Financial Highlights - Schedule of Financial Highlights (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Investment Company, Financial Highlights [Roll Forward]
Net investment income (usd per share)	$ 0.79		$ 0.93
Net assets at end of period	$ 500,308,997	[1],[2]	$ 308,962,908	[3],[4]	$ 174,282,891
Distributions declared	$ 15,489,084		$ 9,929,353
Class FA
Investment Company, Financial Highlights [Roll Forward]
Net Asset Value, Beginning of Period (usd per shares)	$ 29.97		$ 27.64
Net investment income, before expense support (usd per shares)	1.33		0.79
Reimbursements of expense support (usd per share)	(0.21)		0.35
Net investment income (usd per share)	1.12		1.14
Net realized and unrealized gains (usd per shares)	2.78		2.44
Net increase resulting from investment operations (usd per shares)	3.90		3.58
Distributions to shareholders (usd per share)	(1.25)		(1.25)
Net decrease resulting from distributions to shareholders (usd per shares)	(1.25)		(1.25)
Net Asset Value, End of Period (usd per shares)	$ 32.62		$ 29.97
Net assets at end of period	$ 148,716,308		$ 137,237,594
Average net assets	$ 145,353,000		$ 130,940,000
Shares outstanding end of period (in shares)	4,559,000		4,579,000
Distributions declared	$ 5,714,000		$ 5,812,000
Total investment return based on net asset value before total return incentive fee	14.55%		13.27%
Total investment return based on net asset value after total return incentive fee	12.92%		13.16%
Ratios to average net assets:
Total operating expenses before total return incentive fee and expense support	1.41%		1.81%
Total operating expenses before expense support	2.77%		3.10%
Total operating expenses after expense support	3.44%		1.85%
Net investment income before total return incentive fee	4.88%		4.09%
Net investment income	3.52%		4.05%
Total investment return based on net asset value after total return incentive fee			97.00%
Class A
Investment Company, Financial Highlights [Roll Forward]
Net Asset Value, Beginning of Period (usd per shares)	$ 28.76		$ 26.91
Net investment income, before expense support (usd per shares)	0.65		0.10
Reimbursements of expense support (usd per share)	(0.19)		0.53
Net investment income (usd per share)	0.46		0.63
Net realized and unrealized gains (usd per shares)	2.81		2.47
Net increase resulting from investment operations (usd per shares)	3.27		3.10
Distributions to shareholders (usd per share)	(1.25)		(1.25)
Net decrease resulting from distributions to shareholders (usd per shares)	(1.25)		(1.25)
Net Asset Value, End of Period (usd per shares)	$ 30.78		$ 28.76
Net assets at end of period	$ 44,957,765		$ 29,747,587
Average net assets	$ 37,354,000		$ 22,984,000
Shares outstanding end of period (in shares)	1,461,000		1,034,000
Distributions declared	$ 1,531,000		$ 1,052,000
Total investment return based on net asset value before total return incentive fee	13.88%		12.43%
Total investment return based on net asset value after total return incentive fee	11.53%		11.89%
Ratios to average net assets:
Total operating expenses before total return incentive fee and expense support	2.97%		3.51%
Total operating expenses before expense support	5.52%		6.09%
Total operating expenses after expense support	6.13%		4.14%
Net investment income before total return incentive fee	4.06%		2.96%
Net investment income	1.52%		2.32%
Total investment return based on net asset value after total return incentive fee			75.00%
Class T
Investment Company, Financial Highlights [Roll Forward]
Net Asset Value, Beginning of Period (usd per shares)	$ 28.67		$ 27.01
Net investment income, before expense support (usd per shares)	0.39		(0.33)
Reimbursements of expense support (usd per share)	(0.21)		0.47
Net investment income (usd per share)	0.18		0.14
Net realized and unrealized gains (usd per shares)	2.81		2.52
Net increase resulting from investment operations (usd per shares)	2.99		2.66
Distributions to shareholders (usd per share)	(1.00)		(1.00)
Net decrease resulting from distributions to shareholders (usd per shares)	(1.00)		(1.00)
Net Asset Value, End of Period (usd per shares)	$ 30.66		$ 28.67
Net assets at end of period	$ 49,328,483		$ 18,771,713
Average net assets	$ 30,486,000		$ 11,991,000
Shares outstanding end of period (in shares)	1,609,000		655,000
Distributions declared	$ 1,000,000		$ 436,000
Total investment return based on net asset value before total return incentive fee	11.96%		10.79%
Total investment return based on net asset value after total return incentive fee	10.55%		10.11%
Ratios to average net assets:
Total operating expenses before total return incentive fee and expense support	4.93%		5.54%
Total operating expenses before expense support	6.99%		8.21%
Total operating expenses after expense support	7.70%		6.49%
Net investment income before total return incentive fee	2.65%		1.46%
Net investment income	0.59%		0.51%
Total investment return based on net asset value after total return incentive fee			64.00%
Class D
