Subsequent Events - Additional Information (Details) $ in Thousands	1 Months Ended
	Nov. 02, 2021 USD ($) Loan	Sep. 30, 2021 USD ($) Rating	Dec. 31, 2020 USD ($) Rating
Subsequent Event [Line Items]
Total loan commitment amount		$ 5,240,569	$ 4,943,511
Weighted Average Risk Rating | Rating		3.1	3.1
Risk rating | Rating		4
Mixed Use
Subsequent Event [Line Items]
Total loan commitment amount		$ 572,069	$ 586,993
Multifamily
Subsequent Event [Line Items]
Total loan commitment amount		$ 1,249,025	$ 804,838
Four First Mortgage | Subsequent Event
Subsequent Event [Line Items]
Number of first mortgage loans originated | Loan	8
Total loan commitment amount	$ 539,200
Loan commitment principal amount	$ 465,300
First Mortgage Loan | Subsequent Event
Subsequent Event [Line Items]
Number of first mortgage loans originated | Loan	3
Total loan commitment amount	$ 262,200
Loan commitment principal amount	$ 257,100
First Mortgage Loan | Subsequent Event | Mixed Use
Subsequent Event [Line Items]
Percentage of loan commitments repaid	85.70%
First Mortgage Loan | Subsequent Event | Multifamily
Subsequent Event [Line Items]
Percentage of loan commitments repaid	14.30%