Equity - Narrative (Details)		3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 20, 2017 USD ($)	Mar. 31, 2019 USD ($) vote $ / shares shares	Mar. 31, 2018 $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)
Class of Stock [Line Items]
Number of votes (in votes) | vote		1
Percent of organizational and offering costs limit (percent)		15.00%
Days required for reimbursement of excess amounts		60 days
Organizational costs as a percentage of gross offering proceeds (percent)		37.10%
Due to related parties		$ 12,168,000		$ 12,168,000	$ 19,048,000
Written notice needed to amend or terminate the DRP		10 days
Common stock subject to redemption		$ 37,274,000		$ 37,274,000	37,357,000
Stock Redeemed or Called During Period, Shares | shares		3,297,240
Stock Redeemed or Called During Period, Value					6,538,000
Follow-on Offering
Class of Stock [Line Items]
Offering amount in sales of shares	$ 2,200,000,000
Minimum holding period for redemption of stock	1 year
Primary Offering
Class of Stock [Line Items]
Offering amount in sales of shares	$ 2,000,000,000
Distribution Reinvestment Plan
Class of Stock [Line Items]
Common stock of the Company pursuant to the distribution reinvestment plan (in shares)	$ 200,000,000
Share Redemption Program
Class of Stock [Line Items]
Stock Redeemed or Called During Period, Shares | shares		0	217,088
Weighted average price per share (in dollars per share) | $ / shares		$ 0.00	$ 9.15
Share Redemption Program | IPO
Class of Stock [Line Items]
Minimum holding period for redemption of stock		4 years
New Share Redemption Program
Class of Stock [Line Items]
Minimum holding period for redemption of stock		1 year
Redemption price as percentage of Net Asset Value of outstanding shares (percent)		100.00%		100.00%
Minimum ownership percentage under share redemption program (percent)		$ 2,500		$ 2,500
Quarterly redemption cap as percentage of Net Asset Value of outstanding shares (percent)		5.00%
Common stock subject to redemption		$ 37,300,000		$ 37,300,000
Stock Redeemed or Called During Period, Shares | shares		0	0	1,199,463.98
Weighted average price per share (in dollars per share) | $ / shares				$ 9.62
Written notice required to modify or suspend program		30 days
New Share Redemption Program | IPO
Class of Stock [Line Items]
Minimum holding period for redemption of stock		4 years
Organizational and Offering Costs Incurred | IPO
Class of Stock [Line Items]
Cumulative organizational costs		$ 3,700,000		$ 3,700,000
Proceeds from offering		10,000,000
Organizational and offering costs advanced by the Advisor
Class of Stock [Line Items]
Cumulative organizational costs		536,000		536,000
Due to related parties		1,316,000		1,316,000	$ 1,312,000
Due to Affiliates | Organizational and offering costs advanced by the Advisor
Class of Stock [Line Items]
Due from related parties		900,000		900,000
Other Assets | Organizational and offering costs advanced by the Advisor
Class of Stock [Line Items]
Due from related parties		1,300,000		1,300,000
Pro forma | Organizational and offering costs advanced by the Advisor
Class of Stock [Line Items]
Due to related parties		1,500,000		1,500,000
Due from related parties		$ 2,200,000		2,200,000
Common Stock | Share Redemption Program
Class of Stock [Line Items]
Stock Redeemed or Called During Period, Value				$ 11,500,000