2025 May 15, 2025 May 15, 2025 May 15, 2025 May 15, 2025  
Investment Owned, Balance, Principal Amount $ 2,505 $ 2,616        
Investment Owned, at Cost 2,493 2,600        
Investment Owned, at Fair Value $ 2,505 $ 2,616        
Investment, Identifier [Axis]: TOUR Intermediate Holdings, LLC, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.50%, Rate 7.50%, Due 5/15/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TOURIntermediateHoldingsLLCMember whf:TOURIntermediateHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage Investment Banking & Brokerage  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.62% 7.50% 9.62% 9.62% 7.50%  
Investment, Acquisition Date May 19, 2020 May 19, 2020        
Investment Maturity Date May 15, 2025 May 15, 2025 May 15, 2025 May 15, 2025 May 15, 2025  
Investment Owned, Balance, Principal Amount $ 3,182 $ 7,438        
Investment Owned, at Cost 3,150 7,343        
Investment Owned, at Fair Value $ 3,182 $ 7,438        
Investment, Identifier [Axis]: Team Car Care Holdings, First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TeamCarCareHoldingsLLCMember whf:TeamCarCareHoldingsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Automotive Retail [Member] Automotive Retail [Member] Automotive Retail [Member] Automotive Retail [Member] Automotive Retail [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] us-gaap:BaseRateMember us-gaap:BaseRateMember us-gaap:BaseRateMember us-gaap:BaseRateMember us-gaap:BaseRateMember  
Investment, Interest Rate, Floor 1.00% 1.03% 1.00% 1.00% 1.03%  
Investment, Basis Spread, Variable Rate 7.98% 7.98% 7.98% 7.98% 7.98%  
Investment Interest Rate 10.39% 9.02% 10.39% 10.39% 9.02%  
Investment, Acquisition Date Feb. 16, 2018 Feb. 16, 2018        
Investment Maturity Date Jun. 28, 2024 Jun. 28, 2024 Jun. 28, 2024 Jun. 28, 2024 Jun. 28, 2024  
Investment Owned, Balance, Principal Amount $ 14,594 $ 15,286        
Investment Owned, at Cost 14,532 15,193        
Investment Owned, at Fair Value $ 14,594 $ 15,286        
Investment, Identifier [Axis]: Telestream Holdings Corporation First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Telestream Holdings Corporation [Member]          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember   whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Technology Hardware, Storage & Peripherals   Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 1.00%   1.00% 1.00%    
Investment, Basis Spread, Variable Rate 9.25%   9.25% 9.25%    
Investment Interest Rate 12.30%   12.30% 12.30%    
Investment, Acquisition Date May 12, 2022          
Investment Maturity Date Oct. 15, 2025   Oct. 15, 2025 Oct. 15, 2025    
Investment, Identifier [Axis]: Telestream Holdings Corporation First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Telestream Holdings Corporation [Member] Telestream Holdings Corporation [Member]        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 9.25% 8.75% 9.25% 9.25% 8.75%  
Investment Interest Rate 12.30% 9.75% 12.30% 12.30% 9.75%  
Investment, Acquisition Date Oct. 15, 2020 Oct. 15, 2020        
Investment Maturity Date Oct. 15, 2025 Oct. 15, 2025 Oct. 15, 2025 Oct. 15, 2025 Oct. 15, 2025  
Investment Owned, Balance, Principal Amount $ 927 $ 530        
Investment Owned, at Cost 909 517        
Investment Owned, at Fair Value $ 935 $ 549        
Investment, Identifier [Axis]: Telestream Holdings Corporation First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] Telestream Holdings Corporation [Member] Telestream Holdings Corporation [Member]        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals Technology Hardware, Storage & Peripherals  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 9.25% 8.75% 9.25% 9.25% 8.75%  
Investment Interest Rate 12.11% 9.75% 12.11% 12.11% 9.75%  
Investment, Acquisition Date Oct. 15, 2020 Oct. 15, 2020        
Investment Maturity Date Oct. 15, 2025 Oct. 15, 2025 Oct. 15, 2025 Oct. 15, 2025 Oct. 15, 2025  
Investment Owned, Balance, Principal Amount $ 15,886 $ 15,079        
Investment Owned, at Cost 15,570 14,713        
Investment Owned, at Fair Value $ 15,874 $ 15,079        
Investment, Identifier [Axis]: Tensar Corporation First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:TensarCorporationMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Construction & Engineering     Construction & Engineering  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Nov. 20, 2020        
