Investment Securities - Investment Available for Sale (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 89,933	$ 94,871
Allowance for Credit Losses	(3)	(1)
Gross Unrealized Gains	246	1,387
Gross Unrealized Losses	(7,154)	(996)
Securities available for sale	83,022	95,261
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,664	9,419
Allowance for Credit Losses	0	0
Gross Unrealized Gains	4	23
Gross Unrealized Losses	(44)	0
Securities available for sale	8,624	9,442
RMBS, Agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	71,215	72,593
Allowance for Credit Losses	0	0
Gross Unrealized Gains	93	958
Gross Unrealized Losses	(6,603)	(931)
Securities available for sale	64,705	72,620
RMBS, Non-agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	687	792
Allowance for Credit Losses	(3)	(1)
Gross Unrealized Gains	140	205
Gross Unrealized Losses	(2)	0
Securities available for sale	822	996
RMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	71,902	73,385
Allowance for Credit Losses	(3)	(1)
Gross Unrealized Gains	233	1,163
Gross Unrealized Losses	(6,605)	(931)
Securities available for sale	65,527	73,616
CMBS, Agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,060	9,237
Allowance for Credit Losses	0	0
Gross Unrealized Gains	8	195
Gross Unrealized Losses	(494)	(63)
Securities available for sale	7,574	9,369
Other securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,307	2,830
Allowance for Credit Losses	0	0
Gross Unrealized Gains	1	6
Gross Unrealized Losses	(11)	(2)
Securities available for sale	1,297	2,834
Asset-backed Securities
Debt Securities, Available-for-sale [Line Items]
Securities available for sale	$ 566	$ 2,000
US Treasury and Agency securities \| Available-for-sale securities \| Government Contracts Concentration Risk
Debt Securities, Available-for-sale [Line Items]
Percentage of portfolio	97.00%	96.00%

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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