Investments in Real Estate - Schedule of Details of Properties Acquired (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) ft² Property Transaction Unit Key	Dec. 31, 2018 USD ($) ft² Property Transaction Unit Key
Real Estate Properties [Line Items]
Number of Transactions | Transaction	53	32
Number of Properties | Property	582	359
Purchase Price (in thousands) | $	$ 16,997,068	$ 7,293,807
Industrial [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	9	6
Number of Properties | Property	443	270
Sq. Feet | ft²	76,892,000	41,293,000
Purchase Price (in thousands) | $	$ 6,585,263	$ 3,339,387
Industrial [Member] | Jupiter 12 Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	1
Number of Properties | Property	316
Sq. Feet | ft²	63,965,000
Purchase Price (in thousands) | $	$ 5,466,697
Industrial [Member] | Other Industrial Properties [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	8	4
Number of Properties | Property	127	18
Sq. Feet | ft²	12,927,000	5,563,000
Purchase Price (in thousands) | $	$ 1,118,566	$ 539,195
Industrial [Member] | Canyon Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction		1
Number of Properties | Property		146
Sq. Feet | ft²		21,719,000
Purchase Price (in thousands) | $		$ 1,837,213
Industrial [Member] | Meridian Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction		1
Number of Properties | Property		106
Sq. Feet | ft²		14,011,000
Purchase Price (in thousands) | $		$ 962,979
Multifamily [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	32	18
Number of Properties | Property	78	73
Purchase Price (in thousands) | $	$ 4,536,986	$ 2,956,224
Number of units | Unit	23,319	23,324
Multifamily [Member] | Roman Multifamily Portfolio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	1
Number of Properties | Property	14
Purchase Price (in thousands) | $	$ 857,540
Number of units | Unit	3,743
Multifamily [Member] | Other Multifamily Properties [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	31	16
Number of Properties | Property	64	47
Purchase Price (in thousands) | $	$ 3,679,446	$ 1,302,232
Number of units | Unit	19,576	10,515
Multifamily [Member] | EdR Student Housing Portfolio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction		1
Number of Properties | Property		20
Purchase Price (in thousands) | $		$ 1,230,857
Number of units | Unit		10,610
Multifamily [Member] | Wave Multifamily Portfolio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction		1
Number of Properties | Property		6
Purchase Price (in thousands) | $		$ 423,135
Number of units | Unit		2,199
Net Lease Property
Real Estate Properties [Line Items]
Number of Transactions | Transaction	1
Number of Properties | Property	1
Sq. Feet | ft²	8,507,000
Purchase Price (in thousands) | $	$ 4,265,530
Net Lease Property | Bellagio [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	1
Number of Properties | Property	1
Sq. Feet | ft²	8,507,000
Purchase Price (in thousands) | $	$ 4,265,530
Hotel [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	5	7
Number of Properties | Property	34	15
Purchase Price (in thousands) | $	$ 1,053,166	$ 963,458
Number of keys | Key	5,826	2,782
Hotel [Member] | JW Marriott San Antonio Hill Country Resort [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction		1
Number of Properties | Property		1
Purchase Price (in thousands) | $		$ 604,323
Number of keys | Key		1,002
Hotel [Member] | Other Hotel Properties [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction		6
Number of Properties | Property		14
Purchase Price (in thousands) | $		$ 359,135
Number of keys | Key		1,780
Retail [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	4	1
Number of Properties | Property	4	1
Sq. Feet | ft²	750,000	91,000
Purchase Price (in thousands) | $	$ 282,072	$ 34,738
Office Properties
Real Estate Properties [Line Items]
Number of Transactions | Transaction	1
Number of Properties | Property	1
Sq. Feet | ft²	228,000
Purchase Price (in thousands) | $	$ 123,348
Other Properties [Member]
Real Estate Properties [Line Items]
Number of Transactions | Transaction	1
Number of Properties | Property	21
Sq. Feet | ft²	1,347,000
Purchase Price (in thousands) | $	$ 150,703