Variable Interest Entities - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($) investment	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) investment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Aug. 31, 2023 USD ($)
Variable Interest Entity
Assets tranferred	$ 212,967		$ 212,967		$ 207,452
Secured Debt
Variable Interest Entity
Principal amount						$ 79
LLCs designed for the purpose of purchasing pools of residual interests in leases
Variable Interest Entity
Number of co-investments | investment	3		3
Ownership percentage (more than)	50.00%		50.00%
Variable Interest Entity, Primary Beneficiary | Secured Debt
Variable Interest Entity
Principal amount						1,580
Variable Interest Entity, Primary Beneficiary | Automobile loan
Variable Interest Entity
Indirect secured consumer loans						$ 1,740
Variable Interest Entity, Not Primary Beneficiary | Loans provided to VIEs
Variable Interest Entity
Unfunded commitment amounts			$ 1,900		2,100
Variable Interest Entity, Not Primary Beneficiary | CDC investments
Variable Interest Entity
Assets tranferred	$ 1,953		1,953		1,856
Variable Interest Entity, Not Primary Beneficiary | CDC investments | Qualified Affordable Housing Tax Credits
Variable Interest Entity
Assets tranferred	1,600		1,600		1,600
Unfunded commitments in qualifying LIHTC investments	661		$ 661		643
Variable Interest Entity, Not Primary Beneficiary | CDC investments | Qualified Affordable Housing Tax Credits | Minimum
Variable Interest Entity
Unfunded commitments, year expected to be funded			2023
Variable Interest Entity, Not Primary Beneficiary | CDC investments | Qualified Affordable Housing Tax Credits | Maximum
Variable Interest Entity
Unfunded commitments, year expected to be funded			2040
Variable Interest Entity, Not Primary Beneficiary | Private equity investments
Variable Interest Entity
Assets tranferred	222		$ 222		186
Unfunded commitment amounts			171		163
Capital contribution to private equity investments	15	$ 7	36	$ 28
Variable Interest Entity, Not Primary Beneficiary | Loans provided to VIEs
Variable Interest Entity
Assets tranferred	$ 4,011		$ 4,011		$ 4,374