Investment Company, Financial Highlights [Roll Forward]
Net Asset Value, Beginning of Period (usd per shares)	$ 28.24		$ 26.61
Net investment income, before expense support (usd per shares)	0.58		0.03
Reimbursements of expense support (usd per share)	(0.14)		0.26
Net investment income (usd per share)	0.44		0.29
Net realized and unrealized gains (usd per shares)	2.80		2.47
Net increase resulting from investment operations (usd per shares)	3.24		2.76
Distributions to shareholders (usd per share)	(1.13)		(1.13)
Net decrease resulting from distributions to shareholders (usd per shares)	(1.13)		(1.13)
Net Asset Value, End of Period (usd per shares)	$ 30.35		$ 28.24
Net assets at end of period	$ 30,606,947		$ 12,813,290
Average net assets	$ 20,335,000		$ 9,675,000
Shares outstanding end of period (in shares)	1,009,000		454,000
Distributions declared	$ 760,000		$ 405,000
Total investment return based on net asset value before total return incentive fee	13.31%		11.99%
Total investment return based on net asset value after total return incentive fee	11.61%		10.67%
Ratios to average net assets:
Total operating expenses before total return incentive fee and expense support	4.16%		3.93%
Total operating expenses before expense support	6.45%		6.48%
Total operating expenses after expense support	6.91%		5.52%
Net investment income before total return incentive fee	3.77%		2.67%
Net investment income	1.48%		1.08%
Total investment return based on net asset value after total return incentive fee			38.00%
Class I
Investment Company, Financial Highlights [Roll Forward]
Net Asset Value, Beginning of Period (usd per shares)	$ 29.06		$ 27.15
Net investment income, before expense support (usd per shares)	0.60		0.02
Reimbursements of expense support (usd per share)	(0.09)		0.66
Net investment income (usd per share)	0.51		0.68
Net realized and unrealized gains (usd per shares)	2.86		2.48
Net increase resulting from investment operations (usd per shares)	3.37		3.16
Distributions to shareholders (usd per share)	(1.25)		(1.25)
Net decrease resulting from distributions to shareholders (usd per shares)	(1.25)		(1.25)
Net Asset Value, End of Period (usd per shares)	$ 31.18		$ 29.06
Net assets at end of period	$ 168,704,080		$ 57,147,617
Average net assets	$ 106,275,000		$ 35,672,000
Shares outstanding end of period (in shares)	5,410,000		1,967,000
Distributions declared	$ 4,271,000		$ 1,610,000
Total investment return based on net asset value before total return incentive fee	13.39%		12.23%
Total investment return based on net asset value after total return incentive fee	11.76%		12.01%
Ratios to average net assets:
Total operating expenses before total return incentive fee and expense support	3.93%		4.02%
Total operating expenses before expense support	6.25%		6.72%
Total operating expenses after expense support	6.55%		4.34%
Net investment income before total return incentive fee	3.97%		2.78%
Net investment income	1.65%		2.46%
Total investment return based on net asset value after total return incentive fee			88.00%
Class S
Investment Company, Financial Highlights [Roll Forward]
Net Asset Value, Beginning of Period (usd per shares)	$ 30.08		$ 27.56
Net investment income, before expense support (usd per shares)	1.23		0.82
Reimbursements of expense support (usd per share)	0		0.10
Net investment income (usd per share)	1.23		0.92
Net realized and unrealized gains (usd per shares)	2.78		2.64
Net increase resulting from investment operations (usd per shares)	4.01		3.56
Distributions to shareholders (usd per share)	(1.25)		(1.04)
Net decrease resulting from distributions to shareholders (usd per shares)	(1.25)		(1.04)
Net Asset Value, End of Period (usd per shares)	$ 32.84		$ 30.08
Net assets at end of period	$ 57,995,414		$ 53,245,107
Average net assets	$ 56,575,000		$ 19,257,000
Shares outstanding end of period (in shares)	1,766,000		1,770,000
Distributions declared	$ 2,213,000		$ 615,000
Total investment return based on net asset value before total return incentive fee	15.07%		13.36%
Total investment return based on net asset value after total return incentive fee	13.54%		12.80%
Ratios to average net assets:
Total operating expenses before total return incentive fee and expense support	1.67%		2.35%
Total operating expenses before expense support	3.07%		4.15%
Total operating expenses after expense support	3.07%		3.79%
Net investment income before total return incentive fee	5.26%		4.66%
Net investment income	3.86%		3.17%
Total investment return based on net asset value after total return incentive fee			20.00%

[1] Percentages represent fair value as a percentage of net assets for each investment category.

[2] Security may be an obligation of one or more entities affiliated with the named company.

[3] Percentages represent fair value as a percentage of net assets for each investment category.

[4] Security may be an obligation of one or more entities affiliated with the named company.