Real Estate Securities - Schedule of Real Estate Securities Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Current Face	$ 222,649	$ 224,214
Premium/(Discount)	(45,709)	(49,774)
Amortized Cost	206,708	207,992
Gross Unrealized Gains	14,409	8,795
Gross Unrealized Losses	(14,173)	(15,427)
Fair value	$ 206,944	$ 201,360
Weighted Average Coupon	4.26%	3.62%
Weighted Average Yield	10.63%	11.58%
Weighted average useful life	5 years 3 months 21 days	5 years 2 months 12 days
Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Unpaid Principal Balance	$ 8,599,098	$ 6,781,862
Legacy WMC Commercial Loans	8,515,487	6,417,895
Total Non-Agency RMBS \| Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Current Face	139,687	123,318
Premium/(Discount)	(7,823)	(7,895)
Amortized Cost	144,412	128,458
Gross Unrealized Gains	8,284	5,310
Gross Unrealized Losses	(2,981)	(6,189)
Fair value	$ 149,715	$ 127,579
Weighted Average Coupon	3.42%	3.08%
Weighted Average Yield	8.84%	9.40%
Weighted average useful life	6 years	5 years 7 months 24 days
Non-QM Loans \| Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Current Face	$ 48,961	$ 49,516
Premium/(Discount)	(2,412)	(2,772)
Amortized Cost	48,548	49,015
Gross Unrealized Gains	819	1,678
Gross Unrealized Losses	(2,670)	(5,544)
Fair value	$ 46,697	$ 45,149
Weighted Average Coupon	3.05%	2.83%
Weighted Average Yield	6.90%	7.65%
Weighted average useful life	3 years 10 months 24 days	4 years 7 months 13 days
Real estate securities notional amount	$ 43,400	$ 85,600
Retained securities amount	42,200	40,300
Unpaid Principal Balance	555	13,098
Legacy WMC Commercial Loans	572	12,279
Agency-Eligible Loans \| Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Current Face	46,431	51,861
Premium/(Discount)	(2,722)	(3,062)
Amortized Cost	44,336	49,488
Gross Unrealized Gains	1,735	1,555
Gross Unrealized Losses	(116)	(148)
Fair value	$ 45,955	$ 50,895
Weighted Average Coupon	3.53%	3.45%
Weighted Average Yield	7.43%	7.47%
Weighted average useful life	6 years 9 months 10 days	6 years 10 months 28 days
Real estate securities notional amount	$ 71,500	$ 50,400
Retained securities amount	44,000	48,200
Unpaid Principal Balance	95,124	101,570
Legacy WMC Commercial Loans	95,671	102,145
Home Equity Loans \| Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Current Face	37,950	15,526
Premium/(Discount)	(93)	640
Amortized Cost	47,628	26,076
Gross Unrealized Gains	4,820	1,445
Gross Unrealized Losses	(180)	(491)
Fair value	$ 52,268	$ 27,030
Weighted Average Coupon	6.04%	3.40%
Weighted Average Yield	12.09%	16.36%
Weighted average useful life	6 years 7 months 24 days	5 years 3 months 3 days
Real estate securities notional amount	$ 163,200	$ 163,300
Retained securities amount	24,500
Unpaid Principal Balance	121,535	99,863
Legacy WMC Commercial Loans	129,004	103,964
Prime Jumbo Loans \| Residential Portfolio Segment
Debt Securities, Available-for-sale [Line Items]
Current Face	6,345	6,415
Premium/(Discount)	(2,596)	(2,701)
Amortized Cost	3,900	3,879
Gross Unrealized Gains	910	632
Gross Unrealized Losses	(15)	(6)
Fair value	$ 4,795	$ 4,505
Weighted Average Coupon	1.03%	0.97%
Weighted Average Yield	9.23%	9.41%
Weighted average useful life	7 years 8 months 4 days	7 years 11 months 12 days
Real estate securities notional amount	$ 25,500	$ 28,300
Legacy WMC CMBS
Debt Securities, Available-for-sale [Line Items]
Current Face	82,962	100,896
Premium/(Discount)	(37,886)	(41,879)
Amortized Cost	45,076	59,017
Gross Unrealized Gains	6,050	2,577
Gross Unrealized Losses	(10,443)	(8,809)
Fair value	$ 40,683	$ 52,785
Weighted Average Coupon	6.47%	5.13%
Weighted Average Yield	17.52%	16.74%
Weighted average useful life	1 year 6 months 29 days	1 year 9 months 7 days
Unpaid Principal Balance	$ 23,500	$ 23,500
Legacy WMC Commercial Loans	7,100	6,000
Agency RMBS Interest Only
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,220	20,517
Gross Unrealized Gains	75	908
Gross Unrealized Losses	(749)	(429)
Fair value	$ 16,546	$ 20,996
Weighted Average Coupon	4.56%	4.32%
Weighted Average Yield	7.67%	10.35%
Weighted average useful life	5 years 4 months 6 days	6 years 6 months 18 days
Real estate securities notional amount	$ 87,600	$ 107,200

AG Mortgage Investment Trust, Inc. 10-Q