Securities - Summary of Held-to-Maturity and Available-for-Sale Securities Having Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	$ 1,846	$ 1,095
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	44	10
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	1,683	726
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	72	20
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	3,529	1,821
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	116	30
Debt Securities \| U.S. Treasury Obligations
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	45
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	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	317	59
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	7
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	185
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	8
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	502	59
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	15
Debt Securities \| GSE Certificates
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	846	442
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	28	3
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	293	74
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	17
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	1,139	516
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	45	3
Debt Securities \| GSE CMOs
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	491	522
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss	8	4
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	926
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	37
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	1,417	522
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	45	4
Debt Securities \| Asset-backed Securities
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	130
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	135	364
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	2	6
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	265	364
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	3	6
Debt Securities \| Municipal Bonds
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	8	9
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	8	9
Debt Securities \| Corporate Bonds
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value		72
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Unrealized Loss		3
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	99	246
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	1	3
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	99	318
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	1	6
Debt Securities \| Foreign Notes
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	5
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	5
Debt Securities \| Capital Trust Notes
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Fair Value	37	33
Temporarily Impaired Available-for-Sale Securities, Twelve Months or Longer Unrealized Loss	7	11
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	37	33
Temporarily Impaired Available-for-Sale Securities, Total Unrealized Loss	7	$ 11
Equity Securities
Schedule of Investments [Line Items]
Temporarily Impaired Available-for-Sale Securities, Less than Twelve Months Fair Value	12
Temporarily Impaired Available-for-Sale Securities, Total Fair Value	$ 12

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