Other Assets and Liabilities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 USD ($) Loans	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
CECL reserve	$ 173,549,000		$ 0
Increase (Decrease) in current expected credit loss reserve	1,278,000
Current expected credit loss reserve	$ 1,723,000		0
Number of loans receivable | Loans	84
Credit Loss Reserve [Member]
CECL reserve	$ 1,700,000
Increase (Decrease) in current expected credit loss reserve	1,300,000
Unfunded Loan Commitments [Member]
CECL reserve	10,031,000		0
Increase (Decrease) in current expected credit loss reserve	$ 6,800,000
Number of loans receivable | Loans	84
Unfunded loan commitments	$ 3,200,000,000
Accounting Standards Update 2016-13 [Member]
CECL reserve		$ 13,942,000
Current expected credit loss reserve	445,000		$ 445,000
Accounting Standards Update 2016-13 [Member] | Unfunded Loan Commitments [Member]
CECL reserve	3,300,000	$ 3,263,000
Increase (Decrease) in current expected credit loss reserve	$ 10,000,000.0