Debt Securities (Schedule Of Gross Unrealized Losses And Estimated Fair Value Of Securities Available For Sale) (Details) - USD ($) $ in Millions	Dec. 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	$ 1,119	$ 17,379
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(15)	(1,507)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	24,555	10,436
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,807)	(1,928)
Debt Securities, Available-for-sale, Unrealized Loss Position	25,674	27,815
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,822)	(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	716	31
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(46)	(5)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	716	751
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(46)	(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	6	276
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	1,201	903
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(99)	(115)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,207	1,179
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(99)	(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	237	766
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(5)	(50)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	666	53
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(41)	(12)
Debt Securities, Available-for-sale, Unrealized Loss Position	903	819
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(46)	(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	241	9,350
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(3)	(1,005)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	15,144	7,578
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(2,127)	(1,518)
Debt Securities, Available-for-sale, Unrealized Loss Position	15,385	16,928
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,130)	(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	223	7
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(23)	(1)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	223	258
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(23)	(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	612	6,110
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(7)	(400)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	6,583	1,503
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(495)	(249)
Debt Securities, Available-for-sale, Unrealized Loss Position	7,195	7,613
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(502)	(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	493	24
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(23)	(4)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	493	493
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(23)	(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	82	45
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(10)	(4)
Debt Securities, Available-for-sale, Unrealized Loss Position	82	186
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(10)	(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	23	736
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(36)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	879	354
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(35)	(30)
Debt Securities, Available-for-sale, Unrealized Loss Position	902	1,090
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (35)	$ (66)

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