Fair Value - Level 3 Valuation Inputs (Details) $ in Millions	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	$ 535	$ 564
Derivatives	61	157
Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	49,361	52,552
Total Fair Value	535	564
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	28	26
Total Fair Value	487	514
Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	28	26
Total Fair Value	487	514
Derivatives	69	77
Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	28	32
Significant Unobservable Inputs (Level 3) \| Recurring \| Dealer Mark
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	41	45
Mortgage-related \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	1,714	4,770
Mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	28	26
Mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Various
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	28	26
Agency \| Significant Unobservable Inputs (Level 3) \| Recurring \| Consensus
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	323	331
Other mortgage-related \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	168	187
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	164	183
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Various
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	93	100
Other mortgage-related \| Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Total Fair Value	$ 70	$ 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)	0.04720	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)	0.05020	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)	0.04869	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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