Derivatives Volume of Activity (Details) $ in Thousands	3 Months Ended
	Mar. 31, 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	5,440,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(5,040,000)
Derivative, Notional Amount	5,320,000
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	250,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(250,000)
Derivative, Notional Amount	250,000
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	11,034,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(10,151,000)
Derivative, Notional Amount	$ 3,752,000