Investment Securities - Schedule of Investments within the Available for Sale Portfolio that had Unrealized Losses (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Schedule of Investments [Line Items]
Less than 12 months	$ 1,151	$ 1,614
12 months or longer	5,819	5,855
Total fair value	6,970	7,469
Unrealized Losses
Less than 12 months	(3)	(18)
12 months or longer	(884)	(1,017)
Total unrealized losses	(887)	(1,035)
Government agency issued MBS
Schedule of Investments [Line Items]
Less than 12 months	348	663
12 months or longer	2,996	2,992
Total fair value	3,344	3,655
Unrealized Losses
Less than 12 months	(1)	(9)
12 months or longer	(435)	(513)
Total unrealized losses	(436)	(522)
Government agency issued CMO
Schedule of Investments [Line Items]
Less than 12 months	656	675
12 months or longer	1,722	1,744
Total fair value	2,378	2,419
Unrealized Losses
Less than 12 months	(1)	(2)
12 months or longer	(279)	(310)
Total unrealized losses	(280)	(312)
Other U.S. government agencies
Schedule of Investments [Line Items]
Less than 12 months	71	210
12 months or longer	859	863
Total fair value	930	1,073
Unrealized Losses
Less than 12 months	0	(6)
12 months or longer	(129)	(155)
Total unrealized losses	(129)	(161)
States and municipalities
Schedule of Investments [Line Items]
Less than 12 months	76	66
12 months or longer	242	256
Total fair value	318	322
Unrealized Losses
Less than 12 months	(1)	(1)
12 months or longer	(41)	(39)
Total unrealized losses	$ (42)	$ (40)