Fair Value - Level 3 Valuation Inputs (Details) $ in Millions	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	$ 492	$ 564
Derivatives	243	157
Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	61,298	52,552
Total Fair Value	492	564
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	35	26
Total Fair Value	448	514
Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	35	26
Total Fair Value	448	514
Derivatives	80	77
Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	26	32
Significant Unobservable Inputs (Level 3) \| Recurring \| Dealer Mark
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	54	45
Mortgage-related \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	1,198	4,770
Mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	35	26
Mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Various
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	35	26
Agency \| Significant Unobservable Inputs (Level 3) \| Recurring \| Consensus
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	313	331
Other mortgage-related \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	140	187
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	135	183
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Various
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	88	100
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	$ 46	$ 74
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow \| Minimum \| Default Rate
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)	0.04780	0.05300
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow \| Maximum \| Default Rate
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)	0.05080	0.05600
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow \| Weighted Average \| Default Rate
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)	0.04920	0.05448
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Single Vendor
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	$ 1	$ 9

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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