Related Party Transactions - Summary of Components of Due to Affiliates (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Total components due to affiliates	$ 101,983	$ 86
Accrued Stockholder Servicing Fee [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	75,998
Performance Participation Allocation [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	10,952
Advanced Organization and Offering Costs [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	9,389
Accrued Management Fee [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	3,712
Accrued Affiliate Service Provider Expenses [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	1,797
Advanced Expenses [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	$ 135	$ 86