Debt Securities (Schedule Of Gross Unrealized Losses And Estimated Fair Value Of Securities Available For Sale) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 6,444	$ 17,379
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(247)	(1,507)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	20,661	10,436
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,748)	(1,928)
Debt Securities, Available-for-sale, Unrealized Loss Position	27,105	27,815
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,995)	(3,435)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	457	720
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(20)	(55)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	291	31
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(31)	(5)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	748	751
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(51)	(60)
US Treasury Securities [Member]
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	250	276
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2)	(8)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	950	903
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(100)	(115)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,200	1,179
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(102)	(123)
Federal agency securities [Member]
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	51	766
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1)	(50)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	650	53
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(48)	(12)
Debt Securities, Available-for-sale, Unrealized Loss Position	701	819
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(49)	(62)
Residential Agency [Member]
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,189	9,350
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(84)	(1,005)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	14,734	7,578
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,161)	(1,518)
Debt Securities, Available-for-sale, Unrealized Loss Position	16,923	16,928
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,245)	(2,523)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	0	251
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(29)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	253	7
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(25)	(1)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	253	258
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(25)	(30)
Commercial Agency [Member]
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	3,533	6,110
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(145)	(400)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	3,608	1,503
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(392)	(249)
Debt Securities, Available-for-sale, Unrealized Loss Position	7,141	7,613
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(537)	(649)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	457	469
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(20)	(26)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	38	24
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(6)	(4)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	495	493
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(26)	(30)
Commercial Non Agency [Member]
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	58	141
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(6)	(8)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	65	45
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(5)	(4)
Debt Securities, Available-for-sale, Unrealized Loss Position	123	186
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(11)	(12)
Corporate and other debt securities [Member]
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	363	736
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(9)	(36)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	654	354
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(42)	(30)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,017	1,090
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (51)	$ (66)

Unrealized Loss And Fair Value Available For Sale Securities [Line Items]

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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