Derivatives Volume of Activity (Details) $ in Thousands	9 Months Ended
Derivatives Volume of Activity (Details) $ in Thousands	Sep. 30, 2025 USD ($)
Not Designated as Hedging Instrument, Economic Hedge \| U.S. Treasury futures \| Short position
Derivatives [Roll Forward]
Beginning Notional Amount-Long (Short)	$ 1,251,500
Additions	8,707,500
Settlements, Terminations, or Pair-Offs	7,785,500
Ending Notional Amount-Long (Short)	2,173,500
Not Designated as Hedging Instrument, Economic Hedge \| Interest rate swaps \| Short position
Derivatives [Roll Forward]
Beginning Notional Amount-Long (Short)	5,385,000
Additions	2,475,000
Ending Notional Amount-Long (Short)	7,860,000
Not Designated as Hedging Instrument, Economic Hedge \| Interest Rate Swaption \| Long position
Derivatives [Roll Forward]
Beginning Notional Amount-Long (Short)	0
Additions	750,000
Ending Notional Amount-Long (Short)	750,000
Not Designated as Hedging Instrument, Economic Hedge \| Exchange Traded Options \| Long position
Derivatives [Roll Forward]
Beginning Notional Amount-Long (Short)	0
Additions	1,000,000
Ending Notional Amount-Long (Short)	1,000,000
Not Designated as Hedging Instrument, Trading \| TBA securities \| Long position
Derivatives [Roll Forward]
Beginning Notional Amount-Long (Short)	2,419,000
Additions	30,818,000
Settlements, Terminations, or Pair-Offs	30,636,000
Ending Notional Amount-Long (Short)	$ 2,601,000

DYNEX CAPITAL INC 10-Q