STOCKHOLDERS' EQUITY - Summary of Changes in Shares Outstanding for Each Class of Common Stock (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, redemptions, shares	(233,000)	(63,000)	0
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	20,265,000	1,238,000	255,000
Issuance of common stock, Primary shares, shares	28,224,000	18,894,000	968,000
Issuance of common stock, DRIP, shares	943,000	196,000	6,000
Issuance of common stock, redemptions, shares	(233,000)	(63,000)
Issuance of common stock, stock grants	76,000
Issuance of common stock, Stock dividends, shares			9,000
Ending balance, shares	49,275,000	20,265,000	1,238,000
Class T
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	19,759,000
Ending balance, shares	45,240,000	19,759,000
Common stock, shares issued	45,240,000	19,759,000
Class T | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	19,759,000	976,000	7,000
Issuance of common stock, Primary shares, shares	24,705,000	18,643,000	968,000
Issuance of common stock, DRIP, shares	887,000	189,000	1,000
Issuance of common stock, redemptions, shares	(111,000)	(49,000)
Issuance of common stock, stock grants	0
Issuance of common stock, Stock dividends, shares			0
Ending balance, shares	45,240,000	19,759,000	976,000
Class W
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	161,000
Ending balance, shares	2,736,000	161,000
Common stock, shares issued	2,736,000	161,000
Class W | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	161,000	6,000	0
Issuance of common stock, Primary shares, shares	2,584,000	154,000	0
Issuance of common stock, DRIP, shares	36,000	1,000	0
Issuance of common stock, redemptions, shares	(45,000)	0
Issuance of common stock, stock grants	0
Issuance of common stock, Stock dividends, shares			6,000
Ending balance, shares	2,736,000	161,000	6,000
Class I
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	345,000
Ending balance, shares	1,299,000	345,000
Common stock, shares issued	1,299,000	345,000
Class I | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, shares	345,000	256,000	248,000
Issuance of common stock, Primary shares, shares	935,000	97,000	0
Issuance of common stock, DRIP, shares	20,000	6,000	5,000
Issuance of common stock, redemptions, shares	(77,000)	(14,000)
Issuance of common stock, stock grants	76,000
Issuance of common stock, Stock dividends, shares			3,000
Ending balance, shares	1,299,000	345,000	256,000
Class I | Common Stock | Affiliated Entity | BCI IV Advisors LLC (the Advisor)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares issued				20,000