Debt Securities (Schedule Of Gross Unrealized Losses And Estimated Fair Value Of Securities Available For Sale) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,709	$ 1,119
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(9)	(15)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	17,638	24,555
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,617)	(2,807)
Debt Securities, Available-for-sale, Unrealized Loss Position	19,347	25,674
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,626)	(2,822)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	0	0
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	2,759	716
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(471)	(46)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	2,759	716
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(471)	(46)
U.S. Treasury securities
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	92	6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,122	1,201
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(69)	(99)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,214	1,207
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(69)	(99)
Federal agency securities
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	200	666
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(10)	(41)
Debt Securities, Available-for-sale, Unrealized Loss Position	200	903
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(10)	(46)
Residential agency
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,216	241
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(6)	(3)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	12,079	15,144
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,298)	(2,127)
Debt Securities, Available-for-sale, Unrealized Loss Position	13,295	15,385
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,304)	(2,130)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	0	0
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	2,260	223
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(458)	(23)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	2,260	223
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(458)	(23)
Commercial agency
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	383	612
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(3)	(7)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	3,709	6,583
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(220)	(495)
Debt Securities, Available-for-sale, Unrealized Loss Position	4,092	7,195
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(223)	(502)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Estimated Fair Value	0	0
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Estimated Fair Value	499	493
Debt Securities, Held-to-Maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(13)	(23)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	499	493
Debt Securities, Held-to-Maturity, Unrealized Loss Position, Accumulated Loss	(13)	(23)
Commercial non-agency
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	84	82
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(7)	(10)
Debt Securities, Available-for-sale, Unrealized Loss Position	84	82
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(7)	(10)
Corporate and other debt securities
Unrealized Loss And Fair Value On Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	18	23
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	444	879
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(13)	(35)
Debt Securities, Available-for-sale, Unrealized Loss Position	462	902
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (13)	$ (35)

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

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