Fair Value of Financial Instruments - Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets at Fair Value:
Securities	$ 1,277,355	$ 1,387,845
Derivatives	543,229	199,073
Liabilities at Fair Value:
Derivatives	531	10,900
Fair Value, Measurements, Recurring
Assets at Fair Value:
Derivatives	543,229	199,073
Liabilities at Fair Value:
Derivatives	531	10,900
Fair Value, Measurements, Recurring | Agency Securities
Assets at Fair Value:
Securities	6,399,346	4,406,521
Fair Value, Measurements, Recurring | U.S. Treasuries
Assets at Fair Value:
Securities	1,258,020	198,833
Fair Value, Measurements, Recurring | Level 1
Assets at Fair Value:
Derivatives	0	0
Liabilities at Fair Value:
Derivatives	0	0
Fair Value, Measurements, Recurring | Level 1 | Agency Securities
Assets at Fair Value:
Securities	0	0
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasuries
Assets at Fair Value:
Securities	1,258,020	198,833
Fair Value, Measurements, Recurring | Level 2
Assets at Fair Value:
Derivatives	543,229	199,073
Liabilities at Fair Value:
Derivatives	531	10,900
Fair Value, Measurements, Recurring | Level 2 | Agency Securities
Assets at Fair Value:
Securities	6,399,346	4,406,521
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasuries
Assets at Fair Value:
Securities	0	0
Fair Value, Measurements, Recurring | Level 3
Assets at Fair Value:
Derivatives	0	0
Liabilities at Fair Value:
Derivatives	0	0
Fair Value, Measurements, Recurring | Level 3 | Agency Securities
Assets at Fair Value:
Securities	0	0
Fair Value, Measurements, Recurring | Level 3 | U.S. Treasuries
Assets at Fair Value:
Securities	$ 0	$ 0