Other Assets (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Assets [Line Items]
Accumulated goodwill impairment losses	$ 221	$ 221
Gross carrying amount	759	704
Accumulated amortization	494	437
Amortization expense	54	49	$ 212
Tax credit investments	1,147	1,154
Tax credit investments - Affordable Housing partnerships	$ 1,095	1,109
Minimum [Member]
Other Assets [Line Items]
Estimated useful lives	1 year
Maximum [Member]
Other Assets [Line Items]
Estimated useful lives	22 years
Other Expense [Member]
Other Assets [Line Items]
Equity method losses related to QAH investments	$ 128	101	126
Income Tax Provision [Member]
Other Assets [Line Items]
QAH Tax Credits for equity method losses	129	119	$ 97
Other Liabilities [Member]
Other Assets [Line Items]
QAH unfunded commitment	208
Variable Interest Entity, Primary Beneficiary [Member]
Other Assets [Line Items]
Tax credit investments - Affordable Housing partnerships	1,028	$ 1,032
Affordable Housing Program off balance sheet obligation	106
Variable Interest Entity, Primary Beneficiary [Member] | Other Liabilities [Member]
Other Assets [Line Items]
QAH unfunded commitment	$ 189
Latest Year [Member] | Other Liabilities [Member]
Other Assets [Line Items]
Affordable housing tax credits commitment, year to be paid	2035
Earliest Year [Member] | Other Liabilities [Member]
Other Assets [Line Items]
Affordable housing tax credits commitment, year to be paid	2021