Subsequent Events - Gross Proceeds (Detail) - USD ($)	1 Months Ended	3 Months Ended
	May 13, 2020	Mar. 31, 2020	Mar. 31, 2019	Apr. 28, 2020	Sep. 30, 2018
Subsequent Event [Line Items]
Shares (in shares)		962,354	403,313
Net Proceeds to Company		$ 26,231,946
Average Net Proceeds Per Share (in dollars per share)		$ 27.26			$ 26.47
Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)			399,472
Class FA
Subsequent Event [Line Items]
Shares (in shares)		474,091
Net Proceeds to Company		$ 13,091,025
Average Net Proceeds Per Share (in dollars per share)		$ 27.61
Class FA | 2019 Private Placement and Follow On Private Placement [Member]
Subsequent Event [Line Items]
Shares (in shares)		474,091
Proceeds from sale of new shares		$ 13,209,000
Net Proceeds to Company		13,091,025
Class FA | Follow On Private Placement [Member]
Subsequent Event [Line Items]
Sales Load		$ (117,975)
Class A
Subsequent Event [Line Items]
Shares (in shares)		127,375	178,931
Net Proceeds to Company		$ 3,414,258	$ 4,727,303
Average Net Proceeds Per Share (in dollars per share)		$ 26.80			26.42
Class A | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)		120,775	177,162
Proceeds from sale of new shares		$ 3,461,287	$ 5,072,865
Sales Load		(224,005)	(392,249)
Net Proceeds to Company		$ 3,237,282	$ 4,680,616
Class I
Subsequent Event [Line Items]
Shares (in shares)		186,299	185,120
Net Proceeds to Company		$ 5,037,104	$ 4,910,433
Average Net Proceeds Per Share (in dollars per share)		$ 27.04			26.53
Class I | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)		181,784	184,330
Proceeds from sale of new shares		$ 4,914,955	$ 4,889,500
Sales Load		0	0
Net Proceeds to Company		$ 4,914,955	$ 4,889,500
Class T
Subsequent Event [Line Items]
Shares (in shares)		135,653	24,287
Net Proceeds to Company		$ 3,648,838	$ 644,426
Average Net Proceeds Per Share (in dollars per share)		$ 26.90			26.53
Class T | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)		134,641	24,231
Proceeds from sale of new shares		$ 3,802,228	$ 675,000
Sales Load		(180,606)	(32,062)
Net Proceeds to Company		$ 3,621,622	$ 642,938
Class D
Subsequent Event [Line Items]
Shares (in shares)		29,906	14,975
Net Proceeds to Company		$ 791,846	$ 392,096
Average Net Proceeds Per Share (in dollars per share)		$ 26.48			$ 26.18
Class D | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)		27,873	13,749
Proceeds from sale of new shares		$ 738,000	$ 360,000
Sales Load		0	0
Net Proceeds to Company		$ 738,000	$ 360,000
Common Class S- [Member]
Subsequent Event [Line Items]
Shares (in shares)		9,030
Net Proceeds to Company		$ 248,875
Average Net Proceeds Per Share (in dollars per share)		$ 27.56
Common Class S- [Member] | Class S Private Offering [Member]
Subsequent Event [Line Items]
Shares (in shares)		9,030
Proceeds from sale of new shares		$ 255,000
Sales Load		(6,125)
Net Proceeds to Company		$ 248,875
Subsequent Event [Member]
Subsequent Event [Line Items]
Shares (in shares)	387,658
Net Proceeds to Company	$ 10,407,761
Average Net Proceeds Per Share (in dollars per share)	$ 26.85
Subsequent Event [Member] | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	10,440
Proceeds from sale of new shares	$ 276,969
Subsequent Event [Member] | 2019 Private Offering and Public Offering [Member]
Subsequent Event [Line Items]
Shares (in shares)	377,218
Proceeds from sale of new shares	$ 10,432,895
Sales Load	(302,103)
Net Proceeds to Company	$ 10,130,792
Subsequent Event [Member] | Class FA
Subsequent Event [Line Items]
Shares (in shares)	95,551
Net Proceeds to Company	$ 2,594,015
Average Net Proceeds Per Share (in dollars per share)	$ 27.15
Subsequent Event [Member] | Class FA | 2019 Private Placement and Follow On Private Placement [Member]
Subsequent Event [Line Items]
Shares (in shares)	95,551
Proceeds from sale of new shares	$ 2,644,000
Net Proceeds to Company	2,594,015
Subsequent Event [Member] | Class FA | Follow On Private Placement [Member]
Subsequent Event [Line Items]
Sales Load	$ (49,985)
Subsequent Event [Member] | Class FA | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	0
Proceeds from sale of new shares	$ 0
Subsequent Event [Member] | Class A
Subsequent Event [Line Items]
Shares (in shares)	21,413
Net Proceeds to Company	$ 563,776
Average Net Proceeds Per Share (in dollars per share)	$ 26.33			$ 28.74
Subsequent Event [Member] | Class A | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)	17,080
Proceeds from sale of new shares	$ 482,000
Sales Load	(32,825)
Net Proceeds to Company	$ 449,175
Subsequent Event [Member] | Class A | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	4,333
Proceeds from sale of new shares	$ 114,601
Subsequent Event [Member] | Class I
Subsequent Event [Line Items]
Shares (in shares)	44,047
Net Proceeds to Company	$ 1,170,192
Average Net Proceeds Per Share (in dollars per share)	$ 26.57			26.55
Subsequent Event [Member] | Class I | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)	40,490
Proceeds from sale of new shares	$ 1,075,000
Sales Load	0
Net Proceeds to Company	$ 1,075,000
Subsequent Event [Member] | Class I | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	3,557
Proceeds from sale of new shares	$ 95,192
Subsequent Event [Member] | Class T
Subsequent Event [Line Items]
Shares (in shares)	79,603
Net Proceeds to Company	$ 2,098,242
Average Net Proceeds Per Share (in dollars per share)	$ 26.36			27.67
Subsequent Event [Member] | Class T | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)	78,505
Proceeds from sale of new shares	$ 2,172,235
Sales Load	(103,181)
Net Proceeds to Company	$ 2,069,054
Subsequent Event [Member] | Class T | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	1,098
Proceeds from sale of new shares	$ 29,188
Subsequent Event [Member] | Class D
Subsequent Event [Line Items]
Shares (in shares)	10,710
Net Proceeds to Company	$ 278,148
Average Net Proceeds Per Share (in dollars per share)	$ 25.97			25.94
Subsequent Event [Member] | Class D | Proceeds from Offerings
Subsequent Event [Line Items]
Shares (in shares)	9,258
Proceeds from sale of new shares	$ 240,160
Sales Load	0
Net Proceeds to Company	$ 240,160
Subsequent Event [Member] | Class D | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	1,452
Proceeds from sale of new shares	$ 37,988
Subsequent Event [Member] | Common Class S- [Member]
Subsequent Event [Line Items]
Shares (in shares)	136,334
Net Proceeds to Company	$ 3,703,388
Average Net Proceeds Per Share (in dollars per share)	$ 136,334.00			$ 28.15
Subsequent Event [Member] | Common Class S- [Member] | Distribution Reinvestment Plan
Subsequent Event [Line Items]
Shares (in shares)	0
Proceeds from sale of new shares	$ 0
Subsequent Event [Member] | Common Class S- [Member] | Class S Private Offering [Member]
Subsequent Event [Line Items]
Proceeds from sale of new shares	3,819,500
Sales Load	(116,112)
Net Proceeds to Company	$ 3,703,388