Related Party Transactions - Schedule of Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
ARMOUR management fees	$ 8,519	$ 7,886	$ 24,926	$ 23,024
Less management fees waived	(1,950)	(2,100)	(5,850)	(6,600)
Total management fee expense	6,569	5,786	19,076	16,424
U.S. Treasury Securities
Related Party Transaction [Line Items]
U.S. Treasury Securities Purchased			3,992,820	788,919
BUCKLER Securities, LLC | Corporate Joint Venture
Related Party Transaction [Line Items]
Repurchase agreements	3,735,027		3,735,027		$ 1,963,679
Collateral posted on repurchase agreements	3,912,476		3,912,476		2,036,385
Interest on repurchase agreements	$ 21,423	$ 774	28,918	$ 2,938
BUCKLER Securities, LLC | Corporate Joint Venture | U.S. Treasury Securities
Related Party Transaction [Line Items]
U.S. Treasury Securities Purchased			$ 0		$ 100,000