Investment Securities (Summary Of Changes In Accumulated OCI For Available-For-Sale Security) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Unrealized Gains and (Losses), Net	$ (973)	$ (418)	$ 622
Agency Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning OCI Balance	301	719	97
Unrealized Gains and (Losses), Net	(1,015)	(382)	703
Reversal of Unrealized (Gains) and Losses, Net on Realization	42	(36)	(81)
Ending OCI Balance	$ (672)	$ 301	$ 719

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

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- Definition

Other Comprehensive Income Reclassification Adjustment For Sale Of Security Reversal Of Prior Period Unrealized Gain And Losses On Realization

+ References

No definition available.

+ Details

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- Definition

Amount, after tax, of accumulated unrealized gain (loss) on 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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=126968391&loc=d3e681-108580

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- Definition

Amount, after tax and before adjustment, of unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=126968391&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI https://asc.fasb.org/extlink&oid=126968391&loc=d3e637-108580

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