Fair Value - Level 3 Valuation Inputs (Details) $ in Millions	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	$ 765	$ 837
Derivatives	889	171
Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	64,811	88,206
Available-for-sale, at fair value	765	837
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	76	57
Available-for-sale, at fair value	693	753
Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	76	57
Available-for-sale, at fair value	693	753
Derivatives	(7)	131
Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	(42)	(21)
Significant Unobservable Inputs (Level 3) \| Recurring \| Dealer Mark
Fair Value Inputs, Quantitative Information [Line Items]
Derivatives	35	152
Agency \| Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	404	431
Agency \| Significant Unobservable Inputs (Level 3) \| Recurring \| Various
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	76	57
Available-for-sale, at fair value	37	52
Agency \| Significant Unobservable Inputs (Level 3) \| Recurring \| Consensus
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	367	379
Other securities \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	112	137
Available-for-sale, at fair value	297	330
Other securities \| Significant Unobservable Inputs (Level 3) \| Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	0	0
Available-for-sale, at fair value	289	322
Other securities \| Significant Unobservable Inputs (Level 3) \| Recurring \| Various
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	45	53
Other securities \| Significant Unobservable Inputs (Level 3) \| Recurring \| Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	$ 153	$ 175
Other securities \| 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)	0.02580	0.04090
Other securities \| 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)	0.05650	0.04430
Other securities \| 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)	0.05499	0.04220
Other securities \| Significant Unobservable Inputs (Level 3) \| Recurring \| Single Vendor
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, at fair value	$ 91	$ 94
Other securities \| 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 securities \| 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 securities \| 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

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).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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