Segment Reporting - Summary of Total Assets by Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 26,297,356	$ 13,237,158
Multifamily [Member]
Segment Reporting Information [Line Items]
Total assets	8,660,029	5,396,457
Industrial [Member]
Segment Reporting Information [Line Items]
Total assets	10,556,846	3,966,796
Hotel [Member]
Segment Reporting Information [Line Items]
Total assets	2,262,602	1,268,992
Retail [Member]
Segment Reporting Information [Line Items]
Total assets	233,819	136,273
Other Properties [Member]
Segment Reporting Information [Line Items]
Total assets	150,308
Real Estate-Related Securities and Loans [Member]
Segment Reporting Information [Line Items]
Total assets	3,835,460	2,281,033
Corporate [Member]
Segment Reporting Information [Line Items]
Total assets	$ 598,292	$ 187,607