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Organization and Basis of Presentation - Additional Information (Details)					3 Months Ended
	Dec. 05, 2022 USD ($) BusinessDays	Jan. 29, 2020 USD ($) shares	Jan. 16, 2020 USD ($) shares	Sep. 27, 2019 USD ($) shares	Mar. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Aug. 05, 2021 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, net of issuance costs, shares \| shares				10
Issuance of common stock, net of issuance costs				$ 150	$ 4,048,000
Debt instrument percentage					6.00%
Percentage of Secured loan and equipment financing advance offered to purchase	40.00%
Percentage of principal amount of loan or equipment financing advance	100
Percentage of fee for loan and advance	50.00%
Loan or advance fee payable number of days \| BusinessDays	2
Remaining percentage of fee for loan or advance	50.00%
Percentage of daily average aggregate value of outstanding loans and equipment financings	75
Common stock, shares issued \| shares			8,333,333		35,925,764	34,960,672
Proceeds from issuance of common stock			$ 114,400,000		$ 4,156,000
Common stock, value					36,000	$ 35,000
Net proceeds for the sale of investments					36,100,000
Outstanding receivables						0
Other assets
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Unsettled receivables due from the JV					300,000
Fee Income
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Origination and administrative agent fees					$ 500,000
Overallotment Option
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, shares issued \| shares		1,333,333	8,333,333
Proceeds from issuance of common stock		$ 20,000,000.0	$ 125,000,000.0
Private Offerings \| Legacy Funds
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, shares issued \| shares			9,183,185
Common stock, value			$ 137,700,000
Payment of common stock value in cash			$ 108,700,000
Private Offerings \| Equity interests
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, shares issued \| shares			533,332
Common stock, value			$ 8,000,000.0
Payment of common stock value in cash			$ 2,000,000.0
Maximum
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of Secured loan and equipment financing advance offered to purchase	25.00%
Trinity Capital Holdings
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of equity interests acquired					100.00%
i 40 LLC
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Initally contributed capital	$ 21,400,000				$ 5,200,000
Percentage of capital contribution invested in joint venture common equity	30.00%
Joint venture ownership percentage					12.50%
Percentage of capital contribution invested in joint venture debt notes	70.00%
Total Investments at fair value					$ 42,200,000	$ 0
Unfunded capital commitment					16,200,000
i 40 LLC \| Debt
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Total Investments at fair value					3,600,000
i 40 LLC \| Equity
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Total Investments at fair value					$ 1,600,000
JV Partner
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Initally contributed capital	$ 150,000,000.0
Joint venture ownership percentage					87.50%
8.5% Notes \| i 40 LLC
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Debt instrument percentage	8.50%
7.00% Notes due 2025
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Debt instrument percentage			7.00%		7.00%	7.00%
7.00% Notes due 2025 \| Private Offerings
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Proceeds from issuance of common stock			$ 125,000,000.0
Trinity Funding 1, LLC \| Credit Suisse Credit Facility
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Credit facility			$ 300,000,000
TrinCap Funding, LLC \| KeyBank Credit Facility
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Credit facility							$ 350,000,000