Investment In Securities - Carrying Value of Trading Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Principal Amount	$ 3,110,168	$ 2,991,482
Total	3,271,186	3,186,729
Gross Unrealized Loss	(54,779)	(1,871)
Gross Unrealized Gain	1,102	22,562
Fair Value	3,217,509	3,207,420
Agency Securities
Debt and Equity Securities, FV-NI [Line Items]
Principal Amount	2,910,168
Total	3,072,199
Gross Unrealized Loss	(54,625)
Gross Unrealized Gain	1,102
Fair Value	3,018,676
US Treasury Securities
Debt and Equity Securities, FV-NI [Line Items]
Principal Amount	200,000
Total	198,987
Gross Unrealized Loss	(154)
Gross Unrealized Gain	0
Fair Value	198,833
Fannie Mae | Agency Securities
Debt and Equity Securities, FV-NI [Line Items]
Principal Amount	2,253,393	2,420,828
Total	2,382,146	2,585,409
Gross Unrealized Loss	(47,079)	(1,441)
Gross Unrealized Gain	1,056	18,211
Fair Value	2,336,123	2,602,179
Freddie Mac | Agency Securities
Debt and Equity Securities, FV-NI [Line Items]
Principal Amount	656,775	570,654
Total	690,053	601,320
Gross Unrealized Loss	(7,546)	(430)
Gross Unrealized Gain	46	4,351
Fair Value	$ 682,553	$ 605,241