Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Jan. 01, 2021	Mar. 31, 2021	Dec. 31, 2020
Significant Of Accounting Policies [Line Items]
Assets excluding BREIT OP		$ 42,778,765	$ 40,684,015
Liabilities excluding BREIT OP		24,307,427	24,470,008
Investments in equity securities		1,001,297	599,185
Unrealized gains on investments in equity securities		82,300
Unrealized loss on investments in equity securities		37,100
Unrecognized compensation cost		10,908	3,363
Granted deferred rent		4,300
Simply Self Storage Awards [Member]
Significant Of Accounting Policies [Line Items]
Grant date fair value	$ 3,600
Awards performance condition, service period	4 years
Compensation expense		200
Unrecognized compensation cost		$ 3,400
Unrecognized compensation cost, recognized period		3 years 9 months 18 days
Level 3 [Member]
Significant Of Accounting Policies [Line Items]
Mortgage notes, term loans, and secured revolving credit facilities, secured financings on investments in real estate debt, and unsecured revolving credit facilities		$ 33,000	48,600
VIEs [Member]
Significant Of Accounting Policies [Line Items]
Assets excluding BREIT OP		11,400,000	11,500,000
Liabilities excluding BREIT OP		$ 7,900,000	$ 8,000,000