Capital Transactions - Summary of Shares Issued and Proceeds Received in Connection with Offerings (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Investment Company, Capital Share Transactions [Line Items]
Proceeds to Company	$ 1,566	$ 758
Shares (in shares)	1,168	870
Net Proceeds to Company	$ 36,450	$ 25,616
Average Net Proceeds per Share	$ 31.21	$ 29.45
Receivable for shares sold	$ 12,864		$ 0
Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)	1,118	844
Gross Proceeds	$ 35,319	$ 25,243
Sales Load	(435)	(385)
Net Proceeds to Company	$ 34,884	$ 24,858
Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)	50	26
Proceeds to Company	$ 1,566	$ 758
Class A
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)	152	106
Net Proceeds to Company	$ 4,726	$ 3,117
Average Net Proceeds per Share	$ 31.01	$ 29.19
Class A | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)	140	96
Gross Proceeds	$ 4,658	$ 3,040
Sales Load	(307)	(226)
Net Proceeds to Company	$ 4,351	$ 2,814
Class A | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)	12	10
Proceeds to Company	$ 375	$ 303
Class T
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)	93	112
Net Proceeds to Company	$ 2,869	$ 3,285
Average Net Proceeds per Share	$ 30.85	$ 29.25
Class T | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)	85	109
Gross Proceeds	$ 2,744	$ 3,347
Sales Load	(128)	(159)
Net Proceeds to Company	$ 2,616	$ 3,188
Class T | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)	8	3
Proceeds to Company	$ 253	$ 97
Class D
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)	161	64
Net Proceeds to Company	$ 4,937	$ 1,839
Average Net Proceeds per Share	$ 30.58	$ 28.81
Class D | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)	156	61
Gross Proceeds	$ 4,773	$ 1,763
Sales Load	0	0
Net Proceeds to Company	$ 4,773	$ 1,763
Class D | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)	5	3
Proceeds to Company	$ 164	$ 76
Class I
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)	762	588
Net Proceeds to Company	$ 23,918	$ 17,375
Average Net Proceeds per Share	$ 31.37	$ 29.60
Class I | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)	737	578
Gross Proceeds	$ 23,144	$ 17,093
Sales Load	0	0
Net Proceeds to Company	$ 23,144	$ 17,093
Class I | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)	25	10
Proceeds to Company	$ 774	$ 282