Derivatives Volume of Activity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Not Designated as Hedging Instrument, Economic Hedge | U.S. Treasury futures | Short position
Derivatives [Roll Forward]
Derivative, Notional Amount	$ 4,920,000
Derivative, Notional Amount, Derivative Instruments Added	16,040,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(15,460,000)
Derivative, Notional Amount	5,500,000
Not Designated as Hedging Instrument, Economic Hedge | Options on U.S. Treasury futures
Derivatives [Roll Forward]
Derivative, Notional Amount	250,000
Derivative, Notional Amount, Derivative Instruments Added	600,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(700,000)
Derivative, Notional Amount	150,000
Not Designated as Hedging Instrument, Trading | TBA securities | Long position
Derivatives [Roll Forward]
Derivative, Notional Amount	2,869,000
Derivative, Notional Amount, Derivative Instruments Added	24,861,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(26,060,000)
Derivative, Notional Amount	$ 1,670,000