Derivative and Other Hedging Instruments (Fair Value Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Derivative asset, fair value	$ 155,000		$ 155,000			$ 205,000
Derivative liability, fair value	(106,000)		(106,000)			(94,000)
Derivative assets, at fair value	155,000		155,000			205,000
Derivative Liability	(106,000)		(106,000)			(94,000)
U.S. Treasury securities	3,565,000		3,565,000			1,575,000
U.S. Treasury Securities - short	(21,305,000)		(21,305,000)			(16,676,000)
Total - (short)/long, net	(17,740,000)		(17,740,000)			(15,101,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(369,000)	$ 390,000	(1,380,000)	$ 1,492,000
Net Fair Value of Interest Rate Swaps Excluding the Recognition of Variation Margin Settlements as a Reduction of Carrying Value	900,000		900,000			2,300,000
TBA and Forward Settling Agency Securities [Member]
Derivative [Line Items]
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	35,699,000	36,523,000	63,666,000	61,913,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period				(61,734,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	11,000	(29,000)	88,000	(87,000)
Derivative, Fair Value, Net	101,000		101,000			(26,000)
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	45,096,000		45,096,000			39,646,000
Derivative liability, fair value	(20,000)		(20,000)			0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	2,600,000	6,400,000	10,750,000	11,570,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	(5,300,000)	(2,100,000)	(5,300,000)	(7,350,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(236,000)	179,000	(805,000)	837,000
Interest Rate Swap [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative asset, fair value	0		0			22,000
Interest Rate Swaption [Member]
Derivative [Line Items]
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	0		1,500,000	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	0		(1,500,000)	(1,250,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(9,000)		(28,000)	33,000
Interest Rate Swaption [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative asset, fair value	9,000		9,000			39,000
Purchases Of TBAs And Forward Settling Agency Securities [Member]
Derivative [Line Items]
Derivative liability, fair value	(37,000)		(37,000)			(87,000)
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	(35,103,000)	(39,663,000)	(62,214,000)
US Treasury Securities [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	4,000	89,000	(96,000)	275,000
Derivative, Fair Value, Net	(49,000)		(49,000)			83,000
SOFR Futures Contracts
Derivative [Line Items]
Derivative liability, fair value	0		0			(7,000)
Derivative assets, at fair value	8,000		8,000			0
US Treasury Securities [Member] \| Fair Value, Recurring [Member] \| Future [Member] \| Fair Value, Inputs, Level 1 [Member]
Derivative [Line Items]
Derivative assets, at fair value	0		0			(83,000)
Derivative Liability	(49,000)		(49,000)			0
TBA and Forward Settling Agency Securities [Member] \| Fair Value, Recurring [Member] \| Purchases Of TBAs And Forward Settling Agency Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative assets, at fair value	138,000		138,000			61,000
Sale Of TBA And Forward Settling Agency Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative Liability	(37,000)		(37,000)			(87,000)
Sale Of TBA And Forward Settling Agency Securities [Member] \| Fair Value, Recurring [Member] \| Purchases Of TBAs And Forward Settling Agency Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative assets, at fair value	138,000		138,000
Short [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	7,971,000	3,163,000	11,792,000	6,264,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	(4,211,000)	(1,971,000)	(8,188,000)	(3,612,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(139,000)	163,000	(599,000)	501,000
Long [Member] \| US Treasury Securities [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	(12,000)	60,000	(55,000)
Debt Securities, Trading, and Equity Securities, FV-NI	3,545,000	2,427,000	3,545,000	2,427,000	$ 3,216,000	$ 1,585,000	$ 1,815,000	$ 1,492,000
Trading Securities Added During the Period	3,968,000	1,672,000	9,356,000	3,341,000
Notional Amount Of Trading Securities Settlement Expiration During The Period	(3,639,000)	(1,060,000)	(7,396,000)	(2,406,000)
Long [Member] \| SOFR Futures Contracts
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 3,000	$ (3,000)	$ 13,000	$ (13,000)

AGNC Investment Corp. 10-Q