Variable Interest Entities ("VIEs") - Maximum Risk of Loss (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Variable Interest Entity
Carrying Amount	$ 5,992,494	$ 7,804,259
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity
Carrying Amount	74,551
Company's Maximum Risk of Loss	74,551
Variable Interest Entity, Not Primary Beneficiary | Non-Agency CMBS
Variable Interest Entity
Carrying Amount	61,295
Company's Maximum Risk of Loss	61,295
Variable Interest Entity, Not Primary Beneficiary | Non-Agency RMBS
Variable Interest Entity
Carrying Amount	8,402
Company's Maximum Risk of Loss	8,402
Variable Interest Entity, Not Primary Beneficiary | Investments in unconsolidated ventures
Variable Interest Entity
Carrying Amount	4,854
Company's Maximum Risk of Loss	$ 4,854