Related Party Agreements and Transactions - Additional Information (Details)						3 Months Ended	9 Months Ended		12 Months Ended		48 Months Ended	57 Months Ended
	Jan. 01, 2023	Dec. 31, 2022 USD ($)	Sep. 01, 2022 USD ($)	Apr. 01, 2020 USD ($)	Jan. 16, 2019 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) Component	Dec. 31, 2021 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jul. 01, 2021 USD ($)
Related Party Transaction [Line Items]
Performance-based incentive fees							$ 5,691,000	$ 10,638,000	$ 11,681,000
Management fees recognized							26,621,000	27,203,000	36,142,000	$ 36,434,000
Management and performance-based incentive fees payable		$ 9,060,000				$ 9,060,000	9,060,000		9,912,000		$ 9,060,000	$ 9,060,000
Administrative services expense							$ 4,188,000	$ 4,426,000	$ 5,835,000	$ 4,765,000
Investment owned, percent of net assets		242.70%				242.70%	242.70%		251.00%		242.70%	242.70%
Investments at fair value		$ 2,398,120,000				$ 2,398,120,000	$ 2,398,120,000		$ 2,523,173,000		$ 2,398,120,000	$ 2,398,120,000
Investment cost		$ 2,607,174,000				$ 2,607,174,000	$ 2,607,174,000		$ 2,745,829,000		$ 2,607,174,000	$ 2,607,174,000
Interest rate							5.05%		3.56%	3.39%
Co-Investment Holdings
Related Party Transaction [Line Items]
Investment owned, percent of fair value		74.00%				74.00%	74.00%		71.00%		74.00%	74.00%
Investments at fair value		$ 1,783,438,000				$ 1,783,438,000	$ 1,783,438,000		$ 1,783,052,000		$ 1,783,438,000	$ 1,783,438,000
Investment owned percent at cost		69.00%				69.00%	69.00%		65.00%		69.00%	69.00%
Investment cost		$ 1,797,140,000				$ 1,797,140,000	$ 1,797,140,000		$ 1,780,779,000		$ 1,797,140,000	$ 1,797,140,000
Administrative Service Expense | Merx Aviation Finance, LLC
Related Party Transaction [Line Items]
Administrative service expense reimbursements							226,000		300,000	$ 300,000
Merx Administration Agreement | Interest Expense
Related Party Transaction [Line Items]
Administrative service expense reimbursements							544,000		43,000	62,000
AIM
Related Party Transaction [Line Items]
Performance-based incentive fees							5,691,000		11,681,000	0
Management fees recognized							26,621,000		36,142,000	36,434,000
Management fees waived							$ 0		0	0
AIM | Base Management Fee
Related Party Transaction [Line Items]
Management fee annual rate percentage	1.75%
Management fee annual rate percentage												1.50%
Management fee quarter rate percentage	0.4375%											0.375%
Management fee annual rate percentage of average gross assets												1.00%
Management fee quarter rate percentage of average gross assets												0.25%
Average gross assets minimum product percentage												200.00%
AIM | Base Management Fee | Maximum
Related Party Transaction [Line Items]
Management fee annual rate percentage of average gross assets	1.50%
Management fee quarter rate percentage of average gross assets	0.375%
AIM | Performance-based Incentive Fee
Related Party Transaction [Line Items]
Number of components consists in incentive fee | Component							2
AIM | Incentive Fee based on Income
Related Party Transaction [Line Items]
Preferred return multiplying net asset percentage	1.75%										1.75%
Performance-based incentive fees						0
Percentage of pre-incentive fee net investment income	100.00%										100.00%
Catch-up amount multiplying percentage											2.1875%
Pre-incentive fee net investment income description							The Company will pay the Investment Adviser an incentive fee with respect to our pre-incentive fee net investment income in each calendar quarter as follows: (1) no incentive fee in any calendar quarter in which our pre-incentive fee net investment income for the trailing twelve quarters does not exceed the preferred return amount.(2) 100% of our pre-incentive fee net investment income for the trailing twelve quarters, if any, that exceeds the preferred return amount but is less than or equal to an amount (the “catch-up amount”) determined by multiplying 2.1875% by the Company’s net asset value at the beginning of each applicable calendar quarter comprising the relevant trailing twelve quarters.(3) for any quarter in which the Company’s pre-incentive fee net investment income for the trailing twelve quarters exceeds the catch-up amount, the incentive fee shall equal 20% of the amount of the Company’s pre-incentive fee net investment income for such trailing twelve quarters.
Percentage of cumulative pre-Incentive fee net return	17.50%										20.00%
Cumulative pre-Incentive fee net return description							“Cumulative Pre-Incentive Fee Net Return” during the relevant trailing twelve quarters means (x) Pre-Incentive Fee Net Investment Income in respect of the trailing twelve quarters less (y) any Net Capital Loss, since April 1, 2018, in respect of the trailing twelve quarters.
AIM | Incentive Fee based on Income | Legacy Fee
Related Party Transaction [Line Items]
Catch-up amount multiplying percentage	2.1875%
Percentage of cumulative pre-Incentive fee net return	20.00%
AIM | Incentive Fee based on Income | Current Fee
Related Party Transaction [Line Items]
Catch-up amount multiplying percentage	2.1212%
Percentage of cumulative pre-Incentive fee net return	17.50%
AIM | Incentive Fee based on Income | Maximum
Related Party Transaction [Line Items]
Percentage of cumulative pre-Incentive fee net return	17.50%
AIM | Incentive Fee based on Cumulative Net Realized Gains
Related Party Transaction [Line Items]
Percentage of cumulative pre-Incentive fee net return	17.50%	20.00%
Capital gains incentive fee							$ 0
Incentive fees waived							0		0	0
Management and performance-based incentive fees payable		$ 9,060,000				9,060,000	$ 9,060,000		9,912,000		$ 9,060,000	$ 9,060,000
AIM | Fee Offset Agreement
Related Party Transaction [Line Items]
Percentage of management fee revenue earned and incentive fee revenue offset					20.00%
Fee offset step down percentage					10.00%
Fee offset period					7 years
Fee offset period description							The fee offset will be in place for seven years, however the incentive fees realized by AIM and its affiliates after this seven-year period from applicable investments that were raised or made within the seven-year period will also be used to offset incentive fees payable to AIM by the Company.
Management fee offset							$ 178,000		247,000	25,000
AIM | Fee Offset Agreement | Minimum
Related Party Transaction [Line Items]
Aggregate capital of New Aircraft Funds and New Balance Sheet Investments					$ 3,000,000,000
AIA | Administration Agreement
Related Party Transaction [Line Items]
Administrative services expense							4,188,000		5,835,000	$ 4,765,000
Payable for expenses paid		$ 0				$ 0	$ 0		$ 0		$ 0	$ 0
Merx Aviation | First Lien Secured Revolver
Related Party Transaction [Line Items]
Balance of debt amount													$ 150,000
Merx Aviation | First Lien Secured Revolver | Common Equity
Related Party Transaction [Line Items]
Debt conversion, converted into common equity			$ 110,700	$ 105,300
Equity conversion, converted into debt														$ 84,500
Merx Aviation | Minimum | First Lien Secured Revolver
Related Party Transaction [Line Items]
Interest rate				10.00%
Merx Aviation | Maximum | First Lien Secured Revolver
Related Party Transaction [Line Items]
Interest rate				12.00%