Variable Interest Entities - Summary of Investment in Subordinate MBS Backed by Assets Held in Consolidated VIEs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Asset-backed financings at fair value	$ 1,295	$ 17,794	$ 8,771	$ 7,634
Interest income	151,835	162,684	295,394	315,703
Interest expense	171,841	187,390	343,368	366,527
Net investment income	71,198	90,452	145,403	180,818
Loans at fair value	1,377,836		1,377,836		$ 1,433,820
Asset-backed financings at fair value	1,288,180		1,288,180		1,336,731
Variable Interest Entities [Member]
Loans at fair value	(2,739)	(18,253)	(3,979)	(7,236)
Loans at fair value	1,375,838		1,375,838		1,431,689
Asset-backed financings at fair value	1,288,180		1,288,180		1,336,731
Variable Interest Entities [Member] | Subordinate Mortgage Backed Securities [Member]
Loans at fair value	(2,739)	(18,253)	(3,979)	(7,236)
Asset-backed financings at fair value	1,295	17,794	8,771	7,634
Interest income	13,449	13,644	25,557	28,810
Interest expense	11,402	12,791	24,080	25,144
Net investment income	603	$ 394	6,269	$ 4,064
Loans at fair value	1,375,838		1,375,838		1,431,689
Asset-backed financings at fair value	1,288,180		1,288,180		1,336,731
Retained subordinate MBS at fair value pledged to secure Assets sold under agreements to repurchase	$ 78,337		$ 78,337		$ 85,344