Fair Value - Level 3 Valuation Inputs (Details) $ in Millions	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	$ 741	$ 837
Derivatives	496	171
Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	58,253	88,206
Available-for-sale, at fair value	741	837
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	40	57
Available-for-sale, at fair value	674	753
Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	40	57
Available-for-sale, at fair value	674	753
Derivatives	(32)	131
Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	(63)	(21)
Significant Unobservable Inputs (Level 3) | Recurring | Dealer Mark
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	31	152
Mortgage-related securities | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	3,551	4,606
Mortgage-related securities | Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	40	57
Mortgage-related securities | Significant Unobservable Inputs (Level 3) | Recurring | Various
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	40	57
Agency | Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	393	431
Agency | Significant Unobservable Inputs (Level 3) | Recurring | Various
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	156	52
Agency | Significant Unobservable Inputs (Level 3) | Recurring | Consensus
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	237	379
Other mortgage-related | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	288	330
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	281	322
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Various
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	45	53
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	$ 151	$ 175
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow | Total available-for-sale securities | Minimum | Default Rate
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)	0.02160	0.04090
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow | Total available-for-sale securities | Maximum | Default Rate
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)	0.05260	0.04430
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow | Total available-for-sale securities | Weighted Average | Default Rate
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)	0.05073	0.04220
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	$ 85	$ 94
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor | Total available-for-sale securities | Minimum
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)		0.00093
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor | Total available-for-sale securities | Maximum
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)		0.00494
Other mortgage-related | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor | Total available-for-sale securities | Weighted Average
Fair Value Inputs, Quantitative Information [Line Items]
Spreads (percent)		0.00272