Fair Value of Financial Instruments - Fair Value Methodology (Details) - Residential whole loans $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, at fair value	$ 7,532,067	$ 7,511,210
UPB	9,104,409
Marked to Market Approach
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, at fair value	92,200	44,900
UPB	141,900	78,200
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, at fair value	7,478,930	7,459,137
Level 3 \| Discounted Cash Flow and Liquidation Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, at fair value	7,386,723	7,414,218
Level 3 \| Discounted cash flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, at fair value	$ 7,074,347	$ 7,070,535
Level 3 \| Discounted cash flow \| Discount rate \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.073	0.076
Level 3 \| Discounted cash flow \| Discount rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.060	0.062
Level 3 \| Discounted cash flow \| Discount rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.200	0.200
Level 3 \| Discounted cash flow \| Prepayment rate \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.147	0.137
Level 3 \| Discounted cash flow \| Prepayment rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0	0
Level 3 \| Discounted cash flow \| Prepayment rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.465	0.583
Level 3 \| Discounted cash flow \| Default rate \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.016	0.018
Level 3 \| Discounted cash flow \| Default rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0	0
Level 3 \| Discounted cash flow \| Default rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.548	0.543
Level 3 \| Discounted cash flow \| Loss severity \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.120	0.123
Level 3 \| Discounted cash flow \| Loss severity \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0	0
Level 3 \| Discounted cash flow \| Loss severity \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	1.000	1.000
Level 3 \| Liquidation model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities, at fair value	$ 312,376	$ 343,683
Level 3 \| Liquidation model \| Discount rate \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.085	0.088
Level 3 \| Liquidation model \| Discount rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.080	0.080
Level 3 \| Liquidation model \| Discount rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.150	0.200
Level 3 \| Liquidation model \| Annual change in home prices \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Annual change in home prices	3.60%	3.20%
Level 3 \| Liquidation model \| Annual change in home prices \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Annual change in home prices	0.00%	0.00%
Level 3 \| Liquidation model \| Annual change in home prices \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Annual change in home prices	8.70%	9.70%
Level 3 \| Liquidation model \| Liquidation timeline (in years) \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liquidation timeline (in years)	1 year 9 months 18 days	1 year 8 months 12 days
Level 3 \| Liquidation model \| Liquidation timeline (in years) \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liquidation timeline (in years)	1 month 6 days	1 month 6 days
Level 3 \| Liquidation model \| Liquidation timeline (in years) \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liquidation timeline (in years)	4 years 6 months	4 years 6 months
Level 3 \| Liquidation model \| Current value of underlying properties \| Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current value of underlying properties	$ 623	$ 618
Level 3 \| Liquidation model \| Current value of underlying properties \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current value of underlying properties	19	21
Level 3 \| Liquidation model \| Current value of underlying properties \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current value of underlying properties	$ 8,500	$ 8,500

MFA FINANCIAL, INC. 10-Q