Securities - Schedule of Available for Sale Securities in an Unrealized Loss Position (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Held-to-maturity securities:
Temporarily impaired securities, fair value, less than 12 months	$ 1,014	$ 15,728
Temporarily impaired securities, gross unrealized losses, less than 12 months	5	281
Temporarily impaired securities, fair value, 12 months or longer	26,713	22,010
Temporarily impaired securities, gross unrealized losses, 12 months or longer	3,014	3,906
Temporarily impaired securities, fair value	27,727	37,738
Temporarily impaired securities, gross unrealized losses	3,019	4,187
U.S. Treasury, agencies and corporations
Securities available for sale:
Fair value, less than 12 months	50	3,647
Gross unrealized losses, less than 12 months	0	8
Fair value, 12 months or longer	1,819	508
Gross unrealized losses, 12 months or longer	21	36
Fair Value	1,869	4,155
Gross Unrealized Losses	21	44
Agency residential collateralized mortgage obligations
Securities available for sale:
Fair value, less than 12 months	41	91
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	7,877	8,108
Gross unrealized losses, 12 months or longer	1,779	2,193
Fair Value	7,918	8,199
Gross Unrealized Losses	1,779	2,193
Held-to-maturity securities:
Fair value, less than 12 months	173	569
Gross unrealized losses, less than 12 months	2	18
Fair value, 12 months or longer	3,230	3,387
Gross unrealized losses, 12 months or longer	189	314
Fair Value	3,403	3,956
Gross Unrealized Losses	191	332
Agency residential mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	555	11,364
Gross unrealized losses, less than 12 months	2	254
Fair value, 12 months or longer	7,701	3,145
Gross unrealized losses, 12 months or longer	504	618
Fair Value	8,256	14,509
Gross Unrealized Losses	506	872
Held-to-maturity securities:
Fair value, less than 12 months	190	0
Gross unrealized losses, less than 12 months	1	0
Fair value, 12 months or longer	128	134
Gross unrealized losses, 12 months or longer	12	17
Fair Value	318	134
Gross Unrealized Losses	13	17
Agency commercial mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	0	50
Gross unrealized losses, less than 12 months	0	1
Fair value, 12 months or longer	3,868	4,360
Gross unrealized losses, 12 months or longer	355	516
Fair Value	3,868	4,410
Gross Unrealized Losses	355	517
Held-to-maturity securities:
Fair value, less than 12 months	0	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	1,964	2,060
Gross unrealized losses, 12 months or longer	152	203
Fair Value	1,964	2,060
Gross Unrealized Losses	152	203
Asset-backed securities
Held-to-maturity securities:
Fair value, less than 12 months	0	0
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	120	300
Gross unrealized losses, 12 months or longer	2	8
Fair Value	120	300
Gross Unrealized Losses	2	8
Other securities
Held-to-maturity securities:
Fair value, less than 12 months	5	7
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	6	8
Gross unrealized losses, 12 months or longer	0	1
Fair Value	11	15
Gross Unrealized Losses	$ 0	$ 1