Repurchase Agreements And Other Debt (Repurchase Arrangements And Weighted Average Interest Rates Classified By Original Maturities) (Details) $ in Millions	Sep. 30, 2025 USD ($) days	Dec. 31, 2024 USD ($) days
Receivable Under Reverse Repurchase Agreements	$ 21,399	$ 17,137
Repurchase Agreements	$ 74,152	$ 60,798
Weighted Average Interest Rate	4.37%	4.76%
Weighted Average Days to Maturity \| days	12	11
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 20,802	$ 16,676
Maturity Overnight [Member]
Repurchase Agreements	29,500	25,400
30 Days or Less [Member]
Repurchase Agreements	$ 64,913	$ 55,580
Weighted Average Interest Rate	4.38%	4.77%
Weighted Average Days to Maturity \| days	9	10
1 to 3 Months
Repurchase Agreements	$ 3,531	$ 3,782
Weighted Average Interest Rate	4.31%	4.68%
Weighted Average Days to Maturity \| days	64	39
3 to 6 Months
Repurchase Agreements	$ 555	$ 0
Weighted Average Interest Rate	4.46%	0.00%
Weighted Average Days to Maturity \| days	114	0
US Treasury Securities [Member] \| Maturity Overnight [Member]
Repurchase Agreements	$ 1,500	$ 1,400
US Treasury Securities [Member] \| 2 Days to 1 Month [Member]
Repurchase Agreements	$ 5,153	$ 1,436
Weighted Average Interest Rate	4.30%	4.68%
Weighted Average Days to Maturity \| days	2	2
FICC [Member]
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	$ 4,600	$ 3,900
US Government Agencies Debt Securities [Member]
Repurchase Agreements	$ 68,999	$ 59,362
Weighted Average Interest Rate	4.38%	4.76%
Weighted Average Days to Maturity \| days	13	11

AGNC Investment Corp. 10-Q