Segment Reporting - Summary of Total Assets by Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 13,237,158	$ 4,625,308
Multifamily [Member]
Segment Reporting Information [Line Items]
Total assets	5,396,457	2,567,735
Industrial [Member]
Segment Reporting Information [Line Items]
Total assets	3,966,796	636,900
Hotel [Member]
Segment Reporting Information [Line Items]
Total assets	1,268,992	281,242
Retail [Member]
Segment Reporting Information [Line Items]
Total assets	136,273	103,138
Real Estate-Related Securities [Member]
Segment Reporting Information [Line Items]
Total assets	2,281,033	918,975
Other (Corporate) [Member]
Segment Reporting Information [Line Items]
Total assets	$ 187,607	$ 117,318