Debt Securities (Schedule Of Gross Unrealized Losses And Estimated Fair Value Of Securities Available For Sale) (Details) - USD ($) $ in Millions	Jun. 30, 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	$ 5,121	$ 17,379
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(203)	(1,507)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	22,073	10,436
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,126)	(1,928)
Debt Securities, Available-for-sale, Unrealized Loss Position	27,194	27,815
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(3,329)	(3,435)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	0	720
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(55)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	721	31
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(59)	(5)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	721	751
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(59)	(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	247	276
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(7)	(8)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	938	903
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(114)	(115)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,185	1,179
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(121)	(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	282	766
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(8)	(50)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	644	53
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(57)	(12)
Debt Securities, Available-for-sale, Unrealized Loss Position	926	819
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(65)	(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	1,790	9,350
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(73)	(1,005)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	14,765	7,578
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,362)	(1,518)
Debt Securities, Available-for-sale, Unrealized Loss Position	16,555	16,928
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,435)	(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	238	7
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(29)	(1)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	238	258
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(29)	(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	2,567	6,110
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(110)	(400)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,858	1,503
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(528)	(249)
Debt Securities, Available-for-sale, Unrealized Loss Position	7,425	7,613
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(638)	(649)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	0	469
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(26)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	483	24
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(30)	(4)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	483	493
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(30)	(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	0	141
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(8)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	81	45
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(13)	(4)
Debt Securities, Available-for-sale, Unrealized Loss Position	81	186
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(13)	(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	235	736
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(5)	(36)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	787	354
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(52)	(30)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,022	1,090
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (57)	$ (66)

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

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