Investment Maturity Date   Aug. 20, 2025     Aug. 20, 2025  
Investment Owned, Balance, Principal Amount   $ 6,930        
Investment Owned, at Cost   6,797        
Investment Owned, at Fair Value   $ 7,069        
Investment, Identifier [Axis]: Tensar Corporation, First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.75%, Rate 7.75%, Due 8/20/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:TensarCorporationMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Construction & Engineering     Construction & Engineering  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.75%     6.75%  
Investment Interest Rate   7.75%     7.75%  
Investment, Acquisition Date   Nov. 24, 2020        
Investment Maturity Date   Aug. 20, 2025     Aug. 20, 2025  
Investment Owned, Balance, Principal Amount   $ 6,930        
Investment Owned, at Cost   6,797        
Investment Owned, at Fair Value   $ 7,069        
Investment, Identifier [Axis]: The Kyjen Company, LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TheKyjenCompanyLLCMember whf:TheKyjenCompanyLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Household Products [Member] Household Products [Member] Household Products [Member] Household Products [Member] Household Products [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 6.50% 7.00% 7.00% 6.50%  
Investment Interest Rate 9.88% 7.50% 9.88% 9.88% 7.50%  
Investment, Acquisition Date Apr. 05, 2021 Apr. 05, 2021        
Investment Maturity Date Apr. 05, 2026 Apr. 05, 2026 Apr. 05, 2026 Apr. 05, 2026 Apr. 05, 2026  
Investment Owned, Balance, Principal Amount $ 676 $ 385        
Investment Owned, at Cost 669 380        
Investment Owned, at Fair Value $ 632 $ 390        
Investment, Interest Rate, Paid in Kind 0.50%   0.50% 0.50%    
Investment, Interest Rate, Paid in Cash 9.38%   9.38% 9.38%    
Investment, Identifier [Axis]: The Kyjen Company, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TheKyjenCompanyLLCMember whf:TheKyjenCompanyLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Household Products [Member] Household Products [Member] Household Products [Member] Household Products [Member] Household Products [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 7.00% 6.50% 7.00% 7.00% 6.50%  
Investment Interest Rate 10.31% 7.50% 10.31% 10.31% 7.50%  
Investment, Acquisition Date Apr. 05, 2021 Apr. 05, 2021        
Investment Maturity Date Apr. 05, 2026 Apr. 05, 2026 Apr. 05, 2026 Apr. 05, 2026 Apr. 05, 2026  
Investment Owned, Balance, Principal Amount $ 11,347 $ 11,403        
Investment Owned, at Cost 11,228 11,257        
Investment Owned, at Fair Value $ 10,782 $ 11,383        
Investment, Interest Rate, Paid in Kind 0.50%   0.50% 0.50%    
Investment, Interest Rate, Paid in Cash 9.81%   9.81% 9.81%    
Investment, Identifier [Axis]: Token Buyer, Inc First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TokenBuyerIncMember          
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember   whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember    
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember   srt:NorthAmericaMember srt:NorthAmericaMember    
Investment, Industry Sector [Extensible Enumeration] Household Appliances   Household Appliances Household Appliances    
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]   Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]    
Investment, Interest Rate, Floor 0.50%   0.50% 0.50%    
Investment, Basis Spread, Variable Rate 6.00%   6.00% 6.00%    
Investment Interest Rate 9.70%   9.70% 9.70%    
Investment, Acquisition Date May 26, 2022          
Investment Maturity Date May 31, 2029   May 31, 2029 May 31, 2029    
Investment Owned, Balance, Principal Amount $ 6,540          
Investment Owned, at Cost 6,040          
Investment Owned, at Fair Value $ 6,003          
Investment, Identifier [Axis]: Trimlite Buyer LLC First Lien Secured Revolving Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:TrimliteBuyerLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredRevolvingLoanMember     whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Building Products     Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Jul. 27, 2021        
Investment Maturity Date   Jul. 27, 2026     Jul. 27, 2026  
Investment Owned, Balance, Principal Amount   $ 164        
Investment Owned, at Cost   161        
