Investments in Securities - Maturity Information (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Total Carrying Amount
Total carrying amount	$ 614
One Year or Less	2
After One Year Through Five Years	17
After Five Years Through Ten Years	32
After Ten Years	563
Total Fair Value
Total Fair Value	584	$ 696
One Year or Less	2
After One Year Through Five Years	18
After Five Years Through Ten Years	32
After Ten Years	532
Agency securities
Total Carrying Amount
Total carrying amount	414
One Year or Less	0
After One Year Through Five Years	4
After Five Years Through Ten Years	17
After Ten Years	393
Total Fair Value
Total Fair Value	376	426
One Year or Less	0
After One Year Through Five Years	5
After Five Years Through Ten Years	16
After Ten Years	355
Other mortgage-related securities
Total Carrying Amount
Total carrying amount	200
One Year or Less	2
After One Year Through Five Years	13
After Five Years Through Ten Years	15
After Ten Years	170
Total Fair Value
Total Fair Value	208	$ 270
One Year or Less	2
After One Year Through Five Years	13
After Five Years Through Ten Years	16
After Ten Years	$ 177