Other Assets and Liabilities - Summary of Components of Other Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Accrued dividends payable	$ 91,150		$ 91,004
Accrued management and incentive fees payable	21,545		19,158
Accrued interest payable	20,627		20,548
Derivative liabilities	13,749		58,915
Accounts payable and other liabilities	7,725		2,671
Current expected credit loss reserve for unfunded loan commitments	128,945	$ 172,100	173,549	$ 178,050	$ 112,694	$ 0
Total	158,833		202,327
Unfunded Loan Commitments [Member]
Current expected credit loss reserve for unfunded loan commitments	$ 4,037	$ 11,021	$ 10,031	$ 15,002	$ 22,536	$ 0