Investments in Securities - Maturity Information (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Total Carrying Amount
Total amortized cost	$ 39,171
One Year or Less	0
After One Year Through Five Years	33,989
After Five Years Through Ten Years	4,679
After Ten Years	503
Total Fair Value
Total Fair Value	37,567	$ 375
One Year or Less	0
After One Year Through Five Years	32,667
After Five Years Through Ten Years	4,451
After Ten Years	$ 449
Weighted-average interest rate	4.00%
Weighted-average interest rate, One Year or Less	0.00%
Weighted-average interest rate, After One Year Through Five Years	3.97%
Weighted-average interest rate, After Five Years Through Ten Years	4.11%
Weighted-average interest rate, After Ten Years	5.18%
Mortgage-related securities
Total Carrying Amount
Total amortized cost	$ 625
One Year or Less	0
After One Year Through Five Years	7
After Five Years Through Ten Years	115
After Ten Years	503
Total Fair Value
Total Fair Value	570	375
One Year or Less	0
After One Year Through Five Years	7
After Five Years Through Ten Years	114
After Ten Years	449
Non-mortgage-related securities
Total Carrying Amount
Total amortized cost	38,546
One Year or Less	0
After One Year Through Five Years	33,982
After Five Years Through Ten Years	4,564
After Ten Years	0
Total Fair Value
Total Fair Value	36,997	$ 0
One Year or Less	0
After One Year Through Five Years	32,660
After Five Years Through Ten Years	4,337
After Ten Years	$ 0