Investment Securities - Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities	$ 111,069	$ 113,386
Credit loss allowance	10,240	3,182
HTM debt securities	642,979	676,652
Total investment securities	772,887	815,804
VIE eliminations
Debt Securities, Available-for-sale [Line Items]
Equity security	(1,655,836)	(1,666,921)
CMBS
Debt Securities, Available-for-sale [Line Items]
Credit loss allowance	154	172
HTM debt securities	581,525	577,681
CMBS | Non- Controlling Interests
Debt Securities, Available-for-sale [Line Items]
Equity security	197,000	198,900
Before consolidation of securitization VIEs
Debt Securities, Available-for-sale [Line Items]
HTM debt securities	632,739	673,470
Equity security, fair value	10,134	9,840
Total investment securities	2,428,723	2,482,725
Before consolidation of securitization VIEs | RMBS
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities	111,069	113,386
Equity security	427,629	423,183
Before consolidation of securitization VIEs | CMBS
Debt Securities, Available-for-sale [Line Items]
Equity security	$ 1,247,152	$ 1,262,846