Summary of Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Oct. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Significant Of Accounting Policies [Line Items]
Assets excluding BREIT OP		$ 37,032,808,000		$ 37,032,808,000			$ 33,039,823,000
Liabilities excluding BREIT OP		21,800,839,000		21,800,839,000			22,404,026,000
Investments in equity securities		572,849,000		572,849,000			0
Impairment of investments in real estate		6,217,000		12,343,000	$ 0
Granted deferred rent		126,271,000		126,271,000			38,287,000
Subsequent Event [Member]
Significant Of Accounting Policies [Line Items]
Granted deferred rent						$ 9,100,000
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		$ 34,500,000		$ 34,500,000			54,900,000
Discount Rate [Member]
Significant Of Accounting Policies [Line Items]
Rate		0.087		0.087
Discount Rate [Member] | Weighted Average [Member]
Significant Of Accounting Policies [Line Items]
Rate		0.087		0.087
Exit Capitalization Rate [Member]
Significant Of Accounting Policies [Line Items]
Rate		0.099		0.099
Exit Capitalization Rate [Member] | Weighted Average [Member]
Significant Of Accounting Policies [Line Items]
Rate		0.078		0.078
One Hotel Properties [Member]
Significant Of Accounting Policies [Line Items]
Impairment of investments in real estate		$ 6,200,000	$ 0	$ 12,300,000	$ 0
VIEs [Member]
Significant Of Accounting Policies [Line Items]
Percentage of variable interest entity acquired	10.00%
Cost of variable interest entity acquired	$ 19,300,000
Assets excluding BREIT OP		10,800,000,000		10,800,000,000			9,500,000,000
Liabilities excluding BREIT OP		$ 7,700,000,000		$ 7,700,000,000			$ 6,600,000,000