Related Party Transactions - Summary of Components of Due to Affiliates (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Total components due to affiliates	$ 301,581	$ 133,071
Accrued Stockholder Servicing Fee [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	238,496	102,076
Accrued Stockholder Servicing Fee [Member] | Class S Shares, Class D Shares and Class T Shares [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	$ 238,500	$ 102,100
Blackstone Advisory Partners L.P. [Member]
Related Party Transaction [Line Items]
Commission and fees, threshold percentage on gross proceeds from sale of share	8.75%