Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 2,434	$ 5,658
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	33	122
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	3,859	2,911
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	764	752
Debt Securities, Available-for-Sale, Unrealized Loss Position	6,293	8,569
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	797	874
Debt Securities \| U. S. Treasury obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months		1,487
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		4
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer		0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Debt Securities, Available-for-Sale, Unrealized Loss Position		1,487
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss		4
Debt Securities \| U.S. Treasury and Government Agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	343	243
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4	5
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,196	1,156
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	306	346
Debt Securities, Available-for-Sale, Unrealized Loss Position	1,539	1,399
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	310	351
Debt Securities \| GSE certificates
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	239	871
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5	46
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	757	420
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	138	114
Debt Securities, Available-for-Sale, Unrealized Loss Position	996	1,291
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	143	160
Debt Securities \| Private Label CMOs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-Sale, Unrealized Loss Position	4
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	1
Debt Securities \| GSE CMOs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	1,378	2,219
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17	36
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,215	925
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	267	264
Debt Securities, Available-for-Sale, Unrealized Loss Position	2,593	3,144
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	284	300
Debt Securities \| Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	94	61
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	2
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	241	262
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	9	12
Debt Securities, Available-for-Sale, Unrealized Loss Position	335	323
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	10	14
Debt Securities \| Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	7	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-Sale, Unrealized Loss Position	7	16
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	0	0
Debt Securities \| Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	334	698
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	27
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	373	97
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	30	4
Debt Securities, Available-for-Sale, Unrealized Loss Position	707	795
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	33	31
Debt Securities \| Foreign notes
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	19	20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-Sale, Unrealized Loss Position	19	20
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	1	0
Debt Securities \| Capital trust notes
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	23	46
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	2
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	56	34
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	12	10
Debt Securities, Available-for-Sale, Unrealized Loss Position	79	80
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	13	12
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	14	10
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	2
Debt Securities, Available-for-Sale, Unrealized Loss Position	14	14
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	$ 2	$ 2

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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