Investment Securities - Summary of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities	$ 143,980	$ 167,349
HTM debt securities	691,746	544,280
Total investment securities	860,984	736,658
Credit loss allowance	8,610	5,675
VIE eliminations
Debt Securities, Available-for-sale [Line Items]
Equity security	(1,491,786)	(1,425,570)
CMBS
Debt Securities, Available-for-sale [Line Items]
HTM debt securities	538,506	339,059
Credit loss allowance	3,140	0
CMBS \| Non- Controlling Interests
Debt Securities, Available-for-sale [Line Items]
Equity security	182,600	179,500
Before consolidation of securitization VIEs
Debt Securities, Available-for-sale [Line Items]
HTM debt securities	683,136	538,605
Equity security, fair value	11,624	11,247
Total investment securities	2,352,770	2,162,228
Before consolidation of securitization VIEs \| RMBS
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities	143,980	167,349
Equity security	250,424	235,997
Before consolidation of securitization VIEs \| CMBS
Debt Securities, Available-for-sale [Line Items]
Equity security	$ 1,263,606	$ 1,209,030

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