Investment Owned, at Fair Value   $ 161        
Investment, Identifier [Axis]: Trimlite Buyer LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TrimliteBuyerLLCMember whf:TrimliteBuyerLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Building Products Building Products Building Products Building Products Building Products  
Investment, Variable Interest Rate, Type [Extensible Enumeration] CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember CanadianDollarOfferedRateMember  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 10.67% 7.50% 10.67% 10.67% 7.50%  
Investment, Acquisition Date Jul. 27, 2021 Jul. 27, 2021        
Investment Maturity Date Jul. 27, 2026 Jul. 27, 2026 Jul. 27, 2026 Jul. 27, 2026 Jul. 27, 2026  
Investment Owned, Balance, Principal Amount   $ 22,977 $ 22,544      
Investment Owned, at Cost $ 17,681 17,975        
Investment Owned, at Fair Value $ 16,175 $ 17,841        
Investment, Identifier [Axis]: True Blue Car Wash, LLC First Lien Secured Delayed Draw Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TrueBlueCarWashLLCMember whf:TrueBlueCarWashLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.50% 6.82% 6.50% 6.50% 6.82%  
Investment Interest Rate 9.55% 7.82% 9.55% 9.55% 7.82%  
Investment, Acquisition Date Oct. 17, 2019 Oct. 17, 2019        
Investment Maturity Date Oct. 17, 2024 Oct. 17, 2024 Oct. 17, 2024 Oct. 17, 2024 Oct. 17, 2024  
Investment Owned, Balance, Principal Amount $ 4,186 $ 3,103        
Investment Owned, at Cost 4,124 3,073        
Investment Owned, at Fair Value $ 4,103 $ 3,098        
Investment, Identifier [Axis]: True Blue Car Wash, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TrueBlueCarWashLLCMember whf:TrueBlueCarWashLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member] Specialized Consumer Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.88% 6.82% 6.88% 6.88% 6.82%  
Investment Interest Rate 10.01% 7.82% 10.01% 10.01% 7.82%  
Investment, Acquisition Date Oct. 17, 2019 Oct. 17, 2019        
Investment Maturity Date Oct. 17, 2024 Oct. 17, 2024 Oct. 17, 2024 Oct. 17, 2024 Oct. 17, 2024  
Investment Owned, Balance, Principal Amount $ 9,969 $ 8,203        
Investment Owned, at Cost 9,876 8,087        
Investment Owned, at Fair Value $ 9,898 $ 8,130        
Investment, Identifier [Axis]: Turnberry Solutions, Inc., First Lien Secured Revolving Loan, Floor 3.25%, Spread P plus 5.00%, Rate 8.25%, Due 9/2/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TurnberrySolutionsInc.Member whf:TurnberrySolutionsInc.Member        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 3.25% 1.00% 1.00% 3.25%  
Investment, Basis Spread, Variable Rate 5.00% 5.00% 5.00% 5.00% 5.00%  
Investment Interest Rate 11.25% 8.25% 11.25% 11.25% 8.25%  
Investment, Acquisition Date Aug. 10, 2021 Aug. 10, 2021        
Investment Maturity Date Sep. 02, 2026 Sep. 02, 2026 Sep. 02, 2026 Sep. 02, 2026 Sep. 02, 2026  
Investment Owned, Balance, Principal Amount $ 22 $ 86        
Investment Owned, at Cost 21 84        
Investment Owned, at Fair Value $ 17 $ 85        
Investment, Identifier [Axis]: Turnberry Solutions, Inc., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 9/2/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:TurnberrySolutionsInc.Member whf:TurnberrySolutionsInc.Member        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services IT Consulting And Other Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 6.00% 6.00% 6.00% 6.00% 6.00%  
Investment Interest Rate 9.19% 7.00% 9.19% 9.19% 7.00%  
Investment, Acquisition Date Aug. 10, 2021 Aug. 10, 2021        
Investment Maturity Date Sep. 02, 2026 Sep. 02, 2026 Sep. 02, 2026 Sep. 02, 2026 Sep. 02, 2026  
Investment Owned, Balance, Principal Amount $ 6,103 $ 5,791        
Investment Owned, at Cost 6,008 5,689        
Investment Owned, at Fair Value $ 5,973 $ 5,684        
Investment, Identifier [Axis]: Unleashed Brands, LLC, First Lien Secured Delayed Draw Loan, Floor 1.00%, Spread L plus 6.56%, Rate 7.17%, Due 11/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:UnleashedBrandsLLCMember whf:UnleashedBrandsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember whf:FirstLienSecuredDelayedDrawLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Products Leisure Products Leisure Products Leisure Products Leisure Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.50% 5.50% 5.50% 5.50% 5.50%  
Investment Interest Rate 8.62% 6.50% 8.62% 8.62% 6.50%  
