Other Assets (Details Textuals) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Assets [Line Items]
Accumulated goodwill impairment losses		$ 221	$ 221
Gross carrying amount		733	759
Accumulated amortization		532	494
Amortization expense		57	54	$ 49
Tax credit investments		1,124	1,147
Tax credit investments - Affordable Housing partnerships		1,084	1,095
Income tax provision		2,629	1,161	1,670
Expected amortization expense in 2022		52
Expected amortization expense in 2023		50
Expected amortization expense in 2024		44
Expected amortization expense in 2025		21
Expected amortization expense in 2026		11
Expected amortization expense after 2026		$ 23
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update, Number 2014-01
Other Assets [Line Items]
Income tax provision	$ 55
Minimum
Other Assets [Line Items]
Estimated useful lives		1 year
Maximum
Other Assets [Line Items]
Estimated useful lives		22 years
Other Expense
Other Assets [Line Items]
QAH investment losses		$ 226
Equity method losses related to QAH investments			128	101
Income Tax Provision
Other Assets [Line Items]
QAH Tax Credits for equity method losses		135	129	$ 119
Other Liabilities
Other Assets [Line Items]
QAH unfunded commitment		238
Variable Interest Entity, Primary Beneficiary
Other Assets [Line Items]
Tax credit investments - Affordable Housing partnerships		994	$ 1,028
Variable Interest Entity, Primary Beneficiary | Off-Balance Sheet Obligations
Other Assets [Line Items]
Affordable Housing Program off balance sheet obligation		53
Variable Interest Entity, Primary Beneficiary | Other Liabilities
Other Assets [Line Items]
QAH unfunded commitment		$ 192
Earliest Year | Other Liabilities
Other Assets [Line Items]
Affordable housing tax credits commitment, year to be paid		2022
Latest Year | Other Liabilities
Other Assets [Line Items]
Affordable housing tax credits commitment, year to be paid		2036