Securities - Summary of Held-to-Maturity and Available-for-Sale Securities Having Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	$ 2,404	$ 1,846
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	112	44
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	2,225	1,683
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	260	72
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	4,629	3,529
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	372	116
Debt Securities | U.S. Treasury Obligations
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	144	45
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	144	45
Debt Securities | U.S. Government and GSE obligations
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	313	317
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	27	7
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	1,037	185
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	125	8
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	1,350	502
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	152	15
Debt Securities | GSE Certificates
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	598	846
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	31	28
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	259	293
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	34	17
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	857	1,139
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	65	45
Debt Securities | GSE CMOs
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	792	491
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	41	8
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	647	926
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	88	37
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	1,439	1,417
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	129	45
Debt Securities | Asset-backed Securities
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	188	130
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	3	1
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	128	135
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	3	2
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	316	265
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	6	3
Debt Securities | Municipal Bonds
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	7	8
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	1
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	7	8
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	1
Debt Securities | Corporate Bonds
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	313
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	9
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	99	99
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	1	1
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	412	99
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	10	1
Debt Securities | Foreign Notes
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	5	5
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	5	5
Debt Securities | Capital Trust Notes
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	47
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	1
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	37	37
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	7	7
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	84	37
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	8	7
Equity Securities
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	4	12
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	11
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	1
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	15	$ 12
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	$ 1