Investment, Acquisition Date Nov. 30, 2021 Nov. 30, 2021        
Investment Maturity Date Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026  
Investment Owned, Balance, Principal Amount $ 5,133 $ 5,133        
Investment Owned, at Cost 5,091 5,083        
Investment Owned, at Fair Value $ 5,151 $ 5,082        
Investment, Identifier [Axis]: Unleashed Brands, LLC, First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.56%, Rate 7.17%, Due 11/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:UnleashedBrandsLLCMember whf:UnleashedBrandsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Products Leisure Products Leisure Products Leisure Products Leisure Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.50% 5.50% 5.50% 5.50% 5.50%  
Investment Interest Rate 8.62% 6.50% 8.62% 8.62% 6.50%  
Investment, Acquisition Date Nov. 30, 2021 Nov. 30, 2021        
Investment Maturity Date Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026  
Investment Owned, at Fair Value $ 6          
Investment, Identifier [Axis]: Unleashed Brands, LLC, First lien Secured Term Loan, Floor 1.00%, Spread L plus 5.50%, Rate 7.17%, Due 11/19/2026            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:UnleashedBrandsLLCMember whf:UnleashedBrandsLLCMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Leisure Products Leisure Products Leisure Products Leisure Products Leisure Products  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.50% 5.50% 5.50% 5.50% 5.50%  
Investment Interest Rate 8.62% 6.50% 8.62% 8.62% 6.50%  
Investment, Acquisition Date Nov. 30, 2021 Nov. 30, 2021        
Investment Maturity Date Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026 Nov. 19, 2026  
Investment Owned, Balance, Principal Amount $ 3,887 $ 3,887        
Investment Owned, at Cost 3,854 3,848        
Investment Owned, at Fair Value $ 3,887 $ 3,848        
Investment, Identifier [Axis]: WH Lessor Corp., First Lien Secured Revolving Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/26/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JuniperLandscapingHoldingsLLCMember whf:WHLessorCorpMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember whf:FirstLienSecuredRevolvingLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.59% 6.00% 5.59% 5.59% 6.00%  
Investment Interest Rate 8.70% 7.00% 8.70% 8.70% 7.00%  
Investment, Acquisition Date Jan. 22, 2020 Jan. 22, 2020        
Investment Maturity Date Dec. 26, 2024 Dec. 26, 2024 Dec. 26, 2024 Dec. 26, 2024 Dec. 26, 2024  
Investment Owned, at Fair Value $ 5 $ 6        
Investment, Identifier [Axis]: WH Lessor Corp., First Lien Secured Term Loan, Floor 1.00%, Spread L plus 6.00%, Rate 7.00%, Due 12/26/2024            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:JuniperLandscapingHoldingsLLCMember whf:WHLessorCorpMember        
Investment, Type [Extensible Enumeration] whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services Environmental & Facilities Services  
Investment, Interest Rate, Floor 1.00% 1.00% 1.00% 1.00% 1.00%  
Investment, Basis Spread, Variable Rate 5.59% 6.00% 5.59% 5.59% 6.00%  
Investment Interest Rate 8.70% 7.00% 8.70% 8.70% 7.00%  
Investment, Acquisition Date Jan. 22, 2020 Jan. 22, 2020        
Investment Maturity Date Dec. 26, 2024 Dec. 26, 2024 Dec. 26, 2024 Dec. 26, 2024 Dec. 26, 2024  
Investment Owned, Balance, Principal Amount $ 7,490 $ 6,870        
Investment Owned, at Cost 7,412 6,780        
Investment Owned, at Fair Value $ 7,489 $ 6,866        
Investment, Identifier [Axis]: WHF STRS Ohio Senior Loan Fund LLC Equity            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:WHFSTRSOhioSeniorLoanFundLLCMember whf:WHFSTRSOhioSeniorLoanFundLLCMember        
Investment, Type [Extensible Enumeration] Equity Investments Equity Investments Equity Investments Equity Investments Equity Investments  
Investment Owned, at Fair Value $ 22,066 $ 15,607       10,167
Investment, Identifier [Axis]: WHF STRS Ohio Senior Loan Fund LLC Interests            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:WHFSTRSOhioSeniorLoanFundMember whf:WHFSTRSOhioSeniorLoanFundMember        
Investment, Type [Extensible Enumeration] whf:LLCInterestsMember whf:LLCInterestsMember whf:LLCInterestsMember whf:LLCInterestsMember whf:LLCInterestsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Finance [Member] Specialized Finance [Member] Specialized Finance [Member] Specialized Finance [Member] Specialized Finance [Member]  
