Fair Value - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financial assets not carried at fair value:
Loans	$ 17,234,205	$ 18,401,439
HTM debt securities	604,942	676,652
Carrying Value
Financial assets not carried at fair value:
Loans	17,234,205	18,401,439
HTM debt securities	591,948	673,470
Financial liabilities not carried at fair value:
Secured financing agreements, CLOs and SASB	17,076,155	18,177,756
Unsecured senior notes	2,456,583	2,329,211
Fair Value
Financial assets not carried at fair value:
Loans	17,185,073	18,215,072
HTM debt securities	562,523	637,275
Financial liabilities not carried at fair value:
Secured financing agreements, CLOs and SASB	16,926,451	18,017,651
Unsecured senior notes	$ 2,314,681	$ 2,199,135