Investment Securities (Summary Of Net Gain From Sale Of Agency Securities) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Cost of Sale of Fair Value Option Securities	$ (49,440)	$ (4,562)
Cost of Sale of Investment Securities	(49,595)	(4,901)
Proceeds from agency MBS sold	8,795	5,103
Net gain (loss) on sale of investment securities	494	60
Available-for-sale Securities [Member]
Agency MBS sold, at cost	(155)	(339)
Proceeds from agency MBS sold	156	335
Net gain (loss) on sale of investment securities		(4)
Gross gain on sale of investment securities	1	0
Gross loss on sale of investment securities	0	(4)
Securities Remeasured at Fair Value [Member]
Proceeds from agency MBS sold	49,933	4,626
Net gain (loss) on sale of investment securities		64
Gross gain on sale of investment securities	567	66
Gross loss on sale of investment securities	(74)	(2)
Securities (Assets) [Member]
Proceeds from agency MBS sold	50,089	4,961
Net gain (loss) on sale of investment securities	494	60
Gross gain on sale of investment securities	568	66
Gross loss on sale of investment securities	(74)	$ (6)
Cost and Proceeds of Investment Securities [Member] \| Available-for-sale Securities [Member]
Net gain (loss) on sale of investment securities	1
Cost and Proceeds of Investment Securities [Member] \| Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities	493
Gross Gain & Loss of Investment Securities [Member] \| Available-for-sale Securities [Member]
Net gain (loss) on sale of investment securities	1
Gross Gain & Loss of Investment Securities [Member] \| Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities	$ 493

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Cost of Sale of Fair Value Option Securities

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Cost of Sale of Investment Securities

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Net gain (loss) resulting from the sales of securitized, pay-through debt securities collateralized by real estate mortgage loans (mortgages).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 11
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-Section 45
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