Investment, Acquisition Date Jul. 19, 2019 Jul. 19, 2019        
Investment Owned, Balance, Principal Amount $ 20,000 $ 15,000        
Investment Owned, at Cost 20,000 15,000        
Investment Owned, at Fair Value $ 22,066 $ 15,607        
Investment, Identifier [Axis]: WHF STRS Ohio Senior Loan Fund LLC Subordinated Note            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:WHFSTRSOhioSeniorLoanFundLLCMember whf:WHFSTRSOhioSeniorLoanFundLLCMember        
Investment, Type [Extensible Enumeration] Subordinated Debt [Member] Subordinated Debt [Member] Subordinated Debt [Member] Subordinated Debt [Member] Subordinated Debt [Member]  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Specialized Finance [Member] Specialized Finance [Member] Specialized Finance [Member] Specialized Finance [Member] Specialized Finance [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member]  
Investment, Basis Spread, Variable Rate 6.50% 6.50% 6.50% 6.50% 6.50%  
Investment Interest Rate 9.13% 6.61% 9.13% 9.13% 6.61%  
Investment, Acquisition Date Jul. 19, 2019 Jul. 19, 2019        
Investment Owned, Balance, Principal Amount $ 80,000 $ 60,000        
Investment Owned, at Cost 80,000 60,000        
Investment Owned, at Fair Value $ 80,000 $ 60,000       $ 41,073
Investment, Identifier [Axis]: Westrock Coffee Company, LLC, First Lien Secured Term Loan, Floor 1.50%, Spread L plus 8.50%, Rate Westrock Coffee Company, LLC, Due 2/28/2025            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:WestrockCoffeeCompanyLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Packaged Foods & Meats     Packaged Foods & Meats  
Investment, Interest Rate, Floor   1.50%     1.50%  
Investment, Basis Spread, Variable Rate   8.50%     8.50%  
Investment Interest Rate   10.00%     10.00%  
Investment, Acquisition Date   Mar. 20, 2020        
Investment Maturity Date   Feb. 28, 2025     Feb. 28, 2025  
Investment Owned, Balance, Principal Amount   $ 9,105        
Investment Owned, at Cost   9,033        
Investment Owned, at Fair Value   $ 8,923        
Investment, Interest Rate, Paid in Kind   0.25%     0.25%  
Investment, Interest Rate, Paid in Cash   9.75%     9.75%  
Investment, Identifier [Axis]: What If Holdings, LLC First Lien Secured Term Loan            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration]   whf:WhatIfHoldingsLLCMember        
Investment, Type [Extensible Enumeration]   whf:FirstLienSecuredTermLoanMember     whf:FirstLienSecuredTermLoanMember  
Investment, Issuer Geographic Region [Extensible Enumeration]   srt:NorthAmericaMember     srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration]   Interactive Media And Services [Member]     Interactive Media And Services [Member]  
Investment, Variable Interest Rate, Type [Extensible Enumeration]   London Interbank Offered Rate (LIBOR) [Member]     London Interbank Offered Rate (LIBOR) [Member]  
Investment, Interest Rate, Floor   1.00%     1.00%  
Investment, Basis Spread, Variable Rate   6.50%     6.50%  
Investment Interest Rate   7.50%     7.50%  
Investment, Acquisition Date   Oct. 02, 2019        
Investment Maturity Date   Oct. 02, 2024     Oct. 02, 2024  
Investment Owned, Balance, Principal Amount   $ 18,848        
Investment Owned, at Cost   18,609        
Investment Owned, at Fair Value   $ 18,759        
Investment, Identifier [Axis]: What If Media Group, LLC Common Units            
Schedule of Investments [Line Items]            
Investment, Issuer Name [Extensible Enumeration] whf:WhatIfMediaGroupLLCMember whf:WhatIfMediaGroupLLCMember        
Investment, Type [Extensible Enumeration] whf:CommonUnitsMember whf:CommonUnitsMember whf:CommonUnitsMember whf:CommonUnitsMember whf:CommonUnitsMember  
Investment, Issuer Geographic Region [Extensible Enumeration] srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember srt:NorthAmericaMember  
Investment, Industry Sector [Extensible Enumeration] Interactive Media And Services [Member] Interactive Media And Services [Member] Interactive Media And Services [Member] Interactive Media And Services [Member] Interactive Media And Services [Member]  
Investment, Acquisition Date Jul. 02, 2021 Jul. 02, 2021        
Investment Owned, Balance, Principal Amount $ 851 $ 8        
Investment Owned, at Cost 851 850        
Investment Owned, at Fair Value $ 2,327 $ 1,398