Investment Securities - Held-to-Maturity Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	$ 81,486	$ 84,045
Unrealized Gains	0	12
Unrealized Losses	(12,175)	(9,969)
Fair Value	69,311	74,088
U.S. Treasury and agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	1,296	1,345
Unrealized Gains	0	0
Unrealized Losses	(40)	(35)
Fair Value	1,256	1,310
Residential mortgage-backed securities | Agency
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	78,327	80,997
Unrealized Gains	0	6
Unrealized Losses	(12,105)	(9,929)
Fair Value	66,222	71,074
Commercial mortgage-backed securities | Agency
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	1,700	1,695
Unrealized Gains	0	6
Unrealized Losses	(30)	(5)
Fair Value	1,670	1,696
Other
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	163	8
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 163	$ 8