Equity and Redeemable Non-controlling Interest - Schedule of Aggregate Distributions Declared for Applicable Class of Common Stock (Detail)	9 Months Ended
	Sep. 30, 2018 $ / shares
Class S Shares [Member]
Dividends Payable [Line Items]
Aggregate gross distributions declared per share of common stock	$ 0.4699
Stockholder servicing fee per share of common stock	(0.0683)
Net distributions declared per share of common stock	0.4016
Class T Shares [Member]
Dividends Payable [Line Items]
Aggregate gross distributions declared per share of common stock	0.4699
Stockholder servicing fee per share of common stock	(0.0672)
Net distributions declared per share of common stock	0.4027
Class D Shares [Member]
Dividends Payable [Line Items]
Aggregate gross distributions declared per share of common stock	0.4699
Stockholder servicing fee per share of common stock	(0.0199)
Net distributions declared per share of common stock	0.4500
Class I Shares [Member]
Dividends Payable [Line Items]
Aggregate gross distributions declared per share of common stock	0.4699
Net distributions declared per share of common stock	$ 0.4699