Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) $ in Millions	Jun. 30, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	595	609
Fair Value
Less than Twelve Months	$ 2,047	$ 1,674
Twelve Months or Longer	5,377	5,592
Total	7,424	7,266
Unrealized Loss
Less than Twelve Months	8	3
Twelve Months or Longer	797	929
Total	$ 805	$ 932
Debt Securities | GSE CMOs
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	219	223
Fair Value
Less than Twelve Months	$ 2,012	$ 1,636
Twelve Months or Longer	2,800	2,822
Total	4,812	4,458
Unrealized Loss
Less than Twelve Months	8	3
Twelve Months or Longer	394	444
Total	$ 402	$ 447
Debt Securities | U.S. Government agency and GSE obligations
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	33	33
Fair Value
Less than Twelve Months	$ 0	$ 0
Twelve Months or Longer	1,262	1,203
Total	1,262	1,203
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	240	299
Total	$ 240	$ 299
Debt Securities | GSE certificates
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	323	328
Fair Value
Less than Twelve Months	$ 10	$ 38
Twelve Months or Longer	949	1,040
Total	959	1,078
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	141	167
Total	$ 141	$ 167
Debt Securities | U. S. Treasury obligations
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	0
Fair Value
Less than Twelve Months	$ 0
Twelve Months or Longer	0
Total	0
Unrealized Loss
Less than Twelve Months	0
Twelve Months or Longer	0
Total	$ 0
Debt Securities | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	7	11
Fair Value
Less than Twelve Months	$ 0	$ 0
Twelve Months or Longer	167	308
Total	167	308
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	7	6
Total	$ 7	$ 6
Debt Securities | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	5	5
Fair Value
Less than Twelve Months	$ 21	$ 0
Twelve Months or Longer	145	154
Total	166	154
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	4	2
Total	$ 4	$ 2
Debt Securities | Capital trust notes
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	5	5
Fair Value
Less than Twelve Months	$ 0	$ 0
Twelve Months or Longer	33	33
Total	33	33
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	10	10
Total	$ 10	$ 10
Debt Securities | Private Label CMOs
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	2	2
Fair Value
Less than Twelve Months	$ 4	$ 0
Twelve Months or Longer	16	17
Total	20	17
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	1	1
Total	$ 1	$ 1
Debt Securities | Foreign notes
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	0	1
Fair Value
Less than Twelve Months	$ 0	$ 0
Twelve Months or Longer	0	10
Total	0	10
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	0	0
Total	$ 0	$ 0
Debt Securities | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Number of Debt Securities | security	1	1
Fair Value
Less than Twelve Months	$ 0	$ 0
Twelve Months or Longer	5	5
Total	5	5
Unrealized Loss
Less than Twelve Months	0	0
Twelve Months or Longer	0	0
Total	$ 0	$ 0