Securities - Summary of Securities in Unrealized Loss Position (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Held-to-maturity securities:
Temporarily impaired securities, fair value, less than 12 months	$ 29,680	$ 4,830
Temporarily impaired securities, gross unrealized losses, less than 12 months	568	58
Temporarily impaired securities, fair value, 12 months or longer	5,511	29
Temporarily impaired securities, gross unrealized losses, 12 months or longer	316	0
Temporarily impaired securities, fair value	35,191	4,859
Temporarily impaired securities, gross unrealized losses	884	58
Loans pledged as collateral	14,600
U.S. Treasury, agencies and corporations
Securities available for sale:
Fair value, less than 12 months	9,078
Gross unrealized losses, less than 12 months	98
Fair value, 12 months or longer	243
Gross unrealized losses, 12 months or longer	3
Fair value	9,321
Gross unrealized losses	101
Agency residential collateralized mortgage obligations
Securities available for sale:
Fair value, less than 12 months	12,603	2,110
Gross unrealized losses, less than 12 months	315	25
Fair value, 12 months or longer	1,255	0
Gross unrealized losses, 12 months or longer	95	0
Fair value	13,858	2,110
Gross unrealized losses	410	25
Held-to-maturity securities:
Fair value, less than 12 months	96	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	0	24
Gross unrealized losses, 12 months or longer	0	0
Fair value	96	24
Gross unrealized losses	0	0
Agency residential mortgage-backed securities \| Maximum
Held-to-maturity securities:
Gross unrealized losses		1
Agency commercial mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	1,645	2,709
Gross unrealized losses, less than 12 months	75	33
Fair value, 12 months or longer	3,834	0
Gross unrealized losses, 12 months or longer	215	0
Fair value	5,479	2,709
Gross unrealized losses		33
Asset-backed securities(b)
Held-to-maturity securities:
Fair value, less than 12 months	2,450
Gross unrealized losses, less than 12 months	31
Fair value, 12 months or longer	1
Gross unrealized losses, 12 months or longer	0
Fair value	2,451
Gross unrealized losses	31
Asset-backed securities(b) \| Maximum
Held-to-maturity securities:
Gross unrealized losses	1
Other securities
Held-to-maturity securities:
Fair value, less than 12 months	15	5
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	0	0
Gross unrealized losses, 12 months or longer	0	0
Fair value	15	5
Gross unrealized losses	0	0
Other securities \| Maximum
Held-to-maturity securities:
Gross unrealized losses	1
Mortgage-backed securities \| Agency residential mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	3,793	6
Gross unrealized losses, less than 12 months	49	0
Fair value, 12 months or longer	178	5
Gross unrealized losses, 12 months or longer	3	0
Fair value	3,971	11
Gross unrealized losses	52	$ 0
Mortgage-backed securities \| Agency commercial mortgage-backed securities
Securities available for sale:
Gross unrealized losses	$ 290

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