Investments in Securities - Available-for-sale Securities 1 (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	$ 659	$ 714
Allowance for Credit Losses	(2)	(3)
Gross Unrealized Gains in AOCI	10	8
Gross Unrealized Losses in AOCI	(21)	(23)
Total Fair Value	646	696
Agency securities
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	424	445
Allowance for Credit Losses	0	0
Gross Unrealized Gains in AOCI	2	3
Gross Unrealized Losses in AOCI	(21)	(22)
Total Fair Value	405	426
Other mortgage-related securities
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	235	269
Allowance for Credit Losses	(2)	(3)
Gross Unrealized Gains in AOCI	8	5
Gross Unrealized Losses in AOCI	0	(1)
Total Fair Value	$ 241	$ 270