Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	$ 3,171	$ 5,658
Less than Twelve Months, Unrealized Loss	104	122
Twelve Months or Longer, Fair Value	4,090	2,911
Twelve Months or Longer, Unrealized Loss	824	752
Fair Value	7,261	8,569
Unrealized Loss	928	874
Debt Securities | U. S. Treasury obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	1,487
Less than Twelve Months, Unrealized Loss	0	4
Twelve Months or Longer, Fair Value	0	0
Twelve Months or Longer, Unrealized Loss	0	0
Fair Value	0	1,487
Unrealized Loss	0	4
Debt Securities | U.S. Government agency and GSE obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	221	243
Less than Twelve Months, Unrealized Loss	1	5
Twelve Months or Longer, Fair Value	1,399	1,156
Twelve Months or Longer, Unrealized Loss	328	346
Fair Value	1,620	1,399
Unrealized Loss	329	351
Debt Securities | GSE certificates
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	458	871
Less than Twelve Months, Unrealized Loss	14	46
Twelve Months or Longer, Fair Value	739	420
Twelve Months or Longer, Unrealized Loss	148	114
Fair Value	1,197	1,291
Unrealized Loss	162	160
Debt Securities | Private Label CMOs
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	20
Less than Twelve Months, Unrealized Loss	1
Twelve Months or Longer, Fair Value	0
Twelve Months or Longer, Unrealized Loss	0
Fair Value	20
Unrealized Loss	1
Debt Securities | GSE CMOs
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	2,391	2,219
Less than Twelve Months, Unrealized Loss	81	36
Twelve Months or Longer, Fair Value	1,182	925
Twelve Months or Longer, Unrealized Loss	288	264
Fair Value	3,573	3,144
Unrealized Loss	369	300
Debt Securities | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	34	61
Less than Twelve Months, Unrealized Loss	0	2
Twelve Months or Longer, Fair Value	289	262
Twelve Months or Longer, Unrealized Loss	9	12
Fair Value	323	323
Unrealized Loss	9	14
Debt Securities | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	9
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	6	7
Twelve Months or Longer, Unrealized Loss	1	0
Fair Value	6	16
Unrealized Loss	1	0
Debt Securities | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	38	698
Less than Twelve Months, Unrealized Loss	5	27
Twelve Months or Longer, Fair Value	383	97
Twelve Months or Longer, Unrealized Loss	34	4
Fair Value	421	795
Unrealized Loss	39	31
Debt Securities | Foreign notes
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	8	20
Less than Twelve Months, Unrealized Loss	2	0
Twelve Months or Longer, Fair Value	0	0
Twelve Months or Longer, Unrealized Loss	0	0
Fair Value	8	20
Unrealized Loss	2	0
Debt Securities | Capital trust notes
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	1	46
Less than Twelve Months, Unrealized Loss	0	2
Twelve Months or Longer, Fair Value	78	34
Twelve Months or Longer, Unrealized Loss	14	10
Fair Value	79	80
Unrealized Loss	14	12
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	4
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	14	10
Twelve Months or Longer, Unrealized Loss	2	2
Fair Value	14	14
Unrealized Loss	$ 2	$ 2