Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	$ 807	$ 2,357
Less than Twelve Months, Unrealized Loss	2	84
Twelve Months or Longer, Fair Value	6,015	4,198
Twelve Months or Longer, Unrealized Loss	957	777
Fair Value	6,822	6,555
Unrealized Loss	959	861
Other Debt Securities: | U.S. Government agency and GSE obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	181
Less than Twelve Months, Unrealized Loss	0	1
Twelve Months or Longer, Fair Value	1,345	1,362
Twelve Months or Longer, Unrealized Loss	308	290
Fair Value	1,345	1,543
Unrealized Loss	308	291
Other Debt Securities: | GSE certificates
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	46	312
Less than Twelve Months, Unrealized Loss	0	5
Twelve Months or Longer, Fair Value	1,085	843
Twelve Months or Longer, Unrealized Loss	166	141
Fair Value	1,131	1,155
Unrealized Loss	166	146
Other Debt Securities: | Private Label collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	29
Less than Twelve Months, Unrealized Loss	0	1
Twelve Months or Longer, Fair Value	17	0
Twelve Months or Longer, Unrealized Loss	1	0
Fair Value	17	29
Unrealized Loss	1	1
Other Debt Securities: | GSE collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	761	1,835
Less than Twelve Months, Unrealized Loss	2	77
Twelve Months or Longer, Fair Value	2,925	1,312
Twelve Months or Longer, Unrealized Loss	443	304
Fair Value	3,686	3,147
Unrealized Loss	445	381
Other Debt Securities: | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	0
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	193	228
Twelve Months or Longer, Unrealized Loss	3	5
Fair Value	193	228
Unrealized Loss	3	5
Other Debt Securities: | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	0
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	5	6
Twelve Months or Longer, Unrealized Loss	0	0
Fair Value	5	6
Unrealized Loss	0	0
Other Debt Securities: | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	0
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	341	343
Twelve Months or Longer, Unrealized Loss	23	22
Fair Value	341	343
Unrealized Loss	23	22
Other Debt Securities: | Foreign notes
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	0
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	10	9
Twelve Months or Longer, Unrealized Loss	0	1
Fair Value	10	9
Unrealized Loss	0	1
Other Debt Securities: | Capital trust notes
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	0
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	80	81
Twelve Months or Longer, Unrealized Loss	11	12
Fair Value	80	81
Unrealized Loss	11	12
Equity securities:
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	0
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	14	14
Twelve Months or Longer, Unrealized Loss	2	2
Fair Value	14	14
Unrealized Loss	$ 2	$ 2