Investments in Real Estate - Schedule of Details of Properties Acquired (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) Property
Real Estate Properties [Line Items]
Number of Properties	549
Purchase Price | $	$ 11,063,461
Industrial [Member]
Real Estate Properties [Line Items]
Number of Properties	440
Multifamily [Member]
Real Estate Properties [Line Items]
Number of Properties	61
Hotel [Member]
Real Estate Properties [Line Items]
Number of Properties	25
Retail [Member]
Real Estate Properties [Line Items]
Number of Properties	2
Other [Member]
Real Estate Properties [Line Items]
Number of Properties	21
Harrisburg, PA [Member] | Industrial [Member] | 4500 Westport Drive [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Jan. 31, 2019
Purchase Price | $	$ 11,975
Various [Member] | Industrial [Member] | Denali Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	18
Acquisition Date	Sep. 30, 2019
Purchase Price | $	$ 218,151
Various [Member] | Industrial [Member] | Jupiter 12 Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	316
Acquisition Date	Sep. 30, 2019
Purchase Price | $	$ 5,466,697
Various [Member] | Multifamily [Member] | Roman Multifamily Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	14
Acquisition Date	Feb. 28, 2019
Purchase Price | $	$ 857,540
Various [Member] | Multifamily [Member] | Citymark Multifamily 2-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	95.00%
Number of Properties	2
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 97,922
Various [Member] | Multifamily [Member] | Florida MH 4-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	99.00%
Number of Properties	4
Acquisition Month	April & July 2019
Purchase Price | $	$ 33,785
Various [Member] | Multifamily [Member] | Bridge II Multifamily Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	6
Acquisition Month	April, June and July of 2019
Purchase Price | $	$ 420,020
Various [Member] | Multifamily [Member] | Davis Multifamily 2-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	2
Acquisition Date	May 31, 2019
Purchase Price | $	$ 89,687
Various [Member] | Multifamily [Member] | ACG IV Multifamily [Member]
Real Estate Properties [Line Items]
Ownership Interest	95.00%
Number of Properties	2
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 124,971
Various [Member] | Hotel [Member] | Raven Select Service Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	21
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 305,470
Various [Member] | Other [Member] | East Coast Storage Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	97.00%
Number of Properties	21
Acquisition Date	Aug. 31, 2019
Purchase Price | $	$ 150,703
Phoenix AZ [Member] | Multifamily [Member] | Gilbert Heritage Apartments [Member]
Real Estate Properties [Line Items]
Ownership Interest	90.00%
Number of Properties	1
Acquisition Date	Feb. 28, 2019
Purchase Price | $	$ 60,984
Phoenix AZ [Member] | Multifamily [Member] | Elevation Plaza Del Rio [Member]
Real Estate Properties [Line Items]
Ownership Interest	90.00%
Number of Properties	1
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 70,550
Phoenix AZ [Member] | Multifamily [Member] | Angler MH Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	99.00%
Number of Properties	5
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 61,975
Phoenix AZ [Member] | Multifamily [Member] | San Valiente Multifamily [Member]
Real Estate Properties [Line Items]
Ownership Interest	95.00%
Number of Properties	1
Acquisition Date	Jul. 31, 2019
Purchase Price | $	$ 101,089
Kailua Kona HI [Member] | Hotel [Member] | Courtyard Kona [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Mar. 31, 2019
Purchase Price | $	$ 105,587
Las Vegas, NV [Member] | Multifamily [Member] | Roman Multifamily Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	3
Acquisition Month	April & June 2019
Purchase Price | $	$ 259,371
Las Vegas, NV [Member] | Multifamily [Member] | Edge Las Vegas [Member]
Real Estate Properties [Line Items]
Ownership Interest	95.00%
Number of Properties	1
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 61,337
Orlando, FL [Member] | Multifamily [Member] | Courtney at Universal Multifamily [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 77,952
Orlando, FL [Member] | Multifamily [Member] | Amara at MetroWest [Member]
Real Estate Properties [Line Items]
Ownership Interest	95.00%
Number of Properties	1
Acquisition Date	May 31, 2019
Purchase Price | $	$ 73,933
Richland & Kennewick, WA [Member] | Multifamily [Member] | Tri-Cities Multifamily 2-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	95.00%
Number of Properties	2
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 61,616
Savannah, GA [Member] | Industrial [Member] | Morgan Savannah [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 26,254
Savannah, GA [Member] | Multifamily [Member] | Slate Savannah [Member]
Real Estate Properties [Line Items]
Ownership Interest	90.00%
Number of Properties	1
Acquisition Date	May 31, 2019
Purchase Price | $	$ 44,267
Minneapolis, MN [Member] | Industrial [Member] | Minneapolis Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	34
Acquisition Date	Apr. 30, 2019
Purchase Price | $	$ 250,678
Miami, FL [Member] | Multifamily [Member] | Miami Doral 2-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	2
Acquisition Date	May 31, 2019
Purchase Price | $	$ 209,404
Denver & Fort Collins, CO [Member] | Multifamily [Member] | Colorado 3-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	3
Acquisition Date	May 31, 2019
Purchase Price | $	$ 207,137
Atlanta, GA [Member] | Industrial [Member] | Atlanta Industrial Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	61
Acquisition Date	May 31, 2019
Purchase Price | $	$ 203,745
Atlanta, GA [Member] | Multifamily [Member] | Perimeter Multifamily 3-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	3
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 160,941
Atlanta, GA [Member] | Hotel [Member] | Hyatt Regency Atlanta [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Sep. 30, 2019
Purchase Price | $	$ 355,954
Charlotte, NC [Member] | Multifamily [Member] | Anson at the Lakes [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 107,287
Ashburn & Manassas, VA [Member] | Industrial [Member] | D.C. Powered Shell Warehouse Portfolio [Member]
Real Estate Properties [Line Items]
Ownership Interest	90.00%
Number of Properties	7
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 266,322
Simi Valley, CA [Member] | Retail [Member] | El Paseo Simi Valley [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Jun. 30, 2019
Purchase Price | $	$ 39,115
Chicago, IL & Arlington, VA [Member] | Hotel [Member] | Urban 2-Pack [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	2
Acquisition Date	Jul. 31, 2019
Purchase Price | $	$ 143,556
Phoenix & Chandler, AZ [Member] | Multifamily [Member] | Impala MH [Member]
Real Estate Properties [Line Items]
Ownership Interest	99.00%
Number of Properties	3
Acquisition Date	Jul. 31, 2019
Purchase Price | $	$ 30,513
Oregon City, OR [Member] | Multifamily [Member] | Edgewater at the Cove [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Aug. 31, 2019
Purchase Price | $	$ 69,234
Durham, NC [Member] | Industrial [Member] | Patriot Park [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	2
Acquisition Date	Sep. 30, 2019
Purchase Price | $	$ 31,307
Denver, CO [Member] | Multifamily [Member] | Haven 124 [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Sep. 30, 2019
Purchase Price | $	$ 146,208
Signal Hill, CA [Member] | Retail [Member] | Towne Center East [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%
Number of Properties	1
Acquisition Date	Sep. 30, 2019
Purchase Price | $	$ 60,224