Variable Interest Entities - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Accrued expenses and other liabilities	$ 218,582	$ 243,207
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Maximum loss	$ 221,401	223,509
Variable Interest Entity, Not Primary Beneficiary | Multifamily Loan Securitization, Liability
Variable Interest Entity [Line Items]
Maximum loss, percentage of loans	10.00%
Maximum loss	$ 50,901	50,901
Variable Interest Entity, Not Primary Beneficiary | Multifamily Loan Securitization
Variable Interest Entity [Line Items]
Accrued expenses and other liabilities	$ 448	$ 448