Long-Term Debt (Details) - USD ($) $ in Millions		Jul. 27, 2023	Jun. 30, 2023	Sep. 30, 2023	Aug. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-term debt	[1]			$ 16,310		$ 13,714
Automobile loan | Variable Interest Entity, Primary Beneficiary
Debt Instrument [Line Items]
Indirect secured consumer loans					$ 1,740
SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.26161%
Senior Notes | First Charter Capital Trust I and II | SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.26161%
Senior Notes | Fixed Rate/Floating Rate Senior Notes Due July 27, 2029 | Parent Company
Debt Instrument [Line Items]
Principal amount		$ 1,250
Interest rate		6.339%
Senior Notes | Fixed Rate/Floating Rate Senior Notes Due July 27, 2029 | One year prior to maturity date | Parent Company
Debt Instrument [Line Items]
Redemption period		1 year
Senior Notes | Fixed Rate/Floating Rate Senior Notes Due July 27, 2029 | 60 days prior to maturity date | Parent Company
Debt Instrument [Line Items]
Redemption period		30 days
Senior Notes | Fixed Rate/Floating Rate Senior Notes Due July 27, 2029 | 180 days after issue date | Parent Company
Debt Instrument [Line Items]
Redemption period		180 days
Senior Notes | Fixed Rate/Floating Rate Senior Notes Due July 27, 2029 | SOFR | Parent Company
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		2.34%
Secured Debt
Debt Instrument [Line Items]
Principal amount					79
Long-term debt					1,500
Secured Debt | Variable Interest Entity, Primary Beneficiary
Debt Instrument [Line Items]
Principal amount					$ 1,580

[1] Includes $59 and $17 of other short-term investments, $1,728 and $185 of portfolio loans and leases, $(27) and $(2) of ALLL, $11 and $2 of other assets, $15 and $9 of other liabilities, and $1,553 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2023 and December 31, 2022, respectively. For further information, refer to Note 12.