Investments in Securities - Schedule of Available-for-sale Securities Reconciliation (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	$ 584	$ 714
Allowance for Credit Losses	(2)	(3)
Gross Unrealized Gains in AOCI	11	8
Gross Unrealized Losses in AOCI	(29)	(23)
Total Fair Value	564	696
Agency securities
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	405	445
Allowance for Credit Losses	0	0
Gross Unrealized Gains in AOCI	1	3
Gross Unrealized Losses in AOCI	(29)	(22)
Total Fair Value	377	426
Other mortgage-related securities
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	179	269
Allowance for Credit Losses	(2)	(3)
Gross Unrealized Gains in AOCI	10	5
Gross Unrealized Losses in AOCI	0	(1)
Total Fair Value	$ 187	$ 270