Derivatives Volume of Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Not Designated as Hedging Instrument, Economic Hedge | Interest rate swaptions
Derivative [Line Items]
Derivative, Notional Amount	$ (500,000)	$ (500,000)
Additions	0
Not Designated as Hedging Instrument, Economic Hedge | U.S. Treasury futures | Short position
Derivative [Line Items]
Derivative, Notional Amount	(3,940,000)	(3,890,000)
Additions	(4,530,000)
Settlements, Terminations, or Pair-Offs	(4,480,000)
Not Designated as Hedging Instrument, Trading | TBA securities | Long position
Derivative [Line Items]
Derivative, Notional Amount	(1,770,000)	$ (1,530,000)
Additions	(7,813,000)
Settlements, Terminations, or Pair-Offs	$ (7,573,000)