Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	$ 34,183	$ 7,969
Net Amount of Liabilities Presented in the Balance Sheet	18,328	2,471
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MBS	3,215,017	3,181,839
Mortgage loans held for investment, at fair value	3,757	4,268
Total assets carried at fair value	3,252,957	3,194,076
Total liabilities carried at fair value	18,328	2,471
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MBS	0	0
Mortgage loans held for investment, at fair value	0	0
Total assets carried at fair value	0	0
Total liabilities carried at fair value	9,847	2,471
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MBS	3,214,311	3,181,041
Mortgage loans held for investment, at fair value	0	0
Total assets carried at fair value	3,248,494	3,189,010
Total liabilities carried at fair value	8,481	0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MBS	706	798
Mortgage loans held for investment, at fair value	3,757	4,268
Total assets carried at fair value	4,463	5,066
Total liabilities carried at fair value	0	0
Fair Value, Measurements, Recurring | Interest rate swaptions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	28,640	3,202
Fair Value, Measurements, Recurring | Interest rate swaptions | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	0	0
Fair Value, Measurements, Recurring | Interest rate swaptions | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	28,640	3,202
Fair Value, Measurements, Recurring | Interest rate swaptions | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	0	0
Fair Value, Measurements, Recurring | U.S. Treasury futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Liabilities Presented in the Balance Sheet	9,847	2,471
Fair Value, Measurements, Recurring | U.S. Treasury futures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Liabilities Presented in the Balance Sheet	9,847	2,471
Fair Value, Measurements, Recurring | U.S. Treasury futures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Liabilities Presented in the Balance Sheet	0	0
Fair Value, Measurements, Recurring | U.S. Treasury futures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Liabilities Presented in the Balance Sheet	0	0
Fair Value, Measurements, Recurring | TBA securities | Long position
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	5,543	4,767
Net Amount of Liabilities Presented in the Balance Sheet	8,481	0
Fair Value, Measurements, Recurring | TBA securities | Level 1 | Long position
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	0	0
Net Amount of Liabilities Presented in the Balance Sheet	0	0
Fair Value, Measurements, Recurring | TBA securities | Level 2 | Long position
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	5,543	4,767
Net Amount of Liabilities Presented in the Balance Sheet	8,481	0
Fair Value, Measurements, Recurring | TBA securities | Level 3 | Long position
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net Amount of Assets Presented in the Balance Sheet	0	0
Net Amount of Liabilities Presented in the Balance Sheet	$ 0	$ 0