Investment Securities - Securities in Gross Unrealized Loss Position (Details) $ in Millions	Mar. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	$ 51,382	$ 41,701
Fair Value - 12 Months or Longer	18,531	9,410
Fair Value - Total	69,913	51,111
Gross Unrealized Loss - Less than 12 Months	(2,508)	(670)
Gross Unrealized Loss - 12 Months or Longer	(1,836)	(326)
Gross Unrealized Loss - Total	$ (4,344)	$ (996)
Number of securities in gross unrealized loss positions \| security	1,790	740
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	$ 3,960
Fair Value - 12 Months or Longer	0
Fair Value - Total	3,960
Gross Unrealized Loss - Less than 12 Months	(29)
Gross Unrealized Loss - 12 Months or Longer	0
Gross Unrealized Loss - Total	(29)
RMBS, Agency
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	40,778	$ 37,492
Fair Value - 12 Months or Longer	17,358	8,606
Fair Value - Total	58,136	46,098
Gross Unrealized Loss - Less than 12 Months	(2,263)	(632)
Gross Unrealized Loss - 12 Months or Longer	(1,736)	(299)
Gross Unrealized Loss - Total	(3,999)	(931)
RMBS, Non-agency
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	14	3
Fair Value - 12 Months or Longer	0	1
Fair Value - Total	14	4
Gross Unrealized Loss - Less than 12 Months	0	0
Gross Unrealized Loss - 12 Months or Longer	0	0
Gross Unrealized Loss - Total	0	0
RMBS
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	40,792	37,495
Fair Value - 12 Months or Longer	17,358	8,607
Fair Value - Total	58,150	46,102
Gross Unrealized Loss - Less than 12 Months	(2,263)	(632)
Gross Unrealized Loss - 12 Months or Longer	(1,736)	(299)
Gross Unrealized Loss - Total	(3,999)	(931)
CMBS, Agency
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	5,106	2,999
Fair Value - 12 Months or Longer	1,173	803
Fair Value - Total	6,279	3,802
Gross Unrealized Loss - Less than 12 Months	(204)	(36)
Gross Unrealized Loss - 12 Months or Longer	(100)	(27)
Gross Unrealized Loss - Total	(304)	(63)
Other securities
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	1,524	1,207
Fair Value - 12 Months or Longer	0	0
Fair Value - Total	1,524	1,207
Gross Unrealized Loss - Less than 12 Months	(12)	(2)
Gross Unrealized Loss - 12 Months or Longer	0	0
Gross Unrealized Loss - Total	$ (12)	$ (2)

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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