Capital Transactions -Additional Information (Detail) - USD ($)		1 Months Ended		3 Months Ended
	Mar. 07, 2018	Jan. 31, 2020	Apr. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Sep. 30, 2018
Investment Company, Capital Share Transactions [Line Items]
Amount of share requested to be repurchased in excess of proceeds received from its distribution reinvestment plan				$ 1,600,000
Shares Issued, Including Reinvestments				962,354	403,313
Average Net Proceeds per Share				$ 27.26			$ 26.47
Issuance of common shares through distribution reinvestment plan				$ 380,187	$ 101,204
Net Proceeds to Company				26,231,946
Proceeds from Offerings
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)					399,472
Shares offered	$ 1,000,000,000
Sale of stock offering, minimum requirement	$ 5,000
Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Shares offered				100,000,000
Issuance of common shares through distribution reinvestment plan				$ 380,187	$ 101,204
Stock Issued During Period, Shares, Dividend Reinvestment Plan				14,160	3,841
2019 Private Offering, Follow On Private Offering and Public Offering [Member]
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				948,194
Gross Proceeds				$ 26,380,470
Sales Load				(528,711)
Net Proceeds to Company				$ 25,851,759
Class FA
Investment Company, Capital Share Transactions [Line Items]
Common stock, shares authorized (in shares)				7,400,000		7,400,000
Shares Issued, Including Reinvestments				474,091
Average Net Proceeds per Share				$ 27.61
Net Proceeds to Company				$ 13,091,025
Class FA | 2019 Private Placement and Follow On Private Placement [Member]
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				474,091
Gross Proceeds				$ 13,209,000
Net Proceeds to Company				$ 13,091,025
Class FA | 2019 Private Offering [Member]
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				300,000
Number of shares offered in 2019 Private Offering			50,000,000
Class FA | Follow On Private Placement [Member]
Investment Company, Capital Share Transactions [Line Items]
Sales Load				$ (117,975)
Class FA | Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan				$ 0
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0
Common Class S- [Member]
Investment Company, Capital Share Transactions [Line Items]
Common stock, shares authorized (in shares)				100,000,000
Shares Issued, Including Reinvestments				9,030
Average Net Proceeds per Share				$ 27.56
Net Proceeds to Company				$ 248,875
Common Class S- [Member] | Class S Private Offering [Member]
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				9,030
Gross Proceeds				$ 255,000
Sales Load				$ (6,125)
Share price (usd per share)				$ 28.559585492228
Net Proceeds to Company				$ 248,875
Number of shares offered in 2019 Private Offering		50,000,000
Common Class S- [Member] | Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan				$ 0
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0
Class A
Investment Company, Capital Share Transactions [Line Items]
Common stock, shares authorized (in shares)				94,660,000		94,660,000
Shares Issued, Including Reinvestments				127,375	178,931
Average Net Proceeds per Share				$ 26.80			26.42
Net Proceeds to Company				$ 3,414,258	$ 4,727,303
Class A | Proceeds from Offerings
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				120,775	177,162
Gross Proceeds				$ 3,461,287	$ 5,072,865
Sales Load				$ (224,005)	(392,249)
Share price (usd per share)				$ 29.23
Net Proceeds to Company				$ 3,237,282	4,680,616
Class A | Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan				$ 176,976	$ 46,687
Stock Issued During Period, Shares, Dividend Reinvestment Plan				6,600	1,769
Class T
Investment Company, Capital Share Transactions [Line Items]
Common stock, shares authorized (in shares)				558,620,000		658,620,000
Shares Issued, Including Reinvestments				135,653	24,287
Average Net Proceeds per Share				$ 26.90			26.53
Net Proceeds to Company				$ 3,648,838	$ 644,426
Class T | Proceeds from Offerings
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				134,641	24,231
Gross Proceeds				$ 3,802,228	$ 675,000
Sales Load				$ (180,606)	(32,062)
Share price (usd per share)				$ 28.16
Net Proceeds to Company				$ 3,621,622	642,938
Class T | Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan				$ 27,216	$ 1,488
Stock Issued During Period, Shares, Dividend Reinvestment Plan				1,012	56
Class D
Investment Company, Capital Share Transactions [Line Items]
Common stock, shares authorized (in shares)				94,660,000		94,660,000
Shares Issued, Including Reinvestments				29,906	14,975
Average Net Proceeds per Share				$ 26.48			26.18
Net Proceeds to Company				$ 791,846	$ 392,096
Class D | Proceeds from Offerings
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				27,873	13,749
Gross Proceeds				$ 738,000	$ 360,000
Sales Load				$ 0	0
Share price (usd per share)				$ 26.4
Net Proceeds to Company				$ 738,000	360,000
Class D | Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan				$ 53,846	$ 32,096
Stock Issued During Period, Shares, Dividend Reinvestment Plan				2,033	1,226
Class I
Investment Company, Capital Share Transactions [Line Items]
Common stock, shares authorized (in shares)				94,660,000		94,660,000
Shares Issued, Including Reinvestments				186,299	185,120
Average Net Proceeds per Share				$ 27.04			$ 26.53
Net Proceeds to Company				$ 5,037,104	$ 4,910,433
Class I | Proceeds from Offerings
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)				181,784	184,330
Gross Proceeds				$ 4,914,955	$ 4,889,500
Sales Load				$ 0	0
Share price (usd per share)				$ 26.99
Net Proceeds to Company				$ 4,914,955	4,889,500
Class I | Distribution Reinvestment Plan [Member]
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan				$ 122,149	$ 20,933
Stock Issued During Period, Shares, Dividend Reinvestment Plan				4,515	790