Fair Value Measurements - Summary of Fair Value of Financial Assets and Liabilities (Details) - Estimate of Fair Value Measurement - Fair Value Measurements Nonrecurring - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Loans held for investment
Financial assets
Fair value of financial assets	$ 4,617,254	$ 4,867,203
Collateralized loan obligations
Financial liabilities
Fair value of financial liabilities	2,639,314	2,545,691
Secured credit agreements
Financial liabilities
Fair value of financial liabilities	1,087,419	1,162,206
Secured revolving credit facility
Financial liabilities
Fair value of financial liabilities	49,997
Asset-specific financing arrangements
Financial liabilities
Fair value of financial liabilities	123,579
Level I | Loans held for investment
Financial assets
Fair value of financial assets	0	0
Level I | Collateralized loan obligations
Financial liabilities
Fair value of financial liabilities	0	0
Level I | Secured credit agreements
Financial liabilities
Fair value of financial liabilities	0	0
Level I | Secured revolving credit facility
Financial liabilities
Fair value of financial liabilities	0
Level I | Asset-specific financing arrangements
Financial liabilities
Fair value of financial liabilities	0
Level II | Loans held for investment
Financial assets
Fair value of financial assets	0	0
Level II | Collateralized loan obligations
Financial liabilities
Fair value of financial liabilities	0	0
Level II | Secured credit agreements
Financial liabilities
Fair value of financial liabilities	0	0
Level II | Secured revolving credit facility
Financial liabilities
Fair value of financial liabilities	0
Level II | Asset-specific financing arrangements
Financial liabilities
Fair value of financial liabilities	0
Level III | Loans held for investment
Financial assets
Fair value of financial assets	4,644,660	4,899,666
Level III | Collateralized loan obligations
Financial liabilities
Fair value of financial liabilities	2,656,671	2,558,544
Level III | Secured credit agreements
Financial liabilities
Fair value of financial liabilities	1,092,568	$ 1,169,710
Level III | Secured revolving credit facility
Financial liabilities
Fair value of financial liabilities	49,997
Level III | Asset-specific financing arrangements
Financial liabilities
Fair value of financial liabilities	$ 127,263