Derivatives Volume of Activity (Details) $ in Thousands	6 Months Ended
	Jun. 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	10,440,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(10,460,000)
Derivative, Notional Amount	4,900,000
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	(500,000)
Derivative, Notional Amount	0
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	19,045,000
Derivative, Notional Amount, Derivative Instruments Maturing, Settled, Terminated, or Paired-Off	(19,738,000)
Derivative, Notional Amount	$ 2,176,000