Related Party Transactions - Summary of Components of Due to Affiliates (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Total components due to affiliates	$ 623,036	$ 690,143
Accrued Stockholder Servicing Fee [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	572,784	478,539
Performance Participation Allocation [Member]
Related Party Transaction [Line Items]
Total components due to affiliates		141,396
Accrued Management Fee [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	19,869	13,873
Advanced Organization and Offering Costs [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	4,602	6,136
Accrued Affiliate Service Provider Expenses [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	4,606	6,037
Other [Member]
Related Party Transaction [Line Items]
Total components due to affiliates	$ 21,175	$